Hyaenodontidae is a diverse component of the carnivorous guild in early Eocene (Wasatchian) North American mammalian faunas. Although there have been suggestions that early members of the family had diverse locomotor repertoires, few Wasatchian postcrania are adequately described. Here we describe the first known postcranial remains of the rare Wasatchian hyaenodontid Galecyon, based principally on a well-preserved partial skeleton from the Willwood Formation, Wyoming. Galecyon is reconstructed as a 5.2–1.9 kg terrestrial carnivore. Small but significant differences throughout the skeleton distinguish Galecyon from Prolimnocyon. Galecyon is reconstructed as scansorial/generalized terrestrial because these postcranial differences consistently indicate a more terrestrial habit than in the scansorial Prolimnocyon. Among other hyaenodontids, Arfia shows evidence for parallel terrestrial adaptation, whereas Pyrocyon is morphologically intermediate between Galecyon and Prolimnocyon. Manipulation of the well-preserved bones forming the crurotarsal joint of Galecyon provides evidence that contradicts a previous proposal that Arfia, another Wasatchian hyaenodontid, was capable of hind foot reversal. In both genera, movements at the crurotarsal joint were largely restricted to a parasagittal plane. Phylogenetic analysis of a new postcranial character set supports a pattern of relationships for early Eocene hyaenodontids different from that supported by dental morphology. Combining the two data partitions favors most aspects of the dental topology, but the conflict between dental and postcranial data indicates that confident phylogenetic resolution can be elusive, even with relatively dense sampling.

The ray-finned fish Plesiofuro mingshuica from the Triassic non-marine deposits of northern Gansu Province, China, was previously misidentified as a caturid halecomorph. This erroneous taxonomic assignment contributed to the misinterpretation of the age of the Plesiofuro-bearing fossil beds as Early Jurassic. Here, we provide a taxonomic revision of this problematic taxon based on a comparative study including over 500 new specimens. The revised description of Plesiofuro accommodates significant changes to the reconstruction of the snout, skull roof, cheek, circumorbital, and operculogular series, as well as the lower jaw. Results of a cladistic analysis incorporating these new data place Plesiofuro as a stem-group neopterygian. Additionally, phylogenetic results show that both ‘Perleidiformes’ and ‘Peltopleuriformes’ are paraphyletic, encompassing several independent stem-neopterygian subclades. As such, this study sheds new light on one of the least resolved areas of osteichthyan phylogeny: the so-called ‘subholosteans’ of the neopterygian total group.

A collection of Adjidaumo minimus (Matthew, 1903) from the middle Chadronian (late Eocene) of Natrona County, Wyoming, consists of approximately 150 specimens, the largest sample of Adjidaumo from anywhere. The sample includes several partial to nearly complete crania, the most complete cranial material known for the genus. This large sample of a single species allows an examination of the variability in dental and cranial morphology of the species and a more complete description of the skull. The general morphology of the cranium is similar to that of other eomyids and differs most markedly in having a relatively shorter rostrum, an opening for the sphenopalatine vacuity, and a distinct groove on the alisphenoid. Additional topotypic specimens of A. burkei (Russell, 1954) show that it is a distinct species, rather than a synonym of A. minimus as some authors have suggested. Based on age profiles, the population of Adjidaumo from Jenny's Pocket appears to have been attritionally accumulated, whereas that from Al's Pocket was more likely catastrophic. Although the specimens from Jenny's Pocket were preserved in the filling of a burrow along with bones of a mammalian carnivore, examination of the bones and teeth preserved along with modification of the Adjidaumo skulls and jaws from that site indicate that they were more likely the result of predatory activity of a small owl.

The traversodontid cynodont Menadon besairiei, previously known from the ‘Isalo II’ group of Madagascar, is reported for the first time from the Triassic of southern Brazil. New material referable to M. besairiei was collected in the Schoenstatt outcrop (Santa Cruz do Sul municipality), which belongs to the Santacruzodon Assemblage Zone (Carnian) in the Santa Maria Supersequence. Their attribution to the Malagasy taxon is based on the presence of a deep snout; four upper incisors, with procumbent first and second incisors, and three lower, procumbent incisors; five upper postcanines, the first one ‘peg-like’; six lower postcanines, the two most anterior and the most posterior being reduced; the quadrangular form of the postcanines; a pterygoid reaching the jugal and excluding the maxilla from the suborbital fenestra; a mandible with a tall coronoid process covering the last lower postcanine laterally; and a posteriorly projected angular process. A cladistic analysis of traversodontid cynodonts was performed based on a matrix composed of 30 taxa and 78 characters. In the resulting trees, M. besairiei nested within the clade Gomphodontosuchinae, the only traversodontid subclade reasonably well supported. Thus, the presence of M. besairiei is established in the Santa Cruz do Sul fauna, constituting the first record for South America and confirming the previously proposed biostratigraphic correlation between the ‘Isalo II’ and the Santacruzodon Assemblage Zone.

