PALEONTOLOGY IN DECEMBER, 2024

ABSTRACT

The International Commission on Zoological Nomenclature has used its plenary power to conserve the family-group name Tyrannosauridae Osborn, 1906 by giving it precedence over Deinodontidae Cope, 1866 and Dryptosauridae Marsh, 1890 whenever it is considered to be a synonym of either of the two.

LINK(S)

https://www.biotaxa.org/bzn/article/view/86727

ABSTRACT

Allosaurus is one of the most famous theropod dinosaurs, but the validity and relationships between the different species have been confusing and often questioned. Portugal is relevant to the understanding of the genus in light of the discovery of A. europaeus ML415 from the Early Tithonian of Lourinhã and Allosaurus MNHNUL/AND.001 from Andrés. However, the exact classification and validity of these two specimens has always been controversial. The presence of Allosaurus in Portugal is strong evidence for a North America–Europe Late Jurassic dispersal, later supported by other taxa. A detailed cranial description and specimen-based phylogeny were performed and resolved many of the open questions: The diversity of Allosaurus is limited to three named species: A. fragilis, A. europaeus, and A. jimmadseni. Nine autapomorphies were found in A. europaeus, confirming the validity of the species. Phylogenetic analyses place both Portuguese specimens in the genus Allosaurus, based on the following synapomorphies: jugal bone lateral view, relative heights of quadratojugal prongs, the dorsal prong is equal in height, the jugal bone in lateral view shows shallow accessory pneumatization of the antorbital fossa, the palatine pneumatic recess shape is small, and lacrimal horn morphology has a triangular horn. The Andrés specimen is placed with the A. europaeus and they are considered here to be the same species, which is paleo-geographically and biochronologically congruent. A. europaeus and A. jimmadseni are sister taxa and closer to each other than to A. fragilis. The genus is distributed in occurrences from the United States, Germany, and Portugal, and from the Late Kimmeridgian to the Late Tithonian, while the Cenomanian report from Japan is reidentified as Segnosaurus.

LINK(S)

https://cnki.net/KCMS/detail/detail.aspx?dbcode=CJFD&dbname=CJFDAUTO&filename=HBDX202406006&uniplatform=OVERSEA&v=puwVbh87_QUSdknWMH7NezKnMCDxEYawTW3WQEsv7vSS2_S12kf0vqBKGcbSDr-8

ABSTRACT

Allosaurus is one of the most famous theropod dinosaurs, but the validity and relationships between the different species have been confusing and often questioned. Portugal is relevant to the understanding of the genus in light of the discovery of A. europaeus ML415 from the Early Tithonian of Lourinhã and Allosaurus MNHNUL/AND.001 from Andrés. However, the exact classification and validity of these two specimens has always been controversial. The presence of Allosaurus in Portugal is strong evidence for a North America–Europe Late Jurassic dispersal, later supported by other taxa. A detailed cranial description and specimen-based phylogeny were performed and resolved many of the open questions: The diversity of Allosaurus is limited to three named species: A. fragilis, A. europaeus, and A. jimmadseni. Nine autapomorphies were found in A. europaeus, confirming the validity of the species. Phylogenetic analyses place both Portuguese specimens in the genus Allosaurus, based on the following synapomorphies: jugal bone lateral view, relative heights of quadratojugal prongs, the dorsal prong is equal in height, the jugal bone in lateral view shows shallow accessory pneumatization of the antorbital fossa, the palatine pneumatic recess shape is small, and lacrimal horn morphology has a triangular horn. The Andrés specimen is placed with the A. europaeus and they are considered here to be the same species, which is paleo-geographically and biochronologically congruent. A. europaeus and A. jimmadseni are sister taxa and closer to each other than to A. fragilis. The genus is distributed in occurrences from the United States, Germany, and Portugal, and from the Late Kimmeridgian to the Late Tithonian, while the Cenomanian report from Japan is reidentified as Segnosaurus.

