PALEONTOLOGY IN JUNE, 2024

ABSTRACT

Knowledge of Cambrian animal anatomy is limited by preservational processes that result in compaction, size bias, and incompleteness. We documented pristine three-dimensional (3D) anatomy of trilobites fossilized through rapid ash burial from a pyroclastic flow entering a shallow marine environment. Cambrian ellipsocephaloid trilobites from Morocco are articulated and undistorted, revealing exquisite details of the appendages and digestive system. Previously unknown anatomy includes a soft-tissue labrum attached to the hypostome, a slit-like mouth, and distinctive cephalic feeding appendages. Our findings resolve controversy over whether the trilobite hypostome is the labrum or incorporates it and establish crown-group euarthropod homologies in trilobites. This occurrence of moldic fossils with 3D soft parts highlights volcanic ash deposits in marine settings as an underexplored source for exceptionally preserved organisms.

LINK(S)

https://www.science.org/doi/10.1126/science.adl4540

ABSTRACT

The hindlimb of pterosaurs has been much less studied than the pterosaur wing. However, it is relevant to understand the evolution, phylogeny and ecology of these animals. This study provides the first complete and detailed description of the ankle of Pterodaustro guinazui. It documents three ontogenetic stages observed for the fusion of the tibiotarsus: in the youngest specimens the proximal tarsals are not fused to the tibia; in the subadults the tibiotarsus is formed, but with the suture still visible; in the adults, the tibiotarsus is entirely formed, without any suture. The fusion between astragalus and calcaneum precedes tibiotarsal fusion, but in close succession. The medial condyle of the tibiotarsus is made up of the astragalus, and the lateral condyle is composed of the calcaneum and part of the astragalus. The distal tibiotarsus has three articular facets, the most medial of which seems to greatly restrict the flexion-extension movement, a feature atypical of pterosaurs. The lateral part of the distal tibiotarsus, on the contrary, allows a very wide range of movement. Pterodaustro guinazui seems to have had an asymmetrical ankle joint, which could facilitate movements linked to wading behavior. We describe juvenile specimens that retain discrete distal tarsals Ⅱ and Ⅲ (common in the “non-pterodactyloid” pterosaurs), but also more mature specimens with completely fused distal tarsals Ⅱ and Ⅲ (a condition always observed in the late pterodactyloids). Moreover, the lateral distal tarsal (LDT) appears more robust in Pterodaustro than in Peteinosaurus or Dimorphodon, but shares a waisted shape with these taxa, unlike the more robust shape of the LDT of late pterodacty-loids. The new information on the Pterodaustro ankle improves our anatomical knowledge of the basal Pterodactyloidea.

LINK(S)

https://www.app.pan.pl/article/item/app010972023.html

ABSTRACT

Resolving the evolutionary relationships of early diverging (‘basal’) ornithischian dinosaurs is a challenging topic in palaeontology, with multiple competing hypotheses on the phylogenetic relationships of heterodontosaurids, ‘hypsilophodontids’, and other early-diverging forms. These hypotheses cannot be directly compared because they are derived from differently constructed datasets (i.e. distinct samples of taxa and characters). This study aims to address these issues by revising and combining the distinct datasets into a single analysis in order to create the most comprehensive dataset for the investigation of the phylogenetic relationships of early-diverging ornithischians. A diphyletic model of Dinosauria is supported, with silesaurs nesting as members of Ornithischia. Heterodontosauridae is resolved as a clade of non-genasaurian ornithischians, rejecting a potential relationship with Marginocephalia. ‘Hypsilophodontid’ taxa span the neornithischian and ornithopod stem, with Thescelosauridae as the sister taxon to Cerapoda. A more restricted Ornithopoda is composed of five main clades: Hypsilophodontidae, Rhabdodontomorpha, Elasmaria, Dryosauridae and Ankylopollexia. Hypsilophodontidae is a valid clade, reduced to two European Barremian taxa. Rhabdodontomorpha does not contain Muttaburrasaurus as originally proposed, but instead expands to include a North American clade formed by Convolosaurus, Iani and Tenontosaurus. Elasmaria contains all non-dryomorph Gondwanan ornithopods, with its members possessing multiple distinct body plans. New results and comparison with previous studies suggest that some members of Dryosauridae are not ‘true dryosaurids’ but various early euiguanodontians that may be more closely related to either Elasmaria or Ankylopollexia. Results group most ‘hypsilophodontids’ in larger clades, significantly reducing the number and extension of ghost lineages throughout all of Neornithischia. These clades also show a degree of endemism, with different lineages present at different continents in the Late Cretaceous. This new phylogenetic analysis unifying previous works will provide a framework for future studies on origins and relations of early diverging ornithischians, and attempting to find stability among the different competing hypotheses.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/14772019.2024.2346577

ABSTRACT

Dacentrurus armatus was the first stegosaur described in the European Upper Jurassic at the end of the 19th century. The description of a second dacentrurine taxon, ‘Miragaia longicollum’, diagnosed from material non-comparable with the D. armatus holotype, has been controversial, and its validity has been challenged. In this study, we describe a new relatively complete stegosaurian postcranial skeleton from the Villar del Arzobispo Formation (Upper Jurassic, Spain). The systematic study of this new specimen and a comprehensive taxonomic assessment of the material not attributed to Stegosaurus from the Upper Jurassic of Europe, reveal high morphological homogeneity and an absence of morphological criteria for distinguishing two dacentrurine taxa. Therefore, ‘Mi. longicollum’ is proposed as a subjective junior synonym of D. armatus. Moreover, a new diagnosis for D. armatus is suggested based on the holotype and referred specimens. As a result, only two stegosaurian species, Stegosaurus stenops and D. armatus, are recognized in Europe during the Late Jurassic. Finally, the species longispinus from the Morrison Formation (Upper Jurassic, USA) is returned to the genus Alcovasaurus.

