Pycnodonts are a well-known group of neopterygian fossil fishes with an age range from the Late Triassic to the Eocene. In the present work a new genus, Potiguara, is described to acommodate the species from the Potiguar Basin (northeast Brazil) originally described as Coelodus rosadoi and provisonally placed in the genus Ocloedus. Potiguara clearly belongs to the family Pycnodontidae and can be distinguished from Ocloedus by the absence of spines on the dorsal scales, the number of hypochordal elements in the caudal skeleton, and the number of radials in the dorsal and anal fins. The cladistic analysis supports the exclusion of this species from the genus Ocloedus and consequently the creation of the new genus Potiguara.

A size series of 143 specimens of the Permo-Carboniferous temnospondyl Archegosaurus decheni from the Saar-Nahe Basin (south-west Germany), ranging in size from 18 to 280 mm skull length, can be interpreted as an extensive growth series. This study focuses on the reconstruction of ossification sequences and developmental patterns of skull, visceral skeleton, and postcranium in A. decheni. With respect to the dermal skull, the ossification of the postcranium is delayed. The basibranchial starts to ossify after formation of the dermal pectoral girdle, sclerotic ring, stapes, scales, and scapulocoracoid. Initial ossification of the ischium takes place distinctly later than that of the ilium, and the pubis remains entirely cartilaginous. Vertebral centra ossify late, after formation of the ischium. Branchial dentition is resorbed at a skull length of 150 mm, indicating a long larval phase. Carpals and tarsals start to ossify only in the largest individuals. Archegosaurus decheni exhibits no period of obvious metamorphosis, as indicated by the dissociation of developmental events during ontogeny. The delayed formation of scales, scapulocoracoid, and basibranchial, in comparison with the Permo-Carboniferous temnospondyls Sclerocephalus and Onchiodon, may be correlated with the secondary aquatic adaptation of A. decheni throughout its life history. The chronology of ossification of the endocranial elements can be reconstructed. The exoccipital ossifies first, followed by the quadrate, basioccipital, basisphenoid, sphenethmoid, and otic capsule. Comparison with other anamniotic tetrapods shows that the early ossification of the exoccipital and quadrate is a stable pattern, and that there is a tendency to eliminate ossification of the basioccipital and basisphenoid.

We describe the edopoid temnospondyl Nigerpeton ricqlesi from the Upper Permian Moradi Formation of northern Niger on the basis of two partial skulls and tentatively associated postcranial material. This crocodile-like taxon displays several edopoid characters states such as a long prenarial region with enlarged premaxillae, elongated vomers, large, posteriorly tapering choanae, and a jugal that broadens anteriorly. Nigerpeton possesses a unique carnivo rous dentition. It is autapomorphic in its possession of an extremely elongate snout bearing a maxillary bulge that accommodates three hypertrophied caniniform teeth, inner premaxillary tusks, and anterior paired fenestrae, which pierce the skull roof. In addition, both the maxilla and dentary tooth rows show the sporadic appearance of ‘doubled’ tooth positions. The lateral-line system is present at the adult stage, which suggests an aquatic habitat for this taxon. A phylogenetic analysis of Edopoidea and its relatives places Nigerpeton as the sister taxon to the Permo-Carboniferous genus Chenoprosopus from the U.S.A. As with other members of the Moradi tetrapod fauna, the discovery of Nigerpeton strengthens support for the hypothesis that West Africa hosted an endemic fauna at the close of the Paleozoic Era. Biogeographically, we propose that Late Carboniferous and Permian edopoids were geographically widespread and that they twice crossed the Central Pangean mountain chain (between Laurussia and Gondwana) during their evolution. This distribution was later fragmented with the onset of Late Permian climatic warming.

