The 31 crania of the agriochoerid oreodont from the Hancock Mammal Quarry (HMQ) possess character states unique among described agriochoerid species. Characters unique to the HMQ agriochoerid include a triangular P2; a P3 with a posterolingual cone and heart-shaped occlusal outline; a P4 with separate anterolabial and posterolabial cones, but without a posterolingual conule; upper molars with large styles and lacking paraconules; lower molars without lingual cingulids, but possessing small metastylids and parastylids; and a mandibular symphysis that is perpendicular to the tooth row without ventral displacement of the p1. We subjected previous size comparisons to an F-test and Welch's t-test and found that the tooth row lengths of the HMQ agriochoerid have significantly different variance and means from Agriochoeus matthewi crassus (P = .005), a taxon to which this population has previously been assigned. Taken together, these characters are diagnostic of a new species, which we describe here as Diplobunops kardoula. The HMQ specimens show that some of the diagnostic dental characters of agriochoerids currently in use change with wear and may be biased by taphonomy. Furthermore, characters diagnostic of both Agriochoerus and Diplobunops are present in the HMQ agriochoerid, and many of the species-level diagnostic characters of agriochoerids are continuously variable or polymorphic within the HMQ population.

An articulated, 1.5 m long skeleton of a juvenile Chasmosaurus, lacking only the front limbs, pectoral girdles, and terminal caudal vertebrae, was collected from the Dinosaur Park Formation in Dinosaur Provincial Park, Alberta. The short, tall skull has a narrow frill that lacks a posterior embayment. Many of the cranial bones are co-ossified in spite of the small size of the specimen. The nasals form an incipient horncore, and the short, knob-like postorbital horncore lacks sinuses. The palpebral is not fused to the rest of the skull. The frontal fontanelle is keyhole-shaped. The triangular squamosal extends to the back of the parietals. Epiossifications are lacking, although the squamosal margin is thick and scalloped. The parietal has a pronounced midline sagittal crest. Parietal fenestrae, if present, would have been narrow and elongate. There are only 18 maxillary tooth positions. The syncervical comprises three co-ossified, but distinct vertebrae. Anterior caudal vertebrae support unfused caudal ribs. Ossified tendons in the neck, trunk, and sacrum do not extend into the tail. Hind limb proportions are comparable to those of adult ceratopsids. The pedal unguals are distally acute. Skin impressions are similar to those of mature chasmosaurines. Phylogenetic analysis, if all characters are coded as they are seen, suggests that the specimen is a basal chasmosaurine. When size or age dependent characters are recoded as ‘?,’ the specimen groups with other Chasmosaurus. These characters should only be used in phylogenetic analyses when all specimens are mature.

A fragmentary plesiosaur skull from lower Maastrichtian levels of the Conway Formation, New Zealand, is redescribed. Originally regarded as pertaining to two separate individuals, we argue that they represent a single individual belonging to a new aristonectine elasmosaurid, Alexandronectes zealandiensis gen. et sp. nov. This new taxon has common morphologies with other aristonectines such as expansion of the pterygoids extending posteriorly beyond the occipital condyle (as observed in Ar. quiriquinensis and probably in Kaiwhekea katiki) and the presence of an ‘A’-shaped squamosal arch in dorsal view. Otherwise, it is distinguished from these latter species by having different paraoccipital processes, a different mandibular glenoid, and an adult skull comparatively smaller than K. katiki and Aristonectes spp. The new taxon is a morphologically intermediate form between the dorsoventrally high skull of K. katiki and the mediolaterally expanded skulls of Aristonectes spp. The studied specimen is the second genus and species and the third report of an aristonectine recovered from lower Maastrichtian beds of New Zealand, emphasizing the diversity of this group in New Zealand and also indicating that aristonectines could include smaller species than those already known.

