A NEARLY COMPLETE MACROSTOMATAN SNAKE FROM THE EOCENE OF TEXAS

BARTH ANJAN S. BHULLAR; AGUSTÍN SCANFERLA; GABE BEVER; KRISTER SMITH

Cleveland

Congreso; 68th Annual meeting of the Society of Vertebrate Paleontology; 2008

The Chadronian faunas of western Texas, collected largely in the middle of the last century by J.A. Wilson of UT Austin and his field crews, represent a unique slice of biotic time and space. Only the mammal faunas, which contain many unique and evolutionary significant taxa, have been carefully examined. We report the existence of a nearly complete snake skeleton from the West Texas Eocene. Articulated snake material including the cranium is extremely rare in the fossil record; the only other comparable specimens from North America are two incompletely described skeletons of an erycine-like taxon from the River Oligocene and one flattened specimen, now lost, of the taxon Boavus from the Green River Eocene. The Texas macrostomatan lies in a natural position, its body loosely coiled. Nearly the entire postcranium is preserved, and the head is complete save for the anteriormost bones of the snout, the suspensorium, and the basioccipital, supraoccipital, and otooccipitals of the braincase. However, the indurated sandstone matrix is difficult to prepare without specimen damage, and we utilize CT scans for anatomical description. The Texas macrostomatan does not appear to show erycine affinities as suggested for the White River skeletons, nor tropidophiid affinities as suggested for various other Tertiary macrostomatans. Cranially, the abbreviated and expanded parietal, the narrow maxilla, and precise phylogenetic hypothesis is hindered by the lack of consensus regarding the topologyfeatures of the sphenoid show synapomorphies with various groups of ‘boid’ snakes, but a of this part of the snake tree. The neural arches of the mid-trunk vertebrae are unusually tall compared to the centra, a feature shared with taxa assigned to Boavus. If the Texas macrostomatan is nested within a monophyletic Boavus, it would be the first well-preserved specimen of that taxon since the loss of the Green River specimen. Regardless, it represents an opportunity to apply fossil evidence to the problematic question of the phylogeny of small non-colubroid macrostomatan snakes