A new large dissorophid temnospondyl, Buxierophus pouilloni n. gen. n. sp., is described on the basis of a well-preserved adult skeleton found in the Lower Permian bituminous claystone of Buxières-les-Mines, a fossiliferous locality of the Bourbon-l’Archambault Basin (Allier, France). This new taxon, with a skull length of about 12 cm, is characterized by a unique combination of characters: dorsal midline series of osteoderms composed of two series of thin and unornamented osteoderms, some bearing conspicuous peaks dorsally; internal osteoderms with bi- or multi-lobed dorsal articulation surfaces; neural arches of the same length to that of the osteoderm. A phylogenetic analysis places Buxierophus pouilloni n. gen. n. sp. at the base of the Dissorophidae. This new dissorophid had a semi-aquatic lifestyle. It’s completely ossified ceratobranchial skeleton bears ceratobranchials with grooves as clear indication for its fish-like internal gills in adult stage. It represents the only Lower Permian dissorophid from Europe. Buxierophus n. gen. is part of a rich Permian fauna of the Buxières-les-Mines locality, which is considered as a relatively deep and large paleolake deposit.

UUID: http://zoobank.org/pub/4bc42820-21f6-4674-88ff-eed8597733c3

The Paragaricocrinidae is an enigmatic late Paleozoic family of camerate crinoids that retained a robustly constructed calyx more typical of Devonian to Early Mississippian crinoids. The discovery of the oldest member of this family, Tuscumbiacrinus madisonensis n. gen. n. sp., initiated a phylogenetic investigation of the Paragaricocrinidae and consideration of its diversification and paleobiogeographic distribution. Phylogenetic analyses demonstrate the need to describe Tuscumbiacrinus n. gen and conduct revisions to preexisting taxa, resulting in the description of Palenciacrinus mudaensis n. gen. n. sp.; Pulcheracrinus n. gen.; Nipponicrinus hashimotoi n. gen. n. sp.; and Nipponicrinus akiyoshiensis n. gen. n. sp. Megaliocrinus exotericus Strimple is reassigned to Pulcheracrinus n. gen. In addition to having an anachronistic morphology, relatively few specimens are known through the ca. 76-million-year duration of this family. This pattern is unlikely to have resulted from low fossil sampling alone, and instead likely reflects low abundance and/or taxonomic richness of a long-lived waning clade. From its apparent origination in Laurussia during the Mississippian, the Paragaricocrinidae diversified into a cosmopolitan clade. Following a diversity drop during the Pennsylvanian, the Paragaricocrinidae persisted but exemplified characteristics of a dead clade walking until its eventual extinction during the middle Permian (Wordian).

http://zoobank.org/3e5df71c-112f-4556-96c5-a5a62d4a4da9

Gnathodus pseudosemiglaber is an important conodont species for Lower Mississippian biostratigraphy, but differentiating it from morphologically similar species remains difficult due to uncertainties in the intraspecific, ontogenetic, and phylogenetic relationships between taxa. To clarify these uncertainties, a fauna from the Yudong Formation at the Yudong II section in Baoshan, southwestern China, that contains abundant G. pseudosemiglaber was analyzed using population thinking. Quantitative morphometric methods were employed to analyze G. pseudosemiglaber specimens. Six anatomical measurements were taken on specimens of different ontogenetic stages to conduct analyses on normal distribution, correlation, and regression. A geometric morphometric analysis based on 13 landmarks was also performed. The results demonstrated that all analyzed specimens belonged to a single population. The dorsal carina of G. pseudosemiglaber has a growth rate that far exceeds other features on the platform through ontogeny as well as exhibits a series of transverse ridges in adult individuals, which becomes the most prominent diagnostic characteristic of this species. Thus, an amended systematic description for G. pseudosemiglaber is presented. Gnathodus girtyi maxwelli, a previously named species, however, is regarded as a junior synonym of G. pseudosemiglaber. Based on the revised taxonomy of G. pseudosemiglaber, its possible phylogenetic lineages and biostratigraphic use were reviewed. The ancestor of G. pseudosemiglaber is probably G. semiglaber but its descendant is unknown. The range of G. pseudosemiglaber is from the Scaliognathus anchoralis–Doliognathus latus Zone of uppermost Tournaisian to the lower part of the G. bilineatus Zone of middle-upper Visean.

