Meeting Abstract
Despite their unassuming appearance and small size, pipid frogs, including the well-known African Clawed Frog Xenopus, are a diverse and evolutionarily informative group of early-diverging Anura. Though their external morphology is not ostensibly varied, pipid braincases are morphologically diverse. Their small size means that they are often recovered with three-dimensional preservation as fossils. Because molecular evidence is almost never available from fossils, placement of these taxa would normally be based entirely on morphological analyses. Our goal was to use 3D imaging and statistical analysis to analyze morphology and affinities of pipids in a less labor-intensive, faster, and more statistically robust way. Using high-energy Computed Tomography (CT) scanning, we modeled and analyzed the braincase morphology of almost two dozen extant and two extinct pipid species: Oumkoutia anae and a recently discovered pipid from the Oligocene of Tanzania. A 20-landmark analysis of the braincases proved highly informative. We also achieved significant and revealing results regarding allometry across pipids and Xenopus, and regarding the disparity of shape diversity in different areas of the braincase across Xenopus. Using Principal Component Analysis (PCA), we were able to investigate the clustering of species in morphospace across the entirety of sampled taxa and use these data to estimate phylogenetic placement of the two fossil species. While the affinities of Oumkoutia remain unclear, the fossil pipid from Tanzania can be interpreted with confidence to be a close relative of X. itombwensis.
