There is little consistency in the notation and orientation terminology used in discussions of non-mammalian fossil vertebrate dentitions. The standardization of this terminology, as done in the medical and dental sciences, would facilitate all future research on fossil teeth. For mammals, we recommend following convention, where incisors, canines, premolars, and molars are abbreviated as In, Cn, Pn, and Mn (n = tooth number) in upper jaws and as in, cn, pn, and mn in lower jaws. Right, left, and deciduous teeth are indicated by R, L, and D (e.g., DP4, Rp2). For non-mammals, which can have dentigerous premaxillae, maxillae, and dentaries, as well as additional tooth-bearing bones (e.g., vomers, palatines, pterygoids, ectopterygoids, sphenoids, splenials, and even parasphenoids), we encourage identifying teeth using the bone abbreviation (e.g., pmn, mxn, dn, vn, paln). A number and slash (/) combination can be used to distinguish between multiple tooth rows (e.g., Pal1/n, Pal2/n), and specimen-specific maps can be created for very complicated dentitions. We suggest the use of the terms mesial and distal to designate tooth surfaces and directions facing toward and away from the mandibular symphysis. Labial is offered for those surfaces and directions facing the lips or cheeks and lingual for those facing the tongue. We offer the terms basal for the direction toward crown bases, apical for the direction toward crown tips, occlusal for views of the occlusal surfaces, and basal and root apical for views of crown bases and roots, respectively.

A new primitive brachythoracid arthrodire, Uralosteus bashkiricus gen. et sp. nov., is described from two Emsian (late Early Devonian) localities in the Ural Mountains of the Autonomous Republic of Bashkortostan, Russia. The holotype includes bones of the skull and trunk armor associated with numerous scales from one individual, which facilitates the study of isolated microremains. The dermal ornament of distinctive tuberculate ridges suggests a relationship to Errolosteus Young, 1981 from the Emsian of southeastern Australia, but neither form is well enough known for this to be strongly supported in a character analysis. Some isolated placoderm bones with ridged ornament from southeastern Australia are figured, and interpreted to belong to a new form of williamsaspid rather than to Errolosteus. The new genus Uralosteus is referred to the family Buchanosteidae, defined by a unique overlap arrangement of the posterior lateral onto the anterior dorsolateral plate of the trunk armor. Buchanosteids, as a basal brachythoracid group, are a key to understanding the phylogeny of that clade. The type genus Buchanosteus comes from southeastern Australia, but it is now evident that the family was widely distributed in shallow marine environments during the Emsian.

New genera of characoid fossil fishes are described on the basis of remains from the Maastrichtian El Molino Formation and the early late Paleocene Santa Lucía Formation of Bolivia, and the Mio-Pliocene Solimões Formation of Brazil. Comparisons with the Hepsetidae, Erythrinidae, Ctenoluciidae, Acestrorhynchidae, and the characid Hydrocynus allow the following conclusions to be made: the new Bolivian genus lacks some erythrinid synapomorphies but shows notable resemblance to the Acestrorhynchidae, particularly in the pattern of the replacement teeth. The Brazilian genus is included in the erythrinids.

A new species of Lepidotes is described on the basis of two nearly complete specimens from the ?Albian Romualdo Member of the Santana Formation, in the Araripe Basin, northeast Brazil. The new species differs from the other species of Lepidotes previously recorded in western Gondwanaland by the apomorphic presence of an axe-shaped hyomandibula, and by a unique combination of other characters. This is the first record of an articulated Lepidotes from the Santana Formation of the Araripe Basin.

Two new mastodonsaurid temnospondyls are described from the Early to Middle Triassic Cynognathus Assemblage Zone of the Upper Beaufort Group (Karoo Basin) of South Africa. Paracyclotosaurus morganorum, sp. nov. is based on a partial skull from the uppermost part of the Cynognathus Assemblage Zone (Subzone C; late Anisian) in the southern Karoo Basin, and is the first occurrence of the genus Paracyclotosaurus outside of India and Australia. Jammerbergia formops, gen. et sp. nov. is based on a partial skull, presumably from Subzone B (early Anisian) of the Cynognathus Assemblage Zone, and is distinctive in its unique suite of primitive and derived characters. Although the intrarelationships of mastodonsaurids remain largely unresolved, the two most recent analyses are similar in the identification of an ‘advanced’ mastodonsaurid clade whose members are characterized by laterally directed tabular horns. Jammerbergia probably belongs within this clade, albeit within a basal position. Jammerbergia and Paracyclotosaurus share the synapomorphy of large, antero-posteriorly expanded tabulars, and may represent sister taxa. The Cynognathus Assemblage Zone is characterized by three subzones of differing ages and faunas, with no overlap in the temnospondyls between the subzones.

