We report and describe the first sirenian endocranial casts from the West Indies based on three specimens collected from two quarries of the upper Oligocene–lower Miocene Colón Formation, in the province of Matanzas, western Cuba. We assign them to Dugongidae incertae sedis, based on a phylogenetic analysis of fossil and extant sirenians. Thus, these new specimens provide a unique opportunity to describe the endocranial neuroanatomy of this family. The endocasts are suggestive of dugongids with limited vision and olfaction, based on the diminished olfactory and optic nerves. Additionally, we provide a geological reinterpretation of the Colón Formation and its paleoecological setting. Altogether, these data provide further insight into the diversity and evolution of sirenians, especially Caribbean dugongs.

The dicynodonts are an emblematic group of herbivorous therapsids that survived the Permo-Triassic (P-Tr) crisis. Laotian dicynodonts from stratigraphically constrained beds, recently dated using the U-Pb zircon method, yield new insights into terrestrial faunas of Southeast Asia during the latest Permian and earliest Triassic. Summarily described, they were originally attributed to the genus Dicynodon. We provide a new phylogenetic analysis for Laotian dicynodonts, based on three well-preserved skulls, indicating that they belong to two new taxa: Counillonia superoculis, gen. et sp. nov., and Repelinosaurus robustus, gen. et sp. nov. Our phylogenetic analysis of Dicynodontia indicates that (1) Counillonia is closely related to some ‘Dicynodon'-grade taxa and (2) Repelinosaurus is a kannemeyeriiform. The phylogenetic affinities of these new Laotian dicynodonts allow discussion of the survivorship of multiple lineages (Kannemeyeriiformes and ‘Dicynodon'grade dicynodontoids) across the P-Tr crisis. The Laotian dicynodonts also shed new light on the paleobiogeography of Southeast Asia from the late Paleozoic to the early Mesozoic, particularly the timing of collisions between the Indochina, the South China, and the North China blocks. The presence of dicynodonts in Laos, most likely in the Early Triassic, thus implies that the connection between the Indochina Block and the South China Block occurred no later than the latest Permian or earliest Triassic (i.e., when the dicynodonts provide direct evidence for a connection).

A new species of Nothosaurus from the Lower Keuper (Lettenkeuper, Ladinian, Erfurt Formation) of Vellberg-Eschenau, southern Germany, is described on the basis of a nearly complete skull that is only missing the lower jaw. Together with Nothosaurus edingerae, it is the only valid Nothosaurus species exclusively known from the Lower Keuper (Ladinian) of the Germanic Basin. Nothosaurus cristatus, sp. nov., differs from all other nothosaurs by exhibiting a postorbital that is excluded from the orbital margin by the postfrontal, the maxilla, and the jugal. The postfrontal and the maxilla form the posterior orbital margin exclusively. The parietal forms a pronounced and sharp crest anterior to the parietal foramen, which is unique among Nothosaurus. The ectopterygoid bears a long posterior process. A phylogenetic analysis of Nothosaurus cristatus, based on Liu et al. (2014, Scientific Reports 4:7142, doi: 10.1038/srep07142) with modified characters after Lin et al. (2017, Journal of Vertebrate Paleontology, doi: 10.1080/02724634.2017.1278703), yielded a nearly unchanged topology that supported the monophyly of (N. jagisteus (N. cristatus (N. mirabilis + N. tchernovi))).

Hynobiids are a group of small- to moderate-sized salamanders living primarily in Asia. They are a primitive crown-group clade, with a poor fossil record. Several hynobiid-like taxa have been discovered from the Lower Cretaceous strata of northern China during the last 20 years, with Liaoxitriton zhongjiani and Nuominerpeton aquilonaris identified as the oldest known stem hynobiids. However, the record of pre-Cretaceous hynobiid-like taxa is only known by Liaoxitriton daohugouensis, of which both the morphology and the congeneric status with L. zhongjiani remain problematic. Here, we report on a new hynobiid-like salamander, Linglongtriton daxishanensis, gen. et sp. nov., on the basis of two specimens from the Upper Jurassic Lanqi/Tiaojishan Formation (∼160 Ma) of Liaoning Province, China. Linglongtriton is diagnosed by a unique combination of features revealed by both observation under microscope and micro-computed tomography (µCT) scan of the holotype, including nasals separated from each other at the midline; prootic, opisthotic, and exoccipital retained as discrete elements; dentary with a lateral groove; articular not ossified; metacarpal III enlarged; a single centrale; and distal tarsals 4 and 5 fused into a single element. Phylogenetic analysis identified Linglongtriton and several other hynobiid-like taxa, including Liaoxitriton daohugouensis, as stem hynobiids, thereby extending the temporal range of the stem by at least 40 Ma—from the Early Cretaceous (Aptian–Barremian) to the Middle Jurassic (Bathonian). Comparative study of Linglongtriton with living and fossil hynobiids sheds new lights on the evolution and developmental mechanisms of several characters, including nasal separation and tarsal elements.