Eotrachodon orientalis gen. et sp. nov. (latest Santonian of Alabama, southeastern U.S.A.) is one of the oldest and most basal hadrosaurid dinosaurs and the only hadrosaurid from Appalachia (present day eastern North America) with a preserved skull. This taxon possesses a relatively derived narial structure that was until now regarded as synapomorphic for saurolophine (solid-crested or crestless) hadrosaurids. Maximum parsimony analysis places E. orientalis as the sister taxon to Saurolophidae (Saurolophinae Lambeosaurinae). Character optimization on the phylogeny indicates that the saurolophine-like circumnarial structure evolved by the Santonian following the split between saurolophines and lambeosaurines but prior to the major hadrosaurid radiation. Statistical dispersal-vicariance analysis posits an Appalachian ancestral area for Hadrosauridae and subsequent dispersal of their ancestors into Laramidia (present-day western North America) during the Cenomanian.

We report a new enantiornithine bird, Linyiornis amoena gen. et sp. nov., from the Lower Cretaceous Jiufotang Formation in northeastern China. Traces of ovarian follicles indicate that the specimen represents a female individual. The nearly three-dimensional preservation of the new specimen reveals morphological details rarely visible in other Early Cretaceous enantiornithines, allowing more detailed comparison with Late Cretaceous enantiornithines. Differences in the preserved morphology of the right and left coracoids suggest that the appearance of some features is strongly affected by preservation, indicating that the distribution of these features in compressed specimens may need to be reevaluated. Like Late Cretaceous enantiornithine specimens, the holotype of Linyiornis amoena preserves a hypertrophied pit for muscle attachment on the bicipital crest but clearly did not preserve a fossa for the capital ligament, present in Late Cretaceous taxa; we discuss the functional morphology and implications of these features in Linyiornis amoena.

Here we describe the forearm and manus of the ceratosaurian theropod dinosaur Ceratosaurus nasicornis Marsh, 1884, from the Upper Jurassic Morrison Formation of the western U.S.A. Recently removed from exhibition and reprepared, the holotype offers important new information on the morphology of this taxon that bears on the evolution of the forelimb in nonavian theropod dinosaurs more generally. The ulna and radius show particular similarities to those of Dilophosaurus and Eoabelisaurus but lack features that characterize derived abelisaurids. In the manus, Ceratosaurus bears short first phalanges, like more derived taxa in the clade, but retains metacarpals that are much more similar to those of Dilophosaurus, Berberosaurus, and Eoabelisaurus. Taken together, and incorporated with existing phylogenetic data on other ceratosaurs, these data are consistent with the placement of Ceratosaurus as close to Abelisauroidea but basal to Eoabelisaurus. More importantly, they strongly imply that the extremely reduced manus of Limusaurus is a derived condition that does not reflect the primitive state for Ceratosauria and therefore that Averostra is not the most likely placement for a shift in manus digit identity during theropod evolution. Finally, digit reduction began in ceratosaurs that still possessed most phalanges and unguals, and we infer that grasping would have been retained as a primary, if reduced, function in these forms.

The skull and associated postcrania of Nasutoceratops titusi, a basal centrosaurine ceratopsid from the Upper Cretaceous (Campanian) Kaiparowits Formation of Grand Staircase—Escalante National Monument, southern Utah, are herein described. Autapomorphies of this taxon include: an ectonaris that comprises 75% of preorbital skull length; pneumatic nasals; a hyper-robust premaxilla—maxilla contact; a double-faceted, medial flange on the maxilla contributing to the hard palate; and unique supraorbital horncores that are anterolaterally directed, anteriorly curved, torsionally twisted, and relatively enormous. A Bayesian analysis, the first conducted for ceratopsians, is coupled with a parsimony phylogenetic analysis of Centrosaurinae, with both analyses recovering Nasutoceratops as the sister taxon to Avaceratops lammersi from the late Campanian of Montana. Nasutoceratops titusi provides insights into the origins of Centrosaurinae and suggests the existence of a previously unknown clade of short-snouted, long-horned centrosaurines that we here hypothesize to have originated in the southern Western Interior Basin of North America.

