Ernanodon, one of the most enigmatic Asian fossil mammals, was previously known by a single specimen from the late Paleocene (Nongshanian) of China. Here we document the first record of Ernanodon from Mongolia, represented by a nearly complete skeleton from the late Paleocene (Gashatan) of the Naran Bulak locality. The new material provides an opportunity to understand the lifestyle and habits of this rare mammal and reevaluate the arguments used to establish the phylogenetic relationships of Ernanodon. Functional analysis indicates that Ernanodon had very strong forelimbs with large claws and used its forelimbs for scratch-digging. Character analysis reveals numerous similarities in postcranial anatomy between Ernanodon and Palaeanodonta. Phylogenetic analysis supports inclusion of Ernanodon in the order Palaeanodonta and suggests that Palaeanodonta and Pholidota are sister groups.

The Osteostraci are a morphologically diverse group of jawless fishes considered as sister taxon to jawed vertebrates. Fossil Osteostraci therefore have wide-reaching ramifications for our understanding of the origin and evolution of gnathostomes. Their utility in this context is currently impeded by rudimentary taxonomy of faunas from the United Kingdom. Principal among these is a well-preserved, previously undescribed fauna from the Early Devonian (Lochkovian) of Wayne Herbert Quarry, Herefordshire. Here we provide a description of new osteostracan material from this fauna. Anatomical observations of the character-rich, taxonomically informative headshield, combined with quantitative measurements, have permitted identification of 15 variable characters. From these, seven discrete morphogroups are recognized and used to establish the taxonomy of the material. This includes two new species of Zenaspididae (Zenaspis waynensis and Diademaspis janvieri), two new species of Cornuata incertae sedis (Janaspis newtonensis and J. punctata), two indeterminate species, and Pattenaspis whitei, which is redescribed on the basis of new material. Our analyses indicate that cornuate osteostracan species are likely over-split due to erection of new taxa based on poorly preserved type specimens, inadequate consideration of taphonomic character loss, and over-reliance on continuous rather than discrete characters. Furthermore, patterns of dermoskeleton ornamentation and tessellation of Diademaspis janvieri and Cornuata, gen. indet., sp. B are used to infer mechanisms of dermoskeletal growth. These new data allow incorporation of this fauna into scenarios of osteostracan evolution, considerations of gnathostome origin, and studies of global Lochkovian diversity.

An exquisitely preserved skull of Feeserpeton oklahomensis, gen. et sp. nov., collected from the Lower Permian fissure-fill deposits near Richards Spur, Oklahoma, is the newest parareptile from the locality. The specimen comprises an almost complete skull, lacking most of the premaxillae, parts of the jugals, and parts of the braincase. The maxillae and dentaries possess caniniform regions, including large caniniform teeth that are at least twice as large as any other tooth in the jaws. A phylogenetic analysis of Parareptilia that includes the new taxon indicates that the Early Permian F. oklahomensis is a member of the poorly known Lanthanosuchoidea, positioning it as the sister taxon of a clade consisting of Acleistorhinus pteroticus and Lanthanosuchus watsoni. This new taxon adds significantly to our limited knowledge of the early stages of parareptile evolution, as well as the large terrestrial tetrapod diversity found at Richards Spur.

Fossil soft-shelled turtles (Trionychidae) have so far been recognized in all continents except Antarctica, based largely on remains preserving their diagnostic sculptured shell bones. The origin of the group is generally assumed to be in the Early Cretaceous of Asia, whereas they first appear in North America and Europe during the Late Cretaceous and Paleocene, respectively. Here we describe the first record of an indeterminate trionychid from the late early Campanian from southern Sweden, a part of the paleobiogeographically isolated Fenno-Scandian Shield, thus extending the stratigraphic record of the group in Europe back about 15 Ma into the Late Cretaceous. Our finding provides evidence against the currently favored dispersal scenario in which trionychid turtles are interpreted to have come to Europe first during the Paleocene either directly from North America or via Asia. The described indeterminate trionychid possibly represents a relic of a pre-Cretaceous endemic radiation of North European trionychids living mainly on the Fenno-Skandian Shield or it may indicate a potential lower latitude dispersal route of trionychids from Asia to North America via Europe during the Late Cretaceous.

We report a new site with an occurrence of isolated bones of a Palaeochersis-like turtle in Norian-Rhaetian fluvial sediments from southern Poland. The turtle remains are associated with bones of a medium-sized aetosaur, a coelophysoid dinosaur, and a larger carnivorous archosaur, as well as a hybodontid shark, ganoid and dipnoan fishes, and a large temnospondyl.

