The Paleogene nominal species Osteochilus sanshuiensis, Osteochilus longipinnatus, and Osteochilus laticorpus from Sanshui Basin, China, were originally assigned to the extant genus Osteochilus, in the family Cyprinidae. They were lately considered to belong to Catostomidae or the extinct family Jianghanichthyidae. However, the type specimens of the above nominal species have been deemed to be lost, which hindered the corroborated taxonomic assignment of the species. After multiple attempts and inter-institutional efforts, a series of original type specimens were recovered from a warehouse. We herein report the resurfacing and relocation of the specimens, as well as clarify the taxonomic status of those nominal species. Based on the type specimens and our recently collected specimens in the same locality, we propose to revise the three nominal species as one species †Jianghanichthys sanshuiensis comb. nov. One of the best-preserved original type specimens, SYSU R. 741177 is designated to be the lectotype.

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).

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.

The use of horns and frills for sexual display and attack has been proposed and demonstrated in extinct taxa on several occasions, with the ceratopsian dinosaurs as the most iconic example. Niolamia argentina is a large meiolaniid turtle from Patagonia, characterized by the presence of extensive frills and massive horns in the skull. Here, Finite Element Analysis (FEA) is applied in the only known adult skull of N. argentina to assess the cranial performance simulating defensive/ aggressive movements. We tested five different scenarios: (1) hitting with the snout, (2) hitting with the forehead, (3) struggling with the notch between the frill and the horn, (4) stabbing with lateral horns, and (5) caudal torsion of the frills, the last two being the most damaging and stressful scenarios. Together with the lack of skull features related to head-hitting/fighting, we find that, although the cranial structures of Niolamia argentina studied here may indicate a priori that they were for engaging in combat between males, hitting each other with the caudal frills and trying to stab each other may represent highly stressful scenarios. In this sense, we propose that the presence of frills and horns in N. argentina seems to be more suitable for sexual display than for combat behavior.

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.

Triggered by the need to clarify the taxonomic and phylogenetic relationships of multiple Late Jurassic species presently assigned to the genus Furo, the taxonomic status of the widely accepted type species F. orthostomus (Agassiz, 1842) was revised. It was found to be a junior synonym of Lepisosteus dentosus Koenig, 1825, and Eugnathus speciosus Agassiz, 1839, two names that despite their availability have not been used for a valid taxon after 1899. Therefore, for the sake of maintaining stability, this contribution shows that the conditions of Article 23.9 ‘Reversal of precedence’ of the Code have been met, and as a result, the younger valid name Eugnathus [= Furo] orthostomus Agassiz, 1842, has priority over its older synonyms Lepisosteus dentosus Koenig, 1825, and Eugnathus speciosus Agassiz, 1839.

The Late Triassic was home to great tetrapod diversity, with a mixture of endemic Triassic groups and others with extant descendants. These two groups are represented in microvertebrate accumulations, but their fossils are mixed and fragmentary, leading to challenges in confidently identifying them. Among the Triassic endemic groups, drepanosauromorphs are among the most unusual and easily recognized, but many details of their anatomy are obscured by the lack of three-dimensional and matrix-free specimens. Here we describe new material, including a new species, using isolated but three-dimensional drepanosauromorph elements from the Homestead Site at Garita Creek, an Upper Triassic microvertebrate locality near Garita Creek, New Mexico. This site has thus far yielded dozens of isolated drepanosauromorph specimens, including manual/pedal unguals of at least three morphotypes, vertebrae, and caudal unguals (= tail claws). At least two drepanosauromorph species are present based on distinct enlarged ungual morphotypes, with one representing a new Skybalonyx-like species, Unguinychus onyx gen. et sp. nov., and a second form similar to Drepanosaurus. Unguinychus onyx may have been fossorial whereas the second morphotype likely represents an arboreal species, possibly indicating that contemporary drepanosauromorphs had different ecologies. For the first time, we report a potential “small” ungual morphotype, and we present a partial caudal ungual exhibiting features distinct from manual and pedal unguals. The identification of isolated and three-dimensional drepanosauromorph fossils expands the diversity of the clade and demonstrates the usefulness of incorporating microvertebrate data into assemblage studies.