A new brachyopid temnospondyl is described from the Early to Middle Triassic Cynognathus Assemblage Zone of the upper Beaufort Group, Karoo Basin of South Africa. Vanastega plurimidens, gen. et sp. nov. is the third brachyopid taxon from the South African Karoo and is distinguished from all other brachyopids mainly through a combination of primitive and derived character states. The position of the nostrils exceptionally close to and anteriorly confluent with the skull margin represents the single known autapomorphy of V. plurimidens. Incorporation of V. plurimidens into a data matrix modified from a recent PAUP-based study of brachyopoids produces a phylogeny in which V. plurimidens is the sister species to Vigilius wellesi from the Anisian of North America. In addition, the Brachyopoidea appear to be phylogenetically closer to the Dvinosauria than to other Triassic temnospondyls, with weak support for the alternative hypothesis, which places the Brachyopoidea closer to typical Triassic stereospondyls. This suggests that brachyopids are derived dvinosaurians, in agreement with earlier hypotheses of brachyopoid interrelationships. Stratigraphic calibration of this phylogeny reveals significant ghost lineages primarily within the Brachyopidae and Chigutisauridae, but also suggests a ghost lineage for the Brachyopoidea back into the Late Permian of southern Africa.

Pseudophlegethontia turnbullorum, new genus and species, is the third distinct aïstopod known from the Pennsylvanian of Mazon Creek, Illinois. It is morphologically intermediate between the derived phlegethontiids and the more basal, but equally unusual, “ophiderpetontids,” making it crucial to understanding the anatomy of both groups and inferring possible developmental mechanisms leading to the phlegethontiid condition. Like “ophiderpetontids,” Pseudophlegethontia possesses a relatively short body (140 vertebrae), “k-shaped” ribs extending far back on the vertebral column, distinct skull-roof bones, and a temporal opening without a lower temporal bar. However, it has a pointed snout, quadrate condyles well anterior to the occiput, an epipterygoid that rises high on the lateral surface of the braincase, thin gastralia, and no dorsal osteoderms, all of which are phlegethontiid characters. Uniquely, Pseudophlegethontia has an extremely anteroposteriorly elongate quadrate, and an extended postparietal region. Preliminary phylogenetic analysis places it as sister taxon to Phlegethontia, with Oestocephalus, Ophiderpeton, and Lethiscus placed successively basally.

A new elasmosaur, Terminonatator ponteixensis, gen. et sp. nov., from the Upper Campanian Bearpaw Formation of southwestern Saskatchewan, Canada, is one of the youngest plesiosaurs from the Western Interior, and one of the few plesiosaurs for which detailed osteology of both skull and postcrania is available. The skull includes the upper side of the inner ear cavity and a median portion of the roof of the braincase. This taxon is distinguished from other elasmosaurs by a combination of several osteological characters variable among elasmosaurs, as well as the unique feature of a high and pointed coronoid process. Anomalous ossification is seen in the fused or pronged gastralia, development of tubercules in metacarpals, and healed fracture of the limb. The dorsal portion of the braincase is compared with other plesiosaurs, showing a variation in plesiosaur braincase morphology. Identity of carpal and tarsal elements is examined based on recent debates on the homology of mesopodials.

