PALEONTOLOGY IN APRIL, 2024

ABSTRACT

Enantiornithines were the dominant birds of the Mesozoic, but understanding of their diet is still tenuous. We introduce new data on the enantiornithine family Bohaiornithidae, famous for their large size and powerfully built teeth and claws. In tandem with previously published data, we comment on the breadth of enantiornithine ecology and potential patterns in which it evolved. Body mass, jaw mechanical advantage, finite element analysis of the jaw, and traditional morphometrics of the claws and skull are compared between bohaiornithids and living birds. We find bohaiornithids to be more ecologically diverse than any other enantiornithine family: Bohaiornis and Parabohaiornis are similar to living plant-eating birds; Longusunguis resembles raptorial carnivores; Zhouornis is similar to both fruit-eating birds and generalist feeders; and Shenqiornis and Sulcavis plausibly ate fish, plants, or a mix of both. We predict the ancestral enantiornithine bird to have been a generalist which ate a wide variety of foods. However, more quantitative data from across the enantiornithine tree is needed to refine this prediction. By the Early Cretaceous, enantiornithine birds had diversified into a variety of ecological niches like crown birds after the K-Pg extinction, adding to the evidence that traits unique to crown birds cannot completely explain their ecological success.

LINK

https://elifesciences.org/articles/89871

ABSTRACT

A transfer-prepared specimen of Lepidotes (Actinopterygii, Lepisosteiformes) from the Posidonia Shale Formation of south Germany is tentatively identified specifically as L. gigas. The genus and its species are insufficiently defined and in need of revision. The new specimen reveals details of the cranial and pectoral girdle skeletal architecture and previously unknown osteological features of Lepidotes, such as a large foramen on the maxilla and the formation of two tooth-bearing clavicle elements (serrated appendages). Maxillary foramina are also known in the related contemporaneous lepisosteiform Mengius and possibly served for passage of nerve branches supplying either a maxillary pit-line or cutaneous sense organs (taste buds) in a thickened upper lip or barbels. The clavicle elements agree morphologically with those of the Recent Amia. Their function remains obscure.

LINKS

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2330586
https://www.tandfonline.com/doi/epdf/10.1080/02724634.2024.2330586?needAccess=true

ABSTRACT

Historically, the excavation in the 1970s and publication in the 80s of Rhinoceros sinensis hayasakai (now known as Nesorhinus hayasakai) represents a milestone in vertebrate paleontology in Taiwan. However, the type materials (including 22 syntypes) are missing after the 1984 publication due to the lack of proper curation and management and reflect the undervalued vertebrate paleontology in Taiwan. Here we found five original specimens out of 22 in two collections (National Taiwan University and Tainan City Zuojhen Fossil Park). The original 22 specimens were recovered from two geographical localities and geological horizons: northern (Taoyuan, Tunghsiao Formation: Early Pleistocene) and southern (Tainan, Chiting Formation: Middle Pleistocene) Taiwan. Our rediscovery of long-forgotten type materials emphasizes the importance of proper specimen curation. Similarly, by clarifying the historical issues and collecting more fossils, vertebrate paleontology from Taiwan promises to offer novel perspectives to understand the origin of modern biodiversity and large-scale extinctions along the eastern margin of Eurasia.

LINK

https://bioone.org/journals/mammal-study/volume-49/issue-2/ms2023-0070/Rediscovery-of-type-specimens-of-Nesorhinus-hayasakai-Mammalia-Rhinocerotidae-from/10.3106/ms2023-0070.full

ABSTRACT

The emergence of Homo sapiens in Eastern Asia is a topic of significant research interest. However, well-preserved human fossils in secure, dateable contexts in this region are extremely rare, and often the subject of intense debate owing to stratigraphic and geochronological problems. Tongtianyan cave, in Liujiang District of Liuzhou City, southern China is one of the most important fossils finds of H. sapiens, though its age has been debated, with chronometric dates ranging from the late Middle Pleistocene to the early Late Pleistocene. Here we provide new age estimates and revised provenience information for the Liujiang human fossils, which represent one of the most complete fossil skeletons of H. sapiens in China. U-series dating on the human fossils and radiocarbon and optically stimulated luminescence dating on the fossil-bearing sediments provided ages ranging from ~33,000 to 23,000 years ago (ka). The revised age estimates correspond with the dates of other human fossils in northern China, at Tianyuan Cave (~40.8–38.1 ka) and Zhoukoudian Upper Cave (39.0–36.3 ka), indicating the geographically widespread presence of H. sapiens across Eastern Asia in the Late Pleistocene, which is significant for better understanding human dispersals and adaptations in the region.

LINKS

https://www.nature.com/articles/s41467-024-47787-3
https://www.nature.com/articles/s41467-024-47787-3.pdf

ABSTRACT

Aquatic biodiversity changed dramatically at the start of the Paleogene. Although comparatively little is known about global freshwater ecosystems that appeared just after the Cretaceous–Paleogene mass extinction, available data suggest that they were buffered from the worst effects of the extinction event. Here, we describe a nearly complete skeleton of a large-bodied ray-finned fish from a wetland ecosystem that existed fewer than 10 Myr after the end-Cretaceous extinction in western North America. With a maximum length likely exceeding 2 m, †Amia basiloides sp. nov. is one of the largest species in Holostei, a once species-rich clade of ray-finned fishes now survived by the nine living species of gars and bowfins. High-resolution computed tomography scans illuminate the anatomy of †A. basiloides and suggest it was an analogue of living large-bodied, piscivorous freshwater fishes found in the Southern Hemisphere and southern North America. When considered in a phylogenetic context, †A. basiloides shows that close relatives of living bowfins rapidly achieved gigantism in the Early Paleogene of North America after the largest members of an ancient clade closely related to bowfins went extinct. Although the Cretaceous–Paleogene boundary likely induced turnover of freshwater vertebrate predatory guilds, holostean faunas remained ecologically comparable across the extinction due to exceptionally fast episodes of convergence.

LINK

https://academic.oup.com/zoolinnean/advance-article-abstract/doi/10.1093/zoolinnean/zlae042/7659736

ABSTRACT

At the climax of their evolutionary history in the latest Cretaceous, ceratopsian dinosaurs were among the most dominant components of North American and Asian land ecosystems. In other continental landmasses, however, ceratopsians were extraordinarily rare and the affinities of their proposed representatives often turned out to be inconclusive. Arguably the most significant evidence of Ceratopsia from outside North America and Asia is represented by Ajkaceratops kozmai from the Santonian (Upper Cretaceous) of Hungary. We provide a detailed osteological description of Ajkaceratops and highlight its bizarre anatomy. Ajkaceratops has been ‘traditionally’ interpreted to represent a Bagaceratops-like coronosaur, and its occurrence on the European islands was hypothesized to probably result from an early Late Cretaceous dispersal event from Asia. However, while the snout of Ajkaceratops may resemble that of some ceratopsians, closer inspection of the preserved elements indicates that these similarities are largely superficial. While it cannot be ruled out that Ajkaceratops represents a highly peculiar member of the clade, its placement is far from certain. Still, the discovery of Ajkaceratops exemplifies the importance and uniqueness of European dinosaur faunas.

LINK

https://academic.oup.com/zoolinnean/advance-article-abstract/doi/10.1093/zoolinnean/zlae048/7659738?redirectedFrom=fulltext&login=false

ABSTRACT

Among the many terrestrial vertebrate specimens that have been recovered from the Lower Jurassic Blue Lias Formation (Hettangian-Sinemurian) in Dorset, England, there are two partial yet distinctive theropodan hindlimbs that are not currently assigned to any recognised, valid taxon. Originally this material was referred to the early armoured ornithischian taxon Scelidosaurus harrisonii, which had also been recovered from a Lower Jurassic Formation in Southern England. However, this error in assignment was soon realised and corrected in subsequent works, and the material in question reclassified as an indeterminate theropod. More recent works have suggested possible neotheropod or even tetanuran affinities for at least some of this material, but no consensus has yet been reached about its true phylogenetic and taxonomic affinities. The material has never been formally named, even though the material does appear to display a distinct combination of anatomical characteristics. As one of the earliest known Jurassic representatives of Theropoda, understanding this material is important for clarifying the picture of early theropod evolution and biogeographic distribution. This study re-appraises the two specimens, compares, and contrasts them with other known Triassic and Early Jurassic theropods, and tests their possible phylogenetic affinities using three different anatomical datasets: two that are heavily theropod focused and one more general early dinosaur focused. The results of these analyses, in combination with the anatomical comparisons presented herein, suggest that this fragmentary material could represent a distinct, early occurring, and early branching averostran neotheropod. A new genus and species are thus erected for the material.

LINKS

https://palaeo-electronica.org/content/2024/5067-on-an-early-jurassic-theropod
https://palaeo-electronica.org/content/pdfs/1346.pdf

ABSTRACT

Three eusauropod teeth (SDUST-V1064, PMOL-AD00176, PMOL-ADt0005) are reported from the Lower Cretaceous Yixian Formation of Ningcheng, southeastern Inner Mongolia, China. Two of them (SDUST-V1064, PMOL-AD00176) are assigned to early-diverging titanosauriforms in having slightly mesiodistal expansion at the base of the tooth crown, a slenderness index value >2.0 and <4.0, and D-shaped cross section. Furthermore, SDUST-V1064 and PMOL-AD00176 are referred as an Euhelopus-like titanosauriform on the basis of having a sub-circular boss on the lingual surface and an asymmetrical crown-root margin which slants apically, respectively. CT scan data of SDUST-V1064 reveals new dental information of early-diverging titanosauriforms, for example, the enamel on the labial side thicker than that on the lingual side, an enamel/dentine ratio of 0.26 and a boss present on the lingual side of the dentine of the crown.

LINK

https://onlinelibrary.wiley.com/doi/10.1111/1755-6724.15169

ABSTRACT

The Deccan volcanism of India, representing one of the largest flood basalt provinces of the world, has attracted wider attention in recent years because of its supposed role in the mass extinction at the Cretaceous-Palaeogene (K/Pg) boundary. In this context, flora and fauna recovered from the sedimentary beds deposited immediately before the initiation of Deccan volcanism (infratrappean beds) and those deposited during quiescent stages of volcanism (intertrappean beds) assume great significance in understanding the effects of the volcanism on contemporary biota, biogeographic origins and distribution of different taxonomic groups, and the role of volcanism in K/Pg boundary mass extinction. In this paper, a detailed review of the research done on these aspects in the last 4 years is presented.

LINK

https://link.springer.com/article/10.1007/s43538-024-00304-y

ABSTRACT

Siluriformes are considered as primarily freshwater and have frequently been a model for the study of historical biogeography. Among catfishes, the most diverse clade is the Loricarioidei, a Neotropical group for which the fossil record extends back to the Palaeocene of Argentina. Here we describe a fossil from the early Late Cretaceous of Morocco, exhibiting typical morphological traits of the Loricariidae. A phylogenetic analysis integrating morphological characters with a multigene database for the main loricarioid lineages and outgroups highly supports inclusion of the fossil within the Loricariidae. A time-calibrated analysis corroborates the origin of loricarioids at about 112 MYA. The presence of this loricariid in Africa provides evidence that loricarioids have diversified before the separation of Africa and South America. The Moroccan loricariid shows an ancient evolutionary history that, in Africa, ended in the Late Cretaceous but persisted in South America, later surviving the K/Pg extinction.

LINK

https://www.sciencedirect.com/science/article/abs/pii/S1342937X24000947?via%3Dihub

ABSTRACT

Recent years have seen increasing scientific interest in whether neuron counts can act as correlates of diverse biological phenomena. Lately, Herculano-Houzel (2023) argued that fossil endocasts and comparative neurological data from extant sauropsids allow to reconstruct telencephalic neuron counts in Mesozoic dinosaurs and pterosaurs, which might act as proxies for behaviors and life history traits in these animals. According to this analysis, large theropods such as Tyrannosaurus rex were long-lived, exceptionally intelligent animals equipped with “macaque- or baboon-like cognition”, whereas sauropods and most ornithischian dinosaurs would have displayed significantly smaller brains and an ectothermic physiology. Besides challenging established views on Mesozoic dinosaur biology, these claims raise questions on whether neuron count estimates could benefit research on fossil animals in general. Here, we address these findings by revisiting Herculano-Houzel's (2023) work, identifying several crucial shortcomings regarding analysis and interpretation. We present revised estimates of encephalization and telencephalic neuron counts in dinosaurs, which we derive from phylogenetically informed modeling and an amended dataset of endocranial measurements. For large-bodied theropods in particular, we recover significantly lower neuron counts than previously proposed. Furthermore, we review the suitability of neurological variables such as neuron numbers and relative brain size to predict cognitive complexity, metabolic rate and life history traits in dinosaurs, coming to the conclusion that they are flawed proxies for these biological phenomena. Instead of relying on such neurological estimates when reconstructing Mesozoic dinosaur biology, we argue that integrative studies are needed to approach this complex subject.

