Interspecific competition and species replacement explain many evolutionary successions, but these processes are difficult to test. According to recent paleontological research, amebelodontines were predominant proboscideans in faunas of the early to middle Miocene of East Asia. In addition to the abundant Platybelodon, other amebelodontines are known, but they have been largely neglected by researchers. Here we describe two species of Protanancus, Pr. tobieni and Pr. brevirostris, sp. nov., from China. The former was present during the middle Miocene in Tongxin and Qin'an and was previously attributed to Amebelodon or Serbelodon; the latter was present during the early Miocene in the Linxia Basin. Cladistic analysis indicates that the two species appear to represent primitive members of Protanancus. However, the phylogenetic relationship among Protanancus, Platybelodon, and Amebelodon remains unresolved because of their strong parallel evolution. Our study suggests intensive competition between Protanancus and Platybelodon based on similarities in their mandibular morphologies and dental microwear patterns, with the former genus disappearing from East Asia by the late middle Miocene. This scenario is supported by a mechanical model, in which lower tusks with dentinal tubules, as occur in Platybelodon, show greater resistance to the adverse effects of both a heavy load and abrasion than those with concentric laminae, present in Protanancus. The model aids in interpreting the evolution of the inner structure of the lower tusks of amebelodontines, which may have provided a competitive advantages for these species.

Aetosaurs are an extinct clade of quadrupedal, heavily armored archosaurs that had a worldwide distribution during the Late Triassic. Aetosaur fossils from the Upper Triassic Pekin Formation in the Deep River Basin of North Carolina (U.S.A.) consist primarily of isolated osteoderms and, rarely, more associated material. Here we describe a new genus and species, Gorgetosuchus pekinensis, based on an associated incomplete anterior carapace, consisting of a total of 19 nearly complete paramedian and lateral osteoderms from the first 10 rows of armor as well as some associated fragments. An important feature of Gorgetosuchus is that an articulated fifth row of cervical osteoderms almost encloses the neck, with prominent spines on both the dorsal and lateral osteoderms. This is a novel configuration among aetosaurs. Otherwise, NCSM 21723 preserves a mosaic of character states found in Longosuchus, Lucasuchus, or both taxa while simultaneously preserving several more plesiomorphic character states, such as cervical osteoderms that are wider than long. Our reevaluation of other Pekin Formation specimens that various authors have assigned to Desmatosuchus, Longosuchus, or Lucasuchus confirms that some possess characteristics of Lucasuchus, whereas others are not generically determinate. Incorporating Gorgetosuchus into existing phylogenies of aetosaurs results in a reshuffling of basal aetosaur relationships, but a variety of analyses consistently place Gorgetosuchus as a basal desmatosuchine. Using current taxonomic practices, there are at least three aetosaur genera in the Pekin Formation: Lucasuchus, Coahomasuchus, and Gorgetosuchus.

Although the type species of Ophiopsis was long considered O. procera, the genus originally included the single species Ophiopsis muensteri, which subsequent authors moved to Furo. Following the International Commission on Zoological Nomenclature code, Furo muensteri is here recognized as the type species of Ophiopsis by monotypy (Article 68.3). Ophiopsiella, gen. nov., is erected to include all remaining previously described ‘Ophiopsis’ species. Exceptionally well preserved new Ophiopsiella attenuata from the Upper Jurassic plattenkalk of Ettling (Bavaria, Germany) represents the first record of this species from Ettling, allowing for a partial revision of it and Ophiopsiella procera. New evidence allows for an emended diagnosis of Ophiopsiella attenuata, which differs from all other Ophiopsidae in the following combination of features: 27–28 dorsal fin rays, 42 vertical scale rows, and a long, low, posteroventrally inclined dorsal fin lacking elongate anterior fin rays or a strongly concave posterior border. A neotype for O. attenuata is designated, as the type is lost. ‘Ophiopsis’ attenuata actually contains two anatomically different morphotypes corresponding to distinct species, one of which is indistinguishable from ‘Ophiopsis’ procera. Exceptional preservation of the new material provides new morphological information, particularly regarding the dermal cranial bones. This revision changes the known distribution of ophiopsids in the Upper Jurassic of southern Germany and France, with possible broader paleobiogeographic and paleoecological implications for this region during the Late Jurassic. Ophiopsids remain poorly known compared with other halecomorphs (e.g., Amiidae), and closer investigation of their morphology and taxonomic relationships is therefore important to understanding broader patterns of halecomorph evolution.

