The plagiosaurine Gerrothorax pulcherrimus, a ubiquitous faunal component of the Fleming Fjord Formation, is recognized by tubercular ornamentation, contact between the postfrontal and supratemporal, at least two tooth rows on the posterior coronoid, and a posttemporal fenestra that is small or absent. Gerrothorax pulcherrimus also possesses a derived pectoral morphology that includes an interlocking claviculocleithral complex and an interclavicle with paired posterolateral projections and a transversely truncated posterior margin. Gerrothorax pustuloglomeratus is a junior synonym of G. pulcherrimus; other Gerrothorax species cannot be differentiated from G. pulcherrimus. Flat-headed temnospondyls have been interpreted as having achieved a large gape by raising the skull rather than by lowering the jaw. No detailed, corroborating anatomical evidence from the atlanto-occipital joint, however, has ever been adduced. In G. pulcherrimus the widths of the atlantal and condylar facets are comparable, but dorsoventrally the condylar facets are 45% longer than the comparable dimension of the atlantal facets. Elevation of the skull occurred by atlanto-occipital rotation, and was facilitated by a radius of curvature of the dorsal part of the condylar facets that is shorter than that of the inferior part. From a resting, closed mouth position, G. pulcherrimus was capable of elevating the skull through an excursion of approximately 50°, a movement that rotated the quadrate forward and protruded the lower jaw. An elongate, broadly open neural canal in the atlanto-occipital region, and dorsal displacement of the occipital condyles, are related to relieving the spinal medulla of the sharp angular deformation that head lifting might entail.

Osteostracans are Paleozoic jawless vertebrates, likely the sister group to gnathostomes (jawed vertebrates). It was previously believed that the osteostracan dermoskeleton began ossification when the individual neared adult size, restricting further growth once a dermoskeletal covering was achieved. However, we describe here small, well-preserved articulated specimens of the osteostracan Superciliaspis gabrielsei. These specimens are the best-known juvenile osteostracans, and document dermoskeletal development at an evolutionary stage highly relevant to the origin of gnathostomes. Ossification began before the animal reached 20% of adult size. Bones grew by multiple means, including initiation of new bone units, marginal growth, and fusion into larger bones. In the head, paired elements were among the first to ossify. In the trunk dermoskeleton of juvenile heterostracans, bones developed first along the midline, but in Superciliaspis gabrielsei, a lateral to median polarity is seen, with ventrolateral ridge scales the first to appear.

Examining morphological patterns is key to understanding mechanics and function in biological systems. In extinct taxa, there is a lack of observational or behavioral data to use to understand function, and groups without descendants limit the use of modern homologues. The only available evidence for function is the morphological characteristics of the preserved fossils. The purpose of this research is to analyze the functional consequences of variation in the lower jaw morphology in Late Devonian arthrodire placoderms. Landmark-based morphometric data were collected for 94 isolated arthrodire inferognathals (lower jaws) from the Gogo Formation in Western Australia and the Cleveland Shale in Ohio. These data were used to define the morphological differences and variation between two phylogenetically distinct morphotypes. Statistical results indicate fundamental shape differences between the two arthrodire morphotypes (coccosteomorphs and pachyosteomorphs). Differences in the shape of the blade portion of the jaws imply that the extreme coccosteomorph form (determined by Canonical Variate Analysis, CVA) had stiffer jaws with occlusion patterns similar to modern mammalian carnivores, while the extreme pachyosteomorphs (also determined by CVA) had higher mechanical advantage (force transfer) with occlusion patterns similar to modern herbivorous mammals and bamboo sharks. Arthrodires possibly filled a number of diverse feeding niches. Based on morphological disparity analyses, the mostly open basin pachyosteomorphs had greater overall morphological diversity than the reef-dwelling coccosteomorphs. Lower disparity in reef dwelling arthrodires may be due to sampling bias, environmental factors, or competition from other fish groups present in Devonian reef faunas.