The geologic, environmental, and taphonomic context of the Taung Australopithecus africanus skull has been the subject of speculation and sporadic research since its first publication. In order to refine our contextual knowledge of this important hominin fossil, systematic excavations of the Taung fossil site at the Buxton Limeworks, in the Taung district of what is now the North West Province of South Africa, were conducted from 1988 to 1993. The excavations began on the Hrdlička pinnacle, where Aleš Hrdlička had found fossiliferous deposits in 1925. A separate set of deposits, closer to the reconstructed position of the 1924 Australopithecus discovery and more consistent with the historical record of the Taung discovery, was uncovered on the quarry floor, 42 m southwest of and 6 m lower than the nearest Hrdlička deposits. The fossils of these three distinct deposits, known as the ‘Dart deposits,’ are sparsely distributed, representing different taphonomic conditions and most likely older than most previous discoveries. There are 16 cercopithecid fossils and four bovid fossils, along with eggshell, turtle shell, brachiopods, and reed casts. They provide the most immediate context for the depositional conditions of the Taung Australopithecus juvenile.

Including at least 15 extant species, the beaked whale genus Mesoplodon (Cetacea, Odontoceti, Ziphiidae) is by far the most species-rich cetacean genus. Such a high diversity reflects one or several pulses of radiation, most likely involving a sexual selection mechanism affecting shape, size, and position of mandibular tusks. However, the tempo of this diversification is currently poorly constrained due to the scarce fossil record. Based on the reassessment of five partial skulls discovered in Antwerp (north of Belgium), a new fossil species of the genus Mesoplodon, M. posti, sp. nov., is described. Only the second fossil species of the genus currently recognized, it is characterized (among other features) by: transverse sections of the rostrum higher than wide (a feature proposed to correspond to the presence of lower tusks more posterior than the apex of the mandibles); the presence of a basirostral groove at the rostrum base; pentagonal joined nasals; the posterior projection of the premaxilla in the vertex shorter than the nasal backward; and a strong transverse compression of the frontals behind the nasals. Our phylogenetic analysis results in M. posti being nested among extant species of Mesoplodon. Palynological study of the organic-walled phytoplankton from sediment retained in cranial cavities of several specimens indicates an age between 4.86 and 3.9 Ma (Zanclean, early Pliocene). Constituting the first temporally well-constrained fossil species of Mesoplodon, M. posti provides an upper calibration point for the beginning of the radiation(s), having produced a surprisingly high number of extant species in this genus.

Vertebrate microfossil assemblages in terrestrial formations are a promising source of data on the structure of fossil metacommunities. However, the degree to which these deposits capture true, metacommunity-level samples is unknown. Individual deposits may be biased in ways that limit their utility for intra- and inter-formation comparisons. This study describes the composition of ten vertebrate microfossil assemblages collected from the Lower Cretaceous Cloverly Formation in Montana and Wyoming, U.S.A., and evaluates whether the assemblages are sufficiently similar to suggest the presence of a single Cloverly metacommunity, or ‘paleocommunity type.’ The assemblages appear to be biased by factors related to the preferential incorporation and preservation of different taxa and skeletal element types, which compound with decreasing locality sample size. Less productive localities lack whole taxonomic groups, especially small, fully terrestrial vertebrates. Only the two vertebrate microfossil bonebeds approach the known formation richness. High individual tooth counts overrepresent particular species, especially the crocodylians. Despite these biases, the multiple assemblages nevertheless yield statistically similar taxon abundance rank orders, suggesting the presence of a single, formation-wide paleo-metacommunity, which bears resemblance to a viable metacommunity. The aggregate assemblage exhibits an ‘Eltonian pyramid’ trophic hierarchy for both terrestrial and aquatic taxa. Comparing the multiple assemblages synoptically also reveals possible landscape-scale abundance patterns for particular species. Taken together, microvertebrate assemblages offer insight into regional paleo-metacommunities and provide samples for inter-formational comparisons at this level.

