Basal Ornithuromorpha, until recently, was one of the most poorly documented segments of early avian evolution. The known species diversity of the ornithuromorph clade has increased rapidly with the addition of new discoveries from the Early Cretaceous deposits of northeastern China. Reported in this paper is the discovery of a new bird from the Lower Cretaceous Yixian Formation, Liaoning Province, China. The specimen represents a new species, Longicrusavis houi, but bears similarities to Hongshanornis longicresta from the same formation of Inner Mongolia. The two birds are comparable in size and share an unusual sigmoid mandible and elongate hindlimbs relative to their forelimbs. Together these taxa represent a clade (Hongshanornithidae, new taxon) of specialized ‘shorebirds’ whose elongate hindlimbs indicate ecological adaptations different from those of other Jehol ornithuromorphs. Phylogenetic relationships of Mesozoic birds are discussed based on the results of a comprehensive cladistic analysis. New morphological information on Ornithuromorpha is provided through the detailed description of the new taxon together with new information on Hongshanornis.

Several specimens of a fossil fish recently collected from Cretaceous deposits near Changma, Gansu Province, China, are here described as a new genus and species of osteoglossomorph, Shuleichthys brachypteryx. This fish is a stem osteoglossomorph that cannot be included in either the Hiodontiformes or Osteoglossiformes without making either order polyphyletic. The fossils from the Changma locality are exceptionally well preserved, and allow many details of the anatomy of the new fish to be described, including the presence of a postpelvic bone, which was previously only known to be present in the living Hiodon. The relationships of the osteoglossomorph fishes are still not well resolved, and the addition of the new species to previous phylogenetic analyses causes even less resolution to be found. However, the new species appears to be more derived than Lycoptera and Paralycoptera, two other well-known stem osteoglossomorphs.

Mylopharyngodon wui, sp. nov., based on a completely preserved right pharyngeal bone with teeth from a middle Miocene deposit of the IVPP 346 Locality (43°24′53.4″N, 113°07′06.1″E) in the Tairum Nor area of Suniteyou Qi (Banner), Inner Mongolia, China, is described and compared with the living counterpart. It is different from the living black carp in having a generally smaller anterior angle, pharyngeal teeth a1 and a2 almost similar in size, and much rounder teeth a2 and a3. The ecological niche model of the living black carp, based on the Genetic Algorithm for Rule-set Production (GARP), shows that the fossil black carp is no longer in the niche model area, indicating that the regional environment has changed greatly, and that the black carp's niche has shrunk southeastward. The niche model also confirms that the distribution of the black carp is restricted by altitude above sea level. It may be inferred that the Inner Mongolia Plateau has risen more than 1000 m since the middle Miocene if the niche remained stable or evolved little over a long period of time.

A new cichlid referable to the extant genus Gymnogeophagus is described from the Eocene Lumbrera Formation of the Salta Group, northwestern Argentina. †Gymnogeophagus eocenicus, n. sp., presents the synapomorphies that support the genus: absence of supraneurals and a presence of a forward spine in the first dorsal pterygiophore. The existence of an early to middle Eocene—aged species presenting the synapomorphies and the appearance of a modern genus requires the acceptance of an extensive differentiation from the basal cichlid lineages. Extant Gymnogeophagus species are restricted to the La Plata drainage and a few coastal drainages of southern Brazil and Uruguay. The occurrence of an Eocene fossil in the geographical area corresponding to the present distribution of the genus suggests the patterns of distribution and endemism of the Neotropical fish fauna have a very old history in the continent.

