Reptile trackway from the Lee Formation (Lower Pennsylvanian) of south-central Kentucky

Abstract

An Early Pennsylvanian tetrapod trackway, referred to Notalacerta missouriensis Butts, was found in the Rockcastle Sandstone Member (Westphalian A, Upper Carboniferous) of the Lee Formation in McCreary County, Kentucky. Terrestrial characteristics of the trackway, such as digit length, claw marks, gait, and tail drag, suggest that it was made by a member of the primitive reptile family Protorothyrididae. If identified correctly, this is the oldest known reptile trackway in North America. The animal that made the trackway was approximately 0.4 m in length. The pes tracks are slightly larger and set slightly wider than the manus tracks; digits are elongated and slender, and the fourth digit of the pes is the longest. Whereas the slender, long toes indicate a terrestrial form, the gait was more advanced than the sprawling gait typical of the most primitive tetrapods.