In mosasauroids, one of the major groups of Mesozoic marine reptiles, various ecological grades have been identified. However, no data are available concerning the ecology of the poorly known juveniles. Osseous microanatomical organization appears to rely mainly on the biomechanical constraints undergone by organisms. As such, it is considered as a valuable paleoecological marker. The vertebral microanatomy of several juvenile specimens of hydropelvic mosasauroids (whose adult forms are active pelagic swimmers) was analyzed. This study provides data about their growth mode and speed but, above all, reveals that juvenile hydropelvic mosasauroids display microanatomical features comparable to those of adults. This signifies that hydropelvic mosasauroids were already highly efficient swimmers at a very young age, contrary to plesiopelvic forms (i.e., those with a terrestrial-like pelvis and limbs), that were relying on hydrostatic (and not hydrodynamic) regulation of buoyancy and body trim. This study tends to support recent views challenging the old hypothesis of sheltered nurseries and shows that, in mosasauroids, the functional requirements for buoyancy and body trim control are not correlated with individual size.

The plesiosaur specimen NHMUK OR49202, from the Lias Group of Lyme Regis, consists of a complete skull, palate, and mandible, with eight associated cervical vertebrae, including the atlas-axis complex. This juvenile plesiosaur specimen was originally referred to ‘Plesiosaurus’ macrocephalus. However, reexamination indicates that it does not belong to Plesiosaurus and comparison with the type specimen of ‘Plesiosaurus’ macrocephalus (NHMUK OR1336) suggests that it is taxonomically distinct. Therefore, NHMUK OR49202 is made the holotype of a new genus and species: Anningasaura lymense. The specimen possesses plesiomorphic characters, including premaxillae that do not separate the frontals on the midline, narrow cranioquadrate passages, lack of a constricting groove around the occipital condyle, and several autapomorphies not observed in other plesiosaurian taxa: posteromedial processes of the premaxillae (or possible anterior portion of the frontal) forming a dorsoventrally thick, mediolaterally expanded platform; supplementary foramen penetrating the parietal sagittal crest; absence of a pterygoid-vomerine contact; absence of a contact between the pterygoids in palatal aspect; cultriform process of the parasphenoid wider mediolaterally than the combined posterior interpterygoid vacuities; and two closely spaced foramina in the lateral surface of the exoccipital. Anningasaura lymense is a plesiomorphic Early Jurassic taxon, and provides anatomical data that clarify the early evolutionary history of Plesiosauria.

A new Middle Triassic archosaur, Diandongosuchus fuyuanensis, gen. et sp. nov., is described on the basis of a skeleton from the Zhuganpo Member (Ladinian) of the Falang Formation, eastern Yunnan Province, China. It is primarily characterized by the nasal process of the premaxilla extending posteriorly well beyond the external naris, the super-sized coracoid foramen laterally bordered by the scapula, the ischium with a strongly expanded medial portion anteroposteriorly longer than the proximodistal height of the bone, and anteriorly notched cervical osteoderms. D. fuyuanensis is a pseudosuchian on the basis of the crocodile-normal tarsal joint and other features, such as the distal end of the ulna in posterolateral view squared off, osteoderms with a distinct anterior process, the presacral vertebrae dorsally covered by more than one osteoderm, dorsal osteoderm alignment dorsal to presacrals 10–24 staggered, the pubis-ischium contact reduced to a thin proximal contact, and the medial contact of the ischia extensive but the dorsal margins separate. It is from a marine deposit but shows few morphological adaptations of the postcranial skeleton for a semiaquatic way of life when compared with Qianosuchus from the Anisian limestone of the same area. A phylogenetic analysis derived from an existing data matrix suggests that the new archosaur occupies the basal-most position in Poposauroidea and further confirms the poposauroid status of Qianosuchus. On the basis of current information, the discovery of Diandongosuchus does not firmly underscore the affinity of the semiterrestrial vertebrate faunas between the eastern and western regions along the northern coastline of the Tethys.

Estimating the mass of an extinct organism is naturally difficult. Practicality and simplicity means that often some linear measurement is used as a proxy. In the case of non-avian dinosaurs, the total length of the animal (from the snout to the tip of the tail) is sometimes used for this purpose. However, the total length of the tail is unknown in all but very few dinosaurian taxa. Tail length data taken from specimens and the literature are shown here to have remarkable variation both between and within clades (and even within single species). Comparison with body length data shows that total length (including the tail) is therefore a less reliable measure of size than using the snout-vent length of the animal. ‘Snout-sacrum’ lengths are suggested as a more reliable alternative. Total length should not be abandoned, however, both to provide a comparison with older works and specimens lacking complete presacral axial columns, and for communication with the general public.

