Brooks B. Britt

A Suite of Dermestid Beetle Traces on Dinosaur Bone from the Upper Jurassic Morrison Formation, Wyoming, USA

Most studies of insect traces on fossil bone deal with one or two trace morphs found on isolated bone fragments, making it difficult to identify the trace-maker and its behavior. We report the discovery of a suite of insect traces on an articulated Camptosaurus dinosaur skeleton that permits the identification of the trace-maker and interpretations of its behavior. The traces include mandible marks, pits, and shallow bores on cortical bone, and deep, meandering furrows and tunnels (borings) on articular surfaces. The interiors of bones are intensely mined, and the cavities and borings are filled with fine bone fragments (insect frass). The distinctive mandible marks consist of opposing sets of parallel grooves, indicating the maker had two apical teeth set on symmetrical mandibles and that all of the traces were made by a single taxon. Comparison of the fossils with the mandible morphology and bone traces of extant insects indicates dermestid beetles made the traces. Based on extant dermestid behavior, soft tissues were likely absent and the bones were lipid-laden when the traces were made. Examination of more than 5,000 bones from the Morrison and Cedar Mountain formations shows insect traces on bone are common but overlooked and that many bones are substantially damaged by insect mining. The key to the recognition of these important yet subtle traces is a search model and an intense, oblique light source.

Evidence for high taxonomic and morphologic tyrannosauroid diversity in the Late Cretaceous (late Campanian) of the American Southwest and a new short-skulled tyrannosaurid from the Kaiparowits Formation of Utah.

The fossil record of late Campanian tyrannosauroids of western North America has a geographic gap between the Northern Rocky Mountain Region (Montana, Alberta) and the Southwest (New Mexico, Utah). Until recently, diagnostic tyrannosauroids from the Southwest were unknown until the discovery of Bistahieversor sealeyi from the late Campanian of New Mexico. Here we describe an incomplete skull and postcranial skeleton of an unusual tyrannosaurid from the Kaiparowits Formation (Late Cretaceous) of Utah that represents a new genus and species, Teratophoneus curriei. Teratophoneus differs from other tyrannosauroids in having a short skull, as indicated by a short and steep maxilla, abrupt angle in the postorbital process of the jugal, laterally oriented paroccipital processes, short basicranium, and reduced number of teeth. Teratophoneus is the sister taxon of the Daspletosaurus + Tyrannosaurus clade and it is the most basal North American tyrannosaurine. The presence of Teratophoneus suggests that dinosaur faunas were regionally endemic in the west during the upper Campanian. The divergence in skull form seen in tyrannosaurines indicates that the skull in this clade had a wide range of adaptive morphotypes.

A BARREMIAN NEOCHORISTODERE FROM THE CEDAR MOUNTAIN FORMATION, UTAH, U.S.A.

The Choristodera is a poorly understood group of semi-aquatic reptiles comprising about a dozen genera (Table 1 and Ksepka et al., 2005). These include the small, semi-aquatic, lizard-like Lazarussuchus, Cteniogenys, and Monjuroschus; the 2-m long Pachystropheus (considered a sister taxa to Choristodera by Evans and Manabe, 1999); the small, long-necked aquatic forms Shokawa and Hyphalosaurus; the gharial-like Champsosauridae consisting of seven species of Champsosaurus; and the crocodile-like Simoedosauridae (Simoedosaurus, Ikechosaurus, Tchoiria, and ?Khurendukhosaurus). The Champsosauridae and Simoedosauridae are Cretaceous to early Tertiary clades that constitute the Neochoristodera of Evans and Hecht (1993). Although crocodilian in general form, cladistic analyses put choristoderes far from Eosuchia, and even outside the Neodiapsida (Younginiformes + Sauria; Gao and Fox, 1998). The origin of the group is not yet clear and this poor phylogenetic resolution is a reflection of significant gaps in the fossil record of choristoderes. For example, if Pachystropheus is indeed a choristodere, then choristoderes first occur in the Triassic of Europe as large-bodied animals (Storrs and Gower, 1993) but are absent in subsequent assemblages until the Barremian, when a diverse assemblage appears in Asia (Ksepka et al., 2005). Previous to our report, the earliest known North American neochoristoderes were from the Aptian/Albian (Gao and Fox, 1998). This geographic and stratigraphic pattern of distribution led to the hypothesis that large-bodied neochoristoderes had their center of evolution in Asia, save for the Champsosauridae, which likely originated in North America (Gao and Fox, 1998). In this paper, we report on a specimen from the base of the Cedar Mountain Formation in Utah, which is currently assessed as Barremian and, thus, extends back the known range of North American neochoristoderes by at least 10 million years.