LINKS

https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25459

https://anatomypubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ar.25459

ABSTRACT

Five deformed dinosaur eggs are newly discovered from the Upper Cretaceous Jiangjunding Formation in the Laiyang Basin, Shandong Province, China. A new oospecies of Spheroolithidae, Spheroolithus phacelus, was erected based on the spheroid eggs and the developed cone-shaped eggshell unit assemblages. Radial sections of S. phacelus show the inner cone-shaped eggshell units, the middle columnar eggshell units and the outer bush-like eggshell units. Numerous cone-shaped eggshell unit assemblages and large gaps between them are developed in the inner part, columnar eggshell units and small pores emerge in the middle part, and branches of eggshell units appear in the outermost part, forming bush-like microstructures. Spheroolithidae is a typical oofamily of East Asia consisting of Spheroolithus spheroides, S. chiangchiungtingensis, S. quantouensis, S. oosp. and Paraspheroolithus irenensis, which mainly distributed in the Upper Cretaceous of China, South Korea, Japan and Mongolia. The discovery of S. phacelus provides new fossil materials of oogenus Spheroolithus in Spheroolithidae and expands the palaeogeographic distribution of Spheroolithidae in East Asia, which may be eggs of hadrosauroid. The age of these deformed dinosaur eggs could be presumed to be the middle Late Cretaceous (Coniacian–Campanian).

LINK

https://www.sciencedirect.com/science/article/abs/pii/S0195667124000843

ABSTRACT

The vertebrate assemblages of the Albian to Cenomanian Wayan Formation of southeastern Idaho and southwestern Montana’s coeval Vaughn Member of the Blackleaf Formation are dominated by the small, burrowing orodromine dinosaur Oryctodromeus cubicularis. Here, we describe in detail the osteology of Oryctodromeus based on new specimens from Idaho and Montana that add substantially to the preliminary description of the types from Montana, and provide a suite of additional diagnostic characters for the taxon: ilium with elongate preacetabular process; elongate cervical vertebra centra with an anteroposterior length 1.6 times the dorsoventral height; elongate dorsal vertebra centra with an anteroposterior length 1.4 times the dorsoventral height; more than 55 elongate caudal vertebrae enveloped in hypaxial and epaxial ossified tendons; and a femoral head on an elongate neck—similar to that of Koreanosaurus—projecting from the greater trochanter at about 35°. The tail, comprising two-thirds of the animal’s roughly 3 meters length, and associated tendon sheaths in the axial column indicate greater flexibility than previously supposed for ossified tendons or, alternatively, suggest that the Oryctodromeus burrows had separate, or multiple entrances and exits. The elongated and angled femoral head likely facilitated digging via a braced splayed-leg posture. Our phylogenetic analysis incorporates new characteristics and supports the monophyly of Orodrominae, a clade of neornithischian dinosaurs from the middle to Late Cretaceous of Asia and western North America that utilized burrowing.

LINK

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2330581

ABSTRACT

In 1989, the occurrence of 73 associated teeth of the megatooth shark, Otodus megalodon (Lamniformes: Otodontidae) was reported from the late Miocene Tsuchishio Formation in northern Saitama Prefecture, Japan. However, part of the tIn 1989, the occurrence of 73 associated teeth of the megatooth shark, Otodus megalodon (Lamniformes: Otodontidae) was reported from the late Miocene Tsuchishio Formation in northern Saitama Prefecture, Japan. However, part of the tooth set remained uncatalogued. This short note is to document the permanent repository of the remaining teeth officially to the Saitama Museum of Natural History.pan. However, part of the tooth set remained uncatalogued. This short note is to document the permanent repository of the remaining teeth officially to the Saitama Museum of Natural History.

LINK

https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2344813

ABSTRACT

CMN 8917 is a small, partial skull of a duck-billed dinosaur from the upper Campanian Dinosaur Park Formation in what is now Dinosaur Provincial Park, Alberta. It represents one of the few nestling-sized juvenile hadrosaurines known to date. Support for this phylogenetic placement includes a narial vestibule not enclosed within the premaxillary dorsal and lateral processes, the presence of an anterodorsal maxillary process, and a maxillary dorsal process that is longer anteroposteriorly than dorsoventrally. The skull also possesses tooth traits traditionally associated with lambeosaurines, such as secondary ridges on some maxillary and dentary tooth crowns, and denticulation on some maxillary tooth crowns. The occurrence of these features in a juvenile hadrosaurine suggests that they were modified during ontogeny, calling into question their taxonomic utility for identifying juvenile specimens. The dentary teeth of CMN 8917 are similar to those of many adult hadrosaurids in that they possess a concave occlusal surface with steeper lingual and shallower buccal wear zones. This differs from the occlusal surface morphology present in some other juvenile hadrosaurids, which suggests interspecific differences in dental battery development—possibly reflective of dietary differences—occurred during early ontogeny in some taxa.

LINKS

https://journals.library.ualberta.ca/vamp/index.php/VAMP/article/view/29395
https://journals.library.ualberta.ca/vamp/index.php/VAMP/article/view/29395/21461

ABSTRACT

The impressive †Oncorhynchus rastrosus of the Pacific Northwest’s Miocene and Pliocene eras was the largest salmonid ever to live. It sported a hypertrophied premaxilla with a pair of enlarged teeth which the original describers reconstructed as projecting ventrally into the mouth, leading them to assign the species to “Smilodonichthys,” a genus now in synonymy. Through CT reconstruction of the holotype and newly collected specimens, we demonstrate that the famed teeth projected laterally like tusks, not ventrally like sabers or fangs. We also expand the original description to characterize sexual dimorphism in mature, breeding individuals. Male and female †Oncorhynchus rastrosus differ in the form of the vomer, rostro-dermethmoid-supraethmoid, and dentary, much as do other extant species of Oncorhynchus. Male specimens possess a more elongate vomer than do females, and female vomers have concave ventral surfaces and prominent median dorsal keels. The dentary of females has no evidence of a kype, though some specimens of †O. rastrosus have a non-uniform density mesial to the tooth bed, which we interpret as a male kype. Unlike extant Oncorhynchus, male and female †O. rastrosus do not differ in premaxilla shape. Because male and females possess hypertrophied premaxillae and lateral premaxillary spikes, the former common name “Sabertoothed Salmon” no longer reflects our understanding of the species’ morphology. Accordingly, we redub †O. rastrosus the Spike-Toothed Salmon and postulate that its spikes were multifunctional, serving as defense against predators, in agonism against conspecifics, and as a practical aid to nest construction.

LINKS

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0300252
https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0300252&type=printable

ABSTRACT

The Longxiang tracksite (lower Upper Cretaceous, Shanghang Basin) includes twelve didactyl deinonychosaur tracks that fall into two morphologies, differentiated by both size and form. The smaller tracks (∼11 cm long) are referable to the ichnogenus Velociraptorichnus. The larger tracks (∼36 cm long) establish the ichnotaxon Fujianipus yingliangi. Based on the size of the tracks, F. yingliangi has an estimated hip height of over 1.8 m, a size comparable to that of the largest known deinonychosaurs, i.e., Austroraptor and Utahraptor. The reduced form of digit IV, relative to digit III, indicates that F. yingliangi is a probable troodontid. Gigantism evidently evolved independently at least four times within the Deinonychosauria and within at least three major lineages: the Eudromaeosauria, Unenlagiidae, and Troodontidae. In the mid-Cretaceous of Asia, the evolution of F. yingliangi overlapped with that of early large-bodied tyrannosauroids and with previously established large allosaurids (although the latter may have been in decline).

LINKS

https://www.cell.com/iscience/fulltext/S2589-0042(24)00820-4
https://www.cell.com/action/showPdf?pii=S2589-0042%2824%2900820-4

ABSTRACT

The fossil fish Ptychodus Agassiz, 1834, characterized by a highly distinctive grinding dentition and an estimated gigantic body size (up to around 10 m), has remained one of the most enigmatic extinct elasmobranchs (i.e. sharks, skates and rays) for nearly two centuries. This widespread Cretaceous taxon is common in Albian to Campanian deposits from almost all continents. However, specimens mostly consist of isolated teeth or more or less complete dentitions, whereas cranial and post-cranial skeletal elements are very rare. Here we describe newly discovered material from the early Late Cretaceous of Mexico, including complete articulated specimens with preserved body outline, which reveals crucial information on the anatomy and systematic position of Ptychodus. Our phylogenetic and ecomorphological analyses indicate that ptychodontids were high-speed (tachypelagic) durophagous lamniforms (mackerel sharks), which occupied a specialized predatory niche previously unknown in fossil and extant elasmobranchs. Our results support the view that lamniforms were ecomorphologically highly diverse and represented the dominant group of sharks in Cretaceous marine ecosystems. Ptychodus may have fed predominantly on nektonic hard-shelled prey items such as ammonites and sea turtles rather than on benthic invertebrates, and its extinction during the Campanian, well before the end-Cretaceous crisis, might have been related to competition with emerging blunt-toothed globidensine and prognathodontine mosasaurs.

LINK

https://royalsocietypublishing.org/doi/abs/10.1098/rspb.2024.0262

ABSTRACT

Terror birds (Aves, Phorusrhacidae) were large flightless apex predators in South America during the Cenozoic. Here, we estimate a new phylogeny for phorusrhacids using Bayesian inference. We demonstrate phylogenetic evidence for a monophyletic Patagornithinae and find significant support for a distinct crown group associated with the quintessential ‘terror bird’ characteristics. We use this phylogeny to analyse the evolution of body size and cursoriality. Our results reveal that size overlap was rare between co-occurring subfamilies, supporting the hypothesis that these traits were important for niche partitioning. We observe that gigantism evolved in a single clade, containing Phorusrhacinae and Physornithinae. The members of this lineage were consistently larger than all other phorusrhacids. Phorusrhacinae emerged following the extinction of Physornithinae, suggesting the ecological succession of the apex predator niche. The first known phorusrhacine, Phorusrhacos longissimus, was gigantic but significantly smaller and more cursorial than any physornithine. These traits likely evolved in response to the expansion of open environments. Following the Santacrucian SALMA, phorusrhacines increased in size, further converging on the morphology of Physornithinae. These findings suggest that the evolution and displacement of body size drove terror bird niche partitioning and competitive exclusion controlled phorusrhacid diversity.

LINK

https://royalsocietypublishing.org/doi/abs/10.1098/rspb.2024.0235

ABSTRACT

The larger species in many mammalian clades have relatively longer faces than their smaller relatives. This has been shown to be true for extant kangaroos (Macropodinae), who follow the CREA rule of positive facial allometry; but the extinct short-faced kangaroos (Sthenurinae) have not so far been examined. Using linear measurements, rather than CREA techniques, we show here that sthenurine face lengths scale with negative allometry, thus differing from the trend seen in their extant relatives.

LINKS

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2336145
https://www.tandfonline.com/doi/epdf/10.1080/02724634.2024.2336145?needAccess=true

ABSTRACT

The Eocene Geiseltal Konservat-Lagerstätte (Germany) is famous for reports of three dimensionally preserved soft tissues with sub-cellular detail. The proposed mode of preservation, direct replication in silica, is not known in other fossils and has not been verified using modern approaches. Here, we investigated the taphonomy of the Geiseltal anurans using diverse microbeam imaging and chemical analytical techniques. Our analyses confirm the preservation of soft tissues in all body regions but fail to yield evidence for silicified soft tissues. Instead, the anuran soft tissues are preserved as two layers that differ in microstructure and composition. Layer 1 comprises sulfur-rich carbonaceous microbodies interpreted as melanosomes. Layer 2 comprises the mid-dermal Eberth–Katschenko layer, preserved in calcium phosphate. In addition, patches of original aragonite crystals define the former position of the endolymphatic sac. The primary modes of soft tissue preservation are therefore sulfurization of melanosomes and phosphatization of more labile soft tissues, i.e., skin. This is consistent with the taphonomy of vertebrates in many other Konservat-Lagerstätten. These findings emphasize an emerging model for pervasive preservation of vertebrate soft tissues via melanosome films, particularly in stagnation-type deposits, with phosphatization of more labile tissues where tissue biochemistry is favorable.

LINK

https://www.nature.com/articles/s41598-024-55822-y

ABSTRACT

Tlayúa Quarry is an outstanding Early Cretaceous fossil site in Mexico characterized by the beauty and exceptional preservation of its fossils, including fishes, invertebrates and reptiles. For over four decades, Tlayúa Quarry has been the subject of numerous paleontological studies, being considered one of the most important fossil sites in North America. Tlayúa Quarry stands out among other Cretaceous localities of Mexico and North America due to the quality and diversity of its fossils, being identified as a Konservat-Lagerstätte. During the last 20 years, research on the age, paleoenvironments and species diversity of the Tlayúa Quarry has been carried out by Mexican and international paleontologists, substantially improving our knowledge about the locality. Here, a comprehensive synthesis of the history, age, paleoenvironmental models and paleobiodiversity of the Tlayúa Quarry is presented.