In the Late Jurassic Plattenkalk deposits of the Solnhofen Archipelago and of Nusplingen (both southern Germany), there are a considerable number of as yet undescribed genera and species of ganoin-scaled Halecomorphi. Some species were preliminarily assigned to the genus ‘Furo'; however, as noted by previous authors, the taxon ‘Furo’ is not a monophyletic genus. A description of two new genera and species, Zandtfuro tischlingeri and Schernfeldfuro uweelleri is presented here, with further descriptions of new species to follow separately. These new taxa are characterized by a specific combination of features, including: body shape; number of suborbital bones, infraorbitals, extrascapulars, dorsal and caudal fin rays, and vertical scale rows; number and shape of maxillary teeth; presence or absence of sclerotic ring ossification; shape of the ventral postinfraorbital; insertion of dorsal, pelvic, and anal fins; position of lateral line in caudal fin area; and shape and distribution of scales. The more basal Halecomorphi with massive ganoin scales (Parasemionotiformes, Panxianichthyformes, and Ophiopsiformes) remain poorly known, compared with the more advanced halecomorph group of the Amiiformes (especially the Amiidae). Closer investigation of their taxonomic relationship is therefore important for understanding broader patterns of halecomorph evolution.

We describe a new genus and species of extinct ground shark, †Diprosopovenator hilperti, gen. et sp. nov. (Elasmobranchii, Carcharhiniformes), based on a single incomplete skeleton with dentition recovered from basinal marine late Cenomanian (Metoicoceras geslinianum ammonite zone) organic-rich deposits of northern Germany. The new carcharhiniform is characterized by a unique combination of dental morphologies, indicating close architectural resemblance to the family Scyliorhinidae (catsharks). However, the very distinct tooth root morphology readily separates the new taxon from all other scyliorhinids. The extinct Cretaceous carcharhiniform †Pseudoscyliorhinus (represented by †Ps. schwarzhansi and †Ps. reussi) shares tooth root morphologies and vascularization patterns with †Diprosopovenator, gen. nov. We hypothesize that these two sharks form part of an extinct group of carcharhiniforms characterized by a distinct root morphology (viz., low hemiaulacorhize roots with very flat and strongly flared basal faces protruding below the crown labially and mesiodistally and with a well-developed central labiobasal notch). Consequently, we propose a new family of Late Cretaceous carcharhiniforms, †Pseudoscyliorhinidae, fam. nov., to include the new taxon, as well as †Pseudoscyliorhinus. †Pseudoscyliorhinidae, fam. nov., shows a wide European distribution during the Late Cretaceous, ranging from the early Cenomanian to the late Campanian. The longevity of Scyliorhinidae, with a fossil record extending back into the Middle Jurassic, however, remains ambiguous and unresolved; therefore, it may be best to regard the assignment of fossil taxa to Scyliorhinidae as currently uncertain pending further taxonomic work.

Baurusuchidae is a clade of terrestrial crocodyliforms that thrived during the Late Cretaceous in South America. The members of this clade occupied top-predator roles in their habitats. Knowledge about the anatomy, the systematics, and the evolution of baurusuchids has increased profoundly in the past decade. Although aspects of their cranial and postcranial anatomy are becoming clearer, the configuration of the dermal armor remains neglected and little is known about the anatomy of these elements in the clade. The dermal skeleton of baurusuchids is described here in detail in terms of arrangement and morphology, the supposed absence of osteoderms in Pissarrachampsa sera is reevaluated, and a detailed comparison across Crocodyliformes is attempted. The description of the dermal armor, in particular that of the dorsum, revealed an unforeseen variation among baurusuchid taxa, including autapomorphic traits that were added to the diagnosis of taxa. The absence of osteoderms is confirmed for Pissarrachampsa sera based on new specimens, revealing this taxon as the only terrestrial crocodyliform known to lack dermal armor altogether. Comparisons with a diverse range of crocodyliforms revealed that the dorsal shield of baurusuchids is unique among crocodyliforms in terms of arrangement and morphology, and only a few notosuchians approach the condition seen in the clade. This study explores possible biomechanical implications of the unique dorsal shield of baurusuchids and provides information about possible phylogenetic signals, to be tested in future analyses of notosuchian systematics.

