Antarctic Eocene selachians were reported from the La Meseta Formation of Seymour Island and from glacial erratics of Mount Discovery, Antarctica. Seymour Island has produced the most diverse Palaeogene selachian fauna of the Southern Hemisphere so far. Up to now, 23 selachian taxa (20 sharks, 2 rays) have been described from the Eocene of Antarctica. Recent geological and palaeontological investigations on Seymour Island yielded new selachian remains from Lutetian (middle Eocene) deposits. An upper tooth is referred to the requiem shark Carcharhinus and a rostral spine to the sawfish Pristis. These occurrences represent the first Eocene records of both groups in the Southern Hemisphere and extend their geographic distribution. In addition, a fragmentary stinging ray attributed to Myliobatoidea is presented for the first time from Antarctica. The diversity of Eocene La Meseta fishes is reflected.

The original description of the pectoral fin of the rhizodontid Barameda decipiens emphasized the narrowness of the fin, based on a narrow radius and low number of preserved lepidotrichia. Elements of the vertebral column were said to be most similar to the tristichopterid Eusthenopteron. A more complete description of the pectoral fin and vertebral column of Barameda, based on new silicone molds and X-rays, indicates that the fin is much wider than previously estimated and that the radius has a morphology more comparable to that of other rhizodontid taxa. Branching occurs both in the lepidotrichia of the distal fringe of the fin, and at the distal end of the more proximal elongate and unjointed basal elements. The latter branching may be restricted to Barameda and Gooloogongia among the Rhizodontida. Branching and jointing appear to be greater in the trailing edge of the fin, enhancing flexibility in this region. Newly described features of the humerus include the distal groove housing the entepicondylar foramen. The fin element previously identified as the ulnare is reinterpreted as a branchial element (hypobranchial) and a portion of the scapulocoracoid can be recognized. Ten rhachitomous intercentra are preserved, similar to those of Eusthenopteron in possessing well-developed parapophyses, but differing in the presence of these parapophyses on all preserved vertebrae, believed to represent the anterior vertebral column in Barameda.

A new actinopterygian, Roslerichthys riomafrensis gen. et sp. nov., is described from the Rio do Sul Formation (Early Permian) of Mafra, State of Santa Catarina, Brazil. This fusiform ray-finned fish is the smallest so far described for the “Lontras Shales.” R. riomafrensis, gen. et sp nov., is placed into the Amblypterus Group of Gardiner and Schaeffer. Discussion is also offered about the taphonomic processes that led to the exceptional preservation of the fossils of these shales.

Akromystax tilmachiton, gen. et sp. nov., is described from Late Cretaceous Cenomanian beds in the Lebanon. The new taxon is the first new pycnodont to be published from the recently discovered locality of en Nammoura. It is a member of the Pycnodontidae that presents an unexpected combination of primitive and derived characters, including autapomorphies such as: hypertrophy of the lateral laminae of the mesethmoid, covering the lateral portion of the ethmoidal region plus part of the lower jaw; extrascapular bone forming part of the border of the orbit; expansion of the premaxilla, which bears no less than eight molariform teeth arranged in at least two rows; opercular and preopercular bones separated from each other; unique pattern of scale ossification; overlapping of the spines of the ventral keel scales; first ventral keel scale markedly larger than other keel scales. A new type of replacement teeth is reported for the first time in a pycnodontiform fish. Akromystax tilmachiton is at present the most primitive taxon of the family Pycnodontidae, despite its relatively derived characters, and confirms the mosaic evolution of the pycnodonts. The new taxon is present in the localities of Haqel, Early Cenomanian, and en Nammoura, Middle Cenomanian. It is an interesting common element of both localities, indicating that their paleoichthyofaunas, contrary to previous thought, are more similar than other components of their fossil associations.

New rhizodontid pectoral girdle and fin material from Queensland, Australia (Middle Paddock site, Ducabrook Formation, Lower Carboniferous) includes cleithra, clavicles, anocleithra, scapulocoracoids, a humerus, an ulna, and a probable ulnare. The morphology of the humerus, including an enlarged pectoral process and a ball-shaped caput humeri, is comparable to humeri assigned to Strepsodus. This confirms the previous assignment of cleithra and clavicles from Middle Paddock to this genus and thus the presence of Strepsodus in eastern Gondwana. Based on examination of the new pectoral elements from the Ducabrook Formation, we provide new characters for an emended diagnosis of Strepsodus.

