Search

Turtle (Testudines) tracks, Chelonipus torquatus, reported from the early Middle Triassic (Anisian) of Germany, and Chelonipus isp. from the late Early Triassic (Spathian) of Wyoming and Utah, are the oldest fossil evidence of turtles, but have been omitted in recent discussions of turtle origins. These tracks provide significant clues as to how early the turtle Bauplan originated. Turtle trackways are quite distinctive: the manus and pes form tracks nearly parallel to the midline and indicate an unusually wide gait in which the trackway width is nearly equal to the stride length. These tracks do not fit what would be expected to be made by Triassic Pappochelys or Odontochelys, a supposed prototurtle and an early turtle, respectively. In contrast, these tracks are consistent with what would be expected from the Triassic turtles Proganochelys and Palaeochersis. The features inferred to be present in Triassic turtle tracks support the notion that Odontochelys is a derived aquatic branch of the turtl...

We employed the widely-tested biophysiological modeling software, Niche Mapper™ to investigate the metabolic function of Late Triassic dinosaursPlateosaurusandCoelophysisduring global greenhouse conditions. We tested them under a variety of assumptions about resting metabolic rate, evaluated within six microclimate models that bound paleoenvironmental conditions at 12° N paleolatitude, as determined by sedimentological and isotopic proxies for climate within the Chinle Formation of the southwestern United States. Sensitivity testing of metabolic variables and simulated “metabolic chamber” analyses support elevated “ratite-like” metabolic rates and intermediate “monotreme-like” core temperature ranges in these species of early saurischian dinosaur. Our results suggest small theropods may have needed partial to full epidermal insulation in temperate environments, while fully grown prosauropods would have likely been heat stressed in open, hot environments and should have been restricted to cooler microclimates such as dense forests (under any vegitative cover) or those seen at higher latitudes and elevations. This is in agreement with the Late Triassic fossil record and may have contributed to the latitudinal gap in the Triassic prosauropod record.

The last two decades have seen a remarkable increase in the known diversity of basal avialans and their paravian relatives. The lack of resolution in the relationships of these groups combined with attributing the behavior of specialized taxa to the base of Paraves has clouded interpretations of the origin of avialan flight. Here, we describeHesperornithoides miesslerigen. et sp. nov., a new paravian theropod from the Morrison Formation (Late Jurassic) of Wyoming, USA, represented by a single adult or subadult specimen comprising a partial, well-preserved skull and postcranial skeleton. Limb proportions firmly establishHesperornithoidesas occupying a terrestrial, non-volant lifestyle. Our phylogenetic analysis emphasizes extensive taxonomic sampling and robust character construction, recovering the new taxon most parsimoniously as a troodontid close toDaliansaurus,Xixiasaurus, andSinusonasus. Multiple alternative paravian topologies have similar degrees of support, but proposals of basal paravian archaeopterygids, avialan microraptorians, andRahonavisbeing closer to Pygostylia than archaeopterygids or unenlagiines are strongly rejected. All parsimonious results support the hypothesis that each early paravian clade was plesiomorphically flightless, raising the possibility that avian flight originated as late as the Late Jurassic or Early Cretaceous.

The Alcova Limestone is a widely exposed but poorly studied Triassic unit found throughout Wyoming. Although it is used as a regional lithostratigraphic marker bed, the age of the limestone is not well constrained and contention regarding its depositional nature (marine vs. non-marine saline lake) has not been adequately resolved, although the marine hypothesis is more widely accepted. Currently, its age is based on the occurrence of a single basal pistosaurid, Corosaurus alcovensis . We provide the first 87 Sr/ 86 Sr analysis of the Alcova Limestone. The data strongly support a marine origin for this unit. Furthermore, the data provide an age range, based on their placement on the marine strontium curve, that limits the deposition of the Alcova Limestone to the latest Olenekian to earliest Anisian (Early Triassic–Middle Triassic boundary). This placement is consistent with the timing of the Spathian regression recorded in other transitional marine to non-marine strata of the western USA.