We describe and figure a well-preserved, large skull of a rhinoceros, NHMUK 36661, collected in 1860 from Upper Siwalik deposits. This specimen can be referred to Rhinoceros platyrhinus. Comparison with the type material of R. platyrhinus revealed that several specimens previously referred to this taxon, including the lectotype, should instead be assigned to Rhinoceros sp. (potentially R. sivalensis or R. unicornis). Therefore, we here provide new detailed cranial and dental characters for R. platyrhinus, which is currently known only by a few specimens collected from a restricted area of northern India. We suggest that the generic name Punjabitherium erected for R. platyrhinus represents a junior synonym of Rhinoceros due to the morphological affinities of NHMUK 36661 with R. unicornis. A principal component analysis and a cluster analysis confirmed the morphological similarities between R. platyrhinus and R. unicornis. Rhinoceros platyrhinus represents the largest rhinocerotine species in Eurasia and is characterized by a long skull and high-crowned teeth, suggesting that it was a grazer rather than a mixed feeder such as R. unicornis. This is supported by a cluster analysis on the upper teeth. The progressive increase in aridity from ca. 12 Ma to Recent in northern India could have affected the dietary regime of R. platyrhinus towards to a more grazer-like diet.

Ouranopithecus turkae, from the late Miocene of Çorakyerler in Central Anatolia, is considered one of the last known occurrences of great ape in the eastern Mediterranean. The Çorakyerler fauna has previously been correlated with MN 11 to early MN 12 on the basis of biochronology, and its faunal composition has been found to contrast with those from contemporaneous sites. In this paper, we present the magnetostratigraphy of the Çorakyerler site and an expanded interpretation of its paleobiogeographical and paleoecological contexts. The paleomagnetic results reveal two intervals of normal polarity and an intervening interval of reversed polarity in the main fossiliferous section. Of the three likely age correlations spanning 8.13–7.15 Ma (MN 11-MN 12), we favor correlation with chron 4n, with a possible age range of the fossiliferous deposit between 8.11 and 7.64 Ma (late MN 11). The geographic distribution of genus-level faunal similarity and mean hypsodonty show that Çorakyerler is a typical representative of the Pikermian chronofauna with a wide range of faunal similarity, including late Miocene localities from the eastern Mediterranean, eastern Asia, and eastern Africa. Lithological and sedimentological characteristics of the fossiliferous horizon, however, indicate a lacustrine depositional environment and relatively humid local conditions within the more arid regional context. This special setting could explain the unexpected occurrence of a hominid primate at Çorakyerler.

Taphonomic and morphological evidence suggests that Oryctodromeus cubicularis, a basal ornithopod dinosaur from the mid-Cretaceous of Montana, constructed burrows by digging with its forelimbs. Reconstruction of the forelimb musculature of Oryctodromeus was carried out using the extant phylogenetic bracket method, with crocodilians and ratites as the extant analogues, aided by the presence of osteological correlates in Oryctodromeus and other ornithopods. Although reconstructions directly from the extant phylogenetic bracket are relatively conservative, the reconstruction elucidates several potential features related to burrowing. The prominent muscle groups used in burrowing in mammals are the deltoideus scapularis, teres major, latissimus dorsi, and triceps longus. In Oryctodromeus, the deltoideus scapularis, and equivocally the teres major, has broad origin on the strongly posteroventrally expanded distal scapular blade. Neither the origin of the deltoideus scapularis nor that of the teres major produces osteological correlates in extant taxa or Oryctodromeus; however, the ventrally expanded posterior scapular blade would have increased attachment area for the origin of these muscle groups. The presence of the latissimus dorsi is supported by the extant phylogenetic bracket but produces no osteological correlates in Oryctodromeus. The triceps longus originates posterior to the glenoid and inserts on the ulna. Due to the proximity of the triceps longus origin to the glenoid, the triceps longus likely did not provide strong muscle action. Because many mammals and reptiles produce burrows without any morphological specialization, the limited specializations of the deltoideus scapularis and potentially the teres major sufficiently support burrowing capabilities in Oryctodromeus.