Plesiosaurs are an enigmatic, diverse extinct group of Mesozoic marine reptiles well known for their unique body plan with two pairs of flippers and usually an elongated neck. The long neck evolved several times within the clade, yet the evolutionary advantages are not well understood. Previous studies have mainly focused on swimming speeds or flipper locomotion. We evaluated the hydrodynamics of neck length and thickness in plesiosaurs using computational fluid dynamics (CFD) simulations based on the Reynolds-averaged Navier-Stokes (RANS) approach. Simulations were performed of flow patterns forming around five distinctive plesiosaur models, three of different neck lengths (neck/body ratios of 0.2, 0.41, and 0.63) and two of different neck thicknesses (100% and 343% increase compared with cervical vertebrae width). By simulating water flow past the three-dimensional digital plesiosaur models, our results demonstrated that neck elongation does not noticeably affect the force of drag experienced by forward-swimming plesiosaurs. Thicker necks did reduce drag compared with thinner necks, however. The consistent drag coefficient experienced by the three neck lengths used in this study indicates that, at least for forward motion at speeds from 1 to 10 m/s, hydrodynamic implications were not a limiting selective pressure on the evolution of long necks in plesiosaurs. We also tested the effects of bending the long neck during forward motion. Bending a plesiosaur neck evenly in lateral flexion increased the surface area normal to flow and subsequently increased drag force. This effect was most noticeable in the longest-necked forms.

Despite recent advances in noninvasive imaging, Plesiosauria remains one of the least explored clades of reptiles with respect to paleoneuroanatomy. Only partial endocasts, obtained from either latex casts or imprints left on the braincase, have been described. In this contribution, the digital endocasts of three plesiosaurian specimens were analyzed: two referred to the elasmosaurid Libonectes morgani and one to Polycotylidae indet., all from the Late Cretaceous (Turonian) of Goulmima (Morocco). They were computed tomography (CT)-scanned to provide new anatomical information on the plesiosaurian endocast, endosseous labyrinth, and cranial nerves. Results show that the three endocasts are very similar to each other. They appear anteroposteriorly elongated and horizontally oriented in lateral view, with long olfactory tracts, relatively small and incomplete olfactory bulbs, a reduced pineal organ, distinguishable optic lobes, and a possible large cerebellum constituting the main component in size of the endocast. The endocranial features reconstructed here are compared with those of other plesiosaurians, as well as other marine reptiles, notably to discuss their intraspecific and interspecific variability. This study provides pioneer data in order to estimate the impact of both phylogenetic and ecological constraints on the endocranial morphology of plesiosaurians and proposes a few preliminary paleobiological suggestions.

A new taxon of kannemeyeriiform dicynodont, Ufudocyclops mukanelai, is described based on a well-preserved skull from Subzone C of the Cynognathus Assemblage Zone, which are the youngest strata (probably Middle Triassic) of the Beaufort Group (uppermost Burgersdorp Formation) in South Africa. Ufudocyclops mukanelai is diagnosed by its autapomorphic intertemporal morphology: the intertemporal bar in this taxon is ‘X'-shaped—broad anteriorly and posteriorly but distinctly ‘pinched’ at mid-length and bears a deep, triangular depression immediately behind the enormous pineal foramen. The new kannemeyeriiform can also be diagnosed by the presence of a laterally expanded jugal plate beneath the orbit, and highly discrete, ovoid nasal bosses separated by a broad, unornamented median portion of the premaxilla and the nasals. Two partial dicynodont skulls from this subzone, previously identified as specimens of the otherwise Tanzanian taxon Angonisaurus, are also referable to U. mukanelai. Removal of these specimens from the hypodigm of Angonisaurus eliminates a crucial point of correlation between Cynognathus Subzone C and the Manda Beds of Tanzania and suggests that Subzone C preserves a distinct, endemic fauna, not just a southern extension of the better-known Middle–Late Triassic tetrapod faunas from Tanzania and Zambia. Inclusion of Ufudocyclops in a phylogenetic analysis of anomodonts recovers it as an early stahleckeriid, the first record of this clade from the Cynognathus Assemblage Zone.

Thirteen elasmobranch genera, four of which are identified to species, are described from the early to middle Miocene (Burdigalian–Langhian) Awa Group in southwest Japan. Springeria and Narke are the first fossil records of these genera. Of these 13 genera, 10 have bathyal or pelagic Recent species. The deep-sea elasmobranch fauna of the Awa Group is characterized by dominance of Squalus species. The Awa fauna is clearly distinguished from the European Miocene fauna by the lack of abundant small sharks in Palaeocentroscymnus and Squaliolus.