Here we present a detailed anatomical description of cranial and post-cranial remains of a Jurassic turtle, Condorchelys antiqua Sterli, 2008, from the Cañadón Asfalto Formation (Middle Jurassic) in central Patagonia. Although C. antiqua is similar in morphology to the Early Jurassic turtles Kayentachelys aprix and Indochelys spatulata, it differs in that it lacks both pterygoid teeth and a V-shaped suprapygal 2, respectively. In light of new discoveries and reinterpretations of other fossil taxa, we suggest that several changes in the evolution of the skull morphology of turtles (such as the closure of the basipterygoid articulation, the closure of the interpterygoid vacuity, the development of the secondary lateral wall in the braincase, the development of temporal emargination and/or the posterior extension of the crista supraoccipitalis) could be related to the acquisition of a stronger skull to accommodate the modern pulley system. The optimization of these characters in a phylogenetic framework shows that they are coincident with the appearance of trochlear systems (oticum or pterygoidei) in turtles, suggesting a functionally correlated relationship among them.

A new pleurodiran turtle, Cerrejonemys wayuunaiki, from the middle to upper Paleocene, Cerrejón Formation of Colombia, is described on the basis of a complete skull, lower jaw, partial carapace and plastron, two cervical vertebrae, a right coracoid, and both pelvic girdles. Cerrejonemys wayuunaiki shares a suite of diagnostic characteristics with Podocnemididae, including a fully developed, medially extensive cavum pterygoidei that is almost completely covered by the prolonged posterolateral flanges of the pterygoid, a posterior elongation of the secondary roofing of the skull composed of the parietal and the quadratojugal covering two-thirds or more of the cavum tympani, a dentary covered laterally by the surangular, and no contact between the exoccipital and quadrate. Cerrejonemys wayuunaiki is unique among podocnemidids in having ridges on the ventral margin of the dentary, dentaries that form an acute angle at the fused symphysis, and a relatively thick (up to 35 mm) carapace and plastron. Results from a cladistic analysis of panpodocnemidids indicate that C. wayuunaiki is the sister taxon of the genus Podocnemis, which ranges from the Miocene to Recent, implying that stem of Podocnemis spp. were inhabiting tropical South America early in the Paleogene.

In this paper we describe previously unpublished trionychid turtle material, consisting of numerous shell fragments, from two Late Cretaceous (Santonian—early Campanian) localities from Middle Asia and Kazakhstan (Central Asia in the U.S. tradition): Kansai (Tadjikistan) and Shakh-Shakh (Kazakhstan). This material can be attributed to two forms of trionychids present in both localities. One of them is the named species Trionyx riabinini Kuznetsov and Chkhikvadze, 1987, described from Shakh-Shakh. New data on its shell morphology provided by our study allow attribution to the genus Aspideretoides Gardner et al., 1995, known previously only from the Campanian—Maastrichtian of North America. The presence of this taxon in both Middle Asia and North America provides the first clear evidence for the relationship between Cretaceous Asian and North American trionychids. The second form is established as a new species, “Trionyx” kansaiensis, sp. nov., with unclear systematic position within Trionychinae. We lastly present a brief review of other named taxa of Cretaceous trionychids of Middle Asia and Kazakhstan.

A fragmentary skull from the Hell Creek Formation (Maastrichtian) of southwestern North Dakota represents a new taxon of baenid turtle named herein Gamerabaena sonsalla. The length of the frontals, jugal contribution to the labial ridge, and convex contact between the vomer and the pterygoids indicate its affinities with the clade Palatobaena, but the new taxon clearly lacks the great posterior expansion of the triturating surface, complete absence of a lingual ridge, subrectangular skull, and wide angle between the maxillae that diagnose Palatobaena spp. A maximum parsimony analysis provides strong support for G. sonsalla as sister taxon to Palatobaena spp. Gamerabaena sonsalla has several morphological features that are intermediate between Plesiobaena antiqua and the morphologically disparate Palatobaena spp., including orbits that are oriented slightly dorsally and moderately expanded posterior triturating surfaces. Our phylogenetic analysis, combined with stratigraphic arguments, indicates that our skull-based taxon G. sonsalla could belong to the shell-based taxon “Baena” hayi. Similarly, the skull taxa Hayemys latifrons and Eubaena cephalica may be synonymous with the shell taxa Thescelus insiliens and “Baena” hatcheri, respectively.