LINK(S)

https://academic.oup.com/zoolinnean/advance-article-abstract/doi/10.1093/zoolinnean/zlae074/7696911?redirectedFrom=fulltext&login=false

ABSTRACT

New pterosaur tracks from the Cenomanian Candeleros Formation (Neuquén Basin) have been discovered in the Aguada de Tuco locality, northwestern Patagonia, Argentina. Preserved in medium-grained sandstones originating from alluvial deposits, these tracks include both isolated manus and pes impressions. The manus tracks are tridactyl and display a marked asymmetry, while pes tracks exhibit three-digit impressions and a subrectangular to subtriangular shape. The absence of a clearly defined trackway, coupled with the limited preservation quality of the documented pes tracks and distinctions from known pterosaur ichnotaxa, prompted the provisional assignment of these tracks to aff. Pteraichnus isp. They also exhibit a different morphology from previously recorded tracks within the same unit, thus contributing to a greater morphological variability of pterosaur tracks for the Candeleros Formation. Additionally, these tracks are found in association with narrow furrows interpreted as traces left by pterosaur manus and pes claws. Considering the shape and preservation of these tracks and the fragmentary record of pterosaurs from the Neuquén Basin, it is possible to attribute the producers to pterodactyloid pterosaurs. Moreover, the observed variability in manus track size, all sharing a similar morphology, suggests having been produced by individuals of different ages rather than different species of pterodactyloid pterosaurs. This study significantly contributes to our understanding of the pterosaur track record from Gondwana and the Cenomanian worldwide.

LINK(S)

https://www.sciencedirect.com/science/article/abs/pii/S0031018224003274?via%3Dihub

ABSTRACT

Before the rise of dinosaurs and pterosaurs, pseudosuchians—reptiles from the crocodilian lineage—dominated the Triassic land ecosystems. This lineage diversified into several less inclusive clades, resulting in a wide ecomorphological diversity during the Middle and Late Triassic. Some giant pseudosuchians occupied the top of the trophic webs, while others developed extensive bony armor as a defense mechanism, which later evolved as a convergence in the avemetatarsalian lineage. On the other hand, there were groups like the Gracilisuchidae, which was composed of carnivorous forms with lightweight build and less than 1 m in length. The fossil record of gracilisuchids is geographically restricted to China and Argentina, with one ambiguous record from Brazil. In the present study, the first unambiguous gracilisuchid from Brazil is described. Parvosuchus aurelioi gen. et sp. nov. comes from the Dinodontosaurus Assemblage Zone of the Santa Maria Formation, which is associated with the Ladinian-Carnian boundary. Composed of a complete cranium, vertebrae, pelvic girdle and hindlimbs, the new species nests with Gracilisuchus stipanicicorum and Maehary bonapartei in a phylogenetic analysis. Its discovery fills a taxonomic gap in Brazilian pseudosuchian fauna and reveals the smallest known member of this clade from the Dinodontosaurus Assemblage Zone, highlighting the diversity of pseudosuchians during the moment that preceded the dawn of dinosaurs.

LINK(S)

https://www.nature.com/articles/s41598-024-63313-3
https://www.nature.com/articles/s41598-024-63313-3.pdf

ABSTRACT

The Late Cretaceous of western North America supported diverse dinosaur assemblages, though understanding patterns of dinosaur diversity, evolution, and extinction has been historically limited by unequal geographic and temporal sampling. In particular, the existence and extent of faunal endemism along the eastern coastal plain of Laramidia continues to generate debate, and finer scale regional patterns remain elusive. Here, we report a new centrosaurine ceratopsid, Lokiceratops rangiformis, from the lower portion of the McClelland Ferry Member of the Judith River Formation in the Kennedy Coulee region along the Canada-USA border. Dinosaurs from the same small geographic region, and from nearby, stratigraphically equivalent horizons of the lower Oldman Formation in Canada, reveal unprecedented ceratopsid richness, with four sympatric centrosaurine taxa and one chasmosaurine taxon. Phylogenetic results show that Lokiceratops, together with Albertaceratops and Medusaceratops, was part of a clade restricted to a small portion of northern Laramidia approximately 78 million years ago. This group, Albertaceratopsini, was one of multiple centrosaurine clades to undergo geographically restricted radiations, with Nasutuceratopsini restricted to the south and Centrosaurini and Pachyrostra restricted to the north. High regional endemism in centrosaurs is associated with, and may have been driven by, high speciation rates and diversity, with competition between dinosaurs limiting their geographic range. High speciation rates may in turn have been driven in part by sexual selection or latitudinally uneven climatic and floral gradients. The high endemism seen in centrosaurines and other dinosaurs implies that dinosaur diversity is underestimated and contrasts with the large geographic ranges seen in most extant mammalian megafauna.

LINK(S)

https://peerj.com/articles/17224/
https://peerj.com/articles/17224.pdf

ABSTRACT

A new specimen of Haplocanthosaurus is described based on bones excavated from the Late Jurassic Dry Mesa Dinosaur Quarry near Delta, Colorado. The specimen consists of seven dorsal vertebrae and a right tibia and is identified as Haplocanthosaurus based on the dorsally angled transverse processes, tall neural arch peduncles, low parapophyses relative to the diapophyses in the posterior dorsal vertebrae, and the robustness of the tibia combined with a greatly expanded distal articular surface. The discovery adds to our understanding of the biostratigraphy of Haplocanthosaurus, showing this genus is definitively present in the Brushy Basin Member of the Morrison Formation, and making this individual the geologically youngest Haplocanthosaurus specimen on the Colorado Plateau. The identification of this genus adds to the known diversity of sauropods at Dry Mesa Dinosaur Quarry (DMDQ), which is at least six distinct genera, making DMDQ the most diverse single locality of sauropods in the Morrison Formation and the world.

