The Crato Formation is located in the Araripe Basin in Northeastern Brazil, where the Ceara and Pernambuco provinces meet. It is considered Aptian (Early Cretaceous) in age and specimens of Dastilbe occur at many localities in the region of Nova Olinda. Nearly all derive from the Nova Olinda Member, which is the lowest member of the Crato Formation. Dastilbe, a gonorynchiform fish placed within recent Chanidae, has been used as a catchall for small fossil fish specimens for quite some time. The type species of Dastilbe, D. crandalli, was described by Jordan in 1910 from the Early Cretaceous of Riacho Doce, Brazil. More recent studies of Dastilbe are based on the material from the Crato Formation, but detailed morphological descriptions of the skull and postcranial features were lacking. More than 400 specimens from the Crato Formation and Riacho Doce are examined to establish the morphology and emend the diagnosis of Dastilbe crandalli. Two other species were contained in the genus: D. elongatus from Brazil and D. batai from Africa. D. elongatus is synonymous with the type species. D. batai resembles Parachanos and probably belongs to that genus. D. moraesi from a Brazilian locality further south in the Minas Gerais province is known too poorly to allow for comparisons.

Fossil specimens of Neotropical gymnotiform electric fishes from the Yecua Formation (Upper Miocene, Parana basin, Bolivia) are analyzed in the context of a comprehensive study of gymnotiform relationships. Each fossil is analyzed individually and placed in the phylogeny according to characters it actually possesses. Some of the fossils previously referred to Humboldtichthys kirschbaumi can be identified only as Gymnotiformes incertae sedis, others as incertae sedis within recognized suprageneric gymnotiform taxa. The holotype of H. kirschbaumi shares the presence of a striated opercle with some extant species of Sternopygus and Distocyclus and can be placed in the Recent gymnotiform family Sternopygidae; H. kirschbaumi is diagnosed by the presence of a deeply striated opercle in which the striations extend between the dorsal and ventral opercular ridge fields. The analysis indicates the presence of several taxa among the fossil material. The presence of a multispecies assemblage is not uncommon among Recent gymnotiforms inhabiting non-floodplain forest streams, the inferred preservational environment.

A well-preserved vertebral column from the Late Permian of Southern France (Lopingian, La Lieude Formation, Lodève Basin) is described. It is composed of diplospondylous vertebrae and is most comparable with the temnospondyl Tupilakosaurus previously known from the Early Triassic of Greenland and Russia. This new specimen therefore represents the earliest occurrence of a diplospondylous tupilakosaur, and extends the geographic range of the group to Western Europe. It is an aquatic temnospondyl that used the anguilliform undulatory mode of swimming.

Recent fieldwork in the Tropic Shale of southern Utah has resulted in the recovery of two new specimens of the short-necked pliosaurid Brachauchenius lucasi Williston, 1903. Both specimens were recovered in Lower Turonian strata a few meters above the Cenomanian-Turonian Stage boundary as determined from molluscan assemblages found in direct association, and both include skull material. The larger of the two also includes pectoral and pelvic elements previously unknown for this taxon. These specimens represent the first records of B. lucasi from the western margin of the Cretaceous Western Interior Seaway; previously recorded specimens were recovered in Kansas and Texas. The Cenomanian through middle Turonian temporal range of B. lucasi, in addition to its geographic range across the seaway, indicates that this taxon suffered few, if any, negative consequences as a result of global scale oceanographic events, including marine extinctions, that transpired during late Cenomanian-early Turonian time.