An ichthyosaur from the Oxfordian—Kimmeridgian of Melville Island, Northwest Territories, Canada, is redescribed. This specimen was previously referred to as Ophthalmosaurus chrisorum Russell, 1993, but exhibits several features incompatible with this generic assignment. Here, I refer this specimen to a new genus, Arthropterygius, characterized by a basioccipital with an extremely reduced extracondylar area, a foramen for the internal carotid artery located on the posterior surface of the basisphenoid, a humerus with a well-developed distal facet for the articulation of a preaxial accessory element, and a radius and ulna with highly angular proximal surfaces for articulation with the humerus. Arthropterygius can be referred to the Ophthalmosauria based on the presence of a preaxial element anterior to the radius and ulna. This referral is supported by a phylogenetic analysis, in which a sister-group relationship between Arthropterygius and the South American genus Caypullisaurus is recovered. This specimen represents the most complete ichthyosaur from the Canadian Arctic, and has important implications for marine reptile diversity at high latitudes during the Jurassic.

Tylosaurus pembinensis (Mosasauridae; Tylosaurini), from the middle Campanian Pembina Member of the Pierre Shale, exposed near Morden, Manitoba, Canada, is redescribed and removed from the genus Hainosaurus. In support of our reassignment, we highlight incorrect diagnostic features in the original description that were used as support for the assignment of the new species to Hainosaurus (e.g., small suprastapedial process of the quadrate and the presence of 54 vertebrae in the dorsal and pygal series [33 dorsals and 21 pygals]). In contrast, we note that the fully prepared quadrate possesses key Tylosaurus features such as a moderately large-sized suprastapedial process. We also report that of the original 54 ‘pre-chevron’-bearing vertebrae, that 26 are from a second, unrelated species of mosasaur. Of the 29 remaining vertebrae, it is difficult, due to poor preservation, to identify which of these elements are pygals. Although the exact pre-chevron count is unclear, the preserved remains clearly do not support a diagnosis of a high pygal count consistent with Hainosaurus. In recharacterizing Tylosaurus pembinensis, we discuss a number of problematic characters used to diagnose Hainosaurus, in the context of diagnosing Tylosaurus and not for the purpose of revising the European taxon Hainosaurus bernardi.

Revision of the two extinct Javanese crocodylian species Gavialis bengawanicus Dubois, 1908, and Crocodylus ossifragus Dubois, 1908, indicates that only the former is valid and that the latter is a junior subjective synonym of the extant C. siamensis Schneider, 1801. Gavialis bengawanicus is diagnosed by a relatively small number of maxillary and dentary teeth, a modest maxillary process developed into the lacrimal, a W-shaped maxillo-palatine suture, a planar skull table, occlusal pits present exclusively on the dentaries, and relatively small and subcircular supratemporal fossae at maturity. It is the best-known extinct Gavialis, and it probably represents the only valid extinct Gavialis species known outside the Indian subcontinent. Both crocodylians from Java have been found exclusively along with the Stegodon-Homo erectus fauna, which is considered to be largely the result of an Early Pleistocene dispersal from the Siwaliks Hills via the so-called Siva-Malayan route. It is not clear if the dispersal of Gavialis from the Indian subcontinent to Java necessarily required the crossing of salt water barriers, but the possible occurrence of Gavialis remains in Sulawesi and Woodlark, two islands located east of the Huxley and Wallace lines that were never connected to the mainland, can be explained by inferring a marine dispersal. According to the present knowledge of the past distribution of Gavialis, this genus originated in the Indo-Pakistani area in the early Miocene and during the Quaternary dispersed to the Sunda region, possibly reaching western-most Oceania.