LINK(S)

https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25520

ABSTRACT

Caipirasuchus is a genus of sphagesaurid notosuchian from the Bauru Basin (Upper Cretaceous), southeast Brazil. They were small-sized herbivorous/omnivorous animals, that measured around 1 metre in length, and had a wide diversity and geographical dispersion in the basin. Here, we diagnosed the 6th species of the genus, originating from sandstones of the Adamantina Formation in the municipality of Catanduva, São Paulo State. Caipirasuchus presents a significant variation in the morphology of structures in the choana region. In particular, the new species has chambers in the wings of the pterygoids that connect with an extension of the airways, suggesting a region of resonance used in vocalisation. The different palatal structures in Caipirasuchus may be related to distinct bioacoustic signatures and indicate apossible improvement in the social organisation of Caipirasuchus.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2364332

ABSTRACT

Ichthyosaurs, an iconic lineage of Mesozoic marine reptiles, were an important component of recovering ecosystems after the Permo-Triassic Mass Extinction event. Mixosauridae, a clade of small, early-diverging ichthyosaurs, were of particular significance for this process, being abundant predators in Middle Triassic shallow seas. Despite the abundance of well-preserved mixosaurid specimens from South China, Mixosaurus panxianensis remains the only comprehensively described species, hindering our understanding of the variability, taxonomy and diversity of mixosaurids from this re-gion. Here, we report a new species of Mixosaurus, Mixosaurus luxiensis, from Luxi County, Yunnan Province, South China. The wider postorbital skull portion differentiates the new species from Mixosaurus cornalianus and Mixosaurus kuhnschnyderi from central Europe. The non-durophagous dentition, composed of tiny piercing mesial teeth and robust but pointed distal teeth, resembles the dentition of M. cornalianus. However, the distal teeth of M. luxiensis sp. nov. are twice the size of the mesial ones, in contrast to M. cornalianus, in which the mesial and distal teeth are approximately equal in size. The forelimb exhibits a unique morphology, including a proportionally narrow radius, the presence of a peripheral notch on the ulna, and a large metacarpal V. A preliminary phylogenetic analysis suggests a close affinity of the new taxon with M. cornalianus from Western Tethys. Our study introduces important, new anatomical information on Mixosaurus from South China, useful for future studies of mixosaurid diversity.

LINK(S)

https://app.pan.pl/article/item/app011332024.html
https://app.pan.pl/archive/published/app69/app011332024.pdf
https://app.pan.pl/archive/published/SOM/app69-Fang_etal_SOM.pdf

ABSTRACT

Background
Unenlagiine paravians are among the most relevant Gondwanan theropod dinosaur clades for understanding the origin of birds, yet their fossil record remains incomplete, with most taxa being represented by fragmentary material and/or separated by lengthy temporal gaps, frustrating attempts to characterize unenlagiine evolution.

Results and conclusions
Here we describe Diuqin lechiguanae gen. et sp. nov., a new unenlagiine taxon from the Upper Cretaceous (Santonian) Bajo de la Carpa Formation of the Neuquén Basin of Neuquén Province in northern Patagonia, Argentina that fills a substantial stratigraphic gap in the fossil record of these theropods. Although known only from a very incomplete postcranial skeleton, the preserved bones of Diuqin differ from corresponding elements in other unenlagiines, justifying the erection of the new taxon. Moreover, in several morphological aspects, the humerus of Diuqin appears intermediate between those of geologically older unenlagiines from the Neuquén Basin (e.g., Unenlagia spp. from the Turonian–Coniacian Portezuelo Formation) and that of the stratigraphically younger, larger-bodied Austroraptor cabazai from the Campanian–Maastrichtian Allen Formation. Consequently, the morphology of the new taxon appears to indicate a transitional stage in unenlagiine evolution. Phylogenetic analysis recovers Diuqin as a paravian with multiple plausible systematic positions, but the strongest affinity is with Unenlagiinae. The humerus of the new form exhibits subcircular punctures near its distal end that are interpreted as feeding traces most likely left by a conical-toothed crocodyliform, mammal, or theropod, the latter potentially corresponding to a megaraptorid or another unenlagiine individual. Thus, in addition to filling important morphological and temporal gaps in unenlagiine evolutionary history, the new taxon also offers information relating to the paleoecology of these theropods.

LINK(S)

https://bmcecolevol.biomedcentral.com/articles/10.1186/s12862-024-02247-w
https://bmcecolevol.biomedcentral.com/counter/pdf/10.1186/s12862-024-02247-w.pdf

ABSTRACT

Top speed estimates of extinct dinosaurs have been of long-standing interest to gain better understanding of the animals lifestyle and ecology. Tyrannosaurus rex top speeds have been examined using a wide range of methods that draw on more traditional biomechanical formulas, computer simulations, and allometric equations based on mass. However, these calculations may be made more precise using input from contemporary research on anatomy and biomechanics that account for mass allometry and scaling. This study builds on existing studies in anatomy, biomechanical data, and established equations for locomotion to calculate a muscular driven range of top speed for several (n=4) specimens that had sufficient data to undertake this work. When properly refined with additional data on muscle mass allometry and scaling, several adult specimens of T. rex could confidently be placed in a range of top speed from 7.7 to 10.5 m/s, and possibly up to 10.7 m/s. Additionally, a younger specimen of T. rex was analyzed and found to have a higher top speed than the adult T. rex at 6.3 to 14.5 m/s. Although the estimated top speeds in this study are slower than some previous estimates, these results find some support for slow running gaits and reinforce interpretations of T. rex as an active and effective apex predator. Future work can build upon this study by investigating how muscular driven top speeds may affect ontogenetic niche partitioning and prey species regularly targeted by adult T. rex.