LINK

https://link.springer.com/chapter/10.1007/978-3-031-51034-2_17

ABSTRACT

Non-avian maniraptoran eggs are abundant in the Upper Cretaceous of China. Previous studies mainly focused on oviraptorosaur and troodontid eggs which can be classified into the oofamilies Elongatoolithidae and Prismatoolithidae, respectively. Here we report a new possible ootype of dromaeosaurid dinosaur recovered from the Lianhe Formation of the Ganzhou Basin. The new ootaxon, Gannanoolithus yingliangi oogen. et oosp. nov., is remarkable for its symmetrically elliptic shape and two structural layers with an abrupt and straight boundary. It shares a similar elongated shape, interlocked eggshell units, and an angusticanaliculate pore system with those of Deinonychus eggshell-like maniraptoran ootaxa reported from North America, Europe, and East Asia. The new phylogenetic analysis suggests the monophyly of dromaeosaurid and oviraptorosaurian eggs, and troodontid eggs are closely related to bird eggs. Paired eggs of Gannanoolithus might indicate that dromaeosaurid dinosaurs also have paired functional oviducts like oviraptorosaurs and troodontids. In addition, the porosity and EBSD analyses support that these eggs in the mound nests are buried.

LINK

https://www.sciencedirect.com/science/article/abs/pii/S019566712400082X

ABSTRACT

Pinnipeds (seals, sea lions, walruses, and their fossil relatives) are one of the most successful mammalian clades to live in the oceans. Despite a well-resolved molecular phylogeny and a global fossil record, a complete understanding of their macroevolutionary dynamics remains hampered by a lack of formal analyses that combine these two rich sources of information. We used a meta-analytic approach to infer the most densely sampled pinniped phylogeny to-date (36 recent and 93 fossil taxa) and used phylogenetic paleobiological methods to study their diversification dynamics and biogeographic history. Pinnipeds mostly diversified at constant rates. Walruses however experienced rapid turnover in which extinction rates ultimately exceeded speciation rates from 12-6 Ma, possibly due to changing sea-levels and/or competition with otariids (eared seals). Historical biogeographic analyses including fossil data allowed us to confidently identify the North Pacific and the North Atlantic (plus or minus Paratethys) as the ancestral ranges of Otarioidea (eared seals + walrus) and crown phocids (earless seals), respectively. Yet, despite the novel addition of stem pan-pinniped taxa, the region of origin for Pan-Pinnipedia remained ambiguous. These results suggest further avenues of study in pinnipeds and provide a framework for investigating other groups with substantial extinct and extant diversity.

LINKS

https://academic.oup.com/evolut/advance-article/doi/10.1093/evolut/qpae061/7655703
https://watermark.silverchair.com/qpae061.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAA2wwggNoBgkqhkiG9w0BBwagggNZMIIDVQIBADCCA04GCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQM-QTniXsUFC3HMGp3AgEQgIIDHz5ZcMn4wy-IcYo5ab6_zw5FpRfuGFlRIGV8UZ07VAil4Q9LL1XbHqHDBe8IHYxIw-8tiiwdbZxsdYuYl8Y5ML88_U-IUzKoIzmw0PxYhy9tfPe7MfkNAZcBt3J5kgQGTf_SE_zWWhgraMXxHTjVeq0G9Of_XaMsAYkr8_P4TXtifDz5lMxodRkufV-by8GXuEMXvxtl2aWmfjZ0zUmwQQOJrD4zglPo6WBfYYtk4HRrDQrP8NH5w_dYvORvz2UAXIPTTKfuOX12S1N09xBssOccMJwehDLNL-cEfR_1JFSHwTgO6fwK6M8z2gypnIr8SgBDWsZ9RTA8wq60cJAKSRSAPGglcYzWXTuZRaekVVgSKC3lutsbT-Cu8Tr4d0BaDcNGUvlRAqHU2wFETc19Z4i7DvfEmuHtxDqbRpRv5Svg4dBEFldm7NQ-PvFhJHtr8r0gaGkmc8fngB5WEd_Cx2m3iIh-ZvKk0XtmTIDKWVQyVuwmtfjQaUBk7co1JgY-wJwgpghUBJIKO2diUks5FxOJzhIB_e_Vr7FtlR2LMPjXSyIdrdRgFs4CQYYzvCoPW29MkqdWJZnXG5aUdXumYitggIdNu3z4FcF3SE3eZc_G0e88oG1iWpKFfkAwp_seQK6EEVn7NEEmAkyODSMdLJo5-roJUQ19GJ9XQiRhu8z8h_iYLaNvE-peC52myOKyfxNQFYz7LTdsAv57-0UctfFirGvQ_F20Y-nOd6IZXsfhu18_3G6oRwCaTks6aSlonwr-IkDNvq9ZH_SjK1drKj7vqMEwJ_FXBKQalIan91AuFBGavZwgI4zeyC6X9wigpBmV0sxuZs9unIa1GRVfHmFoVWTiJfGb1zxQUvrWDlwSX7RfFaYAd0Uf1bcumeO00kUrLfImHRwot_4DsmSfgqGF04BhoX9vQSNejSSLnPU0lemb2Vigd-j95hcp4Z0OAbCtRxHUY9uiv7aL2BfUMT-x29ll-QpaLn2_S4tihiwLlvYSXlj0oyXi_MsINWCiEDtAwHpGa5peTM3oh6hvFnIqTabP9mRug-fqQbfJdl0

ABSTRACT

Elongated upper canine teeth, commonly known as saber-teeth, have evolved three times within the sub-order Feliformia. The species that wielded them flourished throughout the Cenozoic and have historically been separated into two morphological groups: the dirk-tooths with longer, flatter canines, and the scimitar-tooths with shorter, serrated teeth. However, quantitative morphological analysis has not been conducted on these teeth to determine the true amount of diversity within the group, and how the upper canine morphology of extant feliforms compared to their extinct relatives has also not been explored. Using Geometric Morphometric analysis, it is shown that saber-tooth upper canine morphology is exceptionally diverse, with no extant clade having all its members occupy the same morphospace based on tooth length and curvature. Instead, a neutral basal morphospace is observed for all groups and diversification from this basal position is seen as species become more derived. A distinct and consistent scimitar tooth morphology is also not observed within the morphospace. When compared with extant taxa, several saber-tooth species are seen to be morphologically similar to extant feliforms, several of which exhibit novel dietary strategies in comparison to the obligate carnivore felids. Biomechanical analyses of different actual and theoretical tooth shapes demonstrate that saber-teeth upper canines further represent a functional compromise between sharpness, curvature, and length on the one hand, and robustness and material investment on the other.

LINK

https://anatomypubs.onlinelibrary.wiley.com/doi/full/10.1002/ar.25458

ABSTRACT

The fossil-rich Romualdo Formation (late Aptian/early Albian), Araripe Basin, northeastern Brazil, contains world-renowned Fossillagerstätten characterized by exceptionally preserved fossils. Macroinvertebrates in this formation are primarily represented by mollusks, echinoids, and decapod crustaceans. Mollusk shells are abundant in certain stratigraphic intervals, forming coquinas or shell pavements. Despite recent advances in our understanding of the taxonomy of certain groups, comprehensive taxonomic studies are lacking for almost the entire bivalve fauna. Therefore, a detailed taxonomic analysis is presented here. The described bivalves include four new genera (Araripenomia, Ciceromya, Inversatella, Australoeocallista), and six new species (Araripenomia infirma, Inversatella cearensis, Ciceromya edentulosa, Australoeocallista juazeiroi, Legumen kaririense, and Corbulomima delicata), in addition to Musculus maroimensis, Crassatella maroimensis, “Myrtea” sp. and “Tellina” sp. This bivalve fauna mainly consists of cosmopolitan and endemic brackish/marine genera, with Tethyan affinities. The fauna is not homogeneously distributed in the sedimentary succession of the Romualdo Formation but is constrained to the third order highstand systems tract. Bivalves recorded from muddy facies are strongly dominated by infaunal and semi-infaunal suspension feeders. Assemblages of the sand-dominated facies, with dense shell accumulations of semi-infaunal to epifaunal byssate and infaunal suspension feeders, were formed under shallow, higher energy conditions. Despite the degree of generic endemicity, the mytilids, anomiids, crassateliids, astartids, tellinids, and corbulids are related to the bivalve fauna of the Early Cretaceous Riachuelo Formation of the Sergipe-Alagoas Basin, as previously demonstrated for the bakevelliids and echinoids. Indeed, the Romualdo bivalve fauna is, in part, a modified and impoverished brackish/marine fauna of the Riachuelo Formation.

LINK

https://www.sciencedirect.com/science/article/abs/pii/S0195667124000831

ABSTRACT

Here two long-bone fragments from the Osning Formation (Valanginian – Lower Hauterivian) of the vicinity of Bielefeld, northwestern Germany, are described and referred to pterosaurs. The fragments probably represent parts of a femur and an incomplete wing-finger phalanx, respectively. The preserved features indicate the presence of moderately to large-sized pterodactyloideans. The morphology (cross-section) of the wing-finger phalanx is congruent with the plesiomorphic condition of the group, and potentially excludes at least some derived groups (dsungaripterids, istiodactylids) from closer relationship. A more detailed taxonomic assignment is hampered by the poor state of preservation. The remains are the first known pterosaur specimens from the shallow-marine, littoral deposits of the Osning Formation, and contribute to the still limited record of this group in the Valangian-Hauterivian of northwestern Europe. Within the region of northern Germany, only Targaryendraco wiedenrothi, a targaryendraconid from the Hauterivian, and an undetermined anhanguerian from the Lower Valanginian, both from the wider area of Hannover, Lower Saxony, are known from fragmentary remains. Further material comprises a few skeletal remains and a footprint from the Berriasian of Lower Saxony (Ctenochasma roemeri), as well as some teeth from the Barremian-Aptian of the Sauerland (North-Rhine Westphalia).

LINK

https://www.researchgate.net/publication/379898308_Flugsaurierreste_aus_der_Osning-Formation_Unterkreide_von_Nordwest-Deutschland_Pterosaur_remains_from_the_Osning_Formation_Lower_Cretaceous_of_northwestern_Germany

ABSTRACT

The first dinosaur discovered in the Antarctic continent was the ankylosaur Antarctopelta oliveroi in the 1980s. Nevertheless, since then several hypotheses of phylogenetical relationships have been proposed because these have been depended on how the skeletal remains have been interpreted. The main obstacle for clarifying its phylogenetic position is that many portions of the skeleton remain unknown, in addition to the presence of unknown characters in typical ankylosaurs. Considered an ankylosaurid, nodosaurid, or even a chimaera, a recent proposal based on mostly complete material of a new ankylosaur from Chilean Patagonia provided support for a novel phylogenetic hypothesis: Antarctopelta and other southern ankylosaurs are an early branching clade, the Parankylosauria, whose origin probably dates to the Late Jurassic. In the light of this new view, a redescription of the available skeletal remains is provided together with a new reconstruction of the first Antarctic dinosaur known to the science community.

LINKS

https://aps.chinare.org.cn/EN/10.12429/j.advps.2023.0036

https://aps.chinare.org.cn/EN/PDF/10.12429/j.advps.2023.0036?token=5227fcf300204973b498a639a1c9cbda (https://drive.google.com/file/d/1TXUi9KLDB3Gqwpn-FTK-i3z938VvK4C4/view?usp=sharing)

ABSTRACT

The studied fossil material of birds and mammals from a new Late Pleistocene site in the Stara Planina (Balkan) mountain range is herein presented. The age of the site was determined on the basis of the taxonomic composition of the mammal fauna. A total of 28 taxa (10 birds, 15 small and 3 large mammals) have been identified from 103 bone/teeth specimens. Of these, 14.3% of the established species are extinct/disappeared – Perdix palaeoperdix, Megaloceros giganteus, Ursus ingressus and Cuon sp. Most numerous are the remains of Microtus arvalis-agrestis, representing 42.7% of all finds.

LINKS

https://www.geologica-balcanica.eu/journal/53/1/pp.-105-115

https://www.geologica-balcanica.eu/sites/default/files/articles/Boev_Geol_Balc_53-1_2024.pdf

ABSTRACT

In this work a quantitative and qualitative analysis of the herbivory in foliar elements of the Permian of Mexico was carried out, four functional feeding groups with low occurrence in the paleoflora of the Permian of Mexico were identified. All this data helps to better understand ecological relationships in past ecosystems. The new data come from two formations, Tuzancoa (state of Hidalgo) and Matzitzi (state of Puebla), from the lower and upper Permian respectively. A total of 827 specimens housed in the Paleontology Collection of the FES Zaragoza were analyzed. First, the fossils were identified taxonomically based on morphological characters. Subsequently, the damage observed on the leaf elements was qualitatively analyzed and described. The damages were assigns to functional feeding groups (FFG) and subsequently to damage types (DT). For the Tuzancoa Formation, a total of 241 fossils were identified and assigned to four orders and nine genera, the most abundant being Mariopteris and Taeniopteris. Regarding these, a total of three functional groups were identified: all of them on Comia leaves, margin feeding, hole feeding, and oviposition. Along with this, five types of damage were identified (DT02, DT04, DT05, DT15 and DT101). Another important point to mention is the low percentage of damage frequency that is around 0.82%. For the Matzitzi Formation, a total of 586 fossils were identified, assigned to 11 orders and 25 genera, the best represented being the ferns of the genus Asterotheca and the leaf incertae sedis Velascophyllum. Two functional groups were identified, hole feeding and galling. The first functional group was identified on a Gigantonoclea leaf and belongs to Dt05 group. On the other hand, the galls have a greater diversity of shapes and sizes (DT49, DT117, DT70, DT259 and DT266); These damages are located on foliar elements of Velascophyllum, Cordaites, Calamites, Asterotheca and Diplazites. Once again, a low percentage of damage frequency is observed, around 2.5%. Herbivory studies in Mexico are still in an early stage and it is necessary to continue with this line of research to have a better understanding of plant-insect interactions in late Paleozoic ecosystems.