A new fossil lizard of the genus Pachygenys is described on the basis of a single, partially broken right mandible excavated from an unnamed formation of the Lower Cretaceous Sasayama Group in Hyogo Prefecture, western Honshu, Japan. The mandible exclusively shares a few apparently highly specialized morphological features, such as distinct foreshortening of the dentary tooth row and reduced dentary tooth number (nine), with Pachygenys thlastesa, the type species of the genus from the Lower Cretaceous of eastern China. However, the new species differs from the latter in having a shorter tooth row, anterior and middle teeth with unicuspid crowns (vs. bluntly truncated crowns in the latter), and posterior teeth with unicuspid and simple conical crowns (vs. bluntly truncated crowns in the latter). The specimen described here represents the first unequivocal fossil record of lizards in Japan, with its congeneric species occurring almost concurrently in eastern Eurasia.

Here we describe a new taxon of late Oligocene dugongine from the Western Atlantic and Caribbean region. Known from cranial and postcranial material, Callistosiren boriquensis, gen. et sp. nov., differs from other members of the group by displaying the following unique combination of characters: nasal process of premaxilla tapering but thickened; supraorbital process of frontal dorsoventrally thin (<2 cm) and well developed with recurved, bluntly pointed posterolateral corner; ventral rim of orbit not overhanging the lateral surface of the jugal; pterygoid fossa tall; tusks large, lozenge- or kiteshaped in cross-section, and with enamel confined to the medial side; lacrimals with thin, elongated dorsal process that is wedged between the premaxilla and frontal; and osteosclerotic but minimally pachyostotic ribs and vertebrae. A phylogenetic analysis places Callistosiren as one of the more basal members of the Dugonginae, but we note that the relationships and taxonomy of more derived members are in need of revision. Characters of the cranial morphology, such as the shape and size of the incisor tusks and the nature of the contact between the premaxilla and frontal, indicate that this new taxon may have fed preferentially on large species of seagrasses and their rhizomes. In addition, possession of osteosclerotic but minimally pachyostotic ribs and vertebrae is a unique feature unknown in other extinct dugongines and may indicate foraging behavior not known from other fossil sirenians.

The oldest fossil musk turtles, genus Sternotherus, are reported from the Hemphillian of eastern Tennessee and central Florida. Sternotherus palaeodorus, n. sp., is known from five partial shells discovered at the late Miocene—early Pliocene (7–4.5 Ma; late Hemphillian) Gray Fossil Site in Washington County, Tennessee. Sternotherus palaeodorus possesses an enlarged intergular scute, wide first vertebral scute that overlaps peripheral set 1, posteriorly extensive hypoplastron to peripheral 7 contact, and a posteriorly situated inguinal musk duct pore (characteristics more typically seen in Kinosternon). A cladistic analysis recovered S. palaeodorus within crown group Sternotherus in the strict consensus and on the stem of Sternotherus in the majority rule consensus. Sternotherus bonevalleyensis, n. sp., from the Palmetto Fauna (5.5–5 Ma; late Hemphillian) of central Florida was perhaps contemporaneous with S. palaeodorus and is known only from isolated shell fragments. It is morphologically most similar to the Sternotherus minor complex and Sternotherus depressus. Subsequent Blancan fossils from the Suwannee River of Florida represent aff. S. minor peltifer. Additionally, a fragmentary left hyoplastron of cf. Sternotherus from Haile 19A, Alachua County, Florida, could be the oldest record for the genus (ca. 9–8.5 Ma; early Hemphillian). These accounts reveal that Sternotherus was diverse and moderately well distributed geographically by its first known fossil occurrences and support previous hypotheses that the Sternotherus minor complex evolved in the Gulf coastal plain and dispersed throughout that region since at least the latest Miocene-earliest Pliocene.