LINK(S)

https://www.mdpi.com/1424-2818/17/1/29?fbclid=IwY2xjawHfigBleHRuA2FlbQIxMQABHWs3o3ynXEuuKpFuTToQCUSMl-vETx1PvR4TjLUtIVe_kDnN5T1CAwyw1g_aem_lokNzyVDnfe4a1mp0LNppw

ABSTRACT

Amakusaichthys benammii sp. nov. is described based on specimens recovered from the Campanian shallow marine deposits of the Tzimol Quarry near Comitán, Chiapas, Mexico. The species fits the diagnosis of the basal teleost order Ichthyodectiformes. Moreover, the species is located in the long-nose genus Amakusaichthys because it has two highlight features previously documented in the Japanese species A. goshouraensis, including the elongation of the skull ethmoid region and the reinforcement of the caudal skeleton. The specimens of the new species are preserved in 3D, revealing some outstanding osteological features that support its uniqueness and the amendment of the generic diagnosis; the ethmoid skull region is elongated, causing the long-nose appearance of this fish and the anterior displacement of its ethmopalatine upper jaw articulation away from the orbit. This new Mexican species exhibits numerous distinctive features, including a strongly ornamented skull with multiple pores and short ridges; the presence of two masticatory-like plates at the end of parasphenoid ventral processes, the anterior is a heart-shaped plate and the posterior one is arrow-shaped; the hypural 3 is notably shorter than hypural 2; and the maxilla shows a palatine notch. Comparative and phylogenetic analysis indicates that A. benammii is closely related to A. goshouraensis and the genus Heckelichthys; therefore, these are grouped into the new family Heckelichthyidae. The same comparative essay also suggests that after the critical reviews, Altamuraichthys and Garganoichthys may be part of this family.

LINK(S)

https://palaeo-electronica.org/content/2024/5295-a-long-nose-ichthyodectiform

https://palaeo-electronica.org/content/pdfs/1444.pdf

ABSTRACT

Late Cretaceous marine ecosystems saw a major adaptive radiation of mosasaurids, which evolved highly disparate jaw and tooth morphologies to feed on different prey. A striking pattern seen in mosasaurids was a high diversity of durophagous forms. Durophagy likely evolved several times independently in the mosasaurine genera Globidens, Prognathodon, and Carinodens. Carinodens is unusual in having low, rectangular, laterally compressed teeth. The genus is known from around the world, with the species Carinodens minalmamar and C. belgicus previously reported from the Maastrichtian Phosphates of Morocco. Here, we report a new species of Carinodens, C. acrodon, from the same Maastrichtian Phosphates. It is characterized by teeth with tall crowns, triangular apices, and broad bases. Many of the diagnostic features of this species appear to be plesiomorphies, suggesting the persistence of a primitive species of Carinodens into the latest Maastrichtian alongside the more derived C. minalmamar and C. belgicus. The new species contributes to an emerging pattern of mosasaurid hyperdiversity in the late Maastrichtian of Morocco. A revised faunal list, including stratigraphic range extensions of Khinjaria and Stelladens into the latest Maastrichtian of upper Couche III of the Phosphates of Morocco, suggests at least 16 species of mosasauroid coexisted here.

LINK(S)