LINK(S)

https://www.biorxiv.org/content/10.1101/2024.06.13.596099v1
https://www.biorxiv.org/content/biorxiv/early/2024/06/13/2024.06.13.596099.full.pdf

ABSTRACT

Much of the ecological discourse surrounding the polarising theropod Spinosaurus has centred on qualitative discussions. Using a quantitative multivariate data analytical approach on size-adjusted linear measurements of the skull, we examine patterns in skull shape across a range of sauropsid clades and three ecological realms (terrestrial, semi-aquatic, and aquatic). We utilise cluster analyses to identify emergent properties of the data which associate properties of skull shape with ecological realm occupancy. Results revealed terrestrial ecologies to be significantly distinct from both semi- and fully aquatic ecologies, the latter two were not significantly different. Spinosaurids (including Spinosaurus) plotted away from theropods in morphospace and close to both marine taxa and wading birds. The position of nares and the degree of rostral elongation had the greatest effect on categorisation. Comparisons of supervised (k-means) and unsupervised clustering demonstrated categorising taxa into three groups (ecological realms) was inappropriate and suggested instead that cluster division is based on morphological adaptations to feeding on aquatic versus terrestrial food items. The relative position of the nares in longirostrine taxa is associated with which skull bones are elongated. Rostral elongation is observed by either elongating the maxilla and the premaxilla or by elongating the maxilla only. This results in the nares positioned towards the orbits or towards the anterior end of the rostrum respectively, with implications on available feeding methods. Spinosaurids, especially Spinosaurus, show elongation in the maxilla-premaxilla complex, achieving similar functional outcomes to elongation of the premaxilla seen in birds, particularly large-bodied piscivorous taxa. Such a skull construction would bolster “stand-and-wait” predation of aquatic prey to a greater extent than serving other proposed feeding methods.

LINK(S)

https://peerj.com/articles/17544/
https://peerj.com/articles/17544.pdf

ABSTRACT

The Late Cretaceous was not only the most active epoch of Gondwana fragmentation but also a time of significant climatic and evolutionary activity, which has led to the extinction of many vertebrates. The African continent, the core of the supercontinent Gondwana, which became completely separated by the Late Cretaceous, has a poor and incomplete fossil record of that time when compared with other Gondawa continents. Here we report on an important discovery of a new vertebrate-bearing locality from the Campanian Quseir Formation, Qarn Ganah area near Kharga Oasis, Southwestern Desert, Egypt. Paleontological work has resulted in the discovery of a variety of different vertebrate groups including sharks and bony fishes, turtles, crocodyliforms and dinosaurs. The collected specimens are good preserved isolated elements. One partial sauropod skeleton was found including some vertebrae, ribs and limb bones. The recovered vertebrate fauna will be examined in detail to further refine their identification and to establish their taxonomic affinities and establish their collective relationship with other Late Cretaceous African faunas such as Dinosaurs, crocodyliforms and turtles. The new discovery will not only augment the growing collection of Late Cretaceous vertebrate faunas from Africa but also will improve understanding of global faunal changes and evolution during the late Mesozoic.

LINK(S)

https://journals.ekb.eg/article_358602.html
https://journals.ekb.eg/article_358602_39ff6481ca351c55a618e3c11200c39d.pdf

ABSTRACT

Pterosaur remains have been reported from every continent; however, pterosaur skeletons remain rare. A new pterosaur is presented here, Haliskia peterseni gen. et sp. nov., constituting the most complete specimen from Australia from the upper Albian Toolebuc Formation of the Eromanga Basin (Queensland, Australia). A combination of features, including the presence of a premaxillary crest and curved teeth, and the morphology of the scapulocoracoid, support its referral to Anhangueria. Haliskia can be distinguished from all other anhanguerian pterosaurs based on two dental characters: the 4th and 5th tooth pairs are smaller than the 3rd and 6th, and the 2nd and 5th alveoli are smaller than 3–4 and 6–8. Moreover, the hyoid is 70% the total length of the mandible. The phylogenetic analyses presented here place Haliskia within Anhangueria. In one analysis, Haliskia and Ferrodraco are resolved as sister taxa, with Tropeognathus mesembrinus sister to that clade. The other resolves Haliskia, Mythunga and Ferrodraco in a polytomy within Tropeognathinae. The new Australian pterosaur attests to the success of Anhangueria during the latest Early Cretaceous and suggests that the Australian forms were more taxonomically diverse and palaeobiogeographically complex than previously recognized.

LINK(S)

https://www.nature.com/articles/s41598-024-60889-8
https://www.nature.com/articles/s41598-024-60889-8.pdf

ABSTRACT

Isolated theropod teeth are one of the most common vertebrate fossils that have been found in the Khorat Group of Thailand. Furthermore, several isolated teeth have been discovered from the Upper Jurassic Phu Kradung Formation, located in Phu Noi locality of Kalasin Province, Northeastern Thailand. Three of those theropod teeth from the Phu Noi locality show unique dental features that can be distinguished from previous discovered metriacanthosaurid theropod, including the lateral teeth with mesiolingual twisted mesial carinae extending above the cervix line and braided enamel surface texture. Morphological examination with cladistics and morphometric analyses show that these isolated teeth exhibit the synapomorphies of basal tyrannosauroids, closely related to Guanlong wucaii and Proceratosaurus bradleyi from the Jurassic Period. This paper notes the first report of a basal tyrannosauroid in Southeast Asia as well as significantly contributes to our understanding of paleoecology of the Upper Jurassic Phu Kradung Formation and paleobiogeography of Tyrannosauroidea during the Jurassic Period.