Recent fieldwork in the Tropic Shale of southern Utah has resulted in the recovery of several specimens of short-necked plesiosaurs including both polycotylid plesiosauroids and pliosaurids. This report focuses on the former, whereas the latter are discussed in an accompanying paper. Although the Late Cretaceous Cenomanian/Turonian Stage boundary falls within the lower few meters of the Tropic Shale, all but one of the specimens were found in lower Turonian strata based on molluscan assemblages found in direct association with the skeletal material. The plesiosauroid family Polycotylidae is represented by at least three taxa: (1) the ‘typical’ late Cenomanian/early Turonian Trinacromerum; (2) Eopolycotylus rankini, gen. et sp. nov., a new genus and species that shares synapomorphies with the late Santonian/early Campanian Polycotylus latipinnus; and (3) Palmula quadratus, gen. et sp. nov., another new taxon that shares synapomorphies with unnamed taxa from the late Cenomanian of South Dakota and Japan. Cladistic analysis supports the division of the Polycotylidae into two new subfamilies, here designated the Polycotylinae and the Palmulainae. The Turonian plesiosaur fauna of the Tropic Shale, and consequently the large vertebrate fauna of the Cretaceous Western Interior Seaway, is considerably more diverse than previously realized, and there is no indication that this fauna suffered any negative consequences as a result of global scale oceanographic events, including marine extinctions, that transpired during late Cenomanian-early Turonian time.

One of the most enigmatic species of North American mosasaur, Platecarpus planifrons (Upper Coniacian—Lower Santonian), is re-diagnosed based on reference to the holotype, a new and very well-preserved skull (UALVP 24240), and several other less complete specimens. P. planifrons, once considered a nomen vanum, is diagnosed by a number of characters: separation of prefrontal and postorbitofrontal on ventral surface of frontal; dorsal surface of frontal planar with no mid-sagittal keel; width of preorbital region of frontal greater than interorbital width; frontal with paired posteromedian flanges; anterodorsal border of quadrate with distinct notch; stapedial pit narrow and keyhole shaped. The unexpected preservation of paired septomaxillae and the presence of a clear and well-defined vomer-pterygoid contact in UALVP 24240 are reported. These new osteological data for P. planifrons permit re-evaluation of the species composition of the genus. Arguments are presented for the synonymy of P. coryphaeus with P. ictericus, while retaining the latter as distinct from the generic type, P. tympaniticus. Platecarpus cf. P. somenensis is tentatively retained. Thus, four species of Platecarpus from the Western Interior Seaway of North America are recognized.

In the early 1990s a theropod dinosaur found close to the Triassic-Jurassic boundary of France was assigned to a second species of the genus Liliensternus: L. airelensis (Moon Airel Formation). This contribution reveals that common features that purportedly unite “L.” airelensis with L. liliensterni are more widely distributed among coelophysoids and basal dinosaurs than it was thought. A cladistic analysis reveals that “L.” airelensis is more closely related to the Coelophysidae than to L. liliensterni. A feature that supports this systematic arrangement includes a supraacetabular crest forming a well-developed ridge continuous with the lateral margin of the brevis fossa, with non-distinct notch between both structures. The new genus Lophostropheus, gen. nov., is therefore erected to include the species L. airelensis. Thus, the new combination Lophostropheus airelensis is proposed.

Based on a review of troodontid specimens from the territories of the former Soviet Union, including new discoveries from Uzbekistan, two dental morphotypes can be distinguished among Troodontidae from the Cretaceous of Asia: (1) unserrated teeth, present in Mei from Lujiatun (China; Early Cretaceous: Hauterivian-Barremian), an unnamed taxon from Hövöör (Mongolia; Early Cretaceous: Aptian-Albian), Urbacodon itemirensis, gen. et sp. nov. from Itemir and Urbacodon sp. from Dzharakuduk (Uzbekistan; Late Cretaceous: Cenomanian and Turonian, respectively), and Archaeornithoides from Bayn Dzak and Byronosaurus from Ukhaa Tolgod (Mongolia; Late Cretaceous: Campanian); and (2) serrated teeth, present in Sinornithoides from Huamuxiao (China; Early Cretaceous) and Sinornithoides-like taxa from Khamryn Us (Mongolia; Early Cretaceous: Aptian-Albian), Shestakovo (Russia; Early Cretaceous: Aptian-Albian), and Sheikhdzheili (Uzbekistan; Late Cretaceous: Cenomanian); Troodontidae indet. from Kansai (Tajikistan; Late Cretaceous: Santonian) and Alymtau (Kazakhstan; Late Cretaceous: Campanian), Saurornithoides (Mongolia and China; Late Cretaceous: Campanian-Maastrichtian), and Troodon from Kakanaut and Blagoveshchensk (Russia; Late Cretaceous: Maastrichtian).