Eocene snakes of India have the potential to shed light on the nature of snake diversification on the subcontinent following the Deccan volcanism at the Cretaceous-Paleogene boundary (K-Pg), when India was still a northward-drifting isolated landmass prior to its collision with Asia. Here, we report a diverse snake fauna from the Eocene of Kutch, western India. The fauna, dominated by aquatic forms, includes palaeophiids, a giant madtsoiid, and a possible nigerophiid. The palaeophiids from the middle Eocene (late Lutetian) comprise ?Palaeophis Owen, 1841 and Pterosphenus rannensis n. sp. Together, these taxa enrich the record of fossil snakes in the poorly known late Lutetian of India and represent the youngest record of Palaeophiidae from the Indian subcontinent. Pterosphenus rannensis n. sp. shows intermediate morphology between Palaeophis and Pterosphenus-grade snakes and is phylogenetically the earliest-diverging member of Pterosphenus Lucas, 1898. Additionally, the middle Eocene Pterosphenus biswasi Rage et al., 2003 is reassessed and retained as a valid taxon based on pterapophyseal morphology and overall form. Biogeographic considerations highlight the importance of the Indian fossil record in understanding the origin and diversification of the genus Pterosphenus. The prevalence of niche partitioning is suggested for the palaeophiids, with Pterosphenus rannensis n. sp. recovered from a tidal setting and ?Palaeophis sp. indet. from a marsh/swamp setting. The new Indian madtsoiid from the middle Eocene (early Lutetian) represents a sympatric taxon with the terrestrial/semiaquatic giant Vasuki indicus Datta and Bajpai, 2024 coexisting in a back-swamp marsh setting. The early Eocene (Ypresian) nigerophiid is among the oldest Cenozoic occurrences of this family globally.

UUID: http://zoobank.org/dc529074-73a6-4869-9b49-44caf9e2d956

The first unequivocal fossil of a tupinambine in North America is described on the basis of a single thoracic vertebra from a middle Miocene (Barstovian 2) paleocoastal deposit in southwestern Georgia, USA. Wautaugategu formidus n. gen. n. sp. is a mid- to large-bodied taxon with a unique mosaic of tupinambine features. Vertebral position of the fossil was determined both by qualitative and quantitative methods. This record is coeval with the warmest part of the Neogene, the Middle Miocene Climatic Optimum, when increased temperatures would have made the southeastern United Sates more habitable for this hyperthermic group of lizards. Although the arrival time of tupinambines into North America is still unclear, an increasing number of endemic South American reptiles, including the large-bodied iguanid Ctenosaura, dispersed as far North as Panama by the early Miocene before formation of the Panamanian Isthmus.

http://zoobank.org/58ded940-9082-46ae-8023-4b5f1b01691e

Squamate faunas from the lower Eocene of Europe are rare. We here describe pleurodontan iguanian (potentially Geiseltaliellus Kuhn, 1944), scincoid, and Squamata indet. jaw remains from Cos locality (near the Caylus village, southwestern France). The age of the Cos deposit has been proposed to fit the MP 10−11 interval (MP 10b; late Ypresian). Thus, it either corresponds to the end of the Early Eocene Climatic Optimum (EECO) or slightly postdates it. Although very fragmentary, the finds represent the first evidence of these clades in this locality, which is one of the oldest from Phosphorites du Quercy, adding to the squamate paleobiodiversity of the site. Besides iguanians and scincoids, the fauna also includes gekkotans, glyptosaurids, varanoids, and a constrictor snake. Some of the genera from Cos are known solely from this locality, revealing a crucial part of the squamate history in Europe. In the last few years, our knowledge of the Paleocene and especially early Eocene lizard faunas has increased. This allows a better understanding of the faunas and their changes due to temperature changes and migrations. Records are still very sketchy at European localities, but the overall picture is somewhat clearer, even on a smaller scale. A small but visible drop in lizard diversity appears to be present at localities from MP 8−9 relative to those from MP 7, whereas at MP 10, the diversity slightly increased. This appears to correlate well with observed changes in temperature.