https://www.mdpi.com/1424-2818/17/1/25

ABSTRACT

Enantiornithes are the most successful early-diverging avian clade, their fossils revealing important information regarding the structure of Cretaceous avifaunas and the parallel refinement of flight alongside the ornithuromorph lineage that includes modern birds. The most diverse recognized family of Early Cretaceous enantiornithines is the Bohaiornithidae, known from the Jehol Biota in northeastern China. Members of this clade enhance our understanding of intraclade morphological diversity and elucidate the independent evolution of this unique lineage. Here, we report on a new specimen of bohaiornithid, Neobohaiornis lamadongensis gen. et sp. nov., from the Lower Cretaceous Jiufotang Formation in western Liaoning, China. The holotype specimen is considerably smaller than all other known bohaiornithids (roughly half the size of Bohaiornis). The presence of complete fusion in compound elements strongly suggests it represents a mature or nearly mature individual, and therefore substantially increases the known size range of this clade. This specimen further differs from known bohaiornithids in that it exhibits reduced manual unguals and an increased number of sacral vertebrae, which indicates bohaiornithids evolved increased flight capabilities in parallel to other enantiornithine lineages, such as the Longipterygidae. Traces of the plumage, which are rarely preserved in bohaiornithids, reveal the presence of remiges with rounded distal margins and short crural feathers.

LINK(S)

https://www.nature.com/articles/s41598-024-82869-8

https://www.nature.com/articles/s41598-024-82869-8.pdf

ABSTRACT

Although there is now good representation of shark-bitten bone in the fossil record, shark-bitten shark teeth are still exceedingly rare. A relatively small number of teeth of the Neogene megatooth shark Otodus megalodon (Otodontidae) preserve surface markings that were made when struck by the serrated cutting edge of another O. megalodon tooth. The serration marks are consistent with those of the ichnotaxon Knethichnus parallelum. That these shallowly penetrating surface trace fossils were made as one O. megalodon tooth struck another is confirmed by the preservation of fine parallel gouges made when the serrated cutting edge of one tooth impacted and raked the surface of the receiving tooth. The K. parallelum marks on O. megalodon teeth could have been unintentionally self-inflicted, the result of one tooth striking another in the opposing jaw during forceful occlusion, collateral damage from feeding, or aggressive O. megalodon- on-O. megalodon facial biting (i.e., either from active predatory cannibalism, a feeding frenzy during scavenging, or as a result of a territorial dispute to establish a feeding hierarchy).

LINK(S)

https://www.app.pan.pl/article/item/app011882024.html

https://www.app.pan.pl/archive/published/app69/app011882024.pdf

ABSTRACT

Nothronychus graffami was a large therizinosaur represented by a single well-preserved individual from the Turonian Tropic Shale of southern Utah. It is characterized by an enlarged abdomen, small tail, and an extensively pneumatized axial skeleton, and is frequently regarded as herbivorous. Given the overall tail reduction and the development of a wide fused synsacrum with widely spaced acetabulae, it is reconstructed with an anteriorly rotated femur and a displaced resting ground reaction force anterior to the center of mass. The axis of the ground reaction force would shift laterally during locomotion to maintain stability as observed in extant broad abdomened neornitheans. A waddling gait is inferred for Nothronychus. This pattern is significantly different than in Falcarius, a basal therizinosaurian, where a plesiomorphic narrow abdomen, narrowly spaced acetabulae, and altiliac ilium are observed. Falcarius was capable of a more cursorial gait than derived therizinosaurs. In contrast to Nothronychus, Falcarius was probably at least omnivorous to carnivorous, so herbivory almost certainly evolved within the therizinosaur lineage. Following previous work on Tyrannosaurus and Coelophysis, moment arms were computed for Nothronychus for major muscles spanning the hip, knee, and ankle. A ball-and-socket joint is present at the hip, so three-dimensional movement was considered possible there. The knee and ankle were represented by two-dimensional hinge joints. Some muscles altered their function as the pubis shifted from a propubic orientation to an opisthopubic one. These included flexion to extension and the addition of increased abduction/adduction in the affected muscles. The results supported convergence with an avian locomotor model, such as reduction in M. caudofemoralis longus.