A new elasmobranch, Thrinacoselache gracia, is described from the Bear Gulch Limestone lens (Heath Formation; Sepukhovian) of Montana, with an elongate neurocranial region, occipital region that incorporates several separate vertebral zygal elements, extremely elongate, low body, and anatomically heterocercal, but horizontally oriented tail. Teeth are borne upon the rostrum, palatoquadrate, and mandible. The palatoquadrates articulate with both palatobasal and postorbital processes, as well as with the ethmoid; the hyomandibula articulates with the posterior upper corner of the neurocranium remote from the postorbital process. The mandible is longer than the neurocranium and meets its contralateral element in an extended, but mobile symphysis. Squamation is placoid, except for a dorsal pre-otic shield of elongate denticles. Digestive cavity contents identifiable as elasmobranch and holocephalan indicate that Thrinacoselache was predominantly a piscivore. The teeth are close to isolated teeth described as Thrinacodus, and particularly to the twisted, asymmetrical teeth of T. ferox Turner rather than the symmetrical teeth of the genotype, T. nanus. Tooth asymmetry and elongated preotic scale morphology in Thrinacoselache gracia are attributed to the strong positive allometry of the rostral region relative to the remainder of the neurocranium. The implications of distinctly different growth patterns between Thrinacodus and Thrinacoselache support the removal of T. ferox and its assignment to the new genus. The Thrinacodus-complex is removed from the Phoebodontidae and assigned to the new family Thrinacodontidae. Phylogenetic analysis indicates that Thrinacoselache and Diplodoselache occupy a basal position relative to other elasmobranchs for which holomorphological information is available.

A full description and diagnosis are given of Lawrenciella schaefferi Poplin 1984, from the Pennsylvanian (Late Carboniferous) of Kansas, U.S.A. This taxon is only known by braincases and associated parasphenoids, which are exceptionally well preserved as phosphatic nodules. The external and internal morphology of the endocrania were studied from serial sectionings which allowed detailed three-dimensional reconstructions. The study shows that, besides synapomorphies inherent to basal actinopterans, L. schaefferi displays a set of very peculiar features such as prespiracular fossae, intracranial ossicles, and paired anterior myodomes for nonocular eye muscles. Another conspicuous feature, the notochordal canal ending blindly anteriorly, has been observed until now only in more advanced Triassic actinopterans. The anatomical characters of L. schaefferi indicate, in the light of recent cladistic analyses, that this Carboniferous taxon is a relatively advanced actinopteran compared to basal forms such as Kentuckia, Mimia, or Moythomasia.

A new species of Amiidae, †Cratoamia gondwanica gen. et sp. nov., is here described from the Early Cretaceous Crato Formation of the Araripe Basin, northeast Brazil. The new species, based on complete and nearly complete articulated specimens, includes synapomorphies of the subfamily †Vidalamiinae and the tribe †Vidalamiini. The presence of †Cratoamia in Brazil increases the geographical distribution of the tribe †Vidalamiini into the Southern Hemisphere.

The fissure fills of Richards Spur, Oklahoma, together constitute the most productive Paleozoic continental fossil locality in the world, having produced a wealth of terrestrial vertebrates, including occasional articulated skeletons. A new dissorophoid amphibian is represented by two skulls: an exquisitely preserved, complete small skull and the posterior part of a second skull, almost twice the size of the holotype. The specimens provide detailed information about the skull roof, palate, braincase, and mandible, showing that this new taxon is characterized by a relatively elongate skull with large tabulars and postparietals, and monocuspid, recurved teeth that show no sign of pedicelly. The large, laterally expanded interpterygoid vacuities are covered by a mosaic of small dermal plates, each carrying more than a dozen strongly recurved teeth. A phylogenetic analysis of 17 ingroup taxa and 62 cranial and postcranial characters yielded a single most-parsimonious tree with the new taxon in a monophyletic Amphibamidae as the sister taxon to the Lower Triassic Micropholis from South Africa. In addition, the new analysis supports a basal split of Amphibamidae into two distinct clades, one containing the new taxon, Micropholis, along with Tersomius, and the other comprising Amphibamus, Gerobatrachus, Doleserpeton, Platyrhinops, Plemmyradytes, Eoscopus, and Georgenthalia. The data retrieved from this new taxon provides insights into the evolution and diversity of the Amphibamidae.