Endocranial casts are the only available material to study the evolution of brain morphology through geologic time. However, these are not just casts of brain tissues but also include, e.g., meningeal tissues, blood vessels, and nerves. Tissues surrounding the brain are particularly thick in proboscideans, making the estimation of brain size in extinct proboscideans very tentative. Here the regression of brain mass over cranial capacity—based on data on intraindividual comparison between those two metrics in the literature—is used to estimate the ‘true’ brain mass of extinct mammals. This regression reveals that cranial capacity is allometrically related to brain mass in mammals. The larger the brain, the greater is the difference between brain mass and cranial capacity. Applied to proboscideans, this new method suggests that the thickness of non-neural tissues surrounding the brain has been greatly overestimated in extinct proboscidean species, resulting in the underestimation of brain mass. This data set suggests that a comparatively small brain is likely primitive for Proboscidea and that the representatives of the clade Elephantimorpha have inherited their large brain from their last common ancestor. The largest brain proportional to mass of all Proboscidea belongs to the Quaternary dwarf elephant of Sicily, which would have been comparable to modern humans in encephalization quotient.

A flightless fossil duck (Aves, Anatidae), Shiriyanetta hasegawai, gen. et sp. nov., is described as a member of the Shiriya local fauna, a middle—late Pleistocene marine and terrestrial vertebrate fauna from fissure-fill deposits in the Shiriya area, northeast Japan. The species is represented by isolated bones, including skull fragments, vertebrae, pectoral and pelvic girdle elements, and most of the major limb elements. Osteological features of Shiriyanetta suggest that it had taxonomic affinity with tribe Mergini (seaducks) of subfamily Anatinae, and specifically with Recent Polysticta and Somateria (eiders). Although the overall large size, several unique skeletal features, and the proportions of the limb bones of Shiriyanetta strongly resemble North American seaducks of the genus Chendytes Miller, 1925, extinct relatives of Somateria, most elements of the two genera are diagnostically different from one another. Comparisons of these taxa and other flightless anatids with their relatives show that some of the apparently shared osteological features of Shiriyanetta and Chendytes are probably associated with flightlessness rather than reflecting a close relationship between the two genera. Given that Recent Somateria has an impaired flight ability, or the occurrence of a temporary flightless condition, it is quite possible that Shiriyanetta and Chendytes might have lost their flight ability independently, resulting in the contemporaneous occurrence of flightless ducks on both sides of the Pleistocene North Pacific.

Pareiasaurs were a group of herbivorous reptiles that lived during the middle to late Permian (265–252 Ma) in what is modern-day Europe, Asia, South America, and Africa. Field work in the Moradi Formation of northern Niger has produced multiple elements of the appendicular skeleton of the pareiasaur Bunostegos akokanensis. The considerable size disparity and morphological variation among the elements suggest that they represent ontogenetic stages ranging from relatively juvenile to adult. Here we present the first description of the scapulocoracoid, humerus, radius, ulna, pelvis, and femur of Bunostegos as well as some of the first ontogenetic data for postcranial osteology in pareiasaurs. As with the skull, numerous postcranial autapomorphies characterize Bunostegos, including laterally originating acromion process of the scapula; radius and ulna with continuous articular surface on humerus; paired crests on the olecranon process; ulna longer than humerus; pinched posterior margin of the acetabular rim; robust pelvic symphysis extending the length of the puboischiatic plate; lack of a distinct postaxial flange of the femur; and an elaborated femoral lateral condyle wrapping over the medial condyle. We incorporated data from the appendicular skeleton of Bunostegos into a revised phylogenetic analysis of pareiasaur relationships. The results of this analysis corroborate previous cranial analyses that place Bunostegos between Guadalupian taxa and the Lopingian velosaur subclade. Interestingly, several aspects of its postcranial anatomy suggest that Bunostegos possessed relatively upright forelimb posture, which would be unique among pareiasaurs and possibly Permian amniotes as a whole.