A vertebral element assigned to an Apatosaurus cf. ajax from the Late Jurassic Morrison Formation is described. The specimen exhibits an unusual morphology where two vertebrae are nearly seamlessly fused together, including the haemal arch that spans them. This morphology is thought be the result of a developmental abnormality. CT scans of the specimen reveal a thin zone of dorsoventral thickening between the two neural arches consistent with cortical bone. Contrast in internal morphology differentiates the anterior and posterior vertebral bodies with the anterior expressing greater porosity, which increased accommodation for barite-rich calcite precipitation. No vacuities are observed to suggest the former presence of an intervertebral disk or intervertebral joints: the absence of an intervertebral disc or intervertebral joints is indicative of a condition known as block vertebra. Block vertebrae occur with the loss, or inhibition, of somitocoele mesenchyme early in embyogenesis (i.e., during resegmentation of the somites responsible for the formation of the affected vertebra). The derivatives of somitocoele mesenchyme include the intervertebral disc and joints. Although vertebral paleopathologies are not uncommon in the fossil record, this specimen is the first recognized congenital malformation within Sauropoda. Anat Rec, 297:1262–1269, 2014. © 2014 Wiley Periodicals, Inc.

The Lower Triassic Red Peak Formation of the Chugwater Group has long been considered to have an extremely poor paleontological record, although the cause for the apparent dearth of fossils has yet to be been determined. During the course of fieldwork in central Wyoming numerous vertebrate and invertebrate ichnogenera (n ≥ 11) were observed. Vertebrate tracks and trackways representative of dinosauromorph, archosaur, lepidosaur, and testudinate trackmakers were found (cf. Rotodactylus, Chirotherium barthii, Rhynchosauroides, and cf. Chelonipus respectively). An invertebrate ichnoassemblage composed of at least 6 ichnogenera consistent with the Scoyenia ichnofacies were also found (e.g., Diplichnites, Lockeia, Fuersichnus communis, Palaeophycus striatus, cf. Scoyenia, and cf. Scolicia). The majority of these tracks and traces were found in the upper platy facies (upper 10–20 m of the of the Red Peak Formation), which is thought to be no younger than upper Spathian in age. Sedimentary structures, architectural elements, and lateral stratigraphic relationships support the interpretation of floodplain, fluvial, and lacustrine deposition for the upper platy facies in central Wyoming. The Red Peak Formation vertebrate and invertebrate ichnoassemblages, along with their associated depositional environments, are consistent with a fluviolacustrine (continental) setting comparable to those described from Lower to Middle Triassic strata with a Pangean distribution, including the Moenkopi Formation in the southwestern United States. This ichnoassemblage provides the first opportunity to observe paleoecological diversity and associated paleoenvironments within the Lower Triassic of the Chugwater Group.

Electron transfer between redox active proteins and mineral oxides is important in a variety of natural as well as technological processes, including electron transfer from dissimilatory metal-reducing bacteria to minerals. One of the pathways that could trigger electron transfer between proteins and minerals is redox-linked conformation change. We present electrochemical evidence that mitochondrial cytochrome c (Mcc) undergoes significant conformation change upon interaction with hematite and indium-tin oxide (ITO) surfaces. The apparent adsorption-induced conformation change causes the protein to become more reducing, which makes it able to transfer electrons to the hematite conduction band. Although Mcc is not a protein thought to be involved in interaction with mineral surfaces, it shares (or can be conformed so as to share) some characteristics with multiheme outer-membrane cytochromes thought to be involved in the transfer of electrons from dissimilatory iron-reducing bacteria to ferric minerals during respiration. We present evidence that a 10.1 kDa monohoeme cytochrome isolated and purified from Acidiphilium cryptum, with properties similar to those of Mcc, also undergoes conformation change as a result of interaction with hematite surfaces.