Recent finds of small temnospondyls from the Lower Keuper (Ladinian, Middle Triassic) of southern Germany are referred to a new trematosaurid genus and species, Trematolestes hagdorni. It is the first trematosaurid represented by a nearly complete skeleton. Trematolestes is characterized by an unpaired frontal and a minute lacrimal at the orbital rim wedged in between an extensive prefrontal and a wide maxilla. Further characteristic are keeled, laterally compressed palatal tusks, a strong palatine and ectopterygoid dentition, and minute maxillary and posterior dentary teeth. In the visceral skeleton, ceratobranchial parts of the hyobranchial skeleton and an unpaired basibranchial element are ossified. The ribs bear pronounced spine-like uncinate processes throughout the trunk and anterior tail skeleton. The forelimb is minute, with a strongly abbreviated humerus not exceeding the length of the lower arm, rudimentary radius and ulna, and a small, probably four-fingered hand skeleton. Unlike the situation in capitosauroids, the trunk was deep with an elongated recurved ilium and a highly modified sacral rib. The trunk is composed of 22 vertebrae, while the caudal vertebral count is at least 24, but probably exceeded 30. Phylogenetic analysis suggests that Trematolestes is closely related to the Madagascan genus Tertremoides and together they are nested with the rostrum-bearing slender-headed lonchorhynchines.

Because many fossil pipoid anurans have been described during the past 35 years from Cretaceous deposits in South America and Africa, it is appropriate to revisit some of the earlier ones to have been discovered, viz., Cordicephalus gracilis, C. longicostatus, and Thoraciliacus rostriceps from Israel. Careful examination of Cordicephalus, based on study of previously, as well as newly, prepared specimens, reveals the existence of only one species. Cordicephalus gracilis is redescribed and compared with Thoraciliacus, and the phylogenetic relationships of these genera to other living and fossil pipoid frogs are investigated in a parsimony analysis. Thoraciliacus is basal to a clade containing Cordicephalus, Palaeobatrachus, and all other living and fossil pipids; however, the placement of Cordicephalus with respect to Palaeobatrachus and Pipidae is unresolved. Both Thoraciliacus and Cordicephalus retain the primitive state for several pipid synapomorphies involving the condition of the vomers, parasphenoid, and presence of a tympanosquamosal bone. In contrast to Thoraciliacus, however, Cordicephalus is characterized by several derived characters including possession of an otic capsule modified to accommodate a Eustachian tube and depressed, fully ossified opisthocoelous vertebrae. Despite their lack of many pipid specializations, both Thoraciliaus and Cordicephalus seem to possess many morphological features that typically are associated with aquatic habits. Among these are possession of a flat skull with a short rostrum, short axial column, and relatively long metapodials.

We describe the new ichthyosaur taxon Mixosaurus panxianensis, sp. nov., from the Middle Triassic of Guizhou Province, China. Diagnostic characters of the new species include a short posteroventral jugal process and the absence of external contact between jugal and quadratojugal. The morphologic description of the type specimens amends the knowledge of the postorbital region and the postcranium of the Mixosauridae. The holotype of Mixosaurus maotaiensis, which is very fragmentary and has no taxonomic value at the species level, is found to be undiagnostic, and hence the lately introduced, monospecific genus name for this species needs to be abandoned. Phylogenetic analysis strongly supports the monophyly of the family Mixosauridae. Furthermore, the analysis shows a bifurcation of the family into two sister groups, suggesting the presence of two genera, Mixosaurus and Phalarodon. Mixosaurus, characterized by a relatively short and wide humerus, includes M. panxianensis sp. nov., M. cornalianus, and M. kuhnschnyderi. Synapomorphies of Phalarodon, which contains P. fraasi, P. callawayi, and P. atavus, are a narial shelf and the absence of a maxillary dental groove.