Computed tomography (CT) has become a major tool to elucidate the anatomy of fossil taxa, including the braincase and inner ear. However, sample size is still limited and studies have concentrated mainly on saurischian dinosaurs. Here we report on the braincase anatomy of the Upper Jurassic ornithopod Dysalotosaurus using high-resolution X-ray micro-CT (µCT). The main trunk of the vena capitis dorsalis was found between the parietal and supraoccipital, leading to a nomenclatural revision of cephalic veins and reidentification of their bony correlates. Contrary to the condition in hadrosaurid ornithischians, the posterior semicircular canal is the shortest canal in Dysalotosaurus, whereas the lateral is the longest, lying dorsal to the vestibule, as in basal archosaurs. The anteroventral inclination of the lateral semicircular canal suggests that Dysalotosaurus must have oriented its head dorsally while alert. Because the cochlea is relatively short, Dysalotosaurus had reduced ability to discriminate between high- and low-frequency sounds, as in sauropods, basal ceratopsians, and other basal archosaurs. The metotic foramen, however, was fully subdivided into a fenestra pseudorotunda and a vagus foramen, a derived character for archosaurs that is usually associated with a more refined sense of hearing. Lack of a refined capacity for discrimination of sound frequencies due to a short cochlea together with the equal-sized and thick semicircular canals represent plesiomorphic characters for Dinosauria. The middle and inner ears of Dysalotosaurus bear a mosaic of primitive and derived features, pointing to a more complex evolutionary history of these structures.

We describe the anatomy and bone microstructure of a new subadult specimen of Sapeornis chaoyangensis from the Early Cretaceous of Liaoning Province, China. To date, this is the only known sapeornithid that preserves substantial portions of its plumage. Found in the Yixian Formation, it also represents the oldest known sapeornithid, and as such, extends the stratigraphic range of this lineage 3–5 million years. This specimen also increases our knowledge of sapeornithid skeletal and integumentary anatomy, including previously unrecognized details of the primary and secondary wing feathers. Examination of the characters used to diagnose other named sapeornithid species reveals that such diagnoses have incorporated morphologies that are influenced by either taphonomy or ontogeny. Based on qualitative and quantitative comparisons between the new specimen and other sapeornithid species, we argue that all other named sapeornithids are junior synonyms of S. chaoyangensis.

Several new specimens of the Triassic therocephalian Tetracynodon darti have become available in recent years, allowing substantial corrections and expansions to previous descriptions. We here analyze T. darti in the context of therocephalian relationships and biology, using computed tomographic (CT) scanning to reveal details of the skull. Histological sections, as well as the degree of ossification of individual elements, both suggest that the available specimens are subadults (rather than rapidly growing neonates), and probably yearlings. A maxillary shelf bearing a long suture with the vomer similar to that of Lycideops is present, and T. darti also shares a nasal-lacrimal contact with that taxon. There is no evidence for the presence of maxilloturbinal bones. The postcranial skeleton is slender and similar to that of regisaurids and other small baurioids. The skull bones show clear indentations demarcating the major divisions of the brain, allowing one of the most detailed reconstructions of a non-mammalian therapsid brain published to date. The brain is strikingly plesiomorphic in many features, particularly in the retention of large dorsally positioned optic lobes of the tectum, but generally shows features that are intermediate between gorgonopsians and cynodonts, thus clarifying this stage of the evolution of the synapsid brain. A cladistic analysis of 33 therapsid taxa and 131 morphological characters supports the monophyly of Therocephalia, and there is evidence for a monophyletic Lycideopidae within Baurioidea. Lycideopidae contains species with long snouts, nasal-lacrimal contacts, and incipient secondary palates, including Lycideops, Choerosaurus, T. tenuis, and T. darti.

The genus Notopithecus is the best known and most abundant among the genera traditionally grouped as “Notopithecinae” (Notoungulata, Interatheriidae). Previous studies have described in detail the morphology of the skull of Notopithecus; however, its scarce appendicular bones were poorly characterized. Until now neither skulls nor associated skeletons were known for the other genera of this group. In this paper, the most complete individual of Notopithecus is described. The specimen MPEF-PV 1113 is in the vertebrate paleontology collection at the Museo Paleontológico Egidio Feruglio, Trelew, and comes from Valle Hermoso, Chubut Province, Argentina. It includes the articulated cranium and mandible and most of the postcranial skeleton, with almost all the elements in anatomical position: many articulated vertebrae, scapula, humerus, radius, femur, tibia, fibula, calcaneum, astragalus, metapodials, and phalanges. The present contribution constitutes the first comparative study of the postcranial skeleton associated with the skull of an individual of Notopithecus, clarifying some systematic contradiction relative to the holotype of this taxon; at the same time, most of these elements are known for the first time for notopithecines. The appendicular skeleton of Notopithecus is significantly distinct from other known interatheriine interatheriids such as Federicoanaya sallaensis and Eopachyrucos ranchoverdensis from the Deseadan SALMA or Interatherium and Protypotherium from the Santacrucian SALMA. On the other hand, it presents some similarities with the Mesotheriidae Trachytherus and the generalized notoungulate Colbertia magellanica. The new specimen of Notopithecus offers the potential for morphofunctional studies and improving our understanding of the phylogeny of this group.

