OSTRACODES FROM WAULSORTIAN-LIKE MUDMOUNDS OF CENTRAL TENNESSEE
In east central Tennessee bryozoan-crinoid rich mudmounds occur at the very base of the Fort Payne immediately overlying the Maury Shale. The Tennessee mounds are similar to Waulsortian mounds that were first described from Europe, but are now known to have a worldwide distribution in rocks of early Mississippian age.
Waulsortian ostracodes have been reported only from the Ardennes of central Europe (Coen and Michaels, 1988). A single locality east central Tennessee has yielded a low diversity ostracode fauna recovered from shale beds located near the base of a Waulsortian-like mound. This fauna is important because it represents the first documented occurrence of Waulsortian ostracodes from North America. The Tennessee fauna is of low diversity and dominated by Kirkbya magna (Roth), 1929. It has subordinate numbers of species of Bairdia. This fauna is significantly different than the Waulsortian of the Ardennes, which is more diverse and dominated by several species of Paraparchitids.
The mound assemblage contrasts markedly from shales representing three other environments within the Fort Payne. These include 1) non-mounded shales of Stewart County in west central Tennessee deposited in a sediment-starved basin, 2) pro-deltaic calcareous shales at Baker’s Station in Davidson County, and 3) mid-shelf mixed carbonate-clastic