Among non-avian dinosaurs, troodontids are relatively rare but diverse. The Nemegt Basin in the Mongolian Gobi Desert, which incorporates three of the most fossiliferous beds in the world, is one such region with high troodontid diversity and has also produced eight troodontid taxa until now. The diversity of troodontids is biased towards the two formations, Nemegt and Djadochta. Despite its rich vertebrate fossil record, no troodontids have been described from the Baruungoyot Formation. This faunal absence is perplexing as the Baruungoyot Formation has often been considered intermediate between the other two units in stratigraphy and paleoenvironment, but there are no definite troodontid materials that could fill this ‘gap.’ Here, we report a new troodontid, Harenadraco prima gen. et sp. nov., from the Baruungoyot Formation in Hermiin Tsav, Mongolia. It is represented by an incomplete skeleton that mainly consists of partially articulated left hind limb elements. Harenadraco is small and lightly built like other troodontids, but its tarsometatarsus exhibits extreme slenderness comparable only to Philovenator among cursorial non-avian maniraptorans. It also implies high cursoriality that could be an adaptation of Harenadraco to its environment where potential prey animals like mammals and predators such as eudromaeosaurs were likely to be agile. The discovery of Harenadraco confirms the presence of troodontids in all three formations in the Nemegt Basin.

The lungfish, the extant sister group of the tetrapods, have an evolutionary history illustrated by a fossil record extending for ∼420 million years. The post-Paleozoic fossil record of the clade is almost exclusively restricted to sediments deposited in freshwater paleoenvironments and is characterized by an abundance of highly mineralized tooth plates, whereas cranial and postcranial remains are scarce. Here, we report a sample of isolated tooth plates found in the Upper Triassic Pebbly Arkose Formation of the Mid-Zambezi Basin, Zimbabwe. It consists of pterygoid and prearticular tooth plates from adult individuals, plus some dental plates referred to juvenile individuals, which we refer to a new species of Ferganoceratodus. This discovery provides an opportunity to review briefly the tooth plates of the ‘ptychoceratodontid morphotype’ reported from around the world. We discuss how various occurrences previously referred to Ptychoceratodus may be more appropriately referred, with caution, to Ferganoceratodus. We also describe the histology of the tooth plates of the new species and note similarities with other Mesozoic taxa. The scarcity of histological data for Mesozoic lungfish tooth plates compounds the problem of assigning isolated tooth plates to genus and species level. Ferganoceratodus and closely related taxa arose in the Early Triassic in southern Gondwana and diversified worldwide in the Late Triassic. The genus then became more common in Laurasia during the Jurassic and Early Cretaceous and declined thereafter with relict Late Cretaceous occurrences in Madagascar and South America.

The Taeniodonta comprise one of several groups of eutherians that diversified following the extinction of non-avian dinosaurs, and were among the earliest to achieve a relatively large body in the wake of the mass extinction some 66 million years ago. The fossil record of Taeniodonta is sparse, with much of what is known of their evolution being derived from specimens of early Paleocene age from the San Juan Basin of New Mexico. The record is particularly poor at higher latitudes, and while Schowalteria clemensi—the oldest taeniodont, known from but one specimen from southeastern Alberta—lived alongside dinosaurs and a suite of archaic mammals near the end of the Cretaceous, specimens referable to the order have heretofore not been discovered in Paleocene deposits in Canada, despite nearly 60 years of intensive collecting. I report here on the first evidence of taeniodonts from the Paleocene of western Canada, a record that includes representatives of both families (Huerfanodon, a conoryctid, and Psittacotherium, a stylinodontid). The new records demonstrate not only that taeniodonts occurred at higher latitudes during the early part of the Paleocene in North America, but were exceedingly rare, in keeping with their known occurrences elsewhere. Although taeniodont ecology has been invoked as a possible explanation for their rarity, the comparably sparse records of other large- and small-bodied mammals in local faunas of Paleocene age throughout the Western Interior suggest that taphonomic processes may have played the more significant role.

We report stem group Galliformes from the lower Eocene (Ypresian) London Clay of Walton-on-the-Naze (Essex, U.K.), which are among the oldest known fossils of galliform birds. The specimens are assigned to two new species, ?Paraortygoides argillae, sp. nov. and Waltonortyx bumbanipodiides, gen. et sp. nov. The latter is classified in a new family-level taxon, Waltonortygidae, fam. nov., which differs from other higher-level clades of stem group Galliformes in a proximo-distally narrow caput humeri and a short tuberculum dorsale of the humerus. With regard to these plesiomorphic features and a characteristic morphology of the coracoid, Waltonortyx is similar to early Eocene stem group Galliformes from Mongolia. Wing and pectoral girdle bones of a third, undetermined galliform from Walton-on-the-Naze resemble the Quercymegapodiidae; this fossil also shows a similarity to early Eocene galliforms from Mongolia. The affinities of “Paraortygoides” radagasti Dyke and Gulas, 2002, the only previously described putative galliform from Walton-on-the-Naze, are uncertain and neither its classification in the Galliformes nor its assignment to the taxon Paraortygoides are unequivocally established. For the first time we subjected a larger taxonomic sample of early Paleogene Galliformes to a formal analysis, and even though the resulting phylogenies were poorly resolved, they supported paraphyly of the Quercymegapodiidae, with the Early Miocene taxon Ameripodius being more closely related to the crown group than the late Eocene species of Quercymegapodius. Waltonortyx bumbanipodiides was recovered as the sister taxon of the Mongolian Bumbanipodius transitoria, which indicates early Paleogene dispersal events across the Turgai Strait.