The holotype of Pliophoca etrusca, a partial skeleton from the late Pliocene (Piacenzian) of central Italy, is redescribed. Referred material from the Pliocene of Italy, France, and Spain is compared with the holotype and reassigned to Pliophoca cf. P. etrusca. New dental and postcranial material from the late Pliocene and Pleistocene of Italy is referred to Monachini indeterminate. Purported referred material from Pliocene deposits in the eastern North Atlantic (Lee Creek Mine, North Carolina) likely represents several new monachine taxa rather than Pliophoca etrusca. Using the largest novel data set to date, including extant and fossil monachines and comprising morphological and molecular data, we inferred phylogenetic relationships among monachine phocids. Results of morphological and combined analyses revealed that Pliophoca etrusca is most closely related to the Mediterranean monk seal, Monachus monachus, although this result is not strongly supported. Based on our phylogenetic framework, the origin of Monachini occurred during the early-middle Miocene, centered in either the Tethys Sea orthe West Atlantic.

Exposures of the Bissekty Formation (Upper Cretaceous: middle-upper Turonian) at Dzharakuduk in the central Kyzylkum Desert of Uzbekistan have yielded abundant dinosaurian remains. We report here on cranial and postcranial remains that can be attributed to titanosaurian sauropods. This material is of considerable interest in view of the relative scarcity of sauropod fossils from the Upper Cretaceous of Central Asia. An incomplete braincase originally assigned to the ceratopsian Turanoceratops tardabilis actually belongs to a derived titanosaurian. It shares a number of features (including broad basal tubera and presence of wide depression between basal tubera) with braincases of various derived titanosaurian taxa from Asia and South America. Computed tomographic (CT) scanning of the braincase permitted digital reconstruction of a partial endocast. Overall, this endocast resembles those of other sauropods, although the pituitary fossa is considerably swollen. As in other derived titanosaurians, the abducens nerve passed lateral to the pituitary fossa. The inner ear resembles that of some other titanosaurs in having a very short lateral semicircular canal and that the anterior semicircular canal is only slightly longer than the posterior one. Isolated sauropod teeth from Dzharakuduk have slender, ‘pencil-shaped’ crowns, which often bear high-angle apical wear facets. The caudal vertebrae are gently opisthocoelous rather than procoelous, as is typically the condition on at least the anterior caudals in many other titanosaurs. An anterior caudal vertebra shows extensive pneumatization of its neural arch. The sauropod remains from the Bissekty Formation establish the presence of titanosaurians in Central Asia during the Turonian.

Qijianglong guokr, gen. et sp. nov., represents a mamenchisaurid eusauropod from the Late Jurassic of southern China. The holotype consists of an incomplete skull, partly articulated axial skeleton, and fragmentary appendicular skeleton. A well-preserved braincase and skull roof provide rare insights into the poorly known neurocranial anatomy of mamenchisaurids and reveal a unique combination of characters such as an accessory tuber at the base of planar basipterygoid process and parietal excluding frontal from the anterior margin of the supratemporal fenestra. The cervical vertebrae have a distinct finger-like process extending from the postzygapophyseal process beside a zygapophyseal contact. Qijianglong is the first mamenchisaurid from the Late Jurassic of China that is definitively distinct from Mamenchisaurus, indicating greater morphological and taxonomic diversity of the poorly represented Late Jurassic mamenchisaurids. The occurrence of Qijianglong is consistent with a scenario in which mamenchisaurids formed an endemic sauropod fauna in the Late Jurassic of Asia. Phylogenetically, Qijianglong represents a relatively plesiomorphic mamenchisaurid lineage. The mamenchisaurids form an ancient clade of basal eusauropod dinosaurs that likely appeared in the Early Jurassic. A cladistic analysis highlights the interrelationships of mamenchisaurids and suggests guidelines for mamenchisaurid taxonomic revision. It may be desirable to restrict generic names to the type species in order to avoid confusion.

