Paper No. 29
Presentation Time: 1:30 PM-5:30 PM
INVERTEBRATE ICHNOFAUNA FROM THE MIDDLE PENNSYLVANIAN (DESMOINESIAN) MCALESTER FORMATION (KREBS GROUP), HASKELL CO., OKLAHOMA
New Mexico Museum of Natural History locality 4399, in the Middle Pennsylvanian (Desmoinesian) Keota Sandstone Member, McAlester Formation (Krebs Group) of Haskell County, Oklahoma, yields a diverse invertebrate ichnofauna that includes arthropod tracks, resting traces and feeding trails. The ichnofauna occurs in a 0.8-1.5-m-thick unit of thinly laminated sandstone at the base of the Keota Sandstone Member. These deposits represent a lagoonal setting in a deltaic paleoenvironment. We record the second occurrence of Tonganoxichnus buildexensis Mangano, Buatois, Maples & Lanier, previously known only from the lower Virgilian Tonganoxie Sandstone Member (Stranger Formation) of eastern Kansas. Paleohelcura tridactyla Gilmore is present, extending the North American stratigraphic range of this ichnospecies from the Lower Permian to the Middle Pennsylvanian. Diplichnites gouldi occurs, making this only the second record from the Middle Pennsylvanian. Other ichnotaxa include Diplodichnus biformis, Treptichnus bifurcus, Gordia sp. and Helminthoida sp. There is also an extensive ichnofauna at locality 4399 consisting of tetrapod tracks assigned to two ichnogenera: Pseudobradypus Matthew and Notalacerta Butts. This is the first record of Pseudobradypus in western North America, and the second of Notalacerta. Both ichnotaxa are also known from the Pennsylvanian of eastern North America. A single body impression of an arachnid possibly belonging to the order Palaeoricinulei is also known from this site.