LINK(S)

https://li01.tci-thaijo.org/index.php/tnh/article/view/261261?fbclid=IwZXh0bgNhZW0CMTEAAR0IXDDOVOQ8nGHU0TbEGQHUZ42u_TySQOYbXpsUZoswdL9ZN-1mS6wzUVc_aem_AcpXYRpGzaJ1s8cBbDPgp9BGNwrcCzcC2HA9v76o1-cc1QHV6FpQB13MJbuNt-lRDl1JoVNnCHQLaQDwFzdi1jPa
https://li01.tci-thaijo.org/index.php/tnh/article/view/261261/178438

ABSTRACT

Skeletal remains of archosauriform reptiles from the Lower and lower Middle Triassic Buntsandstein Group in the Central European Basin are rare. This paper reports on a partial, almost completely disarticulated skeleton of a previously unknown archosauriform reptile from the lower Middle Triassic (Anisian) Röt Formation of Rotfelden in Baden-Württemberg (Germany). Marcianosuchus angustifrons gen. et sp. nov. is distinguished by the following combination of features: posterodorsal process of premaxilla slender, slightly inclined posterodorsally, and with rounded apex; posterodorsal surface of frontal covered by slightly diverging, fine longitudinal grooves; squamosal with distinct lateral ridge extending for entire length of element; teeth with proportionately small, weakly recurved crowns; humerus considerably shorter than femur; distal shaft of ischium rod-like, not plate-like; pubis with flat distal portion forming ‘pubic apron’: neural spines of posterior cervical and anterior dorsal vertebrae with transversely greatly expanded apices that are Y-shaped in anterior or posterior view; dorsal vertebrae with centra taller dorsoventrally than long anteroposteriorly; dorsal osteoderms more or less rectangular in outline, longer anteroposteriorly than wide mediolaterally, with slightly rounded anterior and concave posterior margins and bearing dorsal ridge or eminence; and dorsal surfaces of osteoderms with unsculptured anterior region and posterior region bearing keel or eminence and covered by sculpturing of radially arranged grooves and pits. Marcianosuchus angustifrons represents the first definitive record of a non-archosaurian archosauriform from the Buntsandstein Group of Germany. Its body plan most closely resembles that of Euparkeria capensis among well-known non-archosaurian archosauriform reptiles, but the two taxa are clearly distinct.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2357326

ABSTRACT

Titanosuchidae are a group of herbivorous, long-snouted dinocephalians with definitive records known only from the middle Permian Tapinocephalus Assemblage Zone of the Beaufort Group (Karoo Supergroup) of South Africa. Here, the taxonomy of this family is revised; of the nine species currently recognized, only two are found to be valid: Titanosuchus ferox and Jonkeria truculenta, which can be distinguished on the basis of appendicular proportions. Jonkeria boonstrai, J. haughtoni, J. ingens, J. parva, J. rossouwi, and J. vanderbyli are synonymized with Jonkeria truculenta, and J. koupensis is considered a nomen dubium (Titanosuchidae indet.). Several new cranial features are described for J. truculenta, such as pachyostosis of the prefrontals, postorbitals and parietals, and an ontogenetic series for the species is presented.

LINK(S)

https://wiredspace.wits.ac.za/items/875e6463-8c48-4a3e-9d8f-a7134e627354

ABSTRACT

Our understanding of the evolutionary origin of Chordata, one of the most disparate and ecologically significant animal phyla, is hindered by a lack of unambiguous stem-group relatives. Problematic Cambrian fossils that have been considered as candidate chordates include vetulicolians, Yunnanozoon, and the iconic Pikaia. However, their phylogenetic placement has remained poorly constrained, impeding reconstructions of character evolution along the chordate stem lineage. Here we reinterpret the morphology of Pikaia, providing evidence for a gut canal and, crucially, a dorsal nerve cord—a robust chordate synapomorphy. The identification of these structures underpins a new anatomical model of Pikaia that shows that this fossil was previously interpreted upside down. We reveal a myomere configuration intermediate between amphioxus and vertebrates and establish morphological links between Yunnanozoon, Pikaia, and uncontroversial chordates. In this light, we perform a new phylogenetic analysis, using a revised, comprehensive deuterostome dataset, and establish a chordate stem lineage. We resolve vetulicolians as a paraphyletic group comprising the earliest diverging stem chordates, subtending a grade of more derived stem-group chordates comprising Yunnanozoon and Pikaia. Our phylogenetic results reveal the stepwise acquisition of characters diagnostic of the chordate crown group. In addition, they chart a phase in early chordate evolution defined by the gradual integration of the pharyngeal region with a segmented axial musculature, supporting classical evolutionary-developmental hypotheses of chordate origins4 and revealing a “lost chapter” in the history of the phylum.

LINK(S)

https://www.cell.com/current-biology/fulltext/S0960-9822(24)00669-9

ABSTRACT

The Caiuá Group (Cretaceous of Southern Brazil) is famous for the Pterosaur Graveyard site, a location that has yielded hundreds of tapejarid specimens, among other taxa. Previous works had already presented various specimens of Pterosaur Graveyard (PG) tapejarids, reporting on several cranial elements showing substantial anatomical variations. These variations have been interpreted as intraspecific in nature, with all tapejarid specimens having been attributed to a single species, Caiuajara dobruskii. The present contribution reassesses the morphological diversity found in PG tapejarid specimens. Evidence is provided for the interpretation of several variations as interspecific in nature, particularly regarding rostral, palatal, occipital, and third cervical morphology. The present data indicate a segregation of the PG tapejarid specimens between two consistent morphotypes, which are interpreted here as two distinct, coexisting species: Caiuajara dobruskii and Torukjara bandeirae gen. et sp. nov.