We describe the odontocete, Ashleycetus planicapitis, gen. et sp. nov., based on a partial skull that was collected from the upper Rupelian (lower Oligocene) Ashley Formation near Charleston, South Carolina, and place it in the Ashleycetidae, fam. nov. Overall, the cranial morphology of this new species is plesiomorphic; it has an elongate, tabular intertemporal region, external nares well anterior to the antorbital notches, and anteromedially oriented lateral margins of the supraorbital processes. Xenorophus sloanii and Xenorophidae are rediagnosed, and the latter is also redefined as an apomorphy-based clade. This new definition should lead to greater stability because it excludes Archaeodelphis patrius, whose phylogenetic relationships have proven to be problematic. The holotype skull of the archaic odontocete Mirocetus riabinini, from probable upper Rupelian sediments of the lower Maikop beds of Azerbaijan, is redescribed, newly figured, and placed in the Mirocetidae, fam. nov. Previously regarded as an archaeocete, Mirocetus is here shown to be an odontocete. We added Ashleycetus, Albertocetus, and Mirocetus to a recently published supermatrix of morphological and molecular data. Although Ashleycetus, Archaeodelphis, and Mirocetus consistently occupy basal branch(es) within Odontoceti, their exact positions are sensitive to the value of a constant used in implied weighting for cladistics analysis. Three of the characters we find to be odontocete synapomorphies are closely associated with soft tissue structures implicated in the production and transmission of high-frequency sounds during echolocation. Detailed dissections of extant odontocetes are required to determine if these features can be considered evidence of echolocation in extinct taxa.

At ∼23 Ma, large amphicyonid carnivorans participated in the initial Neogene mammal migration passing though the Bering filter en route to North America. Among the migrants were the amphicyonines Cynelos and Ysengrinia, first appearing in early Miocene sediments of the upper Arikaree Group in Nebraska and Wyoming, having entered the New World with chalicotheres, small cervoids, and the cursorial rhinoceros Menoceras. Early representatives of these immigrant carnivores had not, until recently, been recovered from localities along the Pacific coastal corridor of western North America. Here we report the discovery of a unique skull that establishes the presence of an early Neogene species of Cynelos (C. malasi, sp. nov.) in coastal southern California. The skull shares craniodental features with early Miocene species of the genus in Europe. Dentition (P4-M1-M2) and cranial morphology of Cynelos malasi compare with C. helbingi (southern Germany) and C. lemanensis (France, Germany) but uniquely combine size and occlusal detail to preclude assignment to these species. Cynelos malasi is assigned a latest Arikareean (Ar4) age in the North American Land Mammal Age (NALMA) chronology. By the early Miocene, species of Cynelos had dispersed from western Europe to northern Africa and into western North America. Whether the taxon arrived in North America by following a coastal southern Asian route or by Palaearctic dispersal is unconfirmed. Given the similarity between North American and European species of Cynelos, we suspect that the genus spanned Asia during the early Miocene.

 http://zoobank.org/urn:lsid:zoobank.org:pub:6F78C042-8C98-47B3-BFD0-E6943A615197

The Early Triassic ichthyopterygian Chaohusaurus chaoxianensis was previously known from juvenile specimens only. It was considered to represent immature forms of C. geishanensis, which was based on a single adult specimen, because allometric regression lines of the forelimb skeletons suggested that the two name groups fitted along a single growth trajectory. The sample size for the analysis, however, was small (n = 5). We collected new specimens of Chaohusaurus from Majiashan, Chaohu City, Anhui Province, China, through field excavations that started in 2010. New specimens included an immature individual whose forelimb resembled that of mature C. geishanensis, as well as a large adult individual whose forelimb retained the characteristics of immature C. chaoxianensis. Therefore, C. chaoxianensis is not the juvenile of C. geishanensis. With the addition of the new specimens, two growth trajectories are now clearly detected on allometric regression plots (n = 15). The two species are unambiguously distinguished from each other based on a suite of discrete characters that are diagnostic to each species, as well as statistical analyses of forelimb measurements. It is unlikely that the two forms represent the genders of a single species given that C. geishanensis is vastly outnumbered by C. chaoxianensis and completely lacking in major fossiliferous rock layers. Therefore, C. chaoxianensis should be resurrected as a valid species.