A digital cranial endocast of Pucadelphys andinus, a Paleocene metatherian from Bolivia, is described. This is the first cranial endocast described for the taxon and the only one (to date) from a stem marsupial (i.e., non-marsupial metatherian). The Pucadelphys endocast is compared with others generated from skulls from six taxa of extant marsupials (Monodelphis domestica, Didelphis virginiana, Dasyurus hallucatus, Vombatus ursinus, Phascolarctos cinereus, and Dromiciops australis). The Pucadelphys endocast is generally similar to the didelphid marsupial Monodelphis. However, the olfactory bulb casts and the cerebellar space (approximated using vermis cast length) of Pucadelphys are relatively large in comparison to those of these extant marsupials. The cerebral hemisphere casts of Pucadelphys are dorsoventrally thin in comparison to those of the extant marsupials examined here. With other dimensions of the cerebral hemisphere casts being comparable between Pucadelphys and the extant marsupials, this suggests that the overall volume of the cerebral hemispheres was smaller in Pucadelphys. Thus, two possible synapomorphies for crown Marsupialia are a decrease in size of the cerebellar space and an increase in cerebral hemisphere volume.

To develop a widely applicable method to estimate body size in theropods, the scaling relationship between skull length, body length, and body mass was investigated using 13 strictly carnivorous, non-avialan theropod taxa ranging in size from the 1-m Sinosauropteryx prima to the 12-m Tyrannosaurus rex. Body length was obtained from the literature for complete to nearly-complete specimens and body mass was obtained from three-dimensional mathematical slicing of those same specimens to ensure accurate body length-body mass associations. Least-square regressions reveal a tight correlation between skull length and body length (SK-BL) and skull length and body mass (SK-BM). The SK-BL regression is negatively allometric, which indicates that skulls become longer relative to body length with increasing body size. In contrast, the SK-BM regression is positively allometric, indicating that body mass increases faster than skull length with increasing body size. These conclusions confirm that the common practice of scaling isometrically smaller relatives of a given taxon to obtain body length and body mass estimates is not valid. Although predictive equations derived from the regressions fail to predict accurately body size in abelisaurids and juvenile theropods due to their different head/body proportions, they produce accurate body size estimates for theropods of known body size, thus validating their applicability. Body size estimates for Carcharodontosaurus and Giganotosaurus, approaching 13 m and 14 tons, suggest that they may have surpassed Tyrannosaurus in size. A revised body size estimate for a large Spinosaurus specimen suggests a much shorter and heavier animal than recently suggested.

The dicynodont species “Cryptocynodon” parringtoni von Huene, 1942 was described from a single poorly preserved specimen collected from the Upper Permian Kawinga Formation, Ruhuhu Basin, Tanzania. No additional specimens have been referred to the species since its erection. Two new specimens of “C.” parringtoni, which were collected from the Kawinga Formation in 1933, are described. The holotype and new specimens share tusks, the absence of postcanine teeth, a shortened snout, relatively large palatines that contact the premaxillary secondary palate, a blade-like mid-ventral vomerine plate, and an intertuberal ridge between the basisphenoid-basioccipital tubera. The new specimens also allow the description of many previously unknown characters of the species, including an intertemporal region in which the postorbitals extensively overlap the parietals but are relatively horizontally oriented for most of their width; the presence of paired anterior palatal ridges; the absence of a labial fossa; the presence of palatine pads that are rugose posteriorly, but smoother where they contact the secondary palate; the presence of a dorsal process on the anterior end of the epipterygoid footplate; markedly shortened dentary tables; the presence of a posterior dentary sulcus; and the presence of a slit-like mandibular fenestra. Size and proportional differences between the holotype and new specimens suggest that the former is a juvenile. The morphology of the new specimens demonstrates that “C.” parringtoni is not part of Cryptocynodon, Pristerodon, or Diictodon, and the species is referred to a new taxon, Katumbia, gen. nov. A phylogenetic analysis suggests that Katumbia is a member of the large clade that includes Tropidostoma and Kannemeyeria, although its exact position within the clade is uncertain. Confirmation that Katumbia parringtoni, comb. nov., is a distinct, valid dicynodont species that is endemic to Tanzania reinforces the uniqueness of the Ruhuhu fauna and provides further evidence of provinciality among Late Permian terrestrial vertebrates.

