TRACKWAYS FROM THE PENNSYLVANIAN-PERMIAN OF CENTRAL COLORADO

In recent years a number of new vertebrate and tracksites have been found in Late Paleozoic (Pennsylvanian- Permian) deposits from the Central Colorado Trough. We here report four significant new sites, which require future detailed investigation. The first site yields a large Diplichnites trackway from the Pennsylvanian (Atokan-Desmoinesian) Minturn Formation of the McCoy area, where the stratigraphy is well documented. The trackway is 5-6cm wide and represents a large terrestrial myriapod. A second site yields vertebrate tracks from poorly exposed red beds near Buena Vista. The tracks represent large vertebrates tentatively labeled cf. Dimetropus, which is popularly attributed to a Dimetrodon-like pelycosaur or sphenacodontid. The tracksite is thought to be in either the Minturn or Maroon formations, based on local geologic maps. A third site, in theMaroon Formation just west of Glenwood Springs, consists of two parallel trackways of a large vertebrate. The tracks resemble the ichnogenus Ichnotherium. The section is well exposed in this area allowing the tracks to be placed in proper stratigraphic context. A fourth site is known only from an isolated specimen discovered on North Maroon Peak (Maroon Bells area). The specimen reveals several small tetrapod tracks that have not been assigned an ichnogenus label. Collectively these sites point to the untapped ichnological potential of Pennsylvanian-Permian terrestrial ‘red bed' deposits in Colorado. In recent years a renaissance in the study of Late Paleozoic tracks in the greater Rocky Mountain region (especially New Mexico) confirms this potential and provides a basis for ichnotaxonomic comparisons.