A new genus of amphisbaenian reptile, Cuvieribaena carlgansi, is decribed from the late middle Eocene of France. This material from the locality of Le Bretou (Phosphorites du Quercy) is an almost completely preserved mandible. The dentary bears six teeth, with the anterior-most one the largest. The anterior teeth are blunt and enlarged (‘amblyodont’), and their size and amblyodonty decrease posteriorly. The presence of well-developed amblyodont teeth indicates a durophagous diet. Durophagy has already been recognized in some amphisbaenids, and their high skull, short jaws, and robust tooth morphology predispose them to this durophagous lifestyle. Several other amphisbaenid specimens have also been recovered from Le Bretou, mainly trunk vertebrae and two incomplete dentaries. This material and the complete mandible show unambiguous morphological features tying them to Blanidae. Cuvieribaena is the earliest secure record of blanid lizards in the fossil record, confirmed by phylogenetic analysis.

Temnospondyl amphibians are a large and diverse group of early tetrapods, whose paleohistology has been incompletely studied. Here, humeri of Micropholis stowi and Lydekkerina huxleyi from the Karoo Basin of South Africa (Katberg Formation) were thin-sectioned for paleohistological analysis. Diaphyseal bone histology of both taxa exhibits a convergence to fibrolamellar tissue and an absence of lines of arrested growth; additionally, medullary cavities free of trabeculae support terrestrial lifestyles in both Micropholis and Lydekkerina. The presence of azonal tissue in Micropholis is unlike that of other dissorophoids or extant caudatans, suggesting an adaptation to local conditions in the Early Triassic of the Karoo Basin, as well as a complicated and incompletely studied pattern of histological evolution in dissorophoids. Additionally, the propodial histology of these and 12 other taxa were assessed through different broad-scale phylogenetic hypotheses for Temnospondyli. Results reveal convergence towards sustained, non-cyclical growth and an absence of lines of arrested growth in the diaphyses of Early Triassic temnospondyls. The optimization of histological traits on to existing phylogenetic hypotheses is equally parsimonious between the different topologies. Homoplasy among histological characters suggests that evolutionary history in this group is overshadowed by developmental plasticity in bone microstructure, potentially due to environmental and biomechanical constraints. However, the interpretation of these data is limited by small sample size, and increased sampling is required to validate the patterns revealed in this study.

Titanosaurs are the only group of sauropodomorph dinosaurs that possesses osteoderms. The Anacleto and Allen formations (Upper Cretaceous) from northern Patagonia (Argentina) have provided an abundance of these elements, isolated or associated with more or less complete skeletons. Here, we study the morphology, microanatomy, and histology of titanosaur osteoderms found in these stratigraphic units. The size and gross anatomy of the osteoderms are strongly variable, as well as their microanatomy, which ranges from compact structures to those with strong development of cancellous bone. The primary bone tissue is composed of structural fiber bundles that are ossified by dermal metaplasia. Bone pathologies were identified in at least two osteoderms. Bone histology suggests that the osteoderms were entirely imbedded in the stratum compactum of the dermis. Titanosaur osteoderms were probably employed for multiple functions, including mineral storage and defense.

The Early Devonian (Lochkovian) Man On The Hill (MOTH) locality in the Northwest Territories has yielded hundreds of exquisitely preserved specimens of over 72 different species of early vertebrates, greatly increasing our understanding of the diversity of this period. In this paper, we describe three new genera comprising four new species of ischnacanthid acanthodian, based on their dentigerous jaw bones and teeth. This taxonomic diversity reflects some of the diversity of dentition found among ischnacanthiform acanthodians at the MOTH locality, in contrast to their highly conservative body forms. This high diversity of related forms suggests an early radiation in jaw and tooth morphology in Early Devonian ischnacanthiform acanthodians in this region. All ischnacanthiform specimens from MOTH were originally assigned to Ischnacanthus gracilis. However, study of the unique jaw and tooth morphology of MOTH ischnacanthiform specimens indicates that it is unlikely that Ischnacanthus was present at the MOTH locality.