The origins of the distinct sloth lineages are not well documented. The Deseadan SALMA site of Salla-Luribay presents four Tardigrada and constitutes one of the two oldest sloth assemblages. The peculiar glypto-sloth Pseudoglyptodon sallaensis is found together with two orophodontoid taxa and a Megalonychidae. The study of the P. sallaensis remains confirms that is effectively a sloth with various glyptodontoid convergences easily explicable by a grazing way of life. The orophodontids exhibit a common dental pattern with Octodontotherium from Patagonia. Except for the presence of Pseudoglyptodon, the Salla-Luribay Xenarthra assemblage closely resembles the La Flecha site from Santa Cruz province, Argentina. The Megalonychidae are also recorded, which increases the paleogeographic distribution of this clade in the late Oligocene. The phylogenetic status of Pseudoglyptodon remains doubtful and additional material is necessary to resolve it. Two species of Peltephilinae, a Glyptodontidae closely related to Eocoleophorus and Glyptatelus complete the xenarthran assemblage. All of the Bolivian specimens are considerably smaller than the Patagonian forms, a difference that may reflect distinct diets, latitudinal cline, and environments during the end of the Oligocene. The existence of Pseudoglyptodon, four Orophodontidae and two Megalonychidae at the end of the Oligocene (25.65 and 29.4 Ma) in South America is surprising and implies an early diversification of sloths and a Cingulata/Tardigrada split, probably before the Casamayoran, which would be in agreement with predictions based on molecular evidence.

Six new occurrences of carnivorous mammals from Wadi Moghra, early Miocene, Egypt, are described, and the implications of these taxa for interpreting the biogeography of early Miocene mammals are discussed. The new taxa include two hyaenodontid creodonts (Buhakia moghraensis, gen. et sp. nov., and cf. Teratodon) and four carnivorans: an amphicyonid (Cynelos, sp. nov.), two viverrids s. l. (Herpestides aegypticus, sp. nov., and Ketketictis solida, gen. et sp. nov.), and a stenoplesictid (Moghradictis nedjema, gen. et sp. nov.). Previously only two carnivorous mammals, both large creodonts (Hyainailouros fourtaui, Megistotherium osteothlastes), had been reported from Moghra. Together, the eight carnivorous taxa now known from Moghra include not only some representatives of widespread genera common to localities across Eurasia and Africa, but also a number of unique faunal elements, including three new genera and five new species. Evidence for two alternate hypotheses concerning the timing of carnivore migrations events are discussed: 1) an early Miocene (ca. MN 3) event followed by a slightly later (MN 4-5) one; or 2) an even earlier first migration in the late Oligocene-early Miocene (MN 1 or even MP 30), considered here to be the more likely scenario.

In this article, hypotheses about the origin, evolution and dispersal of Megantereon are reviewed using the fossil specimens included in previous comparative studies as well as the remains identified in the late Pliocene site of Fonelas (Spain) and the early Pleistocene localities of Lantian, Lingyi, Longdan, Renzidong (China), and Untermassfeld (Germany). The validity of the two species proposed by Martínez-Navarro and Palmqvist (1995), Megantereon cultridens and M. whitei, is evaluated using tooth measurements and multivariate statistical methods. The hypothesis of sexual dimorphism as an explanation for the morphological variability of Megantereon is tested with a large sample of sexed individuals of Panthera pardus and Panthera leo. Results obtained indicate similar or even smaller differences in tooth dimensions between M. cultridens and M. whitei than between sexes in both leopards and lions, except in the case of the lower fourth premolar. However, in spite of a substantial overlap between both Megantereon species in the size of the upper canine, this tooth reverses the differences found for other tooth measurements, because M. cultridens shows larger cheek teeth on average than M. whitei but smaller sabers. This is confirmed by principal components and discriminant analyses, which reveal that sexual dimorphism in leopards and lions is a matter of tooth size and not of relative proportions and argues against the interpretation of M. cultridens and M. whitei as the sexes (males and females, respectively) of a single species. These results indicate that M. cultridens and M. whitei are valid species, because the differences in tooth measurements exceed those expected from sexual dimorphism and do not reveal the effects of biased sampling. Finally, an analysis of jaw anatomy reveals biomechanical differences between both Megantereon species, related to the relative efficiency of the biting muscles at the level of the lower carnassial.