Istiodactylus sinensis, sp. nov., from the Jiufotang Formation of Liaoning, People's Republic of China, is described on the basis of a single nearly complete and nearly osteologically adult specimen. This is the tenth pterosaur described from this formation and the eighteenth pterosaur species described from northeastern China in almost half as many years. The species is placed in the Istiodactylidae, which was previously a monospecific family of pterodactyloid pterosaurs known only from the Isle of Wight, England. The new form is distinct from the two other istiodactylid species. It is smaller, more plesiomorphic, and younger than Istiodactylus latidens, but larger and more derived than the contemporaneous Nurhachius ignaciobritoi. Istiodactylus sinensis is very similar to I. latidens, so that almost all of the previous autapomorphies of I. latidens are now synapomorphies of Istiodactylus. They differ most in that I. sinensis is much smaller than I. latidens. The length of the wingspan, skull, and most of the preserved limb elements of I. sinensis are about 63 percent of the wingspan and elements of I. latidens. This new specimen demonstrates that Istiodactylus is diagnosed by, among other characters, a dorsoventrally depressed but not laterally expanded rostrum, and the presence of a suborbital vacuity. A dorsal deflection of the alveolar margins of the jaws and a humerus between 55 percent and one and a half times the length of metacarpal IV are synapomorphies uniting the Istiodactylidae and the Anhangueridae.

The braincase of the rauisuchian pseudosuchian archosaur Arizonasaurus babbitti, from the Middle Triassic of the western United States, is described from two specimens. There are no obvious braincase autapomorphies and most of the other braincase features of A. babbitti are plesiomorphic for pseudosuchians/crurotarsans. The results of phylogenetic analyses of archosaurian braincase characters indicate that A. babbitti is not especially closely related to other rauisuchians for which braincase anatomy is known (Batrachotomus kupferzellensis, Saurosuchus galilei, Postosuchus kirkpatricki, Tikisuchus romeri). Given that A. babbitti is a member of a clade that includes Poposaurus and chatterjeeids to the exclusion of most other rauisuchians, braincase data suggest that Rauisuchia are not monophyletic. This is in accordance with a recent appraisal of non-braincase data but, in contrast, our analyses suggest that Poposaurus and its closest allies are more distantly related to Crocodylomorpha than are other rauisuchians.

Cranial elements of Suuwassea emilieae (Sauropoda: Diplodocoidea) from the Upper Jurassic Morrison Formation of Montana, U.S.A., represent one of only a few flagellicaudatan skulls known. Preserved elements include a left premaxilla, a fragment of right maxilla, a right squamosal, a right quadrate, a basicranium and skull roof lacking only the rostral end of the frontals, basipterygoid processes, and parasphenoid rostrum. Autapomorphic features of the skull include: premaxillary teeth projecting parallel to long axis of premaxilla; single optic nerve foramen; postparietal foramen present and larger than parietal foramen; supraoccipital with elongate ventral process contributing little to dorsal margin of foramen magnum; basioccipital not contributing to floor of median condylar incisure; and antotic processes with no dorsal contact with frontals. The basicranium more closely resembles that of Apatosaurus rather than Diplodocus and is also unlike the skull of Dicraeosaurus, despite its possession of a similar postparietal foramen, a feature unique among Morrison Formation sauropods. Pending reanalysis of Tornieria africana, which also possesses it, the postparietal foramen must be viewed as a symplesiomorphic retention in the Dicraeosauridae, with its loss a synapomorphy of the Diplodocidae, or at least of the North American members of the latter clade.

The discovery of the smallest Triceratops skull (UCMP 154452) provides a new ontogenetic end member for the earliest stage of ceratopsid (Centrosaurinae plus Chasmosaurinae) cranial development. The lack of co-ossification among the parietal, squamosals, postorbitals, quadratojugal arch, and the braincase preserves sutural contacts and bone surfaces that later become obscured in adults. The ability to document the early development and morphology of the horns and frill in Triceratops allows a reevaluation of their functional roles. UCMP 154452 shows that the cranial ornamentation of the frill and the postorbital horns were not restricted to adults, but began at an early age in this species. This evidence supports the hypothesis that the function of ceratopsid horns and frills was potentially important for visual communication and species recognition because in this young form it could not have functioned in sexual display. Although some features of UCMP 154452 anticipate or mimic the adult character states, some braincase characters recapitulate the juvenile and adult stages of more basal neoceratopsians.