LINK

https://www.sciencedirect.com/science/article/abs/pii/S0895981124001263

ABSTRACT

A mammutid is described here for the first time from the Late Miocene (MN12 equivalent) deposits of Abkhareh village, Varzeghan region, in the North-Western part of Iran. It is identified as “Mammut” cf. obliquelophus and is represented by an isolated and moderately worn upper third molar with a zygodont crown pattern typical of mammutids. In addition, two upper incisors found associated with the molar and probably belonging to the same individual are assigned as Mammut. The studied material expands the geographic distribution of “Mammut” obliquelophus into Western Asia.

LINKS

https://sjpp.springeropen.com/articles/10.1186/s13358-023-00300-7

https://sjpp.springeropen.com/counter/pdf/10.1186/s13358-023-00300-7.pdf

ABSTRACT

Ichthyosaurs were a highly successful group of marine reptiles in the Mesozoic. The ichthyosaur radiation is part of the recovery from the Permian-Triassic mass extinction. In the Early Triassic, this group underwent extensive global radiation, filling ecological niches for the first time that were later occupied by various other lineages of marine amniotes. However, the evolution of body size in ichthyosaurs is not fully understood, as most large-bodied taxa originate from the Middle Triassic and later, and are mostly known from only a few specimens. In this study, we describe three articulated posterior dorsal vertebrae (IGPB R660) of the ichthyosaur Cymbospondylus sp. from the latest Olenekian Keyserlingites subrobustus zone of the Vikinghøgda Formation of the Agardhdalen area, eastern Spitsbergen, Svalbard. We numerically estimated the total body length of IGPB R660 from dorsal vertebral centrum length using a comparative dataset of other species of the genus and two different allometric analyses. This approach yields total length estimates of 7.5 m and 9.5 m for the individual, respectively, the highest for any unambiguous Early Triassic ichthyosaur find. Earlier, higher estimates of 11 m were based on taxonomically and stratigraphically inconclusive material but do not appear unreasonable based on evidence provided in this paper. Our study underscores both the rapid ecosystem recovery after a major mass extinction and extremely rapid increases in body size in ichthyosaurs after their adaptation to a secondarily aquatic lifestyle.

LINKS

https://link.springer.com/article/10.1007/s12542-023-00677-3

https://link.springer.com/content/pdf/10.1007/s12542-023-00677-3.pdf

ABSTRACT

Here we report the discovery of fossils representing partial vertebral column of a giant madtsoiid snake from an early Middle Eocene (Lutetian, ~ 47 Ma) lignite-bearing succession in Kutch, western India. The estimated body length of ~ 11–15 m makes this new taxon (Vasuki indicus gen et sp. nov.) the largest known madtsoiid snake, which thrived during a warm geological interval with average temperatures estimated at ~ 28 °C. Phylogenetically, Vasuki forms a distinct clade with the Indian Late Cretaceous taxon Madtsoia pisdurensis and the North African Late Eocene Gigantophis garstini. Biogeographic considerations, seen in conjunction with its inter-relationship with other Indian and North African madtsoiids, suggest that Vasuki represents a relic lineage that originated in India. Subsequent India-Asia collision at ~ 50 Ma led to intercontinental dispersal of this lineage from the subcontinent into North Africa through southern Eurasia.

LINKS

https://www.nature.com/articles/s41598-024-58377-0
https://www.nature.com/articles/s41598-024-58377-0.pdf

ABSTRACT

Known since the 19th Century, the compsognathids are among the smallest predatory dinosaurs, and include the first feathered non-avian species found. Traditionally, compsognathids have been considered small and unspecialized coelurosaurs, closer to birds than large-bodied forms like allosauroids and megalosaurids. Yet, all known compsognathids are based on skeletally-immature specimens, and this challenges the accuracy of their traditional phyletic placement. Despite the role of heterochrony in dinosaur evolution is widely recognized, the impact of ontogenetic-biased miscodings in shaping theropod phylogenetics is mostly underestimated. Herein, I show that the standard framework of theropod macroevolution is biased by a series of coding artifacts which violate semaphoront equality prescribed by phylogenetic systematics. I introduce “Ontogenetic State Partitioning” (OSP), a novel coding protocol which integrates ontogenetic and morphological variation under a total evidence approach, and apply it to a densely sampled data set focusing on Mesozoic theropods. The phylogenetic analysis dismissed “Compsognathidae” from being a natural group: its members are identified as juvenile morphs nested among several nonmaniraptoriform tetanuran lineages. Conservatism in the immature body plan and greater disparity among large-sized adults differentiate the predatory communities dominated by non-coelurosaurian species (e.g., the so called “triumvirates”) from the maniraptoriform-tyrannosaurid faunas (herein named “tyrannies”). This clade-specific differentiation among the communities is confirmed by an analysis of the predatory guild structures including all growth stages: triumvirates and tyrannies result as particular cases along a continuum of communities regulated mainly by alternative contributions of the small- and medium-sized classes. The oldest tyrannies (early Late Cretaceous in age) cluster among non-tyranny communities, supporting the hypothesis that tyrannosaurid-dominated faunas acquired their peculiar structure only after the extinction of the non-coelurosaurian components. The macroevolutionary trajectory that led the maniraptoriforms to realize the avian-like biology may have precluded them from occupying hypercarnivorous large-bodied niches: this bauplan constraint would have favored the tyrannosauroids in opportunistically assuming the apex predatory roles in Late Cretaceous Asiamerica but not elsewhere. The large-scale structure of the Cenozoic radiation of birds is coherent with the framework introduced herein.

LINK

https://www.paleoitalia.it/wp-content/uploads/2024/04/Cau_2024_BSPI_ONLINE.pdf

ABSTRACT

Giant ichthyosaurs with body length estimates exceeding 20 m were present in the latest Triassic of the UK. Here we report on the discovery of a second surangular from the lower jaw of a giant ichthyosaur from Somerset, UK. The new find is comparable in size and morphology to a specimen from Lilstock, Somerset, described in 2018, but it is more complete and better preserved. Both finds are from the uppermost Triassic Westbury Mudstone Formation (Rhaetian), but the new specimen comes from Blue Anchor, approximately 10 km west along the coast from Lilstock. The more complete surangular would have been >2 m long, from an individual with a body length estimated at ~25 m. The identification of two specimens with the same unique morphology and from the same geologic age and geographic location warrants the erection of a new genus and species, Ichthyotitan severnensis gen. et sp. nov. Thin sections of the new specimen revealed the same histological features already observed in similar giant ichthyosaurian specimens. Our data also supports the previous suggestion of an atypical osteogenesis in the lower jaws of giant ichthyosaurs. The geological age and giant size of the specimens suggest shastasaurid affinities, but the material is too incomplete for a definitive referral. Ichthyotitan severnensis gen. et sp. nov., is the first-named giant ichthyosaur from the Rhaetian and probably represents the largest marine reptile formally described.

LINKS

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0300289
https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0300289&type=printable

ABSTRACT

Early archosaurs included a range of ecological types—from predators to herbivores and from terrestrial to semi-aquatic forms. Members of the family Ornithosuchidae, traditionally considered active predators, occupy a special position. Their characteristic jaw apparatus structure and the morphology of their postcranial skeleton suggest the development of a unique ecological type among archosaurs, namely, a medium-sized hyperanisodont macrophagous predator. At the same time, some analogs can be noted between ornithosuchids, saber-toothed therapsids, and mammals.

LINK

https://link.springer.com/article/10.1134/S0031030124010064

ABSTRACT

A dorsal vertebra of an ichthyosaur is described from the fluvial deposits of the Kama River (Votkinsk District, Udmurt Republic, Russia). This vertebra belonged to a fairly large ichthyosaur about 5–6 m long, apparently one of the largest ichthyosaurs known from European Russia. The find is redeposited, and it is problematic to establish its exact age: most likely, the vertebra was brought by the Kama River from Jurassic–Cretaceous outcrops located upstream.

LINK

https://link.springer.com/article/10.1134/S0031030123600245

ABSTRACT

The oldest species of the genus Dvinosaurus Amalitzky, 1921—Dvinosaurus gubini sp. nov.—is described from the Sundyr-1 reference locality of the Sundyr faunal assemblage of Eastern Europe (Upper Permian, Upper Severodvinian, Suchonica vladimiri Assemblage Zone) based on abundant bone material. The diagnostic criteria for the new species are its smaller size compared to other dvinosaurs, the narrowest skull, a short and wide zygomatic bone, and the parasphenoid body with a wider base of the cultriform process, which is well ossified with the basisphenoid; a strongly curved dentary with a well-defined symphysial crest extending downward from the labial side of the symphysial surface and, in some cases, with a single symphysial tusk, a large angle (135°–152°) between the clavicular plate and dorsal process of the clavicle, narrow areas of the interclavicle for insertion of the clavicles, and a narrow entepicondylus of the humerus. The small size, narrow skull, single symphysial tusk, and hypocentrum morphology make the new form similar to the basal Dvinosauria, in particular, to ancestral Trimerorhachidae.

LINK

https://link.springer.com/article/10.1134/S0031030123600336

ABSTRACT

A diverse assemblage of fish microremains is reported from the Virgilian (Gzhelian), Upper Pennsylvanian Finis Shale outcrop at Lost Creek Lake near Jacksboro (Texas, USA). The assemblage contains diverse remains of chondrichthyans, rare acanthodians and actinopterygians. The chondrichthyans are represented by a xenacanthimorph, ctenacanthiforms, symmoriiforms, an euselachian, a neoselachian, a petalodontiform, eugeneodontiforms, a helodontiform and euchondrocephalian taxa. The teeth of Bransonella dominate the chondrichthyan microremains. The occurrence of Bransonella lingulata in the Gzhelian Finis Shales of Texas is the youngest in the world. The assemblage includes widely distributed taxa of chondrichthyans. The chondrichthyan fauna from the Finis Shale outcrop differs from the rich faunas of the Kasimovian–Gzhelian from other regions such as New Mexico and Nebraska in the USA, Moscow, Samara and Volgograd regions of Russia, Spain, Germany and the Czech Republic by the dominance of bransonelliform remains and the set of diverse ctenacanthiforms and euchondrocephalians. The new assemblage of fishes demonstrates the presence of chondrichthyan taxa with different food specialisation in the Virgilian faunal community.

LINK

https://link.springer.com/article/10.1007/s12542-023-00679-1

ABSTRACT

Phylodynamic models can be used to estimate diversification trajectories from time calibrated phylogenies. Here we apply two such models to phylogenies of non-avian dinosaurs, a clade whose evolutionary history has been widely debated. While some authors have suggested that the clade experienced a decline in diversity, potentially starting millions of years before the end-Cretaceous mass extinction, others have suggested that the group remained highly diverse right up until the Cretaceous Paleogene (K-Pg) boundary. Our results show that model assumptions, likely with respect to incomplete sampling, have a large impact on whether dinosaurs appear to have experienced a long-term decline or not. The results are also highly sensitive to the topology and branch lengths of the phylogeny used. Developing comprehensive models of sampling bias, and building larger and more accurate phylogenies, are likely to be necessary steps for us to determine whether dinosaur diversity was or was not in decline prior to the end-Cretaceous mass extinction.

LINKS

https://www.cambridge.org/core/journals/cambridge-prisms-extinction/article/mechanistic-phylodynamic-models-do-not-provide-conclusive-evidence-that-nonavian-dinosaurs-were-in-decline-before-their-final-extinction/A4B969E201DF64596175127357991F4B

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/A4B969E201DF64596175127357991F4B/S2755095824000056a.pdf/div-class-title-mechanistic-phylodynamic-models-do-not-provide-conclusive-evidence-that-non-avian-dinosaurs-were-in-decline-before-their-final-extinction-div.pdf

ABSTRACT

Background

Tooth replacement patterns of early-diverging ornithischians, which are important for understanding the evolution of the highly specialized dental systems in hadrosaurid and ceratopsid dinosaurs, are poorly known. The early-diverging neornithischian Jeholosaurus, a small, bipedal herbivorous dinosaur from the Early Cretaceous Jehol Biota, is an important taxon for understanding ornithischian dental evolution, but its dental morphology was only briefly described previously and its tooth replacement is poorly known.