A new Middle Jurassic xinjiangchelyid turtle from China, Xinjiangchelys chowi sp. nov., is described from the Toutunhe Formation of the southern Junggar Basin, southwest of Urumchi (NW China). The material consists of a nearly complete carapace and the right hypoplastron. It shows important autapomorphies of the family Xinjiangchelyidae and the genus Xinjiangchelys: first neural larger than second, anterior peripherals guttered, posterior peripherals expanded, a reduced first thoracic rib, and lateral pegs of the bridge of the plastron. It is distinguished from all other species of Xinjiangchelys by the following autapomorphies: a first costal rib with free rib end, at least two anterolateral peripheral fontanelles of the carapace, a thin plastron with large lateral fontanelles, and a median hypoplastral suture with strong pegs. These features indicate that X. chowi is the most derived xinjiangchelyid turtle hitherto known. Together with X. tianshanensis, this is the oldest xinjiangchelyid turtle known so far. Therefore, a long ghost lineage must be claimed for the Xinjiangchelyidae.

Specimens referred to Osteopygis (Late Cretaceous-Paleocene, North America) represent a chimera, a polyphyletic mixture of taxa. The holotype of Osteopygis (AMNH 1485) and more complete referred postcranial specimens resemble non-marine stem cryptodires (“macrobaenids”). Because the skull material historically referred to Osteopygis shares synapomorphies with cheloniid sea turtles, all current workers accept Osteopygis as a stem-cheloniid sea turtle. Multiple lines of evidence combine to support the hypothesis that sea turtle cranial material is not attributable to Osteopygis. These lines of evidence include: phylogenetic hypotheses of character evolution, the tenuous historical attribution of specimens, and the taphonomy of the Hornerstown Formation. The name-bearing Osteopygis material and referred postcrania are best considered Eucryptodira incertae sedis (cf. “Macrobaenidae”). The cranial specimens formerly assigned to the Osteopyginae now are restricted to the clade Euclastes and those referred to Osteopygis emarginatus are here referred to Euclastes wielandi (comb. nov.). The ‘decapitation’ of Osteopygis reconciles morphological trends within stem cheloniids.

A crushed rauisuchian skull and several vertebrae belonging to a single individual have been found in the Upper Triassic strata at Krasiejów, Poland, probably corresponding in age to the Lehrberg Beds (late Carnian) of Baden-Württemberg, Germany. A maxilla of Teratosaurus suevicus from the early Norian (Stubensandstein at Heslach) is similar to that of the Krasiejów specimen. The dorsal process of the maxilla is more oblique than in T. suevicus, the medial anterior foramen is set on the medial side, contrary to being exposed anteriorly in T. suevicus, and foramina for replacement teeth are not connected by a dental groove and are set in straight line. A new species of Teratosaurus is proposed to accommodate the Polish material, and a more complete diagnosis of the genus is presented.

A well-preserved dentary from the Late Cretaceous of Neuquén Province, Argentina, represents a new taxon of sebecosuchian crocodyliform, Pehuenchesuchus enderi. The specimen retains a number of diagnostic characters and is referable to Sebecosuchia on the basis of two derived features (a longitudinal groove on the lateral surface of the dentary and a sigmoidal tooth row in dorsal view). The new taxon differs from all other sebecosuchians by possessing laterally compressed teeth that lack serrated carinae. A phylogenetic analysis of 30 crocodyliform taxa and two character-taxon matrices, which include many putative sebecosuchians, supports a monophyletic Sebecosuchia. In both analyses, Pehuenchesuchus enderi was resolved as the sister taxon to all other sebecosuchians. A clear division of Sebecosuchia into Sebecidae and Baurusuchidae was not supported.

Numerous megaloolithid eggs of Early Campanian age have been found in Auca Mahuevo in Argentina (Patagonia, Neuquén Province) with diagnostic skeletal embryonic remains in ovo allowing the identification of these eggs as those of titanosaurid dinosaurs. Although fossilization favors the preservation of the eggshell, organic compounds that are often destroyed are commonly recovered in these eggs.