A new specimen of Trogosus from the Akasaki Formation, Amakusa City in Kumamoto Prefecture, Japan, is represented by 12 teeth, mandibular fragments, and cervical vertebral remains of an old individual. This is the most informative specimen of Trogosus from Asia. Comparisons with all known species of Trogosus indicate that the specimen is comparable to the largest species, Trogosus latidens, which has been recorded only from the Bridgerian North American Land Mammal Age. In addition to few diagnostic features of T. latidens except for the large size, the poor preservation of the new specimen makes its taxonomic identification at the species level debatable. However, the presence of the Japanese Trogosus further supports the intercontinental diversity and distribution of the genus via Beringia.

Gliridae is one of the oldest extant families of rodents with a fossil record dating back as far as the early Eocene. Eogliravus wildi, previously known from some isolated teeth from the European early Eocene, represents the oldest and most primitive glirid. The early middle Eocene oil shales of Messel, Germany, yielded an extraordinarily preserved specimen of E. wildi, exhibiting the virtually complete and articulated skeleton, the outline of the pelage, and gut contents consisting of various vegetable matter. E. wildi descended most probably from European small-sized microparamyine ischyromyids. Its protrogomorphous zygomasseteric structure indicates that the myomorphy and hystricomorphy of the extant dormice evolved convergently to other rodent clades. The postcranial skeleton compares well with extant glirids. The postcranial morphology, proportions of the limb segments, bushy tail, and small body size indicate a gracile and swift animal moving among tree branches. The very large orbits suggest nocturnal activity. E. wildi was well adapted to an arboreal or scrub environment, the major habitat of today's dormice.

A mandible and partial skeleton of Rhynchotherium falconeri is described from late Pliocene deposits of the 111 Ranch Locality in southeastern Arizona. The morphology of the mandible and m3 of the 111 Ranch individual is consistent with other specimens of Rhynchotherium and compares closely with previously reported R. falconeri from Arizona, as well as R. simpsoni from Florida. The 111 Ranch specimen is the basis for only the second description of postcranial material for the genus Rhynchotherium, and adds important morphological and ontogenetic attributes to this taxon. A morphometric analysis of specimens including the genotype indicates several junior synonyms are represented and the type specimen for the genus is no longer valid. A suggestion is made to raise F:AM 18225 to type status.

The Barstovian of the northern Rocky Mountains, U.S.A., is known mainly from deposits east of the continental divide; this article provides new information from west of the divide. The biostratigraphic, geologic, magnetostratigraphic, and lithostratigraphic setting is reported for an unusually complete Arikareean, Hemingfordian, and Barstovian stratigraphic section known as the Railroad Canyon Sequence in Montana and Idaho. At least 35 taxa of fossil vertebrates collected from 50 different localities are placed in stratigraphic context. Lithostratigraphic attributes indicate the presence of a freshwater lake during the Arikareean, intermittent saline lakes through much of the Hemingfordian, a late Hemingfordian unconformity (the Mid-Tertiary Unconformity), and absence of persistent lakes through the Barstovian. The sequence records the development of increasingly arid conditions in the depositional basin. A change in bedding attitude and generally coarser sediments above the Mid-Tertiary Unconformity indicate uplift of the region during the Barstovian, possibly accompanied by slight structural tilting. The analysis helps date Barstovian faunas, and provides a useful tie point for correlating the Barstovian Land-Mammal Age to the magnetostratigraphic and radioisotopic scale in the western Rockies, and ultimately to the Global Polarity Time Scale (GPTS). It also suggests that the Mid-Tertiary unconformity is approximately coeval on the eastern and western flanks of the mountains, supporting tectonic models that require regional uplift between ca. 16.8 and 17.5 Ma.