In this paper are described the arvicolines from El Chaparral site (Villaluenga del Rosario, Cadiz, Southwestern Spain). Due to their wide geographical distributions and rapid evolutionary rates, arvicolines are especially useful for biostratigraphical purposes. The stratigraphic layers of El Chaparral have yielded arvicolines remains of the genera Allophaiomys, Iberomys, Pliomys, and Terricola. The presence of these rodents together the other vertebrates recovered allows to determinate the age of the El Chaparral site and compare our data with other Iberian Pleistocene sites, such as of the Sierra de Atapuerca. El Chaparral site ranges between the Jaramillo Subchron (1.07–0.99 Ma) and shortly after the Brunhes-Matuyama transition at 0.78 Ma covering a important time span for the knowledge of the earliest humans occupations in western Europe.

Pterophocaena nishinoi, gen. et sp. nov. (Phocoenidae), from the upper Miocene Wakkanai Formation (9.2–9.3 Ma) in Hokkaido, northern Japan, is described. This is the oldest fossil phocoenid in the western North Pacific, thus extending the fossil record of Phocoenidae an additional approximately 4 million years in the region compared with the previous record. The holotype, composed of a partial skull, with right periotic and tympanic bulla and a postcranial skeleton, has the following apomorphic characters: absence of the premaxillary eminence; posterior half of the hamular process of the pterygoids not separated by palatines; prominent dorsolaterally projecting premaxilla in the facial area; supraorbital process of the maxilla steeply sloping ventrolaterally; posteriorly protruding temporal crest; anteroventrally narrowed and inverted teardrop-shaped temporal fossa; and several short ridges on the tympanosquamosal recess of the squamosal. A comprehensive cladistic analysis (66 ingroup taxa and 278 morphological characters) indicates that Pterophocaena is the most basal phocoenid yet discovered, and that Phocoenidae and Delphinidae are closely related. The discovery of Pterophocaena leads to a review of previous hypotheses for the origin of Phocoenidae, and indicates that phocoenids had already diversified in the Pacific Ocean by late Miocene.

Two new extinct porpoises—Archaeophocaena teshioensis, gen. et sp. nov., and Miophocaena nishinoi, gen. et sp. nov.—are described from the upper Miocene Koetoi Formation (5.5-6.4 Ma) of Hokkaido, Northern Japan. The holotype of the former is composed of a partial skull, whereas the holotype of the latter is composed of a partial skull, right periotic, right stylohyoid, and pelvis. Both species are assigned to Phocoenidae on the basis of a unique combination of phocoenid characters: presences of frontal bosses, nasal protuberances, premaxillary eminences, and fossae for the inferior vestibule. However, they do not have dorsally developed preorbital sinus fossae or high premaxillary eminences, unlike derived phocoenids. Furthermore, their premaxillae contact the nasals (or the right premaxilla alone contacts the right nasal), unlike all other known phocoenids except Pterophocaena. A comprehensive morphological cladistic analysis indicates that the two new extinct species are the second-most basal phocoenids next to Pterophocaena and that Phocoenidae is the sister group of Delphinidae. The cranial morphology of the two new extinct species is intermediate in form between that of phocoenids and delphinids, supporting the hypothesis of a sister relationship for the two groups. Thus, these new species fill not only the morphological gap between Phocoenidae and other families of Delphinoidea but also a temporal gap in the fossil record of phocoenids in the western North Pacific.

In this study we describe an isolated petrosal from the middle Eocene of northwestern Argentina assigned to Dasypodinae (Mammalia, Xenarthra, Cingulata). The specimen was recovered from the Geste Formation, Antofagasta de la Sierra, Catamarca, Argentina. The material is an incomplete right petrosal preserving the pars cochlearis and the anterior third of the pars canalicularis. It is described in detail and compared with extant and fossil cingulates. Additionally, we performed a cladistic analysis in order to define its phylogenetic position. The most remarkable traits of this petrosal include an anteromedially-posterolaterally elongated Promontorium, open cavum supracochleare, wide and smooth crista interfenestralis, roof of the post-promontorial tympanic sinus triangular, reduced, and well separated from the stapedius fossa, and poorly developed epitympanic wing and crista petrosa. The phylogenetic analysis reveals affinities with Dasypus and Stegotherium that are supported by the weakly developed crista petrosa and the reduced dorsal and ventral extension of the cerebellar surface of the pars cochlearis in relation to the size of the internal acoustic meatus. The information provided by this element indicates the existence of several characters that were already present in the Eocene, such as an elongated Promontorium, and a step between the stapedius fossa and the roof of the post-promontorial tympanic sinus. We propose hypotheses of evolutionary change in the auditory region of cingulates, including the medial expansion of the roof of the post-promontorial tympanic sinus and the emergence of a conspicuous crista petrosa.