A detailed description is provided of the 79.5—83.5 Ma-old membrana testacea found in great abundance and in situ in titanosaurid eggs. The fossilized membrana testacea is uniquely preserved and appears in two distinct morphs, each composed of two identifiable layers as observed in extant reptiles and birds. This membrane also shares great similarities with those previously reported occurrences in post-Jurassic dinosaurs. One morph displays a solid calcium carbonate layer with fine preservation of the negative imprints of shell unit nucleation centers each surrounded by coloration reminiscent of stratified microbial communities. The other still displays the mesh-like texture similar to the morphology protein membranes of extant reptiles.

Taphonomic factors that have affected the eggshell structures and the membrana testacea are here interpreted as microbial in origin. This interpretation is further supported by the presence within the voids of the membrane layer of micron-sized, rod-like calcium carbonate structures identical to those precipitated by bacteria in the formation of ooids, while calcium carbonate precipitation outside this membrane consists of characteristic abiotic rhombohedric crystals. The periodic pulse of sedimentation (obrution and stagnation) from overbanking paleorivers in Auca Mahuevo coupled with the presence of organic compounds inside the buried eggs may have produced conditions similar to those observed in conservation Lagerstätten, thus invoking a Lagerstätte status for Auca Mahuevo. Furthermore, the patterns resulting from biomediation observed at this site might serve as a template for investigating other soft-tissue preservation in the fossil record.

The type material of the small theropod dinosaurs Tugulusaurus faciles and Phaedrolosaurus ilikensis from the Lower Cretaceous (?Valanginian–Albian) Lianmugin Formation of Xinjiang, north-western China, is reviewed. Although based on an incomplete and rather poorly preserved specimen, Tugulusaurus can be shown to be valid on the basis of strongly broadened caudal vertebrae with an anteriorly placed neural arch and a short and highly asymmetrical metacarpal I. Phaedrolosaurus, based on an isolated tooth, must be considered a nomen dubium. A partial hind limb originally referred to this taxon can be demonstrated to be a distinct taxon of theropod on the basis of a posteriorly expanded fibular condyle on the proximal tibia and a longitudinal groove on the anterior side of the proximal end of the fibula. It is made the type of a new taxon, Xinjiangovenator parvus gen. et sp. nov. Whereas Tugulusaurus is the most basal coelurosaur known, Xinjiangovenator represents a maniraptoran.

The discovery of a new genus and species of tyrannosauroid from the Demopolis Formation (middle Campanian) of Alabama increases the known diversity of the clade, although it does not elucidate the place of initial dispersal. This subadult tyrannosauroid is the most complete non-avian theropod collected and described from the Cretaceous of eastern North America. In contrast to tyrannosaurids, the new taxon possesses several plesiomorphic characters, including lacrimals that lack a distinct peaked cornual process, and a dorsoventrally shallow horizontal ramus of the maxilla. Autapomorphies include a wide jugal process of the ectopterygoid, a caudal pneumatic foramen of the palatine that pierces the rostral half of the vomeropterygoid process of the bone, an articular surface for the lacrimal on the palatine that is distally positioned on the dorsolateral process, and pedal unguals that have a distinct proximodorsal lip over the articular surface. Cladistic analysis indicates the new taxon is a basal tyrannosauroid and its presence in eastern North America suggests that the recent common ancestor of Tyrannosauridae probably evolved following the transgression of the Western Interior Seaway. Cladistic analysis indicates that Dryptosaurus aquilunguis is also a basal tyrannosauroid but is less derived than the new genus.

The cranium of the hadrosaurid dinosaur Brachylophosaurus canadensis is redescribed on the basis of abundant and complete material from the Lower Campanian Judith River Formation of Malta, northeastern Montana. The diagnosis of this taxon is emended, and the species Brachylophosaurus goodwini is now considered to be a junior synonym of Brachylophosaurus canadensis. Autapomorphies of Brachylophosaurus are: nasal greatly developed into paddle-like solid crest extending caudodorsally, overhanging dorsal region of skull; nasal possessing anteroposteriorly oriented groove terminating in elongated foramen located medial to prefrontal; prefrontal projecting posteriorly and resting dorsomedially over anterior process of postorbital and, more posteriorly, extending ventromedially under nasal; only anterior sharp tip of lacrimal contacting maxilla; jugal with ventrally projecting semicircular flange; extremely elongated, rod-like anterodorsal process of maxilla projecting medial to narial cavity along most of anteroposterior length of external naris; anteroposteriorly short exoccipital-supraoccipital roof posterior and dorsal to foramen magnum.