We present an anatomical redescription and reassessment of the phylogenetic relationships of Sclerosaurus armatus Meyer in Fischer, 1857, a parareptile from the Lower to lower Middle Triassic Buntsandstein of southern Germany and northern Switzerland. This taxon is distinguished from other known parareptiles by the possession of long, posterolaterally projecting spikes formed by supratemporals, posterior dentary teeth with mesiolingually aligned and slightly imbricating crowns, and a narrow band of dorsal dermal armor comprising two or three rows of sculptured osteoderms on either side of the midline. Phylogenetic analysis places Sclerosaurus in the Procolophonidae rather than as the sister taxon of Pareiasauria. Furthermore, certain apomorphic character states, particularly the presence of three spines on the quadratojugal, support its referral to the Leptopleuroninae. Sclerosaurus resembles pareiasaurs in the presence of an intercondylar canal on the distal end of the femur, the absence of gastralia, and having a short tail. It is possibly the largest procolophonid known to date.

New axial and appendicular material permits a detailed re-description of the postcranial skeleton of the derived mid-Maastrichtian California mosasaur genus Plotosaurus. Centrum morphology, vertebral process shape, and extreme hyperphalangy provide compelling evidence to demonstrate that Plotosaurus achieved the highest level of aquatic adaptation among mosasaurs. A re-examination of the type material of P. bennisoni and of P. tuckeri indicates that only one taxon, P. bennisoni, is present, of which P. tuckeri is a junior synonym.

A new eosauropterygian genus and species is described from the middle Anisian (Middle Triassic) of Panxian (Guizhou Province, southwestern China). The new taxon is characterized by an unique specialization of the jaws that form an elongate pointed rostrum furnished with numerous small, monocuspid and vertically oriented teeth with a basally expanded crown and pointed tip, which is quite unlike any other sauropterygian known. Other diagnostic characters include: frontals paired; parietal unpaired; pineal foramen located centrally in broad parietal skull table; two carpal ossification; ilium with distinct preacetabular process at the base of the dorsally extending iliac blade; pubis plate-like and of rounded contours; two tarsal ossifications. The curved and distally expanded humerus, the reversed topological relationship of the clavicle and scapula, and the presence of three sacral ribs indicate sauropterygian affinities of the new taxon, whereas the ‘butterfly-shaped’ or ‘cruciform’ facet for the neural arch on the dorsal centrum surface indicate its eosauropterygian status.

The Upper Triassic Canjilon Quarry in northern New Mexico preserves a vertebrate assemblage typical of the Norian Stage of North America. Although dominated in relative abundance by the phytosaur Pseudopalatus and the aetosaur Typothorax, a more diverse assemblage of smaller forms was previously reported. Additions to the Canjilon Quarry vertebrate assemblage are critically reviewed and described using an apomorphy-based method for assigning taxa. An apomorphy-based approach for compiling and comparing assemblages allows each taxonomic assignment to be a testable hypothesis. Fragmentary yet diagnostic elements that may not be assignable to a species-level taxon can be assigned to a larger clade and thus provide useful information. Additionally, each taxon listed in the assemblage must be tied to a diagnostic specimen listed with a museum specimen number. Using this method for the Canjilon Quarry, we establish the presence of an assemblage that is more similar to other vertebrate quarries near Ghost Ranch than previously thought. The Canjilon Quarry assemblage is restricted to vertebrates from UCMP locality V2816. Vertebrate material housed at the Museum of Comparative Zoology, Harvard, which was reported from the Canjilon Quarry, was not collected from UCMP V2816 but from a nearby locality.