LINK(S)

https://www.tandfonline.com/eprint/MFA8PHASMQTJMBFPDMMM/full?target=10.1080/08912963.2024.2355664

ABSTRACT

Here, we report a new small-bodied reptile taxon, Idiosaura virginiensis gen. et sp. nov., from the Upper Triassic (Carnian) Vinita Formation of the Richmond basin (Newark Supergroup) in east-central Virginia, U.S.A. The material consists of a fragmentary dentary bearing numerous tall cylindrical teeth implanted in a pleurodont fashion into spongy alveolar tissue. Micro-CT scan data reveal an unusual and complex network of interconnected neurovascular canals within the dentary with connections to the alveolar tissue and pulp cavities of the teeth. The external anatomy of the dentary is consistent with that of Triassic kuehneosaurid reptiles, suggesting affinities to that group; the results of a phylogenetic analysis were inconclusive but do not exclude kuehneosaurid relationships. Alongside the recently described Micromenodon pitti (Rhynchocephalia) and Vinitasaura lizae (Lepidosauromorpha), the new taxon adds to the relatively diverse assemblage of small-bodied reptiles known from the Tomahawk microvertebrate bonebed (USNM locality 39981). Relative tooth complexities of I. virginiensis and V. lizae were analyzed using the Orientation Patch Count Rotated method, and results suggest that the rise of lepidosauromorph ecomorphologies specializing for feeding on invertebrates occurred in Triassic communities alongside non-lepidosauromorph taxa with similar mandibulo-dental features, as in kuehneosaurs.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2353636

ABSTRACT

The Upper Cretaceous sauropod fossil record from Romania is abundant, mostly originated from the Maastrichtian deposits of the western-southwestern margin of the Transylvanian Basin, and in the Hațeg and Rusca Montană basins. Most specimens were found in isolation or in low degree of association and only few partial skeletons have been reported. The presence of at least four taxa was recently considered, including three defined forms: Magyarosaurus dacus, Paludititan nalatzensis and “Magyarosaurus” hungaricus. However, the phylogenetic affinities of these taxa within Lithostrotia are still under debate. A large sample of appendicular remains, predominantly composed by unpublished specimens, is described here in detailed to provide new data about the diversity of the sauropods of the Hațeg Island during the Maastrichtian. All specimens show affinities or are compatible with lithostrotian sauropods, even if the availability of characters of some of them does not allow its attribution to this clade. Five morphotypes for the femora, three to four for the humeri, three for the fibulae, and two for the radii, ulnae, manus, pubes, ischia, tibiae, and pedes are established, supporting the presence of four or five taxa in this domain. A unique partial manus morphology characterized by its extreme gracile metacarpals is reported, only surpassed by an unpublished manus found in the Spanish Lo Hueco fossil-site (late Campanian-early Maastrichtian), suggesting that a titanosaurian lineage with extremely elongated manus inhabited the European realm, in both Hațeg and the Ibero-Armorican islands, at the end of the Mesozoic.

LINK(S)

https://www.sciencedirect.com/science/article/pii/S0195667124001095

ABSTRACT

Being one of the first dinosaurs discovered in Romania, Elopteryx nopcsai is a Paravian dinosaur species whose described material is mainly based on proximal femur fragments. All the known remains assigned to this taxon have been collected from the latest Cretaceous (Maastrichtian) deposits of the Hațeg Basin. A similar fragment was collected from the Nălaț-Vad locality and is herein described. It shares multiple similarities with specimens previously related to Elopteryx and fossils related to other taxa, such as Pengornithidae and Oviraptorosauria clades, mentioned herein. The tumultuous history of the systematic classification, its possible synonymy with other taxa, and some aspects regarding the paleoecology of this species are also included in this paper.

LINK(S)

https://biozoojournals.ro/nwjz/content/v20n1/nwjz_e241901_Stoicescu.pdf

ABSTRACT

We report new cranial, dental, and postcranial remains of a new early giraffid from the Middle Miocene of Pakistan: Bramiscus micros nov. gen. nov. sp. (Ruminantia, Giraffidae). The material comes from the fossil site Dhok Bun Amir Khatoon (Chinji Formation 14-11.4 Ma, Lower Siwaliks), located in the Chakwal district (Punjab, Pakistan). Additional remains were identified from the Hasvard Siwaliks Collection. The new findings show fused anterior ossicones, as in Bramatherium. The metatarsals possess a strong medial ridge and a weak lateral ridge, a feature encountered only in Bramatherium perimense. The size of our taxon is smaller than Bramatherium, hence the name. Bramiscus micros nov. gen. nov. sp. coexisted at the same time with other giraffids, such as Progiraffa exigua, Giraffokeryx punjabiensis, Giraffa priscilla, Giraffa punjabiensis, and other still unnamed taxa.

LINK(S)

https://palaeo-electronica.org/content/2024/5228-new-giraffid-genus
https://palaeo-electronica.org/content/pdfs/1243.pdf

ABSTRACT

The known diversity of European middle and late Miocene hominids has increased significantly during the last decades. Most of these great apes were frugivores in the broadest sense, ranging from soft fruit frugivores most like chimpanzees to hard/tough object feeders like orangutans, varying in size from larger than siamangs (over 17 kg) to larger than most chimpanzees (~60–70 kg). In contrast to the frequent sympatry of hominoids in the early-to-middle Miocene of Africa, in no European Miocene locality more than one hominid taxon has been identified. Here we describe the first case of hominid sympatry in Europe from the 11.62 Ma old Hammerschmiede HAM 5 level, best known from its excellent record of Danuvius guggenmosi. The new fossils are consistent in size with larger pliopithecoids but differ morphologically from any pliopithecoid and from Danuvius. They are also distinguished from early and middle Miocene apes, share affinities with late Miocene apes, and represent a small hitherto unknown late Miocene ape Buronius manfredschmidi. With an estimated body mass of about 10 kg it represents the smallest known hominid taxon. The relative enamel thickness of Buronius is thin and contrasts with Danuvius, whose enamel is twice as thick. The differences between Buronius and Danuvius in tooth and patellar morphology, enamel thickness and body mass are indicative of differing adaptations in each, permitting resource partitioning, in which Buronius was a more folivorous climber.