LINK(S)

https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25626

ABSTRACT

Mesosaurs have long been considered to be small to mid-sized aquatic to semiaquatic amniotes that lived in Gondwana during the Early Permian or Late Carboniferous, according to recent research that showed their ghost range extending back to the Pennsylvanian. Previous morphometric analyses based on several hundred mesosaur specimens, including materials from Uruguay, Brazil, South Africa, Namibia, and the Paris National History Museum, provided a comprehensive understanding of mesosaur ontogeny, documented from fetus to adults. As a result, it was possible to determine the approximate size of any individual, measuring just one isolated limb bone, vertebrae, or even cranial elements. Herein, we describe large, poorly preserved and incomplete skulls, as well as axial and appendicular bones, from the Mangrullo Formation Konservat-Lagerstätte of Uruguay that suggest the existence of gigantism in mature mesosaurs reaching more than twice the size of previously described adults and type specimens. The sporadic occurrence of these giant individuals contrasts sharply with the abundant remains of young mesosaurs and, in general, with what is commonly found in the fossil record of vertebrates. The poor preservation of the mature individuals and their presence in coastal areas of the basin is consistent with the hypothesis that older mesosaurs have spent more time near the coast. An alternative hypothesis suggesting pelagic lifestyles is less supported by the available data. Given the preservation of unborn and hatchlings, as well as early juvenile, mature and very mature individuals, the mesosaur record is considered exceptional among early amniotes.

LINK(S)

https://www.mdpi.com/2813-6284/3/1/1

ABSTRACT

The origin of birds from theropod dinosaurs, by any measures, is the most eye-catching evolutionary transition in the history of life, which encompasses numerous extensive morphological and biological changes. Compared to postcranium, little progress has been made regarding the evolutionary assemblage of the birds’ skull, because of few detailed early records of cranial materials of stem lineages. Anchiornis is the oldest known record of the Paraves (~160 Ma), the most inclusive clade that contains all living birds but not Caudipteryx or Epidexipteryx. With hundreds of known specimens, Anchiornis constitutes an ideal taxon for investigating morphological modifications across the theropod-bird transition, but its cranial morphology remains enigmatic. Here we present in-depth description of the cranial morphology of Anchiornis based on three-dimensional reconstruction of a well-preserved specimen, including elements from the temporal and palatal regions that are poorly recognized previously. Our study shows that Anchiornis retains the plesiomorphic dinosaurian condition in having a diapsid akinetic skull. The mixture of cranial characters, shared with dromaeosaurids, troodontids, and stemward avialans, present in Anchiornis demonstrates the complex history of early avialan cranial evolution.

LINK(S)

https://www.vertpala.ac.cn/EN/10.19615/j.cnki.2096-9899.241225

ABSTRACT

New discoveries of the late Silurian fossil fish Dunyu (Eugaleaspidae, Eugaleaspiformes, Galeaspida), Dunyu tianlu sp. nov. and Dunyu sp., are described from the Xiaoxi Formation in Xiushan of Chongqing and Xiushui of Jiangxi, China respectively. D. tianlu sp. nov. can be distinguished from D. longiforus and D. xiushanensis in its nearly equal preorbital and postorbital regions of the headshield. As the currently only known genus of Eugaleaspiformes during the late Silurian, Dunyu not only displays a large morphological difference with galeaspids from both the early Silurian and Early Devonian but also occupies a phylogenetic position that is far from the root of Eugaleaspiformes, which indicates that the lineages nested between Yongdongaspidae and Eugaleaspidae should have diversified before the early Ludlow, even during the Telychian. Discovery of new specimens of Dunyu provides direct evidence on the genus level for the correlation of the late Ludlow strata between the margin and interior of the Yangtze Platform, further supporting that the central part of the Yangtze Platform suffered from widespread transgression in the late Silurian.