This paper describes three collections of vertebrate fossils from the Lower Cretaceous Newark Canyon Formation of Eureka County, Nevada, made by the United States Geological Survey in 1961. Briefly mentioned in the prior literature, these specimens have gone unstudied for more than sixty years, until their recent transfer to the Smithsonian Institution. Re-examination of the materials reveals the first records of neoceratopsian and tyrannosauroid dinosaurs in the Newark Canyon Formation. In addition to augmenting the known vertebrate fauna from this poorly studied stratum, these occurrences provide important new data on otherwise rare taxa during a time of major faunal transition in North America.

The presence of a basal cingulum, fluting, and overall size have been used to differentiate nodosaurid and ankylosaurid teeth for decades. The taxonomic utility of tooth morphology in ankylosaurs, however, has not been quantitatively tested. In addition, new phylogenetic hypotheses recognize four ankylosaur families (Panoplosauridae, Polacanthidae, Struthiosauridae, and Ankylosauridae), rather than the traditional nodosaurid–ankylosaurid dichotomy. Understanding ankylosaur tooth variation could better help identify taxa with ambiguous phylogenetic affinities or allow isolated teeth to test paleoecological questions such as a potential extirpation of mid-Cretaceous ankylosaurids from Laramidia. We analyzed a large sample of ankylosaur teeth using traditional and geometric morphometrics and investigated the utility of size and the presence of a cingulum and fluting for differentiating ankylosaur teeth. Morphometric analyses show that “nodosaurids” had the greatest variation in tooth shape and size. Panoplosauridae and Struthiosauridae account for a large amount of “nodosaurid” variation, whereas basal ankylosaurs, Polacanthidae, and Ankylosauridae share a similar restricted morphospace. Teeth with a crown base length or height over 10 mm are found only in panoplosaurids, struthiosaurids, and Peloroplites, but smaller sizes are found in all clades. A basal cingulum and fluting are associated with Ankylosauridae and Panoplosauridae. Linear discriminant analyses could accurately identify only between 50% and 75% of the teeth in our sample; thus, they should be used in conjunction with size and discrete traits when identifying isolated teeth. With these findings, caution should be used when attempting to use isolated ankylosaur teeth in broader paleoecological questions, and reclassification of museum collections should be undertaken.

The allosauroid theropod dinosaurs of the clade Carcharodontosauridae were the apex predators in terrestrial ecosystems of the Early Cretaceous but were replaced in this ecological niche by Tyrannnosauridae in the Late Cretaceous. Details of this turnover are poorly known because only two transitional ecosystems, containing both carcharodontosaurids and tyrannosauroids, had been recognized to date (Cenomanian Cedar Mountain Formation of Utah, USA, and Turonian Bissekty Formation of Uzbekistan). Moreover, the presence of carcharodontosaurids in the Bissekty Formation, based on a maxilla fragment identified as Ulughbegsaurus uzbekistanensis Tanaka et al., 2021, has been recently questioned. Here we report on the third ecosystem containing both clades of apex predators, the Cenomanian Khodzhakul Formation in Uzbekistan. This new occurrence of Carcharodontosauridae is based on a newly identified maxilla that closely resembles the holotype maxilla of U. uzbekistanensis and is identified as Ulughbegsaurus sp. The revised morphological characters of both specimens support attribution of Ulughbegsaurus to Carcharodontosauridae. We report a novel neurovascular feature of the theropod maxilla—a medial alveolar canal that supplied the alveoli medially and contained tributaries of the palatine vessels in Ulughbegsaurus.

The Caribbean islands represent some of the most biologically diverse places on Earth, but much of that diversity is now at risk due to human impact. Larger islands in the Caribbean host more native species, but small islands still hold together a significant portion of the regional biota. Although our knowledge of extinct and extirpated taxa continues to improve, there are hundreds of islands, each with their own unique faunal histories from where there is little information about their ancient diversity. Sombrero is a very small island (0.38 km2) located within the limits between the Greater and Lesser Antilles and is largely barren of vegetation and freshwater. The island was extensively mined for bird guano in the 1800s, which profoundly altered its topography and fauna. Here, we describe a collection of microvertebrates recovered in 1964 from Sombrero, which documents an unexpectedly high number of colonization events and high extinction rate for this territory. The late Quaternary deposits from the island contain remains of five types of lizards, a snake, a tortoise, and an anuran that colonized the island once it became aerially exposed in the early Pleistocene. The ability for such a small, remote island to have eight colonizing taxa in < 2.5 Ma, provides support for the role that island hopping played in regional biodiversity in the Cenozoic (e.g., GAARlandia), even across small, barren islands. Furthermore, these fossils further show that large scale defaunation also affected vertebrate communities on very small islands in the Caribbean.

