Publications by authors named "Bryan J Small"

Libognathus sheddi, a leptopleuronine procolophonid from the Upper Triassic Cooper Canyon Formation, Dockum Group, West Texas, was based on an isolated left dentary and partial coronoid. New material referable to Libognathus sheddi, from the Cooper Canyon Formation, provides new information on the cranial anatomy. This new cranial material includes the antorbital portion of a skull, a left maxilla and premaxilla, quadratojugals, and dentaries, including intact tooth rows in the upper and lower jaws.

View Article and Find Full Text PDF

The "red siltstone" member of the Upper Triassic Chinle Formation in the Eagle Basin of Colorado contains a diverse assemblage of dinosauromorphs falling outside of Dinosauria. This assemblage is the northernmost known occurrence of non-dinosaurian dinosauromorphs in North America, and probably falls within the Revueltian land vertebrate estimated biochronozone (215-207 Ma, middle to late Norian). Lagerpetids are represented by proximal femora and a humerus referable to .

View Article and Find Full Text PDF

The Carboniferous-Permian transition (CPT) was Earth's last pre-Quaternary icehouse-greenhouse transition, recording major shifts in late Palaeozoic climate regimes and increased continental seasonality over approximately 40 Myr. Its parallels to Quaternary climate change have inspired recent investigations into the impacts of purported rainforest collapse on palaeotropical vertebrate diversity, but little is known about how the protracted spatial dynamics of this transition impacted the emergence of modern tetrapod lineages. Here, we apply ecological ordinance analyses on a dataset of 286 CPT fossil vertebrate localities binned across four physiographic regions forming a palaeoequatorial transect.

View Article and Find Full Text PDF

The origin of the limbless caecilians remains a lasting question in vertebrate evolution. Molecular phylogenies and morphology support that caecilians are the sister taxon of batrachians (frogs and salamanders), from which they diverged no later than the early Permian. Although recent efforts have discovered new, early members of the batrachian lineage, the record of pre-Cretaceous caecilians is limited to a single species, The position of within tetrapod phylogeny is controversial, as it already acquired the specialized morphology that characterizes modern caecilians by the Jurassic.

View Article and Find Full Text PDF