More than any other sauropod dinosaur group, the long-necked herbivores belonging to Diplodocoidea have been defined by their skulls. Their unique skull shape, which is extremely elongate antorbitally, with a transversely broad, square snout packed at its anterior extreme with narrow-crowned, pencil-like teeth, has served as a touchstone for describing the biology of these animals ever since the discovery of the first skull in the late 19th century. In particular, the unusual diplodocoid skull has been discussed frequently in the context of examining feeding behavior, spawning hypotheses ranging from branch stripping, propalinal shearing, and aquatic plant ‘grazing.’ Here, we describe a juvenile skull of Diplodocus (Carnegie Museum 11255) that does not share the unusually blunted snout and anteriorly sequestered teeth seen in adult specimens, suggesting that adults and juveniles may have differed greatly in their feeding behavior, an ontogenetic distinction that may be unique among sauropodomorphs.

Constructing musculoskeletal models of extinct vertebrates requires subjective assumptions about soft tissue parameters rarely preserved in the fossil record. Despite these necessary assumptions about fundamental input values, paleobiologists rarely perform objective tests of best-estimate models before reaching conclusions based on predicted results. The extent to which lack of knowledge on soft tissue anatomy limits the accuracy of running speed estimates of extinct dinosaurs is therefore poorly understood. In this study, a sensitivity analysis is performed on an evolutionary robotics model of the non-avian theropod dinosaur Allosaurus, used previously to estimate maximum running speed in this extinct animal. A range of muscle parameters were varied over the range observed in extant vertebrates, whereas mass-related parameters were altered across the range of published estimates for Allosaurus. Muscle parameters have a linear relationship with maximum running speed, whereas surprisingly total body mass and torso center of mass have little effect. Muscle force values produced the greatest range in predicted running speeds (4.5–10.7 m/s) and stride lengths (4–5.8 m) in the sensitivity analysis, equating to 65.9% and 30.7% variation about the original ‘best-estimate’ prediction, a relatively high potential margin of error. These results highlight the importance of sensitivity analyses in biomechanical modeling of extinct taxa, particularly where values for soft tissues parameters are not tightly constrained. The current range in plausible values for soft tissue properties makes a robust quantitative assessment of behavioral ecology and species interactions in dinosaurian communities extremely difficult.

We report new avian remains from the early Eocene Cambay Formation of Vastan Lignite Mine in western India. Most of the bones belong to the as yet poorly known taxon Vastanavis, of which a new species, V. cambayensis, is described. For the first time, tarsometatarsi of Vastanavis can be identified, which show that this taxon had semi-zygodactyl feet. In overall morphology, Vastanavis closely resembles the species of the Quercypsittidae, which occur in the late Eocene of Europe and are considered stem group representatives of the parrots (Psittaciformes). Several plesiomorphic features indicate, however, that Vastanavis is outside a clade including Quercypsitta and crown group Psittaciformes, and we therefore assign it to a new family, Vastanavidae. Vastanavis corresponds well with an as yet undescribed avian species from the early Eocene London Clay in England, and we conclude that, at least concerning the arboreal taxa, the early Eocene avifauna of India shows some concordances with the much better known one from the early Eocene of Europe. We further describe a distal tarsometatarsus from Vastan Lignite Mine that superficially resembles that of extant New World vultures (Cathartidae), but comes from a roller-sized species.

A new species and genus of acanthisittid wren (Aves: Passeriformes: Acanthisittidae) is described from the Early Miocene (19–16 Ma) St Bathans Fauna from Otago, New Zealand, based on four fossil bones. The first Tertiary fossil passerine to be described from New Zealand, it is similar in size to New Zealand's smallest extant bird, the Rifleman Acanthisitta chloris. A phylogenetic analysis of 53 osteological characters and 24 terminal taxa, including four suboscines, basal corvoids (Menuridae, Atrichornithidae, Climacteridae, Ptilonorhynchidae, Maluridae, Dasyornithidae, Acanthizidae, Pardalotidae, Meliphagidae), and all seven Recent acanthisittid species, identifies it as the sister group to Acanthisitta. This, the first phylogenetic analysis of the basal passerine groups to use morphological characters, recovers a similar pattern of relationships of basal corvoid taxa to that obtained by recent molecular studies. The analysis also suggests that Acanthisitta chloris and the new species are the most deeply nested taxa within the family, suggesting that the radiation of Recent acanthisittids originated no later than the Early Miocene.