A new fossil anguimorph from the Green River Formation of Wyoming represents the first fossil relative of the living Chinese crocodile lizard, Shinisaurus crocodilurus. Its discovery significantly shortens the missing lineage interval and greatly expands the geographic range of the group, previously known only from southern China and northern Vietnam. Although separated by great temporal and physical (geographic) expanses, the new taxon and Shinisaurus show extraordinary morphological similarity. These include characteristics that might otherwise be considered autapomorphies for Shinisaurus, such as a prefrontal contribution to the naris and a subpalpebral fossa. Re-analysis of anguimorph interrelationships yields the hypothesis that Shinisaurus and its ancient cousin represent a basal radiation of Platynota.

The European-Asian taxon Placosaurus is a distinct glyptosaurine lizard that differs from the North American glyptosaurine genera Glyptosaurus, Helodermoides, Paraglyptosaurus, and Proglyptosaurus. Presently, species of Placosaurus can only be discriminated based on frontal morphology. Three species are recognized: Placosaurus rugosus Gervais, 1848–1952, Placosaurus estesi, sp. nov., and Placosaurus mongoliensis, all based on frontal material. Although the Asian species P. mongoliensis is retained in the genus Placosaurus, we consider this taxonomic assignment tentative. The species P. cayluxi, P. galliae, P. gaudryi, and P. margariticeps are considered nomina dubia. “Placosaurus” europaeus, based on a dentary with teeth, is tentatively retained in the genus Placosaurus but this generic assignment is equivocal. The species “P.” quercyi pertains to a new ‘melanosaurin’ and not to Placosaurus.

Paraplacosauriops, gen. nov., is a ‘melanosaurin’ glyptosaurine lizard based on two isolated, nearly complete maxillae from the middle Eocene of France. Paraplacosauriops is known by one species, Paraplacosaurus quercyi (Filhol), a species previously included in the glyptosaurin genus Placosaurus. The taxon Paraplacosauriops quercyi is characterized by an unique heterodont dentition, consisting of large, crushing teeth in both the maxilla and neotype dentary. The dentary is further distinguished by a well-developed intramandibular septum fused to the ventral margin of the Meckelian canal. Paraplacosauriops is known with certainty from the middle Eocene (Lavergne, Phosphorites du Quercy). Fragmentary specimens from the early Eocene (Dormaal, Belgium) are provisionally referred to this taxon. The species Xestops abderhaldeni and X. weigelti are not referable to the genus Xestops and are formally synonymized with each other as Placosauriops weigelti.

The dental attachment site histology and gross morphology of Dinilysia patagonica, a Cretaceous terrestrial snake, is examined in a thin section through the tissue-filled mesial-distal region between tooth positions of a left maxilla, and other partial tooth-bearing bones with teeth. We observed compact zonal bone and cancellous bone forming the maxilla, and alveolar bone (a woven-fibered bone) lining the tooth socket and filling the region between tooth positions. The discovery of alveolar bone in D. patagonica is significant because alveolar bone was found previously in only one other group of squamates, mosasaurs (extinct large marine lizards), and other amniotes with a thecodont tooth-attachment anatomy (archosaurs, mammals). The presence of alveolar bone in D. patagonica, associated with the recent finding of alveolar bone and other tissues associated with thecodonty (alveolar bone, cement, periodontal ligament) in mosasaurs, suggest that these tissues might be broadly distributed among squamates. Dinilysia patagonica is inferred to have a hinged tooth-attachment type, based on the tooth socket morphology and relationship between preserved teeth and the tooth-bearing bone.