LINK(S)

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0301002

ABSTRACT

The fossil record of Mesozoic dinosaurs in Tunisia has long been thought to be restricted exclusively to the southern part of the country. Although tidal and continental environments have been recognized within Cretaceous formations in central Tunisia based on sedimentological analyses, no skeletal remains ascribable to dinosaurs have been found in these deposits. The hypothesis of a possible land connection between central and southern Tunisia during the Early Cretaceous has not been previously explored due to notable lateral variations in facies, marked by the recurrent occurrence of shallow marine deposits separating these domains. The vertebrate ichnological record in the Central Tunisian Atlas was limited to isolated tridactyl footprints exclusively observed in the Albian Kebar Formation. Here, we report the first dinosaur tracks from the pre-Albian Cretaceous (upper Hauterivian–lower Barremian) of central Tunisia. These tracks consist of large tridactyl footprints left behind by medium to large-sized non-avian theropods. They occur within an extensively fractured dolostone bed and exhibit poor morphological preservation. Besides their dimensions, some tracks show morphological features, including broad digit impressions with some terminating in sharp claw traces, low to moderate mesaxony, and a wide divarication angle of the outer digits, reminiscent of the ichnogenus Megalosauripus. However, due to their poor state of preservation and limited number, we refrain from assigning these tracks to the ichnogeneric level and refer to them as indeterminate eubrontid footprints. The occurrence of theropod tracks in the Lower Cretaceous of central Tunisia confirms the sedimentology-based hypotheses about a temporal emergence of parts of this area, which was probably related to tectonic events. We compile previous biostratigraphic, sedimentological, and paleoichnological data to suggest possible periodic connections between the mainland in the south and the tidal flat environments within the central basins. Additionally, two possible scenarios regarding the biogeographic implications of the Jebel Kebar tracks are discussed. The first scenario suggests that a Gondwanan theropod fauna would have been exploring and residing in newly emerged regions of higher latitudes, whereas the alternative scenario posits the existence of a paleogeographic link between the northern margin of Gondwana and Adria, which would have allowed an interchange of theropod faunas between the two landmasses at least in the early Barremian.

LINK(S)

https://www.sciencedirect.com/science/article/abs/pii/S1464343X24001390

ABSTRACT

Sponges are the most basal metazoan phylum1 and may have played important roles in modulating the redox architecture of Neoproterozoic oceans. Although molecular clocks predict that sponges diverged in the Neoproterozoic era, their fossils have not been unequivocally demonstrated before the Cambrian period, possibly because Precambrian sponges were aspiculate and non-biomineralized. Here we describe a late-Ediacaran fossil, Helicolocellus cantori gen. et sp. nov., from the Dengying Formation (around 551–539 million years ago) of South China. This fossil is reconstructed as a large, stemmed benthic organism with a goblet-shaped body more than 0.4 m in height, with a body wall consisting of at least three orders of nested grids defined by quadrate fields, resembling a Cantor dust fractal pattern. The resulting lattice is interpreted as an organic skeleton comprising orthogonally arranged cruciform elements, architecturally similar to some hexactinellid sponges, although the latter are built with biomineralized spicules. A Bayesian phylogenetic analysis resolves H. cantori as a crown-group sponge related to the Hexactinellida. H. cantori confirms that sponges diverged and existed in the Precambrian as non-biomineralizing animals with an organic skeleton. Considering that siliceous biomineralization may have evolved independently among sponge classes, we question the validity of biomineralized spicules as a necessary criterion for the identification of Precambrian sponge fossils.

LINK(S)

https://www.nature.com/articles/s41586-024-07520-y

ABSTRACT

The phylogenetic relationships of the major lineages within Dinosauria have come under intense scrutiny in recent years. In 2017, a radical new hypothesis of early dinosaur evolution, the ‘Ornithoscelida hypothesis’, was proposed, prompting a flurry of work in this area. However, instead of untangling the phylogenetic tree of dinosaurs as hoped, this further research unravelled the scientific consensus on dinosaur origins and their early relationships. Multiple hypotheses have now been proposed, including several that position the ‘traditionally’ non-dinosaurian silesaurids within Dinosauria. There is no sign of an emerging consensus, with all possible combinations of the three major dinosaur clades (Ornithischia, Theropoda and Sauropodomorpha) having been recovered by recent phylogenetic analyses. The existence of several ‘wildcard taxa’ and clades with uncertain affinities around the base of Dinosauria complicates efforts to differentiate these hypotheses. Recent studies have suggested that the data sets used to investigate the phylogenetic relationships of Dinosauria might be fatally flawed. The construction of new data sets with a stronger focus on the logical underpinning of characters, in addition to the inclusion of newly described or redescribed taxa, will likely hold the key to resolving this debate.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/14772019.2024.2345333
https://www.tandfonline.com/doi/pdf/10.1080/14772019.2024.2345333?needAccess=true

ABSTRACT

The Yixian Formation (Lower Cretaceous) in China is famous worldwide for its fossils of early angiosperms, but there has been only one record of flower buds (Archaebuda lingyuanensis) hitherto, in which only the surface of the flower bud was documented while no internal details were known. Such a partial knowledge of flower buds hinders our understanding of the evolution of flowers, and this knowledge lacuna needs to be filled. Our new specimen was collected from an outcrop of the Yixian Formation (Barremian–Aptian, Lower Cretaceous) near Dawangzhangzi, Lingyuan, Liaoning, China. Our observations reveal a new fossil flower bud, Archaebuda cretaceae sp. nov., from the Lower Cretaceous of China. This new record of Archaebuda in the Yixian Formation not only confirms the truthful existence of the expected gynoecium (plus possible androecium) in a flower bud but also underscores the occurrence of typical flowers in the Early Cretaceous. This new information adds first-hand data to flower sexuality, pollination, and evolution.