Few latest Cretaceous mammalian faunas are known from the central part of the Western Interior of North America. Here we report a collection of 28 mammalian fossils (23 isolated teeth, 5 dentulous jaw fragments) from five Upper Cretaceous localities in and around the Pawnee National Grassland (Weld County) in the Cheyenne Basin, northeastern Colorado. At least 10 taxa are represented, including two new multituberculates, a neoplagiaulacid Parikimys carpenteri and a ?cimolomyid Paressonodon nelsoni, which has greatest affinities to Essonodon browni. The new specimens combine with a previously reported sample for a total of 40 mammalian specimens from the area. Using a subsurface model based on geophysical log data, we stratigraphically arranged the fossil localities relative to the top of the Fox Hills Sandstone. Our stratigraphically lowest site is 95 m above the datum and likely near the top of the Laramie Formation. Presence of Meniscoessus collomensis at this site implies a late ‘Edmontonian’ or early Lancian age. The remaining sites are 220, 330, and 410 m above the datum and temporally equivalent to the Cretaceous part of the D1 sequence in the Denver Basin; the stratigraphically highest site is near the predicted Cretaceous—Tertiary boundary. The faunal samples from the latter sites include mostly typical Lancian taxa, except for two new taxa that suggest biogeographic differences with contemporaneous localities from farther north. This stratigraphic succession of fossil localities from northeastern Colorado may offer new perspectives on temporal and biogeographic changes of mammalian faunas leading up to the Cretaceous—Tertiary boundary.

We discuss large tracks recently discovered in Paleocene coal deposits from Svalbard. The age, large size, and excellent preservation of the tracks allows them to be identified to the pantodont Titanoides. This is the earliest evidence of a large mammal on the Arctic islands and the northernmost record from the Paleocene. The traces are described in detail and named Thulitheripus svalbardii, gen. et sp. nov. Large Paleocene pantodonts are previously only known from North America. The presence of pantodonts in the Paleocene strata of Svalbard confirms the postulated DeGeer route for migration of mammals in the Paleocene/Eocene.

Caviidae and Hydrochoeridae (extant Cavioidea s.s.), probably the most peculiar among rodents, are characterized by their evergrowing double-heart-shaped cheekteeth. They have classically been rooted in Eocardiidae, which ranges from Deseadan to ‘Colloncuran’ (late Oligocene-middle Miocene) in Patagonia, although in the Deseadan and Colhuehuapian (early Miocene) remains are very scanty. For the Colhuehuapian, only one species coming from the southern cliff of the Colhué Huapi Lake (Gran Barranca, Chubut, Argentina) was known so far. In this paper, the first Colhuehuapian eocardiids from outside Gran Barranca are reported: Luantus minor, sp. nov., and Chubutomys leucoreios, sp. nov. They are represented by two fragmentary mandibles and a few isolated cheek teeth, from the Trelew Member of the Sarmiento Formation at Bryn Gwyn, lower valley of the Chubut River, Chubut. The new species enlarge the knowledge of eocardiid diversity, and reinforce the hypothesis of a basal dichotomy for the group. L. minor represents one of the smallest species of the series Asteromys Luantus Phanomys Eocardia, which likely gave rise to modern Cavioidea s.s. C. leucoreios pertains to a group of species with precocious hypsodonty and apparently low diversity, but without modern descendant.

