Cranial anatomy and phylogenetic affinities of Bolosaurus major, with new information on the unique bolosaurid feeding apparatus and evolution of the impedance-matching ear.

Resolving the phylogenetic relationships of early amniotes, in particular stem reptiles, remains a difficult problem. Three-dimensional morphological analysis of well-preserved stem-reptile specimens can reveal important anatomical data and clarify regions of phylogeny. Here, we present the first thorough description of the unusual early Permian stem reptile Bolosaurus major, including the first comprehensive description of a bolosaurid braincase.

A Morrison stem gekkotan reveals gecko evolution and Jurassic biogeography.

Geckos are a speciose and globally distributed clade of (lizards, including snakes and amphisbaenians) that are characterized by a host of modifications for nocturnal, scansorial and insectivorous ecologies. They are among the oldest divergences in the lizard crown, so understanding the origin of geckoes () is essential to understanding the origin of , the most species-rich extant tetrapod clade. However, the poor fossil record of gekkotans has obscured the sequence and timing of the assembly of their distinctive morphology.

The affinities of the Late Triassic and the age of crown squamates.

Most living reptile diversity is concentrated in Squamata (lizards, including snakes), which have poorly known origins in space and time. Recently, † from the Late Triassic of the United Kingdom was described as the oldest crown squamate. If true, this result would push back the origin of all major lizard clades by 30-65 Myr and suggest that divergence times for reptile clades estimated using genomic and morphological data are grossly inaccurate.

Evolutionary origins of the prolonged extant squamate radiation.

Squamata is the most diverse clade of terrestrial vertebrates. Although the origin of pan-squamates lies in the Triassic, the oldest undisputed members of extant clades known from nearly complete, uncrushed material come from the Cretaceous. Here, we describe three-dimensionally preserved partial skulls of two new crown lizards from the Late Jurassic of North America.

Re-description of the early Triassic diapsid Palacrodon from the lower Fremouw formation of Antarctica.

The rapid radiation and dispersal of crown reptiles following the end-Permian mass extinction characterizes the earliest phase of the Mesozoic. Phylogenetically, this early radiation is difficult to interpret, with polytomies near the crown node, long ghost lineages, and enigmatic origins for crown group clades. Better understanding of poorly known taxa from this time can aid in our understanding of this radiation and Permo-Triassic ecology.

A developmental staging system and musculoskeletal development sequence of the common musk turtle (Sternotherus odoratus).

Background: The extremely derived body plan of turtles has sparked a great interest in studying their developmental biology. Here, we describe the embryonic development of the Stinkpot, or common musk turtle (Sternotherus odoratus), a small aquatic turtle from the family Kinosternidae.

Results: We identify 20 distinct developmental stages, some comparable to stages described by previous studies on other turtles and some in between these, improving the resolution of the generalities of turtle development.