Aristonectes parvidens Cabrera, 1941, and Morturneria seymourensis (Chatterjee and Small, 1989), two plesiosaurs from the Maastrichtian of South America and Antarctica whose phylogenetical position is controversial, are reviewed and found to be congeneric and conspecific. Most differences between the two type specimens are interpreted as related to ontogenetic growth: Morturneria is based on an immature, whereas Aristonectes is based on an adult, probably an old individual. Aristonectes exhibits an unique set of characters among Plesiosauria: a low and wide ogival skull, a paired vomero-nasal fenestra, a mandible high anteriorly with a very short and high symphysis, a homodont dentition composed of numerous, strongly outwardly directed and poorly ornamented teeth (dental formula: 10–13 premaxillary, at least 51 maxillary and probably 60–65 dentary teeth, depending upon individual ontogeny). Moreover, Aristonectes shares several synapomorphies with the elasmosaurid clade, mainly strongly binocular-shaped and platycoelous cervical centra with lateral ridges. In contrast to cryptoclidids, it retains some plesiomorphic characters (e.g., horizontal jugal and poorly ventrally excavated cheek, glenoid fossa at about the same level as the alveolar row). The dental morphology and peculiar occlusal pattern, forming an interlocking trap, suggest that Aristonectes strained a diet of small, soft organisms from the water.

For the first time, a three-dimensionally preserved skull of the Lower Jurassic leptonectid ichthyosaur Leptonectes cf. tenuirostris is described. The specimen reveals a wealth of new data on the cranial anatomy of basal leptonectid neoichthyosaurs. The osteology of the skull roof differs fundamentally from other well-known post-Triassic ichthyosaurs and is highly autapomorphic. The structure of the sclerotic ring, which is well preserved in situ, is described and it appears plausible that L. cf. tenuirostris was capable of stereoscopic vision. Inadequate description makes comparison to other leptonectids difficult. It can be demonstrated, however, that L. cf. tenuirostris is most similar to L. tenuirostris among known leptonectids. It is fundamentally different from the Upper Liassic Eurhinosaurus longirostris in the osteology of the skull roof and the size and orientation of the major skull openings, making generic distinction of these two species a necessity. At the moment, no autapomorphies are known of the genus Leptonectes, which therefore must be considered as a metataxon that comprises basal leptonectids from the Lower to Middle Liassic.

A new mesoeucrocodylian, Pachycheilosuchus trinquei, from the Lower Cretaceous (Albian) Glen Rose Formation, exhibits progressive caudal-to-cranial vertebral procoely. This modification is characterized by an intermediate semi-procoelous condition in which the posterior condyle is dimpled by a concavity. Pachycheilosuchus differs from all known crocodyliforms in having an expanded maxillary margin that displaces the tooth row medially, and in possessing a cervical shield formed by the complete fusion of six osteoderms. Phylogenetic analysis indicates a sister taxon relationship with the weakly defined Atoposauridae. The presence of variable procoely in both Pachycheilosuchus and the closely related atoposaurid Theriosuchus indicates convergent evolution of the character with Eusuchia. Sediments at the locality were deposited in near-shore, marine-to-brackish waters, suggesting that Pachycheilosuchus inhabited euryhaline marine environments.

New material of Plesiobaena antiqua from the mid-Campanian Judith River Group of Alberta, Canada, fully documents the skeleton in this species and provides evidence regarding variation within the taxon. Size-independent variation is present in the size of the nasals. Variation in the degree of entry of the frontal into the orbital margin is size-related. The shell varies in the presence or absence of the seventh neural, presence of a ninth neural, and fusion of the eleventh and twelfth peripherals. Plesiobaena antiqua is restricted to the Campanian. The late Maastrichtian specimens previously included in the species differ in the absence of the following features: pointed crista supraoccipitalis, parietal-postorbital sutures strongly divergent from midline, maxilla meeting postorbital excluding jugal from orbit margin, short contact between pterygoids at midline, fused first and second peripheral, and first marginal located mostly, or entirely, on nuchal. The late Maastrichtian specimens are distinct from the Paleocene species P. putorius in the degree of development of the skull roof and presence of sulci on the skull roof, but the two taxa share two derived features suggesting that they form a monophyletic clade relative to P. antiqua. The distribution of P. antiqua within the Campanian of North America suggests that it was a member of a northern faunal assemblage.