LINK(S)

https://peerj.com/articles/18760/

https://peerj.com/articles/18760.pdf

ABSTRACT

Abstract Saurophaganax maximus is the designation of a massive theropod dinosaur recovered from the Kenton Member of the Upper Jurassic Morrison Formation in Oklahoma. The theropod was originally given the name Saurophagus maximus but was later revised to Saurophaganax maximus as the former did not conform to ICZN standards. Several autapomorphies were described for S. maximus including the postorbital lacking a postorbital boss, the atlas vertebra lacking facets for a proatlas, cervical vertebrae with nearly vertical postzygapophyses, unique accessory laminae on the holotype neural arch, pneumatized post-pectoral dorsal centra, laterally bowed femora, tibiae without an astragalar buttress and more prominent distomedial crest, less distally divergent fourth metatarsals, and craniocaudally expanded chevrons. However, our re-evaluation of these specimens shows that some of this material, including the holotype, is more parsimoniously referred to diplodocid sauropods found in the same quarry rather than an allosaurid. Because saurischian material referred to S. maximus is likely chimeric but diagnostic, we propose taxonomic revision and hypothesize dual validity. The name Saurophaganax maximus should refer to a previously undiagnosed diplodocid, instead of the large theropod recovered from the Kenton 1 Quarry. The presence of at least one skeletally mature theropod was confirmed through paleohistology of a fourth metatarsal. Despite the similarity of the theropod material to known species of Allosaurus, some decisively theropod specimens feature subtle autapomorphies that suggest a separate species, which we describe as Allosaurus anax sp. nov.

LINK(S)

https://journals.library.ualberta.ca/vamp/index.php/VAMP/article/view/29404
https://journals.library.ualberta.ca/vamp/index.php/VAMP/article/view/29404/21467

ABSTRACT

The middle Eocene coal seams of the Geisel valley in Germany have yielded several remains of giant flightless birds of the taxon Gastornithiformes. These fossils were described as Diatryma geiselensis Fischer, 1978 and represent the latest occurrence of gastornithiforms. Initiated by the discovery of a previously unrecognized, largely complete albeit strongly flattened skull, we revisit the gastornithiform material from the Geisel valley. Most recent authors assigned D. geiselensis and all other gastornithiforms to the taxon Gastornis Hébert, 1855, which has taxonomic precedence over Diatryma Cope, 1876. In this paper we show that D. geiselensis distinctly differs from the late Paleocene and early Eocene Gastornis parisiensis Hébert, 1855 in the morphologies of the scapulocoracoid and tarsometatarsus. We therefore re-establish the taxon Diatryma and comment on its oldest European record, based on a new tarsometatarsus from the British London Clay. The new D. geiselensis skull from the Geisel valley represents only the second skull of a gastornithiform known so far. The upper beak of this specimen differs from a previously reported partial beak of D. geiselensis in a less vaulted culmen. Together with pronounced size differences, this may indicate that D. geiselensis was sexually dimorphic. We also report the first in situ preserved gastrolith in a specimen of D. geiselensis and comment on some aspects of the paleobiology of gastornithiforms.

LINK(S)

https://palaeo-electronica.org/content/2024/5393-review-of-gastornithiformes
https://palaeo-electronica.org/content/pdfs/1438.pdf

ABSTRACT

The Early Jurassic ornithischian dinosaurs in Laurasia are dominated by armored dinosaurs, with other early ornithischian groups being rare. Here, a new taxon, Archaeocursor asiaticus gen. et sp. nov., is reported from the Lower Jurassic of southwestern China. Phylogenetic analysis places Archaeocursor asiaticus as the earliest-diverging ornithischian dinosaur yet discovered in Asia, albeit with weak support. Osteohistological analysis of the femoral cross-section suggests that Archaeocursor asiaticus was a young adult at the time of death, indicating a small body size of approximately 1 meter in body length. This discovery extends the known presence of ornithischian dinosaurs in East Asia to the Pliensbachian or even late Sinemurian stages. Additionally, it points to an earlier dispersal event of Early Jurassic ornithischian dinosaurs from Gondwana to Laurasia, including East Asia, which appears to be independent of, and possibly earlier than, the dispersal of armored dinosaurs.