Different forms of intracranial mobility, including streptostyly, pleurokinesis, and prokinesis, have been postulated for many dinosaurs. The basis for inferring kinesis typically has included the presence of presumably synovial intracranial joints (otic and basal joints) and various ad hoc 'sliding joints' (many without modern parallels), whereas the protractor musculature that would have powered movement at these joints has received little attention. No study has reviewed the evidence underlying these inferences, and the functional mechanisms and evolution of kinesis among dinosaurs have remained unclear. We analyzed the relevant musculoskeletal structures in extant diapsids and extinct dinosaurs to evaluate in general the morphological support for inferences of cranial kinesis in dinosaurs. Four criteria (synovial otic joints, synovial basal joints, protractor muscles, and permissive kinematic linkages) were considered necessary but individually insufficient for the inference of kinesis. Assessing these criteria across dinosaurs reveals that synovial otic and basal joints are almost universally present (even in widely acknowledged akinetic taxa), and most taxa retained protractor musculature. However, unlike fully kinetic extant birds and squamates, almost all dinosaurs lacked the kinematic linkages that would have permitted movement (reduced palatal and temporal articulations, additional flexion zones). Thus, synovial basal and otic joints and protractor musculature are diapsid plesiomorphies, and, in the absence of permissive kinematic linkages, most formulations of nonavian dinosaur kinesis are currently problematic. Alternatively, persistent synovial joints may simply be cartilaginous sites that facilitate cranial growth during ontogeny.

A new large nodosaurid ankylosaur, Peloroplites cedrimontanus, is described from a partial skull and postcranial skeleton found at the PR-2 Quarry located at the base of the Mussentuchit Member of the Cedar Mountain Formation in central Utah. The specimen is about the same size as the contemporary nodosaurid Sauropelta edwardsorum from the Cloverly Formation of Montana, and is of an individual approximately 5–5.5 m long. The skull of Peloroplites differs from that of Sauropelta in the vertical orientation of the suspensorium, non-domed cranium and broad, square premaxillary beak. The quarry is near and roughly at the same level as the CEM Quarry that produced the holotype of the ankylosaurid Cedarpelta bilbeyhallorum. The postcrania of Cedarpelta is described and illustrated based on the paratype and new material. These elements clearly establish that Cedarpelta is closer to Ankylosaurus than to Sauropelta. As a primitive ankylosaurid, there is no a priori reason to assume that the tail club was present. Based on recent finds in China, a hypothesis is presented that the tail club is a derived feature in non-shamosaurine (i.e., ankylosaurine) ankylosaurids.

A new nodosaurid specimen from the Upper Cretaceous Naashoibito Member of the Ojo Alamo Formation in the San Juan Basin, New Mexico is assigned to Glyptodontopelta mimus Ford, 2000 based on characters of internal (histological) and external osteoderm morphology. This specimen is from the same stratigraphic horizon as the holotype (USNM 8610), and because it displays a wide range of osteoderm morphotypes, it can be used as a basis for comparison of osteoderm shape and sculpturing among different ankylosaur taxa. Its unique surface texture differentiates it from other Upper Cretaceous ankylosaurids and nodosaurids (Ankylosaurus, Nodocephalosaurus, Edmontonia, Euoplocephalus, and Panoplosaurus) and demonstrates that G. mimus is a valid taxon. The nodosaurid Edmontonia australis Ford, 2000 is considered a subjective junior synonym of G. mimus based on having the same surface texture and shape of the medial cervical osteoderms. Ankylosaur osteoderms are distinctive to at least the genus level and are commonly found in Upper Cretaceous strata, thus they have great biostratigraphic utility.

