Two skulls of the early Oligocene Colodon from the White River Group in South Dakota are much more derived than previously reported. In particular, morphologies of the facial skeleton and narial region are surprisingly modern, including a deeply retracted nasoincisive incisure, and other indicators of prehensile proboscis development. High-resolution X-ray computed tomography was used to explore the internal anatomy of these tapiroids, and revealed frontal sinuses, and an internal facial skeleton approaching that of modern tapirs. This not only indicates an earlier origin for these anatomical conditions than previously recorded, but in a phylogenetic context indicates that Colodon is more closely related to Tapirus than is Protapirus.
Matthew W. Colbert. The Jackson School of Geosciences, The University of Texas at Austin, Geological Sciences Department, 1 University Station C1100, Austin, Texas 78712-0254 USA
KEY WORDS: Tapiroidea; Colodon; anatomy, cranial; computed tomography; phylogeny
PE Article Number: 8.1.12
Copyright: Society of Vertebrate Paleontology May 2005
Submission: 20 December 2004. Acceptance: 24 March 2005