In this contribution, we describe new specimens of Yacarerani boliviensis from the Cajones Formation (Upper Cretaceous) of Bolivia. We focus on the postcranial anatomy of Y. boliviensis, because this anatomical region is completely unknown in other sphagesaurid notosuchians up to the present. At least eight individuals representing almost the entire postcranial skeleton are described. Although the postcranial anatomy of Yacarerani resembles that of other notosuchians in many features, five autapomorphic characters were identified: pedicles of the atlas bearing a lateral bulge; absence of rounded depressions on the dorsal surface of the anterior to middle dorsal vertebrae; coracoid bearing an oblique crest on its lateral surface; lateromedially compressed anterior ungual phalanges; and femur with a shallow depression for the M. puboischiofemoralis internus 1 and M. caudifemoralis longus. Observed variation in the postcranial anatomy of basal mesoeucrocodylians was incorporated as new characters in a phylogenetic analysis, expanding the postcranial information used in current phylogenetic data sets. The phylogenetic analysis depicts Yacarerani forming a clade with Adamantinasuchus, which is positioned at the base of Sphagesauridae. This family is well nested among a clade of 'advanced notosuchians,' and Mariliasuchus is recovered as its sister group. The cladistic analysis recovered new postcranial synapomorphies for Notosuchia and less inclusive clades, although the fact that many taxa lack postcranial remains limits the number of unambiguous postcranial synapomorphies within Notosuchia.

Pelagornithids or bony-toothed birds were an enigmatic group of very large marine birds that existed throughout most of the Tertiary, with remains recovered in all continents. The currently recognized record of pelagornithids in South America extends from the middle Miocene to the Pliocene. Here, a fragment of a ramus mandibulae recently discovered in the Cerro La Cruz site (Castillo Formation, Lara State, northwestern Venezuela), is assigned to Pelagornis. With an early Miocene age (18.27–18.85 Ma), the fossil constitutes the earliest unequivocal record of the group in South America. The reexamination of another pelagornithid specimen recovered from Capadare Formation (middle Miocene), which was previously assigned to Pelagornithidae indeterminate, allows us to recognize the presence during the Miocene of Venezuela of a second pelagornithid morphotype, here tentatively referred to Pelagornis chilensis Mayr and Rubilar-Rogers, 2010. Originally recorded from the middle Miocene-early Pliocene of Chile, the possible presence of P. cf. P. chilensis during the middle Miocene of Venezuela might represent the first record of this bony-toothed species outside Chile and expands its distribution area by 3500 km, to the tropical waters of northern South America.

The fossil cypriniform fish †Jianghanichthys hubeiensis from Eocene mudstones in Songzi, Hubei, China, was originally assigned to the extant cyprinid genus Osteochilus, then later to the new genus †Jianghanichthys by its original author, but with its familial status uncertain. Other authors subsequently assigned it to the cypriniform family Catostomidae. A detailed comparison of osteological characters shows that †Jianghanichthys is distinguished from all other cypriniforms by having (1) first principal anal fin ray branched; (2) supraorbital sensory canal largely exposed in frontal but roofed by longitudinal flange; (3) supraorbital sensory canal meeting the temporal sensory canal within the parietal; (4) maxilla bearing three dorsal processes; (5) dorsal surface of anterior end of dentary triangular and broad; and (6) the first centrum of †Jianghanichthys has a similar size and prominent posterior concavity to the second centrum. A computed tomography (CT) scan of a matrix-covered skull confirmed these unique characters, as well as that the pharyngeal teeth are either absent or not well formed. A series of phylogenetic analyses, using parsimony criteria and morphological characters, consistently recovers †Jianghanichthys in a polytomy with the non-loach cypriniform families, but it could not be placed within any recent family. Among osteological characters, few unique synapomorphies are shared by Jianghanichthys and recent families of Cypriniformes, whereas a large number of symplesiomorphies with the Catostomidae, Cyprinidae, and Gyrinocheilidae were found, indicating that Jianghanichthys is a stem taxon of Cypriniformes. Therefore, the first family of Cypriniformes known only from fossils, †Jianghanichthyidae, is erected to contain this Eocene cypriniform fish.

A new genus and species of pteraspid heterostracan, Mitraspis cracens, gen. et sp. nov., is described from the Early Devonian (Lochkovian) Drake Bay Formation of Prince of Wales Island, Nunavut, Arctic Canada, where it is associated with a rich shallow marine invertebrate fauna. This pteraspid is most closely related to Canadapteraspis based on the arrangement of its sensory canal system, but shows an elongated morphology most similar to that seen in Rhinopteraspis and Althaspis. The unusually elongated rostrum and dorsal spine suggests adaptation for rapid movement. Analysis of the environments in which pteraspids are preserved in the Early Devonian of the Canadian Arctic shows that the same species may have inhabited a variety of environments ranging from deltaic to shallow marine.