Evolutionarily advanced waterfowl (the modern family Anatidae and its stem members in the order Anseriformes) are a successful bird group, well represented in faunas globally since the late Oligocene. However, the prelate Oligocene history of the evolutionary lineage of Anatidae remains largely unexplored, as these birds are very rare in earlier faunas. This paper describes a remarkable diversity of waterfowl from the lower Oligocene of Kazakhstan (Central Asia), which includes two members of Anatidae, as well as stem-anatids referred to Romainvilliidae and Paranyrocidae. The latter family is represented by the enigmatic swan-sized Cygnopterus, the genus revised here, with new materials confirming its ordinal and familiar assignment. Anatidae are represented by the globally oldest diagnosable taxa for this family, including species in the fossil genus Mionetta, previously known from upper Oligocene–Middle Miocene strata. The paper further addresses two upper Eocene anseriform taxa from Kazakhstan. These data show that diverse assemblages of advanced anseriforms existed in Asia as early as early Oligocene. The presence of several stem-anatid taxa in the late Eocene faunas of Central Asia supports the hypothesis of a possible Eurasian (or Northern Continents) origin of Anatidae, although the subsequent diversification of the group could have occurred in the Australian region.

Fossil snakes of the family Palaeophiidae are primarily known from rare, isolated vertebrae, leading to a poor understanding of the intra- and inter-columnar variation within a palaeophiid species. This leads to ambiguity in the taxonomic identity of these snakes, as in the case of the Eocene-age marine snakes of the genus Pterosphenus, in which the majority of species have been described by characters of problematic taxonomic value. Here, we propose a taxonomic revision of the genus based on an articulated to semi-articulated section of the vertebral column at the anterior to mid trunk-transition of Pterosphenus schucherti discovered from the middle Eocene (Bartonian) Harudi Formation, Kachchh (Kutch) Basin. The characters that separate Pterosphenus schucherti from ‘Pterosphenus schweinfurthi’ and ‘Pterosphenus biswasi,’ viz., the height of the pterapophysis and the anterior concavity of the zygosphene, have been found to be non-diagnostic, and the latter two species have been synonymized with the type species. Additionally, we utilized 2D and 3D landmark-based geometric morphometry to determine the morphometric affinity of palaeophiids amongst the alethinophidian snakes. The body size of the snake was estimated based on extant snakes with a morphometric affinity to Palaeophiidae. The cosmopolitan distribution of Pterosphenus schucherti is modelled based on the sea surface temperature (SST) constraints of the modern cosmopolitan snake Hydrophis platurus, and the known fossil localities of the species. The present findings provide crucial insights into the global paleoecological landscape of the Eocene, and the interactions of Pterosphenus schucherti with other palaeophiid snakes as well as the other Eocene fauna.

Evidence of trophic interactions are not scarce in the fossil record, yet these are mostly represented by fragmentary fossils exhibiting marks of ambiguous significance. Differentiating between marks of active predation and scavenging events is therefore often challenging. Here, we report on a dugongine sea cow skeleton (partial skull and vertebrae) from the Lower to Middle Miocene Agua Clara Formation (Venezuela) with shark and crocodylian bite marks. The sirenian is identified as Culebratherium sp. and preserves crocodylian bite marks across the skeleton. The most conspicuous correspond to deep tooth impacts with dragging effect, concentrated in the rostrum of the specimen. We interpret these as the result of active predation because of the similarity with those produced when a crocodylian holds or rolls a prey. Additionally, shark bite marks can be observed throughout the skeleton, also evidenced by the finding of an isolated tiger shark (Galeocerdo aduncus) tooth associated with this skeleton. Because of the irregular distribution of the shark bite marks, these are interpreted as scavenging. Overall, these findings constitute one of the few records documenting multiple predators over a single prey, and as such provide a glimpse of the trophic networks during the Miocene in the region.