Eggs containing well-preserved skeletons were collected from Bugin-tsav, an Upper Cretaceous locality in the Nemegt Formation, Ömnögov' Aimag, Mongolia. These embryos, found in a weathered nest of eggs, are oviraptorid theropods. Eggshell morphotype is Elongatoolithidae, typical of theropods, including basal birds. Bone histology indicates that all embryos were probably close to hatching, based on the degree of ossification and in comparison with ossification patterns in living birds. Maturity of ossification indicates that oviraptorids hatched at a precocial stage of development. Two of the embryos are relatively large, while the other is 25% smaller, suggesting that size disparity of hatchlings in oviraptorids may be a consequence of asynchrony in egg laying.

The distribution of neck muscles and the shape of the skull shows that Permian and Triassic dicynodonts may be classified into three categories which probably reflect feeding on low, medium and high vegetation. These are distinguished on the basis of the occipital index, the difference between the relative width and height of the occiput, which gives a measure of the relative importance of the lateral and the dorsoventral clusters of neck muscles. The basicranium is relatively shortened in Triassic forms, except in Vinceria, Shansiodon, Tetragonias, and Jachaleria, as has been noted before. Data on skull proportions indicates that the height of the parietal crest may be of little taxonomic use, and that the genus Tetragonias is not a clade. Dicynodonts with dietary preferences at the intermediate level correspond to major branching points in dicynodont phylogeny. High-level feeding adaptations among dicynodonts arose by the middle of the Tatarian (latest Permian) and lasted until the Late Triassic. Specialized low feeders existed only in the Middle Triassic.

Previous reports of the fossil vertebrates from the upper Lower Jurassic La Boca Formation of Tamaulipas, México, presented descriptions of a tritylodontid therapsid, a burrowing diapsid, crocodyliforms, a pterosaur and sphenodontians. Mammaliaform material is rare, consisting primarily of partial lower jaws, some of which are extremely small. Five partial dentaries and one maxilla all have molars of “triconodont” morphology. Two lower jaws clearly show the internal mandibular trough, suggesting attachment of postdentary bones, another two do not possess a trough, and in another its presence or absence cannot be determined. This diversity of forms suggests that during the late Early Jurassic variations on the primitive “triconodont” molar patterns and in lower jaw morphology took place. The mammaliaform specimens from Tamaulipas appear to represent new taxa, but, because of the incomplete preservation of most of the material, only three new genera and species are erected: Bocaconodon tamaulipensis, Victoriaconodon inaequalis, and Huasteconodon wiblei.

The oldest described vombatid, Rhizophascolonus crowcrofti, is known from late Oligocene/early Miocene deposits in South Australia. It was described based on a single isolated tooth originally interpreted to be P3. It is also the only described vombatid known to have had tooth roots, all others being hypselodont. This paper describes two additional isolated teeth referable to this taxon from the same deposit and presents a re-interpretation of the type specimen as an M4. Possible function of the extensive, but asymmetrically distributed, molar enamel is discussed. Analysis of the structure and probable function of all three teeth leads to the hypothesis that R. crowcrofti was rhizophagous.

(Parts of this abstract were presented at the London Evolutionary Research Network [LERN] 5th annual conference at the Natural History Museum in London on September 14, 2007.)

A new plagiolophine equoid from the Eocene of the Iberian Peninsula, Iberolophus gen. nov., is herein reported. This new genus includes two species: I. arabensis sp. nov. (type species) from the Late Eocene (Headonian) of Zambrana (Araba, Basque Country) and I. jimenezi sp. nov. from the late Middle Eocene (Robiacian) of Mazaterón (Soria, Castilla y León). Iberolophus exhibits an unusual dental pattern that has not yet been reported in any other perissodactyl or ungulate to date. A complete (with P1/p1) and very long non-lophoid premolar series, in which premolars exhibit one (in the earlier members) or two (in the later members) high and pointed cusp(s) anteriorly and a low and long backward extended talon/talonid posteriorly, with a bumpy surface texture, is combined with a typical plagiolophine type lophodont and heterodont molar series. The new taxa are ranked as members of the endemic fauna of the Western Iberian Bioprovince. The latter includes the Eocene sites of the central and western Iberian basins (Duero, Almazán, Oviedo, and Miranda-Trebiño Basins), which have yielded Middle and Late Eocene mammal fossil assemblages (mainly perissodactyls, rodents and primates) which differ from those of the Southern Pyrenean Basins and the rest of Europe. The endemism of the perissodactyl faunas persisted during the Late Eocene in the central and western Iberian basins, on the basis that the perissodactyl fossils from the middle Headonian beds at Zambrana (Miranda-Trebiño Basin) are related to endemic taxa from the late Robiacian beds of the Duero, Almazán, and Oviedo Basins.