Results

CT scanning of six specimens representing different ontogenetic stages of Jeholosaurus reveals significant new information regarding the dental system of Jeholosaurus, including one or two replacement teeth in nearly all alveoli, relatively complete tooth resorption, and an increase in the numbers of alveoli and replacement teeth during ontogeny. Reconstructions of Zahnreihen indicate that the replacement pattern of the maxillary dentition is similar to that of the dentary dentition but with a cyclical difference. The maxillary tooth replacement rate in Jeholosaurus is probably 46 days, which is faster than that of most other early-diverging ornithischians. During the ontogeny of Jeholosaurus, the premaxillary tooth replacement rate slows from 25 days to 33 days with similar daily dentine formation.

Conclusions

The tooth replacement rate exhibits a decreasing trend with ontogeny, as in Alligator. In a phylogenetic context, fast tooth replacement and multi-generation replacement teeth have evolved at least twice independently in Ornithopoda, and our analyses suggest that the early-diverging members of the major ornithischian clades exhibit different tooth replacement patterns as an adaption to herbivory.

LINK

https://bmcecolevol.biomedcentral.com/articles/10.1186/s12862-024-02233-2

ABSTRACT

Edmontosaurus regalis is a hadrosaurid represented by abundant fossil material from the late Campanian–early Maastrichtian of what is now Alberta, Canada. Despite its prevalence, juvenile craniomandibular elements of E. regalis are poorly known. A newly collected partial skeleton from the Horseshoe Canyon Formation, UALVP 60425, represents a small saurolophine with a partial skull (skull length ∼500 mm). It can be referred to Edmontosaurini based on the presence of a postorbital fossa and anteroposteriorly long frontals that lack a dorsally oriented nasal contact and contribute significantly to the orbital margin. Despite its small size and presumed immaturity, UALVP 60425 is assigned to E. regalis based on a horizontal shelf on the postorbital process of the jugal. The deep postorbital fossa that, in part, diagnoses E. regalis is acquired during growth. UALVP 60425 shares many features with the Alaskan Prince Creek saurolophine (Ugrunaaluk kuukpikensis); both show consistent anatomical differences in the lacrimal, jugal, and postorbitals from E. annectens throughout their growth series. New data from UALVP 6025 supports referring the Alaskan saurolophine material to Edmontosaurus cf. regalis in the absence of large-sized cranial material from the Prince Creek Formation.

LINK

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2335174

ABSTRACT

The skull of Plioplatecarpus possesses large orbits and a large parietal foramen. Although the large orbits suggest that Plioplatecarpus possessed large eyes with enhanced visual performance, none of the previously described skulls include a sclerotic ring, and so it has been impossible in the past to reconstruct their size or optical properties. A recently collected skull with a sclerotic ring preserved in situ provides for the first time the data to do so. The dimensions of the sclerotic ring demonstrate that, although the f-number of the eyeball was not low enough to support the hypothesis that Plioplatecarpus was adapted to low light conditions, the eyeball was nevertheless large and possessed increased visual acuity and sensitivity that enabled the mosasaur to operate efficiently in both light-rich and light-poor conditions and possibly other conditions of reduced visibility. Proportions of this skull also suggest that Plioplatecarpus possessed a relatively wide binocular field of vision, providing stereoscopic vision, and further increasing both acuity and sensitivity, enhancing its ability to effectively detect and track quickly moving objects under a wide range of light conditions. A greatly enlarged parietal foramen implies the presence of a large parietal eye, the significance of which is uncertain, but it may have enhanced the ability to regulate migratory behavior.

LINK

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2335174

ABSTRACT

The typical mammalian neck consisting of seven cervical vertebrae (C1–C7) was established by the Late Permian in the cynodont forerunners of modern mammals. This structure is precisely adapted to facilitate movements of the head during feeding, locomotion, predator evasion, and social interactions. Eutheria, the clade including crown placentals, has a fossil record extending back more than 125 million years revealing significant morphological diversification in the Mesozoic. Yet very little is known concerning the early evolution of eutherian cervical morphology and its functional adaptations. A specimen of Zalambdalestes lechei from the Late Cretaceous of Mongolia boasts exceptional preservation of an almost complete series of cervical vertebrae (C2–C7) revealing a highly modified axis (C2). The significance of this cervical morphology is explored utilizing an integrated approach combining comparative anatomical examination across mammals, muscle reconstruction, geometric morphometrics and virtual range of motion analysis. We compared the shape of the axis in Zalambdalestes to a dataset of 88 mammalian species (monotremes, marsupials, and placentals) using three-dimensional landmark analysis. The results indicate that the unique axis morphology of Zalambdalestes has no close analog among living mammals. Virtual range of motion analysis of the neck strongly implies Zalambdalestes was capable of exerting very forceful head movements and had a high degree of ventral flexion for an animal its size. These findings reveal unexpected complexity in the early evolution of the eutherian cervical morphology and suggest a feeding behavior similar to insectivores specialized in vermivory and defensive behaviors in Zalambdalestes akin to modern spiniferous mammals.

LINK

https://www.sciencedirect.com/science/article/abs/pii/S2095927324002615

ABSTRACT

Non-avialan theropod dinosaurs had diverse ecologies and varied skull morphologies. Previous studies of theropod cranial morphology mostly focused on higher-level taxa or characteristics associated with herbivory. To better understand morphological disparity and function within carnivorous theropod families, here we focus on the Dromaeosauridae, ‘raptors’ traditionally seen as agile carnivorous hunters. We applied 2D geometric morphometrics to quantify skull shape, performed mechanical advantage analysis to assess the efficiency of bite force transfer, and performed finite element analysis to examine strain distribution in the skull during biting. We find that dromaeosaurid skull morphology was less disparate than most non-avialan theropod groups. Their skulls show a continuum of form between those that are tall and short and those that are flat and long. We hypothesise that this narrower morphological disparity indicates developmental constraint on skull shape, as observed in some mammalian families. Mechanical advantage indicates that Dromaeosaurus albertensis and Deinonychus antirrhopus were adapted for relatively high bite forces, while Halszkaraptor escuilliei was adapted for high bite speed, and other dromaeosaurids for intermediate bite forces and speeds. Finite element analysis indicates regions of high strain are consistent within dromaeosaurid families but differ between them. Average strain levels do not follow any phylogenetic pattern, possibly due to ecological convergence between distantly-related taxa. Combining our new morphofunctional data with a re-evaluation of previous evidence, we find piscivorous reconstructions of Halszkaraptor escuilliei to be unlikely, and instead suggest an invertivorous diet and possible adaptations for feeding in murky water or other low-visibility conditions. We support Deinonychus antirrhopus as being adapted for taking large vertebrate prey, but we find that its skull is relatively less resistant to bite forces than other dromaeosaurids. Given the recovery of high bite force resistance for Velociraptor mongoliensis, which is believed to have regularly engaged in scavenging behaviour, we suggest that higher bite force resistance in a dromaeosaurid taxon may reflect a greater reliance on scavenging rather than fresh kills. Comparisons to the troodontid Gobivenator mongoliensis suggest that a gracile rostrum like that of Velociraptor mongoliensis is ancestral to their closest common ancestor (Deinonychosauria) and the robust rostra of Dromaeosaurus albertensis and Deinonychus antirrhopus are a derived condition. Gobivenator mongoliensis also displays a higher jaw mechanical advantage and lower resistance to bite force than the examined dromaeosaurids, but given the hypothesised ecological divergence of troodontids from dromaeosaurids it is unclear which group, if either, represents the ancestral condition. Future work extending sampling to troodontids would therefore be invaluable and provide much needed context to the origin of skull form and function in early birds. This study illustrates how skull shape and functional metrics can discern non-avialan theropod ecology at lower taxonomic levels and identify variants of carnivorous feeding.

LINK

https://bmcecolevol.biomedcentral.com/articles/10.1186/s12862-024-02222-5

ABSTRACT

The new mamenchisaurid genus name Jingia, published in Historical Biology (The first mamenchisaurid from the Upper Jurassic Dongxing Formation of Guangxi, southernmost China, DOI: 10.1080/08912963.2024.2309287), is pre-occupied by Jingia Chen, 1983, a lepidopteran insect. The new replacement name Jingiella dongxingensis gen. et sp. nov., is proposed for Jingia dongxingensis Ren et al., 2024. The LSID for the genus is urn:lsid:zoobank.org:act:23360967-7D16-4A16-ABB1-E8D18D47948B, and the species is urn:lsid:zoobank.org:act:FE1FCD99- 2C13-4234-A7AA-7EB29891EB51. We are grateful to Vahe Demirjian, Pietro Benvegnù, and Andrea Cau who pointed out the pre- occupation, and thanks to the editor Gareth Dyke for the rapid solving of this issue.

LINK

https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2325806

ABSTRACT

The Missão Velha Formation (Late Jurassic-Early Cretaceous), often referred to as Brejo Santo Formation, is one of the stratigraphic units of the Araripe Basin, included within the Vale do Cariri Group. This locality, characterised by its fluvio-estuarine paleoenvironment, yielded a diverse paleoichthyofauna while its terrestrial vertebrate record is still poorly known, with a single isolated theropod lateral tooth being briefly cited until now. This study aims to revisit this specimen (UERJ-PMB R008) in order to identify it through the current quantitative and qualitative methods. The quantitative analyses were unable to properly classify the Missão Velha specimen to a single theropod group, indicating paravian, piatnitzkysaurid and abelisaurid affinities, while most of cladistic analyses assigned the UERJ-PMB R008 as an abelisaurid tooth. The specimen was finally assigned as an abelisaurid lateral tooth due to its almost straight distal margin, hooked denticles, similarly sized mesial and distal denticles, a lanceolate cross section and an irregular enamel texture. This assignment represents not only the first definitive theropod record for Missão Velha Formation as it is also the oldest abelisaurid record in the South America, filling part of the 30-million-year gap between Eoabelisaurus and Spectrovenator.

LINK

https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2336982

ABSTRACT

The non-neopterygian group †Coccolepididae, a moderately diverse predominantly freshwater family, remains an imperfectly known Mesozoic group of actinopterygians, currently classified within Chondrostei based on the presence of several acipenseriform synapomorphies. Coccolepidids first appear during the Early Jurassic in marine sediments, although their fossils are poorly known from this time, and none have yet been described from the Toarcian (Upper Lias). Here, we describe a new genus and species of coccolepidid fish, †Toarcocephalus morlok gen. et sp. nov. from the Lower Jurassic (Toarcian) Posidonienschiefer Formation of Holzmaden in southern Germany. †Toarcocephalus morlok is diagnosed by a unique combination of characters including a shallow lower jaw with a massive angular, opercle and subopercle equal in size, preopercle that only borders the subopercle but does not reach the opercle; dermal skull bones strongly punctate, with externally smooth upper and lower jaw bones. Discovery of a coccolepidid at Holzmaden represents the first occurrence of the group from a Toarcian deposit, as well as the oldest record of the family in mainland Europe. Both described specimens of †T. morlok were victims of successful predation events: one individual was likely decapitated (pabulite) and the other preserved within a regurgitalite (fossilized oral ejecta). The evolution of Coccolepididae is discussed briefly in relation to a marine/freshwater origin.

LINK

https://palaeo-electronica.org/content/2024/5197-new-toarcian-coccolepidid-fish

ABSTRACT

Cockroach Clypeblattula panda gen. et sp. n. is described from the Lower Cretaceous Laiyang Formation of Shandong Province, China based on a specimen with forewing and pronotum well-preserved. It is characterized by ovoid pronotum with two trapezoid dark stripes, forewing with intercalary space in R with colouration, A with six simple veins, and sparse cross-veins. It is closely related to the Early Cretaceous Pravdupovediac according to colouration of intercalary space in R, but they can be distinguished mainly based on the different wing shapes and the existence of dark macula. The differences between Clypeblattula gen. n., Ocelloblattula, Pseudomantina, Habroblattula and Laiyangia are also briefly discussed. The new genus is another indigenous cockroach of Blattulidae.

LINK

https://www.sciencedirect.com/science/article/abs/pii/S0195667124000806

ABSTRACT

Pectocaris species are intermediate- to large-sized Cambrian bivalved arthropods. Previous studies have documented Pectocaris exclusively from the Cambrian Series 2 Stage 3 Chengjiang biota in Yu’anshan Formation, Chiungchussu Stage in SW China. In this study, we report Pectocaris paraspatiosa sp. nov., and three other previously known Pectocaris from the Xiazhuang section in Kunming, which belongs to the Hongjingshao Formation and is a later phase within Cambrian Stage 3 than the Yu’anshan Formation. The new species can be distinguished from its congeners by the sparsely arranged endopodal endites and the morphologies of the abdomen, telson, and telson processes. We interpret P. paraspatiosa sp. nov. as a filter-feeder and a powerful swimmer adapted to shallow, agitated environments. Comparison among the Pectocaris species reinforces previous views that niche differentiation had been established among the congeneric species based on morphological differentiation. Our study shows the comprehensive occurrences of Pectocaris species outside the Chengjiang biota for the first time. With a review of the shared fossil taxa of Chengjiang and Xiaoshiba biotas, we identify a strong biological connection between the Yu’anshan and Hongjingshao Formations.