Most autapomorphies of the junior synonym species Brachylophosaurus goodwini originated from misplacement of a nasal fragment and individual variation of the jugal. The new osteological information supports Brachylophosaurus canadensis as the sister taxon to Maiasaura peeblesorum, and suggests that the two taxa form a robust and basal clade within the Hadrosaurinae. Two new characters are discussed as phylogenetically informative for hadrosaurids: the mediolateral and anteroposterior predentary proportions and the length of the prequadratic process of the squamosal.

A new taxon of the Prophaethontidae (Aves) is described from the phosphatic beds of the Ouled Abdoun Basin, Morocco. Lithoptila abdounensis gen. et sp. nov. is represented by a single, well-preserved neurocranium, dated as upper Paleocene (Thanetian) on the basis of the selachians identified in the matrix. This specimen is the oldest known African neornithine bird and the oldest record of the Prophaethontidae. It bears some striking resemblance to Prophaethon shrubsolei Andrews, 1899, from the lower Eocene (Ypresian) London Clay of the Isle of Sheppey, England. Aside from general proportions of the neurocranium, this new taxon differs from Prophaethon shrubsolei in many respects, such as the shape and position of the crista temporalis, impressio glandulae nasalis, surface of contact with the os lacrimale, and tuberculum basilare. This justifies its assignment to a new genus and species. A cladistic analysis of 47 osteological characters supports the monophyly of the Prophaethontidae and a sister-group relationship between the Prophaethontidae and Phaethontidae. The Pelecaniformes are polyphyletic, and the clade comprising the Phaethontidae and Prophaethontidae is the sister-group of the Procellariiformes.

Choristoderan material from a microvertebrate horizon in the Czech Republic extends the history of the group into the early-middle Miocene. On cranial and vertebral morphology, the new Czech material most closely resembles Lazarussuchus inexpectatus from the Upper Oligocene of France. The morphological similarity supports attribution of the Czech material to the genus Lazarussuchus, but the combination of a smaller and more rounded upper temporal fenestra and the absence of accessory articular facets on the vertebrae distinguish the Czech form from the type species. The articulated skull of L. inexpectatus, re-examined for this study, and the disarticulated material of L. dvoraki sp. nov. complement each other, and permit a better understanding of skull morphology in this enigmatic genus. They demonstrate clearly that the lower temporal fenestra in Lazarussuchus was secondarily closed by apposition of the squamosal, jugal, quadratojugal, and postorbitofrontal.

Lizard remains are described from the late Quaternary Camping Americano locality, situated about 5 km south-southwest of Monte Hermoso (38°57′47″ S, 61°22′48″ W) in Buenos Aires province, Argentina. Remains consist of 40 dentary fragments, 15 partial maxillae, and one vertebra. Two liolemids (Liolaemus multimaculatus and Liolaemus darwinii), one gekkonid (Homonota sp.), and one teiid (Cnemidophorus sp.) are recognized. Only the first two species live in the Camping Americano area at present. Divergence of the Liolaemus multimaculatus group might have taken place during development of the late Quaternary Pampean Aeolian System. Climate change in the southern Pampean Region during the last several thousand years might explain the disappearance of gekkonid and teiid taxa from the Camping Americano area.

The Burgersdorp Formation in the Beaufort Group of the South African Karoo Basin records a diverse and rich vertebrate fauna that is referred biostratigraphically to the Cynognathus Assemblage Zone. Recent collecting efforts, and taxonomic and biostratigraphic studies on this formation, resulted in a proposed subdivision of the Cynognathus Assemblage Zone into three subzones informally known as A, B, and C. Cynodont fossils constitute an important component of the fauna of the uppermost subzone C of the Cynognathus Assemblage Zone. As in the middle subzone B, cynognathids, diademodontids, and trirachodontids are represented in subzone C, although the latter group–instead of Diademodon–is the dominant taxon. The presence of Cynognathus in the faunas of the three subzones confirms that this genus is the correct choice as the index taxon of the assemblage zone. The large size attained by trirachodontid specimens from subzone C represents an unusual characteristic. One complete skull measured 160 mm in length, although fragmentary remains of other specimens indicate even larger sizes. These skull lengths are well above the 100 mm that characterize trirachodontids recovered from the older subzones A and B. The large size, and particularly the ovoid overall pattern of the upper gomphodont postcanines allows the assignment of the trirachodontid specimens from subzone C to Cricodon metabolus, previously known from the Manda Formation in Tanzania. The Cynognathus Assemblage Zone of South Africa is shown to be the most temporally complete Early-Middle Triassic nonmarine sequence in southern Gondwana, and is the template against which other sequences of similar age may be compared.