Computed tomographic scan data of three premaxillae, a maxilla, and a dentary of Dicraeosaurus hansemanni allow reconstruction of the tooth replacement pattern in this taxon. Four or five replacement teeth are present in each of the four tooth families of the premaxilla. The interalveolar septum is labially interrupted, and an alveolar trough is formed. In the maxilla, the number of replacement teeth decreases in a caudal direction from four to one per tooth family. The dentary bears 16 alveoli, and the number of replacement teeth decreases caudally from three to one per tooth family. Replacement rates are around 20 days for the premaxillary and rostral maxillary teeth of Dicraeosaurus, which confirms the presence of high tooth replacement rates in Diplodocoidea. Replacement teeth of the dentary are less than half as large as those of the upper jaw, and replacement rates are around 50 days for the rostral dentary teeth. Hypothetical reconstruction of Zahnreihen yields a potential z-spacing of 1 with simultaneous front-to-back tooth replacement. Most probably, the rostralmost teeth in Dicraeosaurus were used for food acquisition, whereas the more caudally positioned teeth served only as a guide and as a lateral limit for the food within the mouth. The teeth of the dentary were less prone to wear than those of the upper jaws. These findings are in agreement with the reconstructions of Dicraeosaurus as a selective mid-height browser.

The Chiweta Beds of Malawi have yielded a diverse late Permian fossil tetrapod fauna that correlates with that of the Cistecephalus Assemblage Zone of the South African Karoo Supergroup. Amongst the fossil therapsids from the Chiweta Beds is the well-preserved skull and lower jaw of a burnetiamorph, a group of biarmosuchians with numerous bosses and swellings on the skull. This specimen was reported in a preliminary paper in 2005 as the first burnetiamorph described outside of South Africa and Russia. Reanalysis of the morphology and phylogeny of this specimen places Lende chiweta, gen. et sp. nov., as the sister taxon to the clade formed by Proburnetia (Paraburnetia (Pachydectes, Bullacephalus, Burnetia, Niuksenitia)). The greatest diversity of this basal therapsid group is from South Africa, with six of nine described genera and a stratigraphic range that extends from the middle Permian Tapinocephalus Assemblage Zone to the upper Permian Dicynodon Assemblage Zone. Bearing in mind the constraints that govern fossil preservation, current data suggest that what is now southern Africa may have been the area of origin for burnetiamorphs. Under this premise, what is now central Africa represented a corridor that allowed migration of representatives of the group between the southern and northern portions of Pangea during the late Permian.

Dicynodont therapsids were discovered in the Permian Usili Formation (Ruhuhu Basin, Tanzania) in the 1930s and in the Permian Ruhuhu Formation in the 1960s, with further collections being made in 2007, 2008, and 2012. Here we describe two fragmentary mandibles that represent a new morphotype of emydopoid dicynodont. One specimen was collected in the middle fossiliferous horizon of the Ruhuhu Formation, and the other originated in the overlying Usili Formation. Three synapomorphies support the placement of these specimens in the emydopoid subclade Kingoriidae: mandibular fenestra occluded by the dentary; curved ridge that follows the profile of the symphysis present on the edge between the anterior and lateral surfaces of the dentary; and posterior dentary sulcus absent. The specimens may represent a new dicynodont species, a previously known species for which mandibular material was unknown, or an intraspecific variant of Dicynodontoides nowacki. Regardless of which of these options is correct, the specimens constitute the first taxon with a stratigraphic range extending from the likely middle Permian middle fossiliferous horizon of the Ruhuhu Formation into the late Permian Usili Formation. They also improve our understanding of the middle Ruhuhu tetrapod fauna, which previously consisted only of Endothiodon tolani.

Newly discovered baenid turtle specimens from the middle Campanian Kaiparowits Formation of southern Utah are described herein as a new taxon, Arvinachelys goldeni, gen. et sp. nov. The holotype consists of a nearly complete articulated skeleton and shell. The skull was scanned using micro-computed tomography (mCT) to gain a better understanding of its internal anatomy. This baenid possesses two distinct external nares almost completely separated by a dorsal projection of the premaxillae and a ventral extension of the nasals, an autapomorphic feature among known baenid taxa. The skull is wedge-shaped with a broad rostrum and laterally expanded nasals. The importance of skull/shell associations is exemplified by Arvinachelys goldeni, because isolated shells attributable to this taxon had previously been assigned to the genus Plesiobaena, whereas phylogenetic analysis of more complete material supports a sister relationship with the Maastrichtian taxon Hayemys latifrons. These taxa are relatively basal within the Baenodda, a nested clade within Baenidae. The general shell morphology exhibited by Plesiobaena antiqua, Peckemys brinkman, and Palatobaena cohen was previously hypothesized to support a monophyletic clade that included those three taxa, along with Cedrobaena putorius, Gamerabaena sonsalla, Palatobaena bairdi, and Palatobaena gaffneyi. However, the inclusion of Arvinachelys goldeni, gen. et sp. nov., in a phylogenetic analysis of Baenidae indicates that the character states exhibited by those taxa are representative of plesiomorphic states within Baenodda, and the phylogenetic relationships within this clade are in need of reevaluation.