Silurian sponges and some associated fossils from the Heceta Limestone, Prince of Wales Island, southeastern Alaska

Abstract A small faunule of hypercalcified agelasiid demosponges has been recovered from outcrops of the Silurian Heceta Formation on Prince of Wales Island in southeastern Alaska. Included are abundant Girtyocoeliana epiporata (Rigby and Potter, 1986), of the Girtyocoeliidae Finks and Rigby, 2004; fragments of Alaskaspongiella laminosa n. gen. and sp., Polyplacospongia nodosa n. gen. and sp., and Monolaminospongia gigantia n. gen. and sp., of the Auriculospongiidae Termier and Termier, 1977, and Cladospongia alaskensis n. gen. and sp., Virgulaspongia uniforma n. gen. and sp., and Stipespongia laminata n. gen. and sp. of the Preperonidellidae Finks and Rigby, 2004. Also included are a few fossils of uncertain taxonomic placement, including Turbospongia biperforata n. gen. and sp., along with a small, chambered, tubular fragment and several porous tubular stems that may be additional poriferans. Some isolated octactine-based heteractinid spicules were also recovered from the etched residues.

Caelestiventus hanseni gen. et sp. nov. extends the desert-dwelling pterosaur record back 65 million years

Pterosaurs are the oldest known powered flying vertebrates. Originating in the Late Triassic, they thrived to the end of the Cretaceous. Triassic pterosaurs are extraordinarily rare and all but one specimen come from marine deposits in the Alps. A new comparatively large (wing span >150 cm) pterosaur, Caelestiventus hanseni gen. et sp. nov., from Upper Triassic desert deposits of western North America preserves delicate structural and pneumatic details not previously known in early pterosaurs, and allows a reinterpretation of crushed Triassic specimens. It shows that the earliest pterosaurs were geographically widely distributed and ecologically diverse, even living in harsh desert environments. It is the only record of desert-dwelling non-pterodactyloid pterosaurs and predates all known desert pterosaurs by more than 65 Myr. A phylogenetic analysis shows it is closely allied with Dimorphodon macronyx from the Early Jurassic of Britain.A new species of Late Triassic pterosaur, Caelestiventus hanseni, predates all other known desert pterosaurs by 65 million years, showing that from an early point in their evolution, pterosaurs were widely geographically distributed and capable of dwelling in harsh environments.

Pennsylvanian Sponges from the Graford Formation, Wise County, Texas

Abstract A variety of Pennsylvanian sponges have been recovered from exposures along the shore of Lake Bridgeport and in nearby areas in Wise County, north-central Texas. Calcareous and hexactinellid sponges have locally weathered out of the Jasper Creek Shale (=upper Lake Bridgeport Shale) and the overlying Devils Den Limestone of the Graford Formation, of Late Pennsylvanian Missourian age. The Demospongea protomonaxonids Heliospongia excavata King, 1933, and Coelocladia spinosa Girty, 1908 are represented in the studied collections by several specimens, as is the new genus and species Luterospongia texana. Agelasid ceractinomorph demosponges are represented by the fissispongiid Fissispongia jacksboroensis King, 1938, the maeandrostiid Maeandrostia kansasensis Girty, 1908, and the girtycoeliid, Girtycoelia typica King, 1933. Sponges of the Class Hexactinellida and the amphidiscophorid Family Stiodermatidae are represented by an extensive suite of specimens of the new genus and species Dermosphaeroidalis irregularis. Representatives of the hexactinellid reticulosid sponges include some unusually large specimens of the vase-shaped Endoplegma calathus Finks, 1960, of the Family Docodermatidae, and fragmental specimens of ?Stereodictyum orthoplectum Finks, 1960, of the Family Stereodictyidae. One unclassified root tuft fragment is also described and illustrated. Much of this diverse sponge fauna was endemic to the western embayment of Pangaea.