A mammalian upper molariform tooth recovered from the Late Triassic (Carnian) Tiki Formation of the South Rewa Gondwana Basin, India, is described as a new taxon, Tikitherium copei, gen. et sp. nov. Coming from such an ancient horizon, the tooth is remarkable in having on its crown, which is supported by three roots, three buccally placed cusps forming an obtuse triangle, another prominent cusp with two associated shearing crests in the posterolingual corner, and a talon-like depression anterior to the latter. The molar with its several derived features, though showing partial similarity with those of some seemingly allied early mammalian dentitions, stands apart as a distinctly different entity in detailed comparison. Through close examination of the Tikitherium upper molar, its probable occlusal relationship with the unknown lower dentition is suggested. The posterolingual cusp with its two shearing crests and basin, appearing as a significant apomorphy, probably indicates the development of a better mode of mastication by grinding. The molar of Tikitherium copei, may thus be regarded as the earliest representative of several independent evolutionary developments of the grinding mechanism found in later mammalian groups such as the boreosphenidans, australosphenidans, shuotheriids, and docodonts.

Species of the early Paleocene (Puercan North American Land Mammal Age) triisodontid Eoconodon were among the first eutherians in the northern Western Interior to evolve body masses significantly larger than those of the latest Cretaceous mammals of the area. Description of additional specimens of Eoconodon nidhoggi from the Tullock Formation, northeastern Montana, sets the stage for formal diagnosis of a new species of Eoconodon, E. ginibitohia sp. nov., in the Betonnie-Tsosie local fauna, Puercan 2, Hemithlaeus kowalevskianu–Taeniolabis taoensis Zone, San Juan Basin, New Mexico. The taxonomic diversity of the species of Eoconodon as well as their stratigraphic and biogeographic ranges support the hypothesis that the first representatives of the clade entered the Western Interior at the beginning of the Puercan as immigrants from currently poorly sampled areas probably in North America or Asia. During the Puercan the clade both diversified and expanded its biogeographic range in the Western Interior.

Except for the few specimens previously reported from the late middle Eocene of North Africa (Algeria) and more recently from South Asia (Myanmar), the fossil record of anomaluroid rodents is relatively scarce for the Paleogene Period. In this paper, we describe new material, notably a skull, of the anomaluroid taxon Pondaungimys anomaluropsis Dawson et al., 2003, recently described from the latest middle Eocene Pondaung Formation in Central Myanmar (South Asia). Pondaungimys shows a dental pattern very similar to that of Nementchamys, an anomaluroid rodent previously reported from roughly coeval deposits in Algeria. Although Nementchamys and Pondaungimys have a dental pattern relatively more primitive in some respects than that of Miocene and modern anomalurids, in other respects they show a derived dental complexity that leads us to consider both taxa as the closest outgroups of the Anomaluridae sensu stricto (the true scaly-tailed flying squirrels) within the Anomaluroidea. Pondaungimys clearly demonstrates that the evolutionary history of the anomaluroid rodents is not limited to Africa. The widespread South Asian-North African distribution of the late middle Eocene forms strongly suggests that faunal exchanges between Africa and Asia took place during the Paleogene, a statement supported by other mammalian groups.

A new species of squirrel, Sciurus olsoni, from the late Miocene (Clarendonian) of Nevada, is distinguished from other species of Sciurus by its smaller size and minor differences in the cheek teeth. It is the first Miocene record of the extant genus Sciurus, and the first record of a tree squirrel (tribe Sciurini) in North America between the early Miocene (Arikareean) and the Pleistocene. This late Miocene occurrence in North America suggests that the history of tree squirrels in North America was probably continuous through the Neogene, and the intermittent fossil record is due both to preservation bias and to their never having been abundant as living elements of fossil faunas; they are rare even where they do occur in deposits that are otherwise very richly fossiliferous. The later Tertiary and Pleistocene radiation of tree squirrels may have originated in North America.