LINK

https://peerj.com/articles/17230/

ABSTRACT

Saber-tooths, extinct apex predators with long and blade-like upper canines, have appeared iteratively at least five times in the evolutionary history of vertebrates. Although saber-tooths exhibit a relatively diverse range of morphologies, it is widely accepted that all killed their prey using the same predatory behavior. In this study, we CT-scanned the skull of Barbourofelis fricki and compared its cranial mechanics using finite element analysis (FEA) with that of Smilodon fatalis. Our aim was to investigate potential variations in killing behavior between two dirk-toothed sabretooths from the Miocene and Pleistocene of North America. The study revealed that B. fricki had a stoutly-built skull capable of withstanding stress in various prey-killing scenarios, while the skull of S. fatalis appeared less optimized for supporting stress, which highlights the highly derived saber-tooth morphology of the former. The results may indicate that B. fricki was more of a generalist in prey-killing compared to S. fatalis, which experiences lower stresses under stabbing loads. We hypothesize that morphological specialization in saber-tooths does not necessarily indicate ecological specialization. Our results support the notion that morphological convergence among saber-toothed cats may obscure differences in hunting strategies employed to dispatch their prey. Our findings challenge the assumption of the universally assumed canine-shear biting as the prey-killing behavior of all saber-toothed cats. However, further research involving a wider range of dirk and scimitar-toothed forms could provide additional insights into the diversity of cranial biomechanics within this fascinating group of extinct mammalian predators.

LINK

https://anatomypubs.onlinelibrary.wiley.com/doi/full/10.1002/ar.25451

ABSTRACT

Testudines are one of the best-represented taxonomic groups among the Paleogene taxa of the Duero Basin (Castile and Leon Autonomous Community, central Spain). Among them, Neochelys (Podocnemidide) and Allaeochelys (Carettochelyidae) are most abundant, allowing the population to be assessed for osteological anomalies. The abundance of postcranial remains of both taxa allows us to identify several individuals with potential anomalies, mostly in their shells. Some of them have already been described in previous studies, but most of them are still unpublished. The objective of this study is to analyze in detail the anomalous Neochelys and Allaeochelys remains. As a result, different categories of causal agents (such as bacteria, fungi, parasites, or trauma) have been identified as potential producers of the anomalies in these freshwater turtles. Information regarding the pathogenesis and healing stages of some of these anomalies is provided.

LINK

https://anatomypubs.onlinelibrary.wiley.com/doi/full/10.1002/ar.25443

ABSTRACT

The genus Vitisma Vršanský, 1999 is characterised by a shield-like, convex pronotum with transverse margins, scleroritized forewings with sometimes white macula, long clavus and rather simplified venation (simple Sc, straight and expanded M veins, CuA narrow and branched, A simple, R reaching apex). The hindwing venation is similar to the Blattulidae with a distinct pterostigma, but R1 is comb-like and CuA branched. The first record of Vitisma coriacea sp. n. in Burmese amber extends its palaeogeographic distribution to Gondwana, similar to other Umenocoleoidea. So far, the genus was only known from sediments in Spain, Russia, Mongolia, and possibly Japan. It also suggests that representatives of Vitisma inhabited warmer, tropical forest biomes.

LINK

https://www.mapress.com/zt/article/view/zootaxa.5437.2.8

ABSTRACT

Twenty phalanges are preserved in total in the Keton specimen, the first whole skeleton, of Desmostylus. This paper presents their re-description, because in the previous studies, their comparison of the specimen was incomplete, there was morphological contradiction, and so their identification is doubtful, moreover, there were no photo plates. An ecomorphological analysis was performed to restore the forelimb function of all desmostylians including phalanges of the Desmostylus described here. As a result, the following has become clear：the desmostylians had a lateral-type limb posture, preserving primitive features as a mammal；the degree of the lateraltype limb posture in the forelimb in Desmostylus is higher than in Paleoparadoxia；the desmostylians are fundamentally terrestrial graviportal animals, because they do not have fin but subunguligrade manus and pes； when the position of the forelimbs is assumed to reflect the swimming position in the water, Desmostylus strokes both forelimbs simultaneously, and it can be concluded to have been more adapted to diving than Paleoparadoxia.

LINK

https://www.gmnh.pref.gunma.jp/wp-content/uploads/bulletin28_04.pdf

ABSTRACT

Among the least studied portion of the pterosaur skeleton is the palate, which tends to be poorly preserved and commonly only visible from one side (the ventral portion). Even in well-preserved specimens, the bones tend to be fused, with the limits of individual palatal elements obscured. To shed new light on this region, we employed advanced X-ray imaging techniques on the non-pterodactyloid Kunpengopterus (Wukongopteridae), and the pterodactyloids Dsungaripterus (Dsungaripteridae), Hongshanopterus (Istiodactylidae), and Hamipterus (Hamipteridae). Our analyses revealed the presence of sutures between palatal bones in Dsungaripterus and Kunpengopterus, which resulted in different interpretations of the relation between palatine, ectopterygoid, and pterygoid, leading to a new identification of the palatal openings. Furthermore, our study shows six main observations such as the variation of the angle between the palatine rami and the variation in the relative sizes of the palatal openings. We also point out that the presence of a maxillopalatine fenestra (previously identified as postpalatine fenestra), is unique within Diapsida. Although much more work needs to be done, we showed that advanced X-ray imaging techniques open a window for understanding pterosaur cranial anatomy and provide a new perspective for investigating the evolutionary history of these flying reptiles.

LINK

https://www.nature.com/articles/s42003-024-06132-6

ABSTRACT

The fossil record of cheetahs in eastern Asia is notably scarce and predominantly fragmented, leaving the evolution of this lineage in eastern Asia largely enigmatic. In this study, we present new findings from two early Middle Pleistocene sites, the upper deposits (L2) of Jinyuan Cave (Dalian) and Zhoukoudian Loc.13 (Beijing). These specimens are identified here as Acinonyx pleistocaenicus and represent the latest and largest-sized member of the species. Acinonyx pleistocaenicus shows a suit of craniodental traits that distinguishes it from the earlier Early Pleistocene A. pardinensis, and relates it to modern A. jubatus, and should be regarded as a valid species. Shortly after the age represented by Zhoukoudian Loc. 13 (0.6–0.7 Ma), the giant cheetah was replaced by much smaller and morphologically different Acinonyx intermedius. This transition supports the independence of these two species, and the latter was likely a new immigrant from Africa around the Early-Middle Pleistocene boundary, together with Panthera spelaea, Panthera pardus, and Parahyaena prisca.

LINK

https://www.sciencedirect.com/science/article/abs/pii/S0277379124001628?via%3Dihub

ABSTRACT

The abundance of shark and actinopterygian fossils in the Cretaceous and Paleogene strata of the Atlantic Coastal Plain is well documented; but much remains unknown about the survivorship patterns of these major components of shallow marine faunas in the western Atlantic through the K/Pg mass extinction. To shed light on this subject, we describe an assemblage of new actinopterygian, chondrichthyan, and reptilian microfossils recently recovered from the Maastrichtian Navesink and Maastrichtian–Danian Hornerstown formations at the Jean and Ric Edelman Fossil Park at Rowan University in Mantua Township, New Jersey. The new microfossils clarify extinction patterns across the K/Pg, create temporal and geographic range extensions for several taxa, and expand the known fauna of this regionally-rare and important K/Pg-boundary locality. We report 11 new additions to the vertebrate fauna of Edelman Fossil Park, the first Paleocene record of Saurocephalus lanciformis, the first Cretaceous records of Paralbula marylandica and Palaeogaleus vincenti, and the first recovery of gar and dercetid fish remains from the Paleocene in New Jersey (the last indicating that these fish survived the K/Pg extinction in the western Atlantic). Geographic range extensions include: Notidanodon brotzeni into the Western Hemisphere, Saurocephalus into northeastern North America and Phyllodus paulkatoi to the eastern coast of North America. A dentary of a juvenile alligatorid, Bottosaurus harlani, indicate that the mandible exhibited isometric growth through ontogeny. Our findings generally agree with other studies that these groups were significantly impacted by the extinction event, that extinctions were selective, and recovery was slow. This wealth of novel insights garnered from microfossils in this study highlights their critical importance for elaborating past faunas and illuminating the character of ancient ecosystems. We therefore recommend microsieving as a fruitful method for future faunal studies of shallow-marine strata and predict that such efforts will frequently yield similar important insights.

LINK

https://www.app.pan.pl/article/item/app011172023.html

ABSTRACT

East Asia, being the evolutionary center of Coelodonta, offers a unique opportunity to explore the spatiotemporal paleoecologies of this genus. This study utilized bulk and serial stable carbon and oxygen isotope analyses on the Coelodonta nihowanensis and other ungulates from the Longdan fauna as well as two modern goats in the Linxia Basin, aiming to explore the paleoecology of C. nihowanensis at the periphery of the Tibetan Plateau during the Early Pleistocene. The isotopic results of these mammals indicated that C3 vegetation was possibly a major component of the local environment in the Linxia Basin, which was influenced by a seasonal summer monsoon. C. nihowanensis specimens in the Longdan fauna were possibly mixed feeders, as indicated by the wide distribution of their δ13C values and the intermediate δ18O values compared to other coexisting ungulates. Moreover, the comparison of the δ13C and δ18O values of similar taxa from the Linxia and Nihewan basins has revealed spatiotemporal differences in the paleoclimate and paleoenvironments of these two regions throughout the Early Pleistocene. This provides a holistic framework for understanding the paleoecology of the C. nihowanensis. The isotopic results of the C. nihowanensis in the Linxia and Nihewan basins suggested varied foraging ecologies across different sites and time spans during the Early Pleistocene. This underscores the adaptability of the C. nihowanensis to diverse environments from west to east in northern China. By scrutinizing the evolutionary ecological history of the woolly rhinoceroses from its ancestor, Coelodonta thibetana, to its final form, Coelodonta antiquitatis, this study sheds light on the ecological adaptation of this genus from the Pliocene to Late Pleistocene, spanning its migration from the Tibetan Plateau to northern Eurasia.

LINK

https://www.frontiersin.org/articles/10.3389/fevo.2024.1377000/full

ABSTRACT

Numerous surveys and three excavation and surface collection field seasons resulted in the discovery of numerous megafaunal remains and that of a medium-sized felid in a new site located on the coastal plain of the Gulf of Venezuela, in Western Falcón State. The faunal assemblage is represented by South American natives such as megatheres (cf. Eremotherium laurillardi), an indeterminate mylodontid and a glyptodont (probably related to Glyptotherium) and Nearctic representatives such as gomphotheres (Notiomastodon platensis), equids (Equus sp.) and a feline (Felidae cf. Leopardus pardalis), providing novel information for the distribution of some of these mammals. Radiocarbon indicates that this deposit is at least 40,000 years old. Lithic artefacts of a kind reported for other Pleistocene sites in the region document the presence of humans in Cauca, but as these cultural remains were found on the surface, their association with the fauna is uncertain.

LINK

https://fr.pensoft.net/article/119967/list/1/

ABSTRACT

Supposed dinosaur remains were collected between 1859 and 1906 in the Lower Cretaceous Recôncavo Basin (Northeast Brazil). Since these materials remained undescribed, and most were considered lost. Recently, some of these historical specimens were rediscovered in the Natural History Museum of London, providing an opportunity to revisit them after 160 years. The specimens come from five different sites, corresponding to the Massacará (Berriasian-Barremian) and Ilhas (Valanginian-Barremian) groups. Identified bones comprise mainly isolated vertebral centra from ornithopods, sauropods, and theropods. Appendicular remains include a theropod pedal phalanx, humerus, and distal half of a left femur with elasmarian affinities. Despite their fragmentary nature, these specimens represent the earliest dinosaur bones discovered in South America, enhancing our understanding of the Cretaceous dinosaur faunas in Northeast Brazil. The dinosaur assemblage in the Recôncavo Basin resembles coeval units in Northeast Brazil, such as the Rio do Peixe Basin, where ornithopods coexist with sauropods and theropods. This study confirms the presence of ornithischian dinosaurs in Brazil based on osteological evidence, expanding their biogeographic and temporal range before the continental rifting between South America and Africa. Additionally, these findings reinforce the fossiliferous potential of Cretaceous deposits in Bahia State, which have been underexplored since their initial discoveries.

New Elasmarian Ornithopod Dinosaur Tietasaura derbyiana.