In 1855, Ferdinand Hayden collected a single tooth from the Judith River badlands of central Montana. Joseph Leidy named this specimen the following year as Troodon formosus. We describe troodontid material from the coeval Two Medicine Formation of Montana that compares closely to the recently resurrected and previously synonymized Stenonychosaurus inequalis from the lower Dinosaur Park Formation of Alberta. We uphold that synonymy but recognize T. formosus as the senior synonym. Troodon formosus is distinguished from other troodontids by a maxilla with an anteriorly more broadly rounded maxillary fenestra, low-angled nasal process with stepped anterior portion, large palatal shelf, and 23 teeth; more pronounced basioccipital tubera; L-shaped to triangular frontal; and relatively shorter metatarsal III with convex to flat anterior face at maximum breadth. Phylogenetic analysis places T. formosus within the Troodontinae, a clade with poor within-group resolution. The T. formosus holotype was diagnostic at time of description. Despite numerous complications over the taxon’s long history, the original name of 1856 has come to encompass a robust and specific species concept despite originally fragmentary material. Troodon formosus best satisfies the International Code of Zoological Nomenclature’s tenants of priority and stability. Recent proposals to re-establish Stenonychosaurus inequalis as the proper name encounter an equally problematic and undiagnostic type specimen. Instead of either of these types, we propose that material from the Two Medicine Formation (Museum of the Rockies, MOR 553) would best serve as a neotype for Troodon formosus.

Previous typification acts are reviewed herein, in light of the International Code of Zoological Nomenclature, to correct improper procedures while raising new type specimens for Theriosynoecum silvai, Darwinula martinsi and Cypridea araripensis, after loss of the original ones.

Early Miocene land mammals from eastern North America are exceedingly rare. Over the past several decades a small, but significant, vertebrate fauna has been recovered by paleontologists and citizen scientists from the Belgrade Formation at the Martin Marietta Belgrade Quarry in eastern North Carolina. This assemblage has 12 land mammal taxa, including beaver (Castoridae), stem lagomorph, carnivorans (Mustelidae, Ailuridae), horses (Equidae), rhinoceros (Rhinocerotidae), tapir (Tapiridae), peccary (Tayassuidae), anthracothere (Anthracotheriidae), entelodont (Entelodontidae), and protoceratid (Protoceratidae). Taken together, the biochronology of this Maysville Local Fauna indicates a late Arikareean (Ar3/Ar4) to early Hemingfordian (He1) North American Land Mammal Age (NALMA). This interval, which includes the Runningwater Chronofauna, documents numerous important Holarctic immigrants, including Amphictis, Craterogale, and cf. Menoceras found at this locality. Strontium isotope stratigraphy (SIS) of shark teeth collected in situ from the Belgrade Formation yield an age of 21.4 ± 0.13 Ma, which validates the age of interbedded land mammals within this unit. It also is consistent with the late Arikareean (Ar3/Ar4) biochronology and Aquitanian Neogene marine stage. New SIS analyses of oysters (Striostrea gigantissima) and clams (Chione) from this mine, previously assigned to late Oligocene or Late Miocene, are significantly older (28.0 ± 0.22 Ma and 27.6 ± 0.26 Ma, respectively) than the land mammals. Depending upon stratigraphic interpretations, these may confirm an older marine facies within the Belgrade Formation. This locality is important because of its marine and terrestrial tie-ins that facilitate intercalibration of both NALMAs and Cenozoic marine stages.

According to the International Code of Zoological Nomenclature (ICZN, 1999), the Principle of Homonymy (Article 52) states that when two or more taxa are distinguished from each other, they must not be denoted by the same name because this would cause confusion. Consequently, in a case of homonymy, only the senior name may be used as valid (Art. 52.2). The ICZN (1999) also indicates that if the rejected junior homonym has no known available and potentially valid synonym, it must be replaced by a new substitute name (Art. 60.3), that is, a replacement name.