LINK(S)

https://www.mdpi.com/2079-7737/13/6/413

ABSTRACT

The Triassic period (251.9–201.4 Ma) is the first period of the Mesozoic Era, initiating after the Permian-Triassic mass extinction and ending at the Triassic-Jurassic mass extinction. This period witnessed the origin of modern ecosystems, and also the rise of the dinosaurs. This influence on both geological and ecological history of the Earth has prompted close attention to the paleoclimate and paleoecology of the Triassic period over the last 60 years. This review builds on past work to summarize knowledge of Triassic climate and ecology, especially focusing on data acquired over the last decade for key South American strata. The main climatic events that occurred in the Triassic period can be subdivided in three key intervals, from the base to top: pre-, syn- and post-Carnian Pluvial Episode (CPE). Each of these three intervals corresponds with major climatic events or episodes, positioned relative to the Permian-Triassic mass extinction, CPE, and Triassic-Jurassic mass extinction. The pre-CPE interval of the Early and Middle Triassic represents relatively warm and dry conditions. The CPE of the earliest Late Triassic marks a global increase in effective precipitation (precipitation minus evaporation) for at least 1–2 Myr, causing major floristic and faunal turnovers and possibly triggering the rise of the dinosaurs. The post-CPE interval of the Late Triassic represents a return to warm and dry conditions. Triassic deposits in Brazil and Argentina represent windows for investigating the interrelationship(s) between changes in climate, floras, and faunas. Alternate triggers for dinosaur diversification are also evaluated, including classical considerations of competition, opportunism, and body temperature, in addition to more novel and subtle factors.

LINK(S)

https://www.sciencedirect.com/science/article/abs/pii/S0895981124001998

ABSTRACT

Pachystropheus rhaeticus is a primarily marine diapsid reptile found in Upper Triassic (Rhaetian) deposits in Britain and continental Europe. Although known for a long time, Pachystropheus remains an enigma. It was identified as the oldest choristodere based on similarities between postcranial bones and a sole cranial element. Here, we re-study all available Pachystropheus material, including new specimens, identifying all skeletal elements that are plausibly referrable to the genus. We reject some previous dubious identifications and show that reports of an ectopterygoid, the only cranial element of Pachystropheus described, were incorrect and that supposed skull elements belong to coelacanth fishes. Furthermore, we present CT data for the first time and new palynological data from Pachystropheus-bearing strata, providing a clearer picture of its stratigraphic distribution and the paleoecology of the Penarth Group. The reassessment of its phylogeny using new character informative data, places Pachystropheus as the last of the thalattosaurs, a lineage of marine reptiles abundant throughout the Triassic. We demonstrate that a specimen of Pachystropheus previously reported from the Lower Jurassic is more likely from the Late Rhaetian, and therefore the taxon does not extend across the end-Triassic Extinction. Moreover, this extends the known geological range of thalattosaurs from the Norian–Rhaetian boundary to the latest Rhaetian. Similarities in the postcranial skeleton between Pachystropheus and other askeptosauroid thalattosaurs, particularly Endennasaurus acutirostris, suggest it was able to move on land, but was most likely a primarily marine predator with an ecological niche distinct from coeval marine reptiles (placodonts, ichthyosaurs) and carnivorous fishes (hybodont sharks, actinopterygians).

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2350408
https://www.tandfonline.com/doi/pdf/10.1080/02724634.2024.2350408?needAccess=true

ABSTRACT

The presence of Dromornithidae in the Australian Cenozoic fossil record was first reported in 1872, yet although eight species and hundreds of specimens are known, key information on their morphology remains elusive. This is especially so for their skulls, which contributes to a lack of resolution regarding their relationships within Galloanserae. The skull of the Pleistocene dromornithid, Genyornis newtoni, was initially described in 1913. Additional fossils of this species have since been discovered and understanding of avian skull osteology, arthrology, and myological correlates has greatly advanced. Here we present a complete redescription of the skull of Genyornis newtoni, updating knowledge on its morphology, soft-tissue correlates, and palaeobiology. We explore the diversity within Dromornithidae and make comprehensive comparisons to fossil and extant galloanserans. Furthermore, we expand on the homologies of skull muscles, especially regarding the jaw adductors and address the conflicting and unstable placement of dromornithids within Galloanserae. Findings support generic distinction of Genyornis newtoni, and do not support the close association of Dromornithidae and Gastornithidae. We thus recommend removal of the dromornithids from the Gastornithiformes. Considering character polarities, the results of our phylogenetic analyses, and palaeogeography, our findings instead support the alternative hypotheses, of dromornithids within, or close to, the Suborder Anhimae with Anseriformes.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2308212
https://www.tandfonline.com/doi/pdf/10.1080/08912963.2024.2308212?needAccess=true

ABSTRACT

Abundant and diverse pterosaur records have been reported from the Jehol Biota since the end of the last century, including an early reported member, Haopterus gracilis, from the Yixian Formation. The referral of Haopterus gracilis has been a subject of debate since its discovery. Various phylogenetic analyses have suggested different positions for Haopterus gracilis, including the sister taxon of the Ornithocheiroidea or placed differently in the Pteranodontoidea. Recent research has proposed that Haopterus gracilis is the sister-taxon of the Lebanese istiodactyliform Mimodactylus libanensis. Here we redescribe the holotype and only specimen of Haopterus gracilis, a relatively complete skeleton of a juvenile individual in detail using Micro-CL scanning. Haopterus possesses several pteranodontoid features including a stout scapula shorter than the coracoid, a sternum with a constriction posterior to the sternocoracoid articulations, and humeri with trapezoidal deltopectoral crests and constricted mid-shafts. A close affinity between Haopterus and istiodactylids has been suggested by several researchers, whereas some features of Haopterus revealed here distinguish Haopterus from istiodactylids, including the low skull with a long rostrum occupying more than half the skull length anterior to the jaw articulation, and a long tooth row with different tooth morphologies. The phylogenetic position of Haopterus was reevaluated by utilizing a more comprehensive character matrix derived from three previous matrices. The new analysis revealed Haopterus in the Pteranodontoidea and, within this clade, it was an istiodactyliform. The study of Haopterus holds potential significance in enhancing our understanding of the morphology and taxonomy of short-toothed pteranodontoids.

LINK(S)

https://www.sciencedirect.com/science/article/abs/pii/S019566712400106X