A new species of the ankylosaur Struthiosaurus from the Upper Cretaceous (lower Campanian) of the Villeveyrac-Mèze Basin, southern France, is described from a partial skeleton that includes distal dorsal vertebrae, synsacrum and pelvic girdle. Struthiosaurus languedocensis, sp. nov. is a small-sized nodosaurid (less than 3 m length) characterised by distal dorsal centra that are very compressed laterally and hourglass in shape in ventral view; ischium directed immediately caudal from the acetabulum, with a robust shaft that does not taper distally and that is weakly curved in a caudoventral orientation. The synsacrum of S. languedocensis consists of ten co-ossified vertebrae, including five dorsals, four sacrals and a caudal. Among ankylosaurs, only Polacanthus foxii has a similar synsacral count, but there are significant differences in the pelvic structure between Struthiosaurus and Polacanthus. The presence of an ischium lacking a distinct nodosaurid-like ventral flexion appears to be diagnostic for the genus Struthiosaurus, as suggested by additional remains recovered from the upper Campanian of Laño (Iberian Peninsula). Current data suggests that Struthiosaurus is represented by different species in southwestern and central Europe.

The skull material of a new iguanodontian dinosaur, Fukuisaurus tetoriensis gen. et sp. nov., discovered from the fluvial deposits of the Lower Cretaceous Kitadani Formation, Tetori Group, Fukui Prefecture, Japan, is described here. Some features of Fukuisaurus show affinities with Iguanodon, Ouranosaurus, and Altirhinus, referred to as Iguanodontidae by some. A phylogenetic analysis using mainly cranial characters shows that Fukuisaurus is a definitive derived non-hadrosaurid iguanodontian and implies that Fukuisaurus is more derived than the clade of Iguanodon Ouranosaurus and more basal to the clade of Altirhinus, Probactrosaurus, Eolambia, Protohadros, Bactrosaurus, Telmatosaurus, and hadrosaurids. It also supports that Iguanodontidae is paraphyletic by the exclusion of Altirhinus as suggested previously. The presence of Fukuisaurus indicates a wider geographical distribution of the group in eastern Asia. The occurrences of derived non-hadrosaurid iguanodontians from the Kitadani Formation and other formations in Japan support a dispersal of this group into eastern Asia by the Early Cretaceous and its temporal range extension in Japan. Fukuisaurus possesses a strong maxilla-vomer articulation, indicative of the independent acquisition of a non-pleurokinetic skull (not present in Hypsilophodon, Iguanodon, and hadrosaurids).

The first braincase belonging to an Early Cretaceous sauropod from North America is described. The diagnostic characters of this well preserved partial braincase are: prominent supraoccipital crest, with a distinct median ridge extending almost to the foramen magnum; short, ventrally directed basitubera, divided by a deep groove extending to the basipterygoid; single foramen for cranial nerve XII; accessory foramen for cranial nerve XI. A lack of juvenile characters suggests this specimen, although quite small, belongs to an adult individual. Comparison of this specimen with other sauropod crania indicates strong similarities with brachiosaurids and titanosaurids.

Stegoceras (sensu lato) has been the recipient of a number of species. Most have been placed into synonymy with S. validum, some have been transferred to other genera (i.e., Gravitholus, Ornatotholus), whereas others have been interpreted as being sexual dimorphs. A parsimonious phylogenetic analysis using 49 characters, which include 9 new cranial characters based on pachycephalosaur frontoparietal domes, now permits a revision of the genus Stegoceras.

This analysis concludes that Stegoceras validum (sensu stricto) is a primitive, incipiently-domed pachycephalosaur that is characterized by a well-developed squamosal shelf and open supratemporal fossae. It is the sister taxon to the fully-domed Pachycephalosaurinae. The taxon Ornatotholus browni has a parietal and displays features identical to S. validum and is therefore a subjective junior synonym. Specimens consisting of flat, paired frontals are immature individuals of S. validum. The holotype of “Stegoceras” lambei, and all morphotypes of this species, are unique in the construction of the posterior squamosal region and are placed in a new genus, Colepiocephale. Colepiocephale lambei is known solely from the Foremost Formation and is the oldest diagnostic pachycephalosaur from North America. An incomplete, and indeterminate, skull from the upper part of the Milk River Formation (upper Santonian) has the distinction of being the oldest known North American pachycephalosaur. “S.” sternbergi lacks a posterior squamosal shelf and has squamosals directed laterally and is placed in a new genus, Hanssuesia, as H. sternbergi. Although the taxon Gravitholus albertae displays some characters (i.e., retention of the posterior squamosals separated by a distinct median parietal) and is similar to H. sternbergi in some respects, the holotype is too incomplete for any definitive diagnosis and thus it is considered a nomen dubium. Sphaerotholus is a subjective junior of Prenocephale and the species Sphaerotholus buchholtzae is a subjective junior synonym of Prenocephale edmontonensis. The taxa Prenocephale brevis, P. edmontonensis, and P. goodwini, form a monophyletic clade with monotypic Asian taxa Prenocephale prenes and Tylocephale gilmorei as an unresolved sister group. They are united by the possession of a distinct row of nodes on the squamosal and parietals. Tylocephale, if valid, is interpreted as the sister taxon to the Prenocephale clade.

