FAUNA AND DEPOSITIONAL ENVIRONMENT OF A LATE PENNSYLVANIAN VERTEBRATE FOSSIL LOCALITY IN SOUTHEASTERN KANSAS

A new fossil locality in eastern Greenwood County, near Toronto, Kansas discovered in the Snyderville (Shale) member of the Oread (Limestone) Formation (Pennsylvanian, Virgilian) contains an abundance of disarticulated vertebrate fossils weathering out of a paleosol. This new locality lies stratigraphically between the well-known Garnett and Hamilton fossil localities, although geographically separate from both of them.

Currently identified taxa from the new site include the lungfish Sagenodus c.f. S. serratus, xenacanthid sharks, eryopoid and embolomere amphibians, and diadectomorph, ophiacodontid, and sphenacodontid pelycosaurs. The fossils appear to be preserved via mineral replacement, though permineralization is frequent. Preservation quality maintains fine details, although the majority of specimens are broken. So far, no fossil invertebrates or plants have been recovered. Tetrapods are the most common fossils, while xenacanths are far less common. Sagenodusspecimens are rare, with only three tooth plates found to date.

Three paleosols are present at the locality, which are separated by one or more layers of red-brown clays. These clay layers contain abundant diagenetic calcareous and ferric concretions. No marine deposits are present. The alternation of clays and paleosols indicate there were multiple periods of clay deposition followed by periods of nondeposition and soil formation. The fossils are weathering out of an approximately 24.5 m exposure of a 6 cm horizon in the upper portion of lowest paleosol layer. Few thin coal lenses found in the same horizon as the fossils indicate that the region was vegetated.

The presence of the paleosols, the abundance of tetrapod fossils, and the lack of marine strata and fossils suggest that the environment of deposition was terrestrial. The fossil fish are taxa found in both marine and freshwater deposits, which indicates the nearby presence of water, but does not indicate a specific environment. Together, the evidence suggests a probable fluvial floodplain depositional environment.