The genus Sivameryx (Cetartiodactyla: Anthracotheriidae), found in both Asia and Africa, is considered of Asian origin. Recent excavations in the Negev region of southern Israel led to the discovery of a new early Miocene site called Kamus Junction. Among the fossils recovered at Kamus Junction is an upper molar of Sivameryx palaeindicus. Although known species of Sivameryx have often been distinguished by size, comparisons of the new specimen with known Sivameryx teeth from Asia and Africa emphasize the need for caution when assigning Sivameryx fossils to species based on size alone. This record of Sivameryx highlights the importance of the Levant as a corridor connecting Eurasia and Africa. The new find, along with other recent finds, demonstrates that the Levantine Corridor facilitated faunal dispersal events that shaped modern biotas as early as the early Miocene.

Crocodilian remains from the Oligocene fossil locality of Monteviale, northeastern Italy, have historically been referred to different genera, but all material was recently assigned to Diplocynodon cf. D. rateliiPomel, 1847. The purpose of the present work is to clarify the systematics of the known crocodilian remains from Monteviale. The largest collection is housed in Padua, Italy, but museums in La Rochelle, France; Basel, Switzerland; and London, United Kingdom reposit crocodilian remains of uncertain provenance but which are clearly from either Monte Bolca or Monteviale. Radiogenic strontium isotope ratios were measured on the embedding lignite of those specimens to investigate their provenance. The material belongs to the genus Diplocynodon, but it clearly differs from D. ratelii because the nasal elements are excluded from the external nares. Diplocynodon from Monteviale shares the same general suture pattern of the skull with the two species D. tormis and D. muelleri. Diplocynodon muelleri and specimens from Monteviale are also congruent in terms of shape and proportion of the supratemporal fenestrae. However, a revision of D. muelleri is currently needed; thus, the Monteviale species is identified as Diplocynodon cf. D. muelleri. In order to examine the relationships of Diplocynodon from Monteviale, a phylogenetic analysis was carried out and points to a particularly close relationship among D. muelleri, D. tormis, and the Diplocynodon from Monteviale. The occurrence of Asiatosuchus in Monteviale is rejected, supporting the hypothesis of a reduction in crocodilian diversity around the Eocene-Oligocene boundary in Europe.

We describe new specimens of the Miocene moschid Hispanomeryx, from the early Vallesian sites of Castell de Barberà (CB) and Ecoparc de Can Mata (ECM), Vallès-Penedès Basin, representing the first Iberian record of Hispanomeryx outside the inner Miocene basins. Fossils from ECM constitute Hispanomeryx lacetanus, sp. nov., the first Hispanomeryx to be described with a ‘Palaeomeryx fold (external postprotocristid).’ Fossils from CB constitute the first unambiguous record of Hispanomeryx aragonensis outside its type locality (La Ciesma-1B, Ebro Basin, Spain) and allow us to describe for the first time the upper molars of this species. Our phylogenetic analysis of Hispanomeryx places H. andrewsi from China as the sister group of a clade containing two European lineages. One of the latter places H. daamsi in a clade with the sister species H. duriensis and H. lacetanus, sp. nov., and the other groups together the two forms of H. aragonensis (type series from La Ciesma-1B plus the new material from CB). Emended diagnoses for the genus Hispanomeryx and all previously described species are presented. The new Hispanomeryx material from the Vallès-Penedès Basin constitutes the first unambiguous forest-dwelling Hispanomeryx ever recorded in Iberia, demonstrating that the previous lack of Hispanomeryx fossils in the Vallès-Penedès Basin was due to insufficient sampling rather than to paleoecological absence. It is therefore apparent that Hispanomeryx was as environmentally plastic as its relative Micromeryx, inhabiting similar habitats that varied from dry and open to humid and forested.