A juvenile maxilla of Moropus with DP3-M1, collected from the early Hemingfordian (He1) Picture Gorge 36 local fauna of the Rose Creek Member of the John Day Formation of Oregon, U.S.A., is the best-preserved chalicothere specimen yet collected from the John Day Basin. It also provides additional understanding of early Miocene Schizotheriinae (Perissodactyla, Chalicotheriidae) in western North America. Although Coombs et al. attributed all of the John Day chalicotheres to Moropus oregonensis, the new specimen resembles in size and morphology some of its early Hemingfordian contemporaries from the Runningwater Formation of the Great Plains and is referred to Moropus sp. Moropus sp. can thus be added to the oreodont Merycochoerus magnus, the amphicyonid Daphoenodon (Borocyon) robustum, the dromomerycid Barbouromeryx, the moschid Parablastomeryx schultzi, and the equid Parahippus pawniensis as John Day taxa with close relatives in the early Hemingfordian of the Great Plains. Further, the identification of the fragmentary chalicothere fossils from the John Day Formation is made more complex by the likely presence of more than one species there during the early Miocene.

Clupeid fishes are abundant in the Eocene fossiliferous limestone of Monte Bolca, representing by far the most common group from this celebrated locality. However, despite of their abundance, the clupeid fishes from Monte Bolca have seldom been investigated. An analysis of about 300 well-preserved clupeid specimens from Monte Bolca housed in several institutions clearly indicates that more than 95% of the available material belongs to different developmental stages of a single taxon, traditionally referred to as †Clupea catopygoptera Woodward. †Bolcaichthys, a new genus of clupeid fish, erected to contain †Clupea catopygoptera Woodward from the Eocene of Monte Bolca, Italy, is described and compared with extant and fossil genera of the family Clupeidae. This new genus shows a unique combination of characters (head length approximately one third to one quarter standard length; skull roof with 10–14 frontoparietal striae; mouth terminal; two supramaxillae; edentulous jaws and palate; complete series of about 20–22 abdominal keeled scutes with ascending arms; no dorsal scutes; five or six branchiostegal rays; eight supraneurals; 40–42 vertebrae and 20–22 pleural ribs; three epurals) supporting its recognition as a new genus of the family Clupeidae. Paleobiological considerations suggest that the presence of a very large number of schooling clupeids belonging to the genus †Bolcaichthys at all stages of development (larval, juvenile, and adult) support the hypothesis that the sediments were deposited close to the coast in a context subject to the ecological influence of the open sea.

A new pterosaur species, Cimoliopterus dunni, sp. nov., is described based on a partial rostrum from the upper Cenomanian Britton Formation in the Eagle Ford Group of north-central Texas. The holotype preserves alveoli for a minimum of 26 upper teeth and bears a thin premaxillary crest that begins above the fourth pair of alveoli. The rostrum, characterized by a slight lateral flare, lacks the pronounced lateral expansion found in ornithocheirids and anhanguerids. The tip of the snout is small and blunt, and the anterior face of the rostrum is oriented posteroventrally, forming an approximately 45° angle with the anterior portion of the palate. The anteroventrally oriented first pair of alveoli is directed more ventrally than anteriorly. Phylogenetic analysis suggests that Cimoliopterus dunni and Cimoliopterus cuvieri, from the Cenomanian Grey Chalk Subgroup in Kent, England, are basal pteranodontoids that are closely related to Aetodactylus halli from the middle Cenomanian Tarrant Formation of north Texas. Cimoliopterus dunni marks only the second known occurrence of Cimoliopterus, extending its geographic range from Europe to North America. In conjunction with Coloborhynchus wadleighi from the upper Albian Pawpaw Formation, Cimoliopterus dunni provides unambiguous evidence of biogeographic linkages between the pterosaur faunas of North America and Europe in the middle Cretaceous.