LINK(S)

https://www.sciencedirect.com/science/article/pii/S2589004224028682

ABSTRACT

Noasaurus leali is a small (~2 m) carnivorous theropod and the nominal genus of the clade Noasauridae, one of the two radiations of abelisauroid ceratosaurs predominantly present in the Southern Hemisphere during the Mesozoic. This eponymous theropod from the Maastrichtian Lecho Formation of Salta, Argentina, is known from an incomplete skeleton of which the strongly curved manual ungual is the most peculiar element. We here provide for the first time a comprehensive description of the holotypic specimens of Noasaurus, whose phylogenetic position was explored using three independent datamatrices on theropod relationships. This species is diagnosed by several apomorphies such as a dorsal ridge in the maxillary fossa, a strongly arched quadrate, a cervical neural arch with anterior epipophyseal prongs, and a manual ungual with a subtriangular flexor fossa delimited by a V-shaped ridge. Results of the phylogenetic analyses recovered Noasaurus closely related to Velocisaurus, Masiakasaurus, and Laevisuchus, which together form a Late Cretaceous radiation of small-bodied noasaurids restricted to the Southern Hemisphere. The peculiar morphology of the lateral dentition and manual unguals suggests that Noasaurus was an opportunistic carnivore feeding on small prey items and a possible piscivore gaffing fish with its specialized hand claws.

LINK(S)

https://academic.oup.com/zoolinnean/article-abstract/202/4/zlae150/7926352

ABSTRACT

There are significant uncertainties surrounding the theropod Balaur bondoc, ranging from its phylogenetic position to basic aspects of its paleobiology, such as its diet. In the absence of structures that can be clearly correlated with a paleobiological hypothesis, such as dentition, this study aims to approximate these aspects using other anatomical elements, such as the hind claws. In this work, the probable paleobiology of the taxon is inferred by comparing the posterior pedal ungual phalanx II of Balaur bondoc with representatives of various subclades of Dromaeosauridae and Avialae, as well as extant taxa with known ecologies used as references, through 2D geometric morphometrics. Preliminary results suggest that the morphology of the pedal ungual phalanx II of Balaur bondoc is consistent with a predominant cutting and tearing function.

LINK(S)

https://www.researchgate.net/publication/387090081_NEW_CONTRIBUTIONS_TO_THE_PALEOBIOLOGY_OF_Balaur_bondoc_DINOSAURIA_THEROPODA_THROUGH_GEOMETRIC_MORPHOMETRICS

ABSTRACT

Therapsids were a dominant component of middle–late Permian terrestrial ecosystems worldwide, eventually giving rise to mammals during the early Mesozoic. However, little is currently known about the time and place of origin of Therapsida. Here we describe a definitive therapsid from the lower–?middle Permian palaeotropics, a partial skeleton of a gorgonopsian from the island of Mallorca, western Mediterranean. This specimen represents, to our knowledge, the oldest gorgonopsian record worldwide, and possibly the oldest known therapsid. Using emerging relaxed clock models, we provide a quantitative timeline for the origin and early diversification of therapsids, indicating a long ghost lineage leading to the evolutionary radiation of all major therapsid clades within less than 10 Myr, in the aftermath of Olson’s Extinction. Our findings place this unambiguous early therapsid in an ancient summer wet biome of equatorial Pangaea, thus suggesting that the group originated in tropical rather than temperate regions.

LINK(S)