Stenotholus kohleri is formally recognized as a junior synonym of Stygimoloch spinifer. Based on the presence of hypertrophied nodes Stygimoloch spinifier and Pachycephalosaurus wyomingensis are united in the clade Pachycephalosaurini new taxon.

Small-to-medium size Late Cretaceous pachycephal

The Middle Jurassic sauropod Cetiosaurus is significant both historically and in terms of its potential phylogenetic relationships. The anatomy and taxonomy of this form are poorly understood because inadequate diagnoses have allowed the proliferation of species names and the referral of very fragmentary specimens. A review of Cetiosaurus species indicates that all, except C. oxoniensis, are unavailable or nomina dubia. The current type species, C. medius, can no longer be regarded as a valid taxon. Previous suggestions that Cardiodon is a senior subjective synonym of Cetiosaurus cannot be sustained because the two forms do not share any autapomorphies. It is proposed that the generic name Cetiosaurus be retained, with C. oxoniensis as the new type species. The most complete specimen of C. oxoniensis (a partial skeleton from Bletchingdon Station, Oxfordshire) is redescribed and compared with other sauropods. Cetiosaurus is rediagnosed on the basis of autapomorphies, including: (1) ‘pyramid’-shaped neural spines in posterior cervical and anterior dorsal vertebrae; (2) loss of the spinodiapophyseal lamina on all dorsal vertebrae; (3) anterior chevrons with anteroposteriorly compressed distal shafts; (4) distal caudal centra have a ‘tongue’-like projection at the dorsal midline of their articular ends; and (5) a distinct triangular hollow on the lateral surface of the ilium at the base of the pubic process.

Largely fragmentary fossils from sites in New South Wales, Victoria, and Queensland, Australia document terrestrial and marine vertebrate faunas of Aptian–Albian age. The natural cast of a large tooth from the Griman Creek Formation, Lightning Ridge, New South Wales, records the presence of a hitherto unknown member of the fauna. Although reference to one of the groups of crocodyliforms that evolved complex, mammal-like postcanine teeth cannot be excluded, the fossil more likely represents a species of synapsid. In some respects it is similar to lower postcanines of traversodontids. Greater morphological similarities to upper molars of dryolestids make reference of this tooth to this group more likely. Current Mesozoic Laurasian and Gondwanan fossil records include mammals with cheek teeth of similar large size.

We describe a skull and fragments of lower jaws of a ceratomorph perissodactyl from the Arshantan (Eocene) strata of the Zaysan Basin, eastern Kazakstan, and refer these specimens to Isectolophus latidens (Osborn, Scott, and Speir, 1878). The material from the Zaysan Basin is indistinguishable from the holotypes of Isectolophus bogdulensis Reshetov from Mongolia and Homogalax reliquius Qi from China. These two species are junior subjective synonyms of I. latidens. The presence of I. latidens, known also from Bridgerian strata of North America, in Asian deposits of Arshantan age provides further support for a correlation between the Arshantan and the Bridgerian land-mammal “ages.”

A succession of five fossiliferous levels near Buia in the northern Danakil (Afar) Depression of Eritrea has produced an abundant early Pleistocene fauna including a ca. 1.0 Ma cranium of Homo. Elephas is well represented at many sites; with one exception the entire Buia Elephas sample represents a relatively derived member of the Elephas recki lineage. Univariate and multivariate analysis of dental characters demonstrates that the Buia sample is intermediate between E. recki ileretensis (Koobi Fora, Ileret) and E. r. recki (Beds 3 and 4 at Olduvai). The biologic reality of the separation of E. recki into five chronologically successive subspecies is questionable. Our analysis supports the hypothesis that E. r. ileretensis and E. r. recki form a single phyletic lineage.