LINK

https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2318406

ABSTRACT

The first paleontological works on Mesozoic vertebrates from Portugal, carried out from the end of the 19th and the first half of the 20th century, provided the discovery of significant collections of vertebrate fossils. These collections are particularly relevant because they include several specimens collected from different regions of the Lusitanian Basin (some of the sites are currently inaccessible), whose fossil record is poorly known. Theropod remains are relatively scarce and generally consist of fragmentary material, mostly assigned to the megalosaurid Megalosaurus from the Middle Jurassic of England, the first dinosaur to be named and a “wastebasket” taxon used by many scientists to identify theropod material. The studied fossils mostly consist of isolated teeth and vertebrae collected from Upper Jurassic levels of the coastal region, with also some material from Lower and Upper Cretaceous strata from the central and northern sectors of the Lusitanian Basin. Here specimens attributed to Megalosaurus from different Portuguese institutions are reviewed and their taxonomic affinity and stratigraphic context are updated. Most specimens actually belong to different theropod groups, including several isolated teeth from different Upper Jurassic localities here assigned to Ceratosaurus, Torvosaurus, and Allosaurus, as well as an isolated tooth from the Lower Cretaceous that is attributed to an indeterminate allosauroid. Other theropod remains consist mostly of vertebral fragments of indeterminate avetheropods and allosauroids. Elements of other dinosaur groups are also represented, including a few vertebrae here referred to stegosaurians and iguanodontians, as well as a vertebra and some appendicular remains attributed to sauropods. Two vertebrae assigned to thalattosuchians were also identified. The study of this collection allows to better characterize the diversity of Late Jurassic dinosaur faunas from different areas of the Lusitanian Basin and provides some data on the poorly known Cretaceous fossil record of theropods from Portugal.

LINK

https://www.app.pan.pl/article/item/app011132023.html

ABSTRACT

The first paleontological works on Mesozoic vertebrates from Portugal, carried out from the end of the 19th and the first half of the 20th century, provided the discovery of significant collections of vertebrate fossils. These collections are particularly relevant because they include several specimens collected from different regions of the Lusitanian Basin (some of the sites are currently inaccessible), whose fossil record is poorly known. Theropod remains are relatively scarce and generally consist of fragmentary material, mostly assigned to the megalosaurid Megalosaurus from the Middle Jurassic of England, the first dinosaur to be named and a “wastebasket” taxon used by many scientists to identify theropod material. The studied fossils mostly consist of isolated teeth and vertebrae collected from Upper Jurassic levels of the coastal region, with also some material from Lower and Upper Cretaceous strata from the central and northern sectors of the Lusitanian Basin. Here specimens attributed to Megalosaurus from different Portuguese institutions are reviewed and their taxonomic affinity and stratigraphic context are updated. Most specimens actually belong to different theropod groups, including several isolated teeth from different Upper Jurassic localities here assigned to Ceratosaurus, Torvosaurus, and Allosaurus, as well as an isolated tooth from the Lower Cretaceous that is attributed to an indeterminate allosauroid. Other theropod remains consist mostly of vertebral fragments of indeterminate avetheropods and allosauroids. Elements of other dinosaur groups are also represented, including a few vertebrae here referred to stegosaurians and iguanodontians, as well as a vertebra and some appendicular remains attributed to sauropods. Two vertebrae assigned to thalattosuchians were also identified. The study of this collection allows to better characterize the diversity of Late Jurassic dinosaur faunas from different areas of the Lusitanian Basin and provides some data on the poorly known Cretaceous fossil record of theropods from Portugal.

LINK

https://www.app.pan.pl/article/item/app011132023.html

ABSTRACT

The question of what the ancient life cycle of tetrapods was like forms a key component in understanding the origin of land vertebrates. The existence of distinct larval forms, as exemplified by many lissamphibians, and their transformation into adults is an important aspect in this field. The temnospondyls, the largest clade of Palaeozoic–Mesozoic non-amniote tetrapods, covered a wide ecomorphological range from fully aquatic to terrestrial taxa. In various species, rich ontogenetic data have accumulated over the past 130 years, permitting the study of early phases of temnospondyl development. In temnospondyls, eight ontogenetic phases have been identified in which the skeleton formed. In branchiosaurids and the eryopiform Sclerocephalus, large parts of the ossification sequence are now known. Most taxa in which small specimens are preserved had aquatic larvae with external gills that superficially resemble larval salamanders. In the edopoids, dvinosaurs, and eryopiforms, the larvae developed slowly, with incompletely ossified axial and appendicular skeletons, but possessed a fast-developing dermal skull with strong teeth. Irrespective of adult terrestriality or a fully aquatic life, there was no drastic transformation during later ontogeny, but a slow and steady acquisition of adult features. In dissorophoids, the limbs developed at a much faster pace, whereas skull formation was slowed down, especially in the amphibamiforms, and culminating in the neotenic Branchiosauridae. In the zatracheid Acanthostomatops, slow but profound transformation led to a fully terrestrial adult. The basal dissorophoid Stegops retained rapid development of dermal skull bones and established a fully dentigerous, strongly ossified palate early. In Micromelerpeton, formation of the last skull bones was slightly delayed and metamorphosis remained a long and steady phase of morphological transformations. In amphibamiforms, metamorphosis became more drastic, with an increasing number of events packed into a short phase of ontogeny. This is exemplified by Apateon, Platyrhinops, and Amphibamus in which this condensation was maximised. We distinguish three different types of metamorphosis (morphological, ecological and drastic) that evolved cumulatively in early tetrapods and within temnospondyls.

LINK

https://onlinelibrary.wiley.com/doi/10.1111/brv.13084

ABSTRACT

We describe upupiform, coraciiform, and possible piciform birds from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). The material includes partial skeletons of a new species of a small upupiform bird, Waltonirrisor tendringensis, gen. et sp. nov., which is the earliest known representative of the Upupiformes. Three very similar species of stem group rollers are assigned to Laputavis robusta, Septencoracias morsensis, and S. simillimus, sp. nov. These species only differ in minor features, which raises the possibility that the taxon Sepencoracias Bourdon, 2016 is a junior synonym of Laputavis Dyke, 2001. A smaller stem group roller from Walton-on-the-Naze resembles the North American primobucconid species Primobucco mcgrewi. We also describe two species of a new genus-level taxon, Pristineanis, gen. nov., which shows close affinities to the North American “Neanis” kistneri and may be a stem group representative of the Piciformes. In many aspects of their postcranial osteology, the stem group Coracii from Walton-on-the-Naze, as well as the new taxon Pristineanis, resemble coeval Trogoniformes from this fossil site. Because trogons are the extant sister taxon of the Picocoraciades – the clade including the Upupiformes, Coraciiformes, and Piciformes –, the shared similarities are likely to be plesiomorphic for this latter clade. Early Cenozoic representatives of the Upupiformes and Coraciiformes were much smaller than their extant relatives, which suggests that the Picocoraciades are an avian example of Cope’s Rule that postulates a tendency for size increase in evolutionary lineages over time.

LINK

https://link.springer.com/article/10.1007/s12542-024-00687-9

ABSTRACT

Knowledge of the Campanian-Maastrichtian titanosaurian sauropods from southern South America has increased markedly in recent years. Several taxa have been reported from northern Patagonia, as well as few taxa from southern Patagonia that were described in the last years. However, titanosaurs from the end-Cretaceous of Central Patagonia are poorly known. Here we report the associated remains of a new species of a titanosaurian sauropod from the La Colonia Formation found in northern Chubut Province. Titanomachya gimenezi gen. et sp. nov. is represented by a caudal vertebra and appendicular elements. Titanomachya, is interpreted as a member of Lithostrotia, sharing derived features with saltasaurids and bearing unique characteristics in the astragalus. The astragalus morphology of Titanomachya display an intermediate form between Colossosauria and Saltasauroidea, allowing articulation between zeugopodium and autopodium with contributions from both the tibia and fibula. The type specimen is a small-sized adult, estimated at 5.8–9.8 tons. Comparative analyses reveal distinct sauropod faunas in different Patagonian regions and Brazilian formations during the Campanian – Maastrichtian. In northern Patagonia, aeolosaurines and saltasaurines predominate, while in southern Patagonia predominate colossosaurians and other large titanosaurs. The less well-known sauropod fauna from central Patagonia includes aeolosaurines, eutitanosaurs, and the addition of small-bodied saltasauroids such as Titanomachya.

LINKS

https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2332997
https://www.tandfonline.com/doi/epdf/10.1080/08912963.2024.2332997?needAccess=true

ABSTRACT

Pycnodont fishes were a successful clade of neopterygian fishes that are predominantly found in shallow marine deposits. However, throughout their long 180 million year reign (Late Triassic–end Eocene), they made multiple incursions into both brackish and freshwater environments. This fossil record mostly consists of fragmentary dental material, but articulated specimens are known from Early Cretaceous lacustrine localities in Spain. This review article aims to document all non-marine occurrences of Pycnodontiformes throughout most of the Mesozoic and early Paleogene. This review highlights two interesting trends in the history of non-marine habitat colonization by pycnodonts: (1) a huge spike in non-marine occurrences during the Cretaceous; and (2) that most occurrences in non-marine localities occurred at the latest Cretaceous period, the Maastrichtian. The high number of colonization events within the Cretaceous lines up with extreme climatic events, such as high temperatures resulting in high sea levels which regularly flooded continental masses, allowing pycnodonts easier access to non-marine habitats. The increased presence of pycnodonts in brackish and freshwater habitats during the Maastrichtian might have played a role in their survival through the K/Pg extinction event. Freshwater habitats are not as vulnerable as marine ecosystems to environmental disturbance as the base of their food chain relies on detritus. Pycnodonts might have used such environments as a refuge and began to occupy marine waters after the K/Pg extinction event.

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https://www.mdpi.com/1424-2818/16/4/225

ABSTRACT

Sabertoothed mammalian predators, all now extinct, were almost exclusively feloid carnivorans (Eutheria, Placentalia): here a couple of extinct metatherian predators are considered in comparison with the placental sabertooths. Thylacosmilus (the “marsupial sabertooth”) and Thylacoleo (the “marsupial lion”) were both relatively large (puma-sized) carnivores of the Plio-Pleistocene in the Southern Hemisphere (Argentina and Australia, respectively). Both carnivores have captured the public imagination, especially as predators that were somehow analogous to northern placental forms. But a more detailed consideration of their morphology shows that neither can be simply analogized with its supposed placental counterpart. While Thylacosmilus did indeed have saber-like canines, many aspects of its anatomy show that it could not have killed prey in the manner proposed for the sabertoothed felids such as Smilodon. Rather than being an active predator, it may have been a specialized scavenger, using the hypertrophied canines to open carcasses, and perhaps deployed a large tongue to extract the innards. Thylacoleo lacked canines, and its supposedly “caniniform” incisors could not have acted like a felid's canines. Nevertheless, while its mode of dispatching its prey remains a subject for debate, it was clearly a powerful predator, likely to be capable of bringing down prey bigger than itself while hunting alone. In that regard, it may have filled the ecomorphological role proposed for placental sabertooths, and so despite the lack of canines can be nominated as the true “marsupial sabertooth” out of the two extinct taxa.

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https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25444

ABSTRACT

Oviraptorosaurians were a theropod dinosaur group that reached high diversity in the Late Cretaceous. Within oviraptorosaurians, the later diverging oviraptorids evolved distinctive crania which were extensively pneumatised, short and tall, and had a robust toothless beak, interpreted as providing a powerful bite for their herbivorous to omnivorous diet. The present study explores the ability of oviraptorid crania to resist large mechanical stresses compared with other theropods and where this adaptation originated within oviraptorosaurians. Digital 3D cranial models were constructed for the earliest diverging oviraptorosaurian, Incisivosaurus gauthieri, and three oviraptorids, Citipati osmolskae, Conchoraptor gracilis, and Khaan mckennai. Finite element analyses indicate oviraptorosaurian crania were stronger than those of other herbivorous theropods (Erlikosaurus and Ornithomimus) and were more comparable to the large, carnivorous Allosaurus. The cranial biomechanics of Incisivosaurus align with oviraptorids, indicating an early establishment of distinctive strengthened cranial biomechanics in Oviraptorosauria, even before the highly modified oviraptorid cranial morphology. Bite modelling, using estimated muscle forces, suggests oviraptorid crania may have functioned closer to structural safety limits. Low mechanical stresses around the beaks of oviraptorids suggest a convergently evolved, functionally distinct rhamphotheca, serving as a cropping/feeding tool rather than for stress reduction, when compared with other herbivorous theropods.

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https://www.nature.com/articles/s42003-024-06137-1

ABSTRACT

A small sample of vertebrate fish scales, predominantly those of a thelodont agnathan, the turiniid Turinia sp. cf. T. nachoi, and a few from the acanthodian gnathostome Nostovicina laticristata, have been found in the Lower Devonian Güneyyaka Formation in the Ovacik slice of the Tahtalidağ Nappe north of Alanya (Antalya Unit) in the Antalya region, southwest Anatolia, southern Turkey. The area is considered to have been on the northern Gondwana margin at that time. The fish microfossils support a Lochkovian to possible early Pragian at youngest (Early Devonian) age for the limestone beds, and are amongst the oldest known Turkish vertebrate fossils.