https://www.nature.com/articles/s41467-024-54425-5

https://www.nature.com/articles/s41467-024-54425-5.pdf

ABSTRACT

Xenodens calminechari is a mosasaurid taxon named by Longrich et al. (2021) based on the holotype MHNM.KH.331, a left maxilla with several teeth. This holotype was obtained nonscientifically (without technical supervision) from an area in Morocco that yields many manipulated or forged specimens. Examination of Longrich et al. (2021) reveals four tooth crowns occupy what appear to be two alveoli in MHNM.KH.331, and there is potential adhesive connecting the tooth crowns to the maxilla on their lateral sides. We argue that the articulated tooth crowns of this taxon were artificially placed in the maxilla, rendering at least two apomorphies of this taxon the product of forgery. Longrich et al. (2021)'s claims of fused tooth ‘roots' in MNHM.KH.331 are instead calcified periodontal ligament and alveolar bone that have ankylosed, resembling the typical mosasaurid condition. Differing tooth crown morphology does not preclude the referral of the teeth of this specimen to a younger ontogenetic stage of another mosasaur (possibly Carinodens) because many extant lizard species show drastic ontogenetic changes in the dentition. We argue that Xenodens calminechari represents a nomen dubium. This specimen constitutes a confluence of two persistent problems in vertebrate paleontology: material sourced from commercial excavations that has not been adequately tested for forgery, and taxa named from tooth-based holotypes that ignore the potential for intraspecific dental variation and interspecific convergence in dental characters, as are common in squamates. We suggest that Longrich et al. CT scan MHNM.KH.331, and we supply CT examples for identifying artificially added tooth crowns to Moroccan mosasaur jaws. Finally, we provide recommendations for the designation of mosasaurid holotypes.

LINK(S)

https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25612

https://anatomypubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ar.25612

ABSTRACT

Archaeological deposits from Waterfall Bluff Rock Shelter (Eastern Cape) span from Marine Isotope Stage 3 (~39–29 ka) to the mid-Holocene (~8 ka), showing persistent human occupations. The site’s consistent proximity to the shoreline and stable coastline over millennia makes it key for exploring human settlement patterns. This study reports on preliminary results of identifiable fauna from Marine Isotope Stage 3 to the Early Holocene layers at Waterfall Bluff. The identified species may suggest a mosaic environment, although caution is warranted given the small sample size. Furthermore, leopard seal remains were recovered in layers dating to the Last Glacial Maximum. This is the first direct evidence of a leopard seal recovered from Pleistocene and Holocene archaeo-faunal assemblages along the South African coast.

LINK(S)

https://sajs.co.za/article/view/17449

ABSTRACT

The Lower Jurassic Lufeng Formation of China has long been recognized for its diverse early-diverging sauropodomorph dinosaurs, with eight genera and ten species, representing more than half the Laurasian records. In this paper, we describe a new genus and species of non-sauropodan sauropodomorph, Lishulong wangi gen. et sp. nov., from Yunnan Province in southwestern China. This new taxon is represented by a partial skeleton including the skull and nine articulated cervical vertebrae, which differs from other Lufeng forms in both cranial and cervical characteristics. It bears several autapomorphies of the nasal process, the maxillary neurovascular foramen, and the cervical neural spine. Phylogenetic analysis reveals that Lishulong is an early-diverging member of the Sauropodiformes, and the sister-taxon of Yunnanosaurus. Elucidating the novel osteology of Lishulong, it possessed the largest sauropodomorph cranial material currently identified from the Lufeng Formation, not only enriches the diversity of the Lufeng dinosaur assemblage, but also enhances our understanding of the character evolution in early-diverging sauropodiforms. Furthermore, information about paleobiogeographic distributions indicates that Early Jurassic sauropodomorphs, especially Chinese taxa, have maintained multiple dispersions and exchanges within Pangaea.

LINK(S)