Brachyprosopus broomi was described in 1937 based on a specimen from the Tapinocephalus Assemblage Zone (Karoo Basin, South Africa), but it was largely overlooked by subsequent workers. We have identified several new specimens that show that Brachyprosopus is a valid taxon. An autapomorphy for the taxon is a curled lateral edge of the squamosal that forms a lateral wall of the external adductor fossa. Other important characters are absence of anterior median palatal ridges; maxillary tooth rows bounded laterally by a shelf; unfused vomers; raised margins of the interpterygoid vacuity; broad intertemporal region; pineal boss; dentary tables; and a long, wide posterior dentary sulcus that extends posterior to the dentary teeth. Chelydontops altidentalis is a junior synonym of B. broomi. A phylogenetic analysis places Brachyprosopus among basal dicynodonts, not as a close relative of Endothiodon. It is noteworthy that some characters, such as well-developed medial maxillary tooth rows and the shape of the palatines, are shared by Brachyprosopus, Pristerodon, Endothiodon, and Niassodon, hinting that a final resolution of relationships among toothed dicynodonts remains to be achieved. Most Brachyprosopus specimens are from the upper Abrahamskraal Formation (Moordenaars and Karelskraal members). One specimen is from low in the Koonap Formation, just above the lowermost maroon mudrocks of the Beaufort Group, and an exact correlation between this level and the strata of the Abrahamskraal Formation is uncertain. Therefore, it is likely that the stratigraphic range of Brachyprosopus extends throughout the Tapinocephalus zone and possibly down into the Eodicynodon Assemblage Zone.

New end-stage juvenile specimens of Pachycephalosaurus from the Upper Cretaceous Hell Creek Formation, Montana, confirm the earliest expression of squamosal nodes, parietal ornamentation, and jugal morphology in the smallest and presumably youngest individuals yet known. High-resolution computed tomography of the slightly thickened, undomed parietal reveals a dense cortex, a highly cancellous interior of irregularly shaped erosion cavities, and bony trabeculae indicative of primary, fast growing bone. The parietal, with its highly ornamented septum morphology and patent sutures, is nearly identical to the holotype of ‘Dracorex hogwartsia,’ and combined with these new internal histological details, supports the alternative interpretation that ‘D. hogwartsia’ is a juvenile Pachycephalosaurus wyomingensis. The squamosal nodes grow into an array of horns and secondary nodes exemplified by the pachycephalosaurin ‘Stygimoloch spinifer’ considered in this study to be a subadult P. wyomingensis. Unlike the squamosal ornamentation, the hypertrophied midline row of parietal nodes is transient as the frontoparietal dome expands later in ontogeny. We propose the term ‘ontogimorph’ as a substitute for ‘semaphoront’ to describe these taxon-specific morphological variants that grow allometrically and express extreme cranial morphology along a postnatal growth continuum ontogenetically. These juvenile-, sub-adult-, and adult-specific features in the skull of Pachycephalosaurus may have allowed the visual identification of ontogimorphs and signal their changing sociobiological status.

Ontogenetic sequence and life stage determination among the desmostylians are poorly understood and known mostly from the study of dental eruption. Advanced-age life stages are nearly unknown. New material of an individual Desmostylus from the late middle to late Miocene of Orange County, California, represents the most ontogenetically advanced described specimen of the genus and helps characterize a more complete ontogenetic sequence. The material consists of a partial mandible that exhibits bony swellings, indicative of Desmostylus, but also lacks postcanine teeth (dental senescence). Comparisons with known juvenile Desmostylus and adult-stage individuals with similar bony swellings, but that still exhibit postcanine teeth, provide evidence that the Orange County specimen is that of an elderly Desmostylus. By incorporating the characteristics of this specimen into the ontogenetic sequence of the genus, a complete eruption pattern of the lower jaw can be recreated. The development of the mandible and tooth eruption sequence in Desmostylus is similar to the characteristic ontogeny of Afrotheria. In Afrotheria, the eruption of the final set of molars is delayed until the mandible has grown to maximum length. Desmostylia has been placed in Afrotheria, suggesting that the similarities in ontogenetic sequences may derive from a shared ancestry. Recent studies that place Desmostylia as stem perissodactyls suggest that the Afrotheria-like dental ontogeny may be independently derived within Desmostylia, or Desmostylus.