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https://www.tandfonline.com/doi/full/10.1080/03115518.2024.2329931

ABSTRACT

The Jurassic period was a time of major diversification for Mesozoic marine reptiles, including Ichthyosauria, Plesiosauria and thalattosuchian Crocodylomorpha. The latter originated in the Early Jurassic and thrived during the Late Jurassic. Unfortunately, the Middle Jurassic, a crucial time in their evolution, has a poor fossil record. Here, we document the first evidence of macrophagous/durophagous Machimosaurini-tribe teleosauroid thalattosuchians from the late Bajocian (ca 169 Ma) in the form of three robust tooth crowns with conical blunt shapes and anastomosed pattern of thick enamel ridges towards the apex, associated with the skeleton of a large ichthyosaur lacking preserved tooth crowns. The tooth crowns were found on the posterior section of the lower jaw (left angular), a lacrimal and the axis neural arch of the ichthyosaur. In addition, some of the distal sections of the posterior dorsal ribs of the ichthyosaur skeleton exhibit rounded bite marks and some elongated furrows that fit in size and shape with the Machimosaurini teeth. These marks, together with the absence of healing in the rib bone are interpreted here as the indicators of peri- to post-mortem scavenging by a Machimosaurini teleosauroid after the large ichthyosaur carcass settled on the floor of a shallow ocean.

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https://royalsocietypublishing.org/doi/10.1098/rsos.240071

ABSTRACT

The southern Mendoza province, located in the northern region of Patagonia, was inhabited by hunter-gatherer groups until historic times. Previous archaeological studies have reported canid remains among faunal assemblages, which were assumed to be part of the human diet. However, the taxonomic identification and significance of these canids within human groups have raised questions. In this study, we used ancient DNA analysis, morphological examination and stable isotope analysis (δ13Ccol and δ15N) to re-evaluate the taxonomic assignment of a canid discovered at the Late Holocene burial site of Cañada Seca. Previous morphological identifications suggested that it belonged to the genus Lycalopex, but our results conclusively demonstrate that the individual belongs to the extinct fox species Dusicyon avus. This finding expands Dusicyon avus’ known geographical distribution to Patagonia’s northern extremity. Furthermore, statistical predictions based on genetic divergence undermine the hypothesis that hybridization between Canis and Dusicyon, facilitated by the introduction of domestic dogs, played a role in the extinction of Dusicyon species. On the other hand, our findings indicate that a Dusicyon avus individual shared a similar diet and was probably buried alongside humans, suggesting a close relationship between the two species during their lives and deaths.

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https://royalsocietypublishing.org/doi/10.1098/rsos.231835

ABSTRACT

Molecular clock estimates suggest the origin of Annelida dates back to the Ediacaran period, which is in discordance with the first appearance of this taxon in the early Cambrian, as evidenced by the fossil records of stem-group and basally branching crown-group annelids. Using new material from the early Cambrian Guanshan biota (Cambrian Series 2, Stage 4), we re-interpret Gaoloufangchaeta bifurcus Zhao, Li & Selden, 2023, as the earliest known errantian annelid. Gaoloufangchaeta has a prominent anterior end bearing three pairs of putatively sensory appendages and a pair of anterior eyes; a muscular eversible pharynx with papillae is identified. The presence of enlarged parapodia with acicula-like structures and long capillary chaetae suggests a pelagic lifestyle for this taxon. Our phylogenetic analyses recover Gaoloufangchaeta within the Phyllodocida (Pleistoannelida, Errantia), extending the origin of Errantia back to the early Cambrian. Our data are in line with the hypothesis that Annelida diverged before the Cambrian and indicate both morphological and ecological diversification of annelids in the early Cambrian.

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https://royalsocietypublishing.org/doi/10.1098/rsos.231580

ABSTRACT

The bone-eating worm Osedax is a speciose and globally distributed clade, primarily found on whale carcasses in marine environments. The earliest fossil evidence for Osedax borings was previously described in plesiosaur and sea turtle bones from the mid-Cretaceous of the United Kingdom, representing the only unequivocal pre-Oligocene occurrences. Confirming through CT scanning, we present new evidence of Osedax borings in three plesiosaur specimens and, for the first time, identify borings in two mosasaur specimens. All specimens are from the Late Cretaceous: one from the Cenomanian of the United Kingdom, two from the Campanian of the southeastern United States, and two from the Maastrichtian of Belgium. This extends the geographic range of Osedax in the Cretaceous to both sides of the northern Atlantic Ocean. The bones contain five borehole morphotypes, potentially created by different species of Osedax, with the Cenomanian specimen containing three morphotypes within a single tooth. This combined evidence of heightened species diversity by the Cenomanian and broad geographic range by the Campanian potentially indicates an earlier origin and diversification for this clade than previously hypothesized. Preservational biases indicate that Osedax was probably even more widely distributed and speciose in the Cretaceous than apparent in the fossil record.

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https://royalsocietypublishing.org/doi/10.1098/rspb.2023.2830

ABSTRACT

The Itaboraí Basin, municipality of Itaboraí, Rio de Janeiro state, Brazil, preserved an Early Eocene vertebrate assemblage. Among its representatives, Metatheria comprises its most diverse clade, with a minimum of 29 genera and 43 species. Considering this diversity, large-sized taxa (based on didelphid standards, i.e., between 1 kg and 3.3 kg) are represented by Didelphopsis, Protodidelphis and Patene, each considered to have explored different trophic niches. However, the discovery of a new large-sized metatherian from this locality, here named Xenocynus crypticus gen. et sp. nov., indicates that the trophic complexity of Itaboraí’s metatherians could not be so well-defined. Xenocynus crypticus gen. et sp. nov. is identified by the presence of its reduced StD, long postmetacrista, short protocone, talonid's area much smaller than the one of trigonid, spaced paraconid and metaconid (bases are not in contact), molar series increasing in size from m1 to m4, deep maxillary pits between upper molars, and robust symphysis. We included Itaboraidelphys camposi, X. crypticus gen. et sp. nov. and other large-sized taxa in two PCA analyses, the first considering morphometric measurements and the second considering some morphofunctional indexes, to test their placement in morphospace. Our analyses indicated that these taxa exhibit distinctive morphometric and morphofunctional patterns, suggesting low trophic niches overlapping between them. The results indicate that X. crypticus gen. et sp. nov. was a generalized carnivore (insectivory-carnivory), more specialized than the insectivorous/omnivorous Itaboraidelphys camposi, but less specialized than the larger Patene simpsoni, a carnivorous taxon.

LINK

https://www.sciencedirect.com/science/article/abs/pii/S0895981124001172?via%3Dihub

ABSTRACT

The Jurassic record of South American theropods is scarce, being represented by only seven nominal species. Four of these species (Eoabelisaurus mefi, Asfaltovenator vialidadi, Condorraptor currumili and Piatnitzkysaurus floresi) have been found in Toarcian-aged localities in the Cañadón Asfalto Formation (Chubut Province, Argentina) and, as a result, this unit has the highest known diversity of Jurassic theropods on the continent. A dentary with teeth in situ (MPEF-PV 6775) was found close to the base of this formation and differs from the other species from the unit with overlapping morphology. MPEF-PV 6775 resembles the dentary of the Late Jurassic North American theropod Ceratosaurus in being a robust bone, with a strong dorsal curvature in lateral view, and having relatively tall tooth crowns. MPEF-PV 6775 was scored in two matrices that have a broad taxonomic sample focused on Theropoda and the new specimen was recovered in large polytomies with other early neotheropods. A third analysis was conducted scoring MPEF-PV 6775 into a matrix focused in ceratosaurs because of its morphological similarities to Ceratosaurus. In this analysis, MPEF-PV 6775 was recovered as the sister taxon to Ceratosaurus, sharing with the later a ventral margin of the dentary that is strongly convex anteroposteriorly. These results suggest that MPEF-PV 6775 is a ceratosaurian and probably a ceratosaurid. Thus, our results indicate a higher taxonomic diversity of theropods and, in particular, ceratosaurs in the Cañadón Asfalto Formation. MPEF-PV 6775 seems to provide more evidence for the presence of ceratosaurids in the Jurassic of South America, together with isolated teeth described from the Late Jurassic of Uruguay and some analyses that recovered Eoabelisaurus and Berberosaurus within this clade.

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https://www.tandfonline.com/doi/full/10.1080/14772019.2024.2318262

ABSTRACT

Very large unidentified elongate and rounded fossil bone segments of uncertain origin recovered from different Rhaetian (Late Triassic) fossil localities across Europe have been puzzling the paleontological community since the second half of the 19th century. Different hypotheses have been proposed regarding the nature of these fossils: (1) giant amphibian bones, (2) dinosaurian or other archosaurian long bone shafts, and (3) giant ichthyosaurian jaw bone segments. We call the latter proposal the ‘Giant Ichthyosaur Hypothesis’ and test it using bone histology. In presumable ichthyosaur specimens from SW England (Lilstock), France (Autun), and indeterminate cortical fragments from Germany (Bonenburg), we found a combination of shared histological features in the periosteal cortex: an unusual woven-parallel complex of strictly longitudinal primary osteons set in a novel woven-fibered matrix type with intrinsic coarse collagen fibers (IFM), and a distinctive pattern of Haversian substitution in which secondary osteons often form within primary ones. The splenial and surangular of the holotype of the giant ichthyosaur Shastasaurus sikanniensis from Canada were sampled for comparison. The results of the sampling indicate a common osteohistology with the European specimens. A broad histological comparison is provided to reject alternative taxonomic affinities aside from ichthyosaurs of the very large bone segment. Most importantly, we highlight the occurrence of shared peculiar osteogenic processes in Late Triassic giant ichthyosaurs, reflecting special ossification strategies enabling fast growth and achievement of giant size and/or related to biomechanical properties akin to ossified tendons.

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https://peerj.com/articles/17060/

ABSTRACT

Skeletal remains of sauropod dinosaurs have been known from Australia for over 100 years. Unfortunately, the classification of the majority of these specimens to species level has historically been impeded by their incompleteness. This has begun to change in the last 15 years, primarily through the discovery and description of several partial skeletons from the Cenomanian–lower Turonian (lower Upper Cretaceous) Winton Formation in central Queensland, with four species erected to date: Australotitan cooperensis, Diamantinasaurus matildae, Savannasaurus elliottorum, and Wintonotitan wattsi. The first three of these appear to form a clade (Diamantinasauria) of early diverging titanosaurs (or close relatives of titanosaurs), whereas Wintonotitan wattsi is typically recovered as a distantly related non-titanosaurian somphospondylan. Through the use of 3D scanning, we digitised numerous specimens of Winton Formation sauropods, facilitating enhanced comparison between type and referred specimens, and heretofore undescribed specimens. We present new anatomical information on the holotype specimen of Diamantinasaurus matildae, and describe new remains pertaining to twelve sauropod individuals. Firsthand observations and digital analysis enabled previously proposed autapomorphic features of all four named Winton Formation sauropod species to be identified in the newly described specimens, with some specimens exhibiting putative autapomorphies of more than one species, prompting a reassessment of their taxonomic validity. Supported by a specimen-level phylogenetic analysis, we suggest that Australotitan cooperensis is probably a junior synonym of Diamantinasaurus matildae, but conservatively regard it herein as an indeterminate diamantinasaurian, meaning that the Winton Formation sauropod fauna now comprises three (rather than four) valid diamantinasaurian species: Diamantinasaurus matildae, Savannasaurus elliottorum, and Wintonotitan wattsi, with the latter robustly supported as a member of the clade for the first time. We refer some of the newly described specimens to these three species and provide revised diagnoses, with some previously proposed autapomorphies now regarded as diamantinasaurian synapomorphies. Our newly presented anatomical data and critical reappraisal of the Winton Formation sauropods facilitates a more comprehensive understanding of the mid-Cretaceous sauropod palaeobiota of central Queensland.

LINK

https://peerj.com/articles/17180/

ABSTRACT

Ultrastenos willisi from the Oligocene of the Riversleigh World Heritage Area, was described as a mekosuchine crocodylian with a gavial-like, longirostrine morphology. However, the rostrum is not preserved, and the reconstruction rests on a set of inferences that are based on the shape of a mandibular fragment and a cranial reconstruction that was assembled from non-joining fragments. Contrasting with the reconstruction are the proportionally small supratemporal fenestrae and the blunt, molariform posterior teeth, which are discordant with the slender longirostrine morphotype. The issue is resolved by the discovery that QM F31076, a posterior skull fragment (‘White Hunter cranial form 1’), which has been referred to U. willisi, is likely to be the missing posterior end of the extremely brevirostrine holotype of ‘Baru’ huberi. QM F31076 ‘White Hunter cranial form 1’ can be further linked to the holotype of ‘B’. huberi via their matching size, preservation and dermal ornamentation. ‘White Hunter cranial form 1’, in turn, shares a combination of cranial apomorphies with U. willisi and belongs to the same species, indicating that U. willisi is a junior subjective synonym of ‘B’. huberi. However, previous phylogenetic analyses have found that ‘Baru’ huberi is more closely related to other mekosuchine genera than it is to Baru. Consequently, Ultrastenos is retained as a valid genus, and the new combination Ultrastenos huberi is established. With the discovery that Ultrastenos is not a longirostrine taxon there are no longer any known longirostrine mekosuchines, suggesting that the otherwise disparate Mekosuchinae failed to occupy this region of morphospace.

LINK

https://palaeo-electronica.org/content/2024/5183-ultrastenos-revised