The fossil shrews (Soricidae, Lipotyphla, Mammalia) from the Pliocene continental deposits of Tollo de Chiclana (Guadix Basin, southern Spain) are described. Remains of Asoriculus gibberodon, Blarinoides aliciae, Petenyia hungarica, Paenelimnoecus pannonicus, Myosorex meini, and an indeterminated species of Soricidae have been recognized. With the exception of A. gibberodon, these species are very uncommon in the south of the Iberian Peninsula; in fact, this finding represents the first record of Petenyia, Blarinoides, Paenelimnoecus, and Myosorex in the Guadix Basin. The changes in the abundance of Soricidae in the studied levels indicate wet and warm climatic conditions during the late Ruscinian and early Villanyian, and a decrease in the temperature and precipitation in the late Villanyian.

Cranial and dentognathic remains of Trocharion albanense (Carnivora, Mustelidae, Leptarctinae) from the Vallès-Penedès Basin (Barcelona, Spain), ranging from the middle to the late Miocene, are described. Most of the newly described material comes from several sites of the Abocador de Can Mata (ACM) section (in the municipal term of els Hostalets de Pierola), but remains from other Catalan localities (Sant Quirze, Castell de Barberà, and Can Llobateres) are also described. The material from ACM includes two partial crania and several mandibles. This enables description of several aspects of craniodental morphology previously unknown for this taxon, such as the presence of first upper premolars, as well as the presence of a conspicuous and rhomboid double temporal crest. Accordingly, an emended diagnosis of the genus Trocharion is provided, together with a differential diagnosis with respect to other leptarctine genera. A cladistic analysis based on craniodental features is consistent with Trocharion being the basalmost member of the Leptarctinae, and suggests that the carnassial notch (still present in this taxon) was independently lost in leptarctines and in other mustelids.

Dental mesowear and microwear are used to determine diet in the palaeothere Plagiolophus minor from a sequence of four localities across the Eocene—Oligocene transition in Europe: La Débruge, Soumailles, and Ronzon in France, and Frohnstetten in Germany. Plagiolophus minor was the only member of its family to survive more than fleetingly the mammalian faunal turnover, the Grande Coupure, which occurred during the earliest Oligocene in Europe. P. minor has a browsing diet at all the localities studied, but shows changes in the proportion of fruit and abrasive material. There is a decrease in the proportion of fruit between La Débruge and Frohnstetten (before the Grande Coupure) and an increase in the proportion of abrasive leaves across the Grande Coupure. There are two steps in increasing abrasiveness, one before the Grande Coupure and one across the Grande Coupure. The increase in abrasiveness across the Grande Coupure coincides with the timing of the Oi-1 glaciation. After the Grande Coupure, there is no change in diet for the first ∼0.3 Ma.

A new, well-preserved mysticete fossil is described and diagnosed here as Joumocetus shimizui, gen. et sp. nov. The holotype specimen was recovered from the earliest Late Miocene, Haraichi Formation, Annaka Group, Gunma Prefecture, Japan. Although many cetotheres have been found from the Pacific realm, the Cetotheriidae sensu stricto is relatively rare in terms of taxonomic diversity and also abundance of specimens. Joumocetus will be the fourth genus of the Cetotheriidae sensu stricto from the Pacific and the geologically earliest and most archaic Cetotheriidae sensu stricto yet reported. Joumocetus retains a number of primitive characteristics, and our phylogenetic analysis indicates that Joumocetus is placed basally among the Cetotheriidae sensu stricto. Our analysis clearly indicates a monophyly of the Cetotheriidae sensu stricto and of a clade that consists of Balaenopteridae, Eschrichtiidae, and cetotheres. The results also indicate the monophyly of the following two groups: cetotheres not belong to Cetotheriidae sensu stricto (= Isanacetus-group) and Cetotheriidae sensu lato (= Isanacetus-group Cetotheriidae sensu stricto); however, the monophylies of these groups are not well supported by bootstrap analysis. Consequently, the relationships and definition of these mysticete taxa remain unclear. Based on the present study and a review of previous studies, we suggest that the Isanacetus-group is a paraphyletic taxon that includes the ancestors of two clades, Balaenopteridae Eschrichtiidae and the Cetotheriidae sensu stricto.