Several abnormal caudal vertebrae are described in an indeterminate sauropod specimen from ?Middle—Late Jurassic strata of Niger. The anterior and posterior articular surfaces of caudal vertebrae 7–11 exhibit erosive perforations (‘holes’) of the subchondral compact bone into the trabecular bone of the vertebral centrum. Additionally, the vertebral centra of caudal vertebrae 17 and 18 are fused and show a bulging mass of abnormal bone growth, most probably caused by infection. The erosive lesions of the anterior tail vertebrae closely resemble the morphological and radiological characteristics of Schmorl's nodes in humans and other mammals, in which the gel-like nucleus pulposus of the intervertebral discs penetrates through the endplate into the cancellous bone of the vertebral body and creates an erosive cavity of mushroom-like shape. The diagnosis of Schmorl's nodes in this sauropod, however, would be incompatible with the extant phylogenetic bracket and osteological correlates that suggest that dinosaurs had no intervertebral discs. Rather, they possessed synovial joints with a joint space filled with synovial fluid between adjacent vertebral centra. Therefore, the lesions can best be interpreted as subchondral cysts and as an analog of Schmorl's nodes in synovial joints. Similar to Schmorl's nodes, the regular pattern and location of the lesions suggest that the cysts were caused by axial stress. One may hypothesize that the fusion of caudals 17 and 18 led to altered mechanical loading that may have facilitated rupture of the articular cartilage and subchondral bone and forced synovial fluid into the spongiosa of the vertebral centra.

A new early Miocene large castorid, Minocastor godai gen. et sp. nov., from the Dota locality, Gifu Prefecture in central Japan, is described on the basis of dentaries and teeth. The material comes from the Kani basin, where limnofluviatile clay and sandstones of the Nakamura Formation (Mizunami Group) are exposed on the southern (left) bank of the Kiso River. It represents the richest sample of a Miocene small mammal in the Japanese fossil record thus far known. Based on jaw and tooth morphology, this new castorid most likely represents a primitive anchitheriomyine. However, it lacks the marked striations on the incisors that are characteristic of the advanced large, middle Miocene anchitheriomyines like Anchitheriomys and Amblycastor. The new castorid shares this dental feature with other primitive anchitheriomyines from Asia and North America, like Propalaeocastor, Oligotheriomys, and Miotheriomys. For these genera, a new tribe, Minocastorini, is proposed as sister group to the Anchitheriomyini. The incisor enamel microstructure of the new castorid largely exhibits plesiomorphic characters but also apomorphic features such as pseudo-pauciserial Hunter-Schreger bands. Additionally, the outer portion of the enamel band is rather thick in comparison to that of other beavers. Based on the rodent taxa associated with Minocastor godai gen. et sp. nov., Dota can be correlated with European Neogene mammal units MN 3/4. Magnetostratigraphic studies and radiometric dates obtained from the Mizunami Group indicate that Dota is more likely correlated with MN 3, with an absolute age of around 18.5 Ma.

We report the discovery of the earliest European carnivoraforms, based on two new taxa from the latest Paleocene of France and Romania. A new species of Vassacyon, V. prieuri, from the locality of Rivecourt (MP6b; Oise, France) (MP = Mammalian Paleogene reference levels) is described based on a dentary fragment and isolated teeth. This species displays several primitive features compared with species of Vassacyon known from the early Eocene of North America and Europe. A second Paleocene carnivoraform, cf. Gracilocyon sp., is described based on fragmentary specimens from the locality of Jibou (MP6b; Transylvania, Romania). Carnivoraformes were previously unknown in Europe before the Eocene, and Vassacyon prieuri and cf. Gracilocyon sp. are their oldest records in Europe. These discoveries favor the hypothesis of a dispersal of these two genera from Europe to North America during the Paleocene-Eocene Thermal Maximum. Vassacyon prieuri and cf. Gracilocyon sp. strengthen support for the level MP6b and its correlation with the Clarkforkian. The geographic origin of the Carnivoraformes remains unknown. However, based on the observed biochronological and geographic distributions of the carnivoraforms, we infer a possible Asian origin for this group. In this scenario, Gracilocyon and Vassacyon dispersed to Europe during the Clarkforkian MP6b time, probably together with rodent taxa, whereas Uintacyon dispersed from Asia to North America shortly after rodents and tillodonts.