A partial postcranial skeleton from the late Eocene of the Shara Murun region of northern China is described as a new genus and species of fossil pangolin, Cryptomanis gobiensis. Cryptomanis displays numerous diagnostic pangolin characteristics, including enrolled lumbar zygapophyses and fissured ungual phalanges. Like the anatomically similar North American Eocene pangolin Patriomanis, it retains primitive mammalian features such as a convex astragalar head and a prominent femoral third trochanter that are lost in extant pangolins. The systematic position of Cryptomanis within Pholidota is not unambiguously resolved. It is tentatively placed in the family Patriomanidae, which we restrict to Cryptomanis and the closely similar Patriomanis. Cryptomanis differs from modern pangolins in its more robust proximal limb elements, its lack of a greatly enlarged third manual digit, its slender tail, and its more elongate, grasping pedal digits. These traits suggest an animal well adapted for digging but with a tendency toward a semi-arboreal lifestyle. This new genus and species represents the oldest and most northerly Asian record of pangolins, and indicates that pangolins were widely distributed throughout Laurasia during the Eocene. It is consistent with a Laurasian origin for pangolins.

An internal mandibular fenestra and chamber are found in many fossil hyracoids. The internal mandibular fenestra is located on the lingual surface of the mandibular corpus and opens into a chamber within the mandible. The mandibular chamber is maximally developed in late Eocene Thyrohyrax meyeri and early Oligocene Thyrohyrax domorictus from the Fayum Province of Egypt. The function of this chamber is unknown as it is not found in extant hyraxes, nor is it known to occur in any other mammal. In Thyrohyrax, this feature appears to be sexually dimorphic because it is confined to roughly one half of the specimens that otherwise cannot be separated by dental characteristics or measurements. It has been suggested that the chamber is found in females based on the presumed distribution of this character in other fossil hyracoids.

Fossils from Fayum Quarry L-41, preserving the sexually dimorphic anterior dentition, show that, in Thyrohyrax meyeri and Thyrohyrax domorictus, the internal mandibular chamber is found in males. In Thyrohyrax litholagus, an internal mandibular fenestra and inflated mandibular chamber occurs in males whereas females show the variable presence of an internal mandibular fossa or fenestra but lack an expanded chamber. Other genera show differing patterns of sexual variation in which some Fayum hyracoids have an internal mandibular fenestra in both sexes but with the greatest development of the mandibular chamber occurring in males. We review functions proposed for the internal mandibular chamber and suggest that it housed a laryngeal air sac that may have had a vocal function by acting as a resonating chamber.

Early Miocene zapodids from Saudi Arabia are represented by two closely related species: Arabosminthus quadratus and Arabosminthus isabellae sp. nov. The new taxon differs from the other species of Asiatic zapodids in lacking the anteroconid on m1. A cladistic analysis involving species of Arabosminthus, Heterosminthus, Parasminthus, and Shamosminthus provides evidence that “Heterosminthus” gansus, and perhaps “Gobiosminthus” qiui, and “Parasminthus” huangshuiensis should be reallocated to Arabosminthus. This genus appears to represent an important clade of zapodid rodents basal to Parasminthus spp. Heterosminthus spp.

Three partial skulls of odontocetes from the Miocene of Antwerp and Kessel, northern Belgium (southern North Sea Basin) are described here as a new genus and species of beaked whale (Ziphiidae), Archaeoziphius microglenoideus. This small new whale is one of the most archaic beaked whales, because of its low vertex, thin and laterally directed premaxillary crests, low contact between the supraoccipital and the frontals on the vertex, and its free atlas. It is also characterized by the strong transverse compression of the frontals on the vertex and a reduced glenoid surface on the squamosal; the two last characters might be considered as derived. Nasals wider than the frontals on the vertex might group A. microglenoideus with the extant larger genera Berardius and Tasmacetus; the nodular frontals and the premaxillary crests are more similar to the condition in Berardius. A sediment sample from the cetacean-bearing strata at Kessel is dated with dinoflagellate cysts as middle Miocene, tentatively late Langhian to early Serravallian, i.e., from ca. 15 Ma to ca. 13.2 Ma. Archaeoziphius microglenoideus is therefore the oldest reported beaked whale known by cranial material.