A new species of Crocuta (spotted hyenas), Crocuta eturono n. sp., from the Early Pliocene of the Turkana Basin, Kenya is described. The species has been recovered from LO6S, a site in the Kataboi Member of the Nachukui Formation, on the western side of Lake Turkana. The site is dated to >3.4 Ma. The new species differs from all previously identified species of Crocuta in its length proportions of the cheek teeth, having a very long m1 and short p3 and p4. The species is also tentatively identified from the Tulu Bor Member of the Koobi Fora Formation, east side of Lake Turkana. The new species provides information for a discussion of the structure of the hyena guild in eastern Africa 4–3 Ma. Three groups of taxa are identified with distinct distributions. It is hypothesized that specific ecomorphologies of each group account for these distinctions.

The fossil record of Neotropical Lutrinae is very incomplete, with a few specimens of Lontra and three records of Pteronura. The published records of Pteronura correspond to remains of Pteronura sp. from Lujanian beds in Entre Ríos province (Argentina) and P. brasiliensis found in the “Late Pleistocene” of Brazil, but they lack stratigraphic context and their age could range from at least 380–0.9 Ka. P. brasiliensis, the giant river otter, inhabits rivers and lakes of northern central South America, and has been related to the North American fossil otter Satherium. In this work we describe and compare a very complete specimen of Pteronura found in Entre Ríos province using classical morphological descriptive and multivariate analyses, discuss the importance of this specimen for the fossil record of the taxon, and perform a preliminary phylogenetic analysis. The specimen agrees in morphometric and qualitative characters with the recent species P. brasiliensis, but is slightly larger and presents some minor differences in skull and dental morphology. These differences are interpreted as intraspecific variation, thus the fossil is interpreted as P. brasiliensis. In the phylogenetic analysis, the studied specimen clusters with P. brasiliensis, corroborating the taxonomic determination and supporting a relationship between Satherium and Pteronura. The specimen is the first fossil record of the genus for Argentina, and the oldest corroborated record, with a 130–125 Ka tentative age.

Merycopotamus thachangensis, sp. nov. (Cetartiodactyla, Anthracotheriidae, Bothriodontinae) was discovered from a mined sand pit in Tha Chang village in Nakhon Ratchasima Province, northeastern Thailand. The specimen is a nearly complete cranium with left P3-M3 and right M1-M3. It is the first known Merycopotamus in Thailand. The new species has a nearly divided mesostyle with a remnant at the base. No small crest is developed from the buccal style on upper molars. The postparacrista and premetacrista are parallel, pointing buccally to distobuccally. The major palatine foramen is positioned at P2–P3. The naso-frontal suture is lobe-like. There is a single supraorbital foramen with a distinct groove. There is no contact between the nasal and lacrimal bones. M. thachangensis shows a mixture of derived and primitive features that distinguish it from the previously known species of Merycopotamus. The new Thai species might have evolved from M. medioximus in the early late Miocene of Siwaliks, though the retention of and/or secondary reversal to primitive character states in M. thachangensis makes it difficult to determine the phylogenetic relationships of the new species to the other Merycopotamus species. Although the provenance of other mammalian fossils from the Tha Chang area is problematic, our analyses have indicated that they can be sorted into three fossil assemblages of middle Miocene, late Miocene and early Pleistocene age. M. thachangensis is most likely late Miocene in age, possibly late late Miocene.