During the mid-Cretaceous, multituberculate mammal communities were restructured, as ‘plagiaulacidan’ multituberculates, common from the Middle Jurassic through Early Cretaceous, began to be replaced by the Cimolodonta, a clade that would come to be the most abundant and diverse group of mammals during the Late Cretaceous and early Paleocene. Although these broad strokes of multituberculate evolutionary history are well documented, the only fossil assemblage detailing this rise of the Cimolodonta during the Early–Late Cretaceous transition comes from the Mussentuchit Member of the Cedar Mountain Formation in central Utah. Here, we report on nine new multituberculate specimens from the Wayan Formation of southeastern Idaho, representing the second and northernmost record of multituberculate mammals from near the Early–Late Cretaceous boundary of North America. The Wayan assemblage consists of isolated cimolodontan premolars and molars representing at least four taxa, including one new species, Cimolodon akersteni. The presence of Cimolodon in the Wayan assemblage represents the earliest occurrence of this genus and the first appearance of a clade nested within Cimolodonta (the Cimolodontidae). Only two species are shared between the Wayan Formation and the Mussentuchit Member, cf. Paracimexomys perplexus and Bryceomys intermedius. All other specimens differ morphologically from any known mid-Cretaceous multituberculate species. The differences in the Wayan and Mussentuchit multituberculate local faunas could be due to differences in age, biogeography, paleoenvironment, sampling bias, or some combination of these factors. These new specimens reveal a greater diversity of mid-Cretaceous multituberculates than was previously recognized and provide new insights into the early evolution of Cimolodonta.

Giant birds, comparable in size to elephant birds and moa, have never been reported from Europe. Here, we describe a femur from the lower Pleistocene of the north Black Sea area (Crimea) that is referred to Pachystruthio dmanisensis, comb. nov., a giant bird with an estimated body mass of about 450 kg. This value makes this extinct bird one of the largest known avians (comparable to Aepyornis maximus) and the only bird of such giant size in Europe and the Northern Hemisphere in general. In contrast to very large insular birds, Pachystruthio dmanisensis was a good runner, which may be explained by its coexistence with large carnivoran mammals. Pachystruthio dmanisensis and associated assemblage of fossil mammals are shared with the Dmanisi locality in Georgia (∼1.8–1.7 Ma); thus, this giant bird was likely a typical component of eastern European faunas at the time of early hominin arrival. We suggest that Pachystruthio dmanisensis, together with early Homo and a variety of mammals, reached the northern Black Sea region via the southern Caucasus and Anatolia, because the older (Pliocene) finds of this fauna are known from Georgia and Turkey.

In 1889, Florentino Ameghino erected Patriarchus palmidens, based on a specimen from a western outcrop of the Santa Cruz Formation (early Miocene) and associated it with the ‘Notohippidian stage’. Later, Ameghino added seven other species to the genus from eastern localities of the same formation. Since 1900, Patriarchus has been considered to be a junior synonym of Protypotherium. Here, we present a systematic revision and recognize the genus Patriarchus as monospecific, with Pa. palmidens characterized by i1–c mesiodistally expanded, labially convex, and similar in size; i1–c with a short lingual sulcus that does not extend to the base of the teeth and ‘V’-shaped in occlusal view; p1 labially and lingually bilobate, with trigonid larger than talonid; and i1–p1 in a continuous series without overlapping. Five of the remaining species are recognized as belonging to Protypotherium. Therefore, Patriarchus is presently monospecific (Pa. palmidens) and restricted to the western region of Santa Cruz Province, particularly to the Río Bote locality. Patriarchus is included for the first time in a cladistic analysis to discover its phylogenetic relationships within the Interatheriidae. It is nested within the most derived Interatheriinae and is recovered as the sister group of the Laventan Miocochilius; this clade is, in turn, the sister group of Cochilius plus Interatherium. These results support the hypothesis that the origin of the Miocene Interatheriines was a single evolutionary event.

The Upper Cretaceous (Cenomanian) limestone quarry of Haqel, Lebanon, is home to one of the largest diversities of fossil actinopterygians in the Mesozoic, particularly of pycnodontiform fishes. Here, we describe a pycnodontiform fish, Flagellipinna rhomboides, gen. et sp. nov., from this locality based on four specimens. It is considered a member of the derived family Pycnodontidae due to the presence of a postparietal process. This taxon is distinct from other pycnodontids due to its diamond-shaped body, whip-like dorsal fin, postcloacal scales with forward-pointing spines, and acute anterior profile with a concave slope, giving it a ‘hunchback’ appearance. The prognathous snout armed with molariform teeth suggests that this pycnodont preyed on a variety of shelled animals from crevices. The smallest specimen is distinct in that it has a larger orbit size, no spines on the contour scales, poorly ossified skull roof bones, a notochord partially covered by arcocentra, and lacks whip-like filament on the dorsal fin, which suggest that it is a juvenile/subadult. The differences between the juvenile/subadult and other larger specimens suggest a change in ecological niche occupation during ontogeny, going from a generalized forager that lived in complex, reef habitats to moving into deeper waters to feed from crevices on the reef edge. These findings provide a more complete picture of the possible life history strategies that pycnodontiforms may have used in order to exploit different resources throughout their lives.