https://peerj.com/articles/18629/

https://peerj.com/articles/18629.pdf

ABSTRACT

As the first group of tetrapods to achieve powered flight, pterosaurs first appeared in the Late Triassic. They proliferated globally, and by the Late Jurassic through the Cretaceous, the majority of these taxa belonged to the clade Monofenestrata (which includes the well-known Pterodactyloidea as its major subclade), typified by their single undivided fenestra anterior to the orbit. Here, a new taxon Melkamter pateko gen. et sp. nov., represented by the specimen MPEF-PV 11530 (comprising a partial cranium and associated postcranial elements), is reported from the latest Early Jurassic (Toarcian) locality of Queso Rallado (Cañadón Asfalto Formation) and referred to the clade Monofenestrata, increasing our previously known taxonomic and geographic representations, and temporal range for this clade. This occurrence marks the oldest record of Monofenestrata globally and helps to shed critical light on the evolutionary processes undergone during the ‘non-pterodactyloid’-to-pterodactyloid transition within the Pterosauria. In addition, another single isolated tooth from the same locality shows ctenochasmatid affinities. These finds further elucidate the still-poor Gondwanan Jurassic pterosaur fossil record, underscoring that most of our current ideas about the timing and modes of pterosaur evolution during that period are largely based on (and biased by) the pterosaur fossil record of the Northern Hemisphere.

LINK(S)

https://royalsocietypublishing.org/doi/10.1098/rsos.241238

https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.241238

ABSTRACT

The Lower Cretaceous Wealden Supergroup of southern England yields a diverse assemblage of theropod dinosaurs, its taxa being represented by fragments in addition to some of the most informative associated skeletons of the European Mesozoic. Spinosaurids, neovenatorid allosauroids, tyrannosauroids and dromaeosaurids are among reported Wealden Supergroup clades. However, the majority of relevant specimens are from the Barremian Upper Weald Clay and Wessex formations, and theropod diversity in the older Berriasian–Valanginian Hastings Group has remained poorly known, the fragmentary specimens reported thus far remaining enigmatic both in terms of phylogenetic affinities and sometimes provenance. A better understanding would be welcome given the paucity of Berriasian–Valanginian dinosaurs worldwide. Here, we describe an assemblage of Hastings Group theropod teeth from the Valanginian Wadhurst Clay Formation, mostly collected from the Ashdown Brickworks locality near Bexhill, East Sussex. These teeth were assessed using phylogenetic, discriminant and machine learning analyses and were found to include members of Spinosauridae, Tyrannosauroidea and Dromaeosauridae, in addition to others that remain of uncertain affinity within Coelurosauria. The taxa appear distinct from those already known from Wealden Supergroup strata: the spinosaurid cannot be referred to Baryonyx or the tyrannosauroid to Eotyrannus, for example, but we have not named new taxa at this time. Combined with other findings in the Wadhurst Clay Formation, our study indicates that Valanginian theropod diversity was comparable to that of younger Wealden Supergroup units, implying that the ‘characteristic’ theropod components of Wealden faunas were established early in the deposition of this famous geological succession.

LINK(S)

https://onlinelibrary.wiley.com/doi/full/10.1002/spp2.1604

https://onlinelibrary.wiley.com/doi/epdf/10.1002/spp2.1604

ABSTRACT

A plesiosaur specimen collected from Ellesmere Island (Nunavut, Arctic Canada) by Danish geologist Johannes Troelsen in 1952 is described for the first time. The plesiosaur is late Berriasian to early Valanginian in age based on palynostratigraphy. The specimen is the only plesiosaur known from the Lower Cretaceous of the Sverdrup Basin in the Canadian Arctic, and is assigned to the cryptoclidid genus Colymbosaurus. From a taxonomic point of view, the presence of vertebrae from several regions and four propodials improve our understanding of the morphology of the genus. Furthermore, Colymbosaurus is shown to have survived through the Jurassic–Cretaceous transition. Its presence in the Sverdrup Basin is additional evidence for the connectivity of Arctic Canada and the Svalbard region during the Jurassic–Cretaceous transition, at a time when sea levels were low and microplankton, like dinoflagellates, experienced enhanced provincialism. Last but not least, the new plesiosaur adds to our knowledge of the palaeoenvironment of the Sverdrup Basin, ranking at the top of a food chain that is largely unrecorded from the area, due to adverse taphonomy and diagenesis.

LINK(S)

https://www.app.pan.pl/article/item/app011482024.html

https://www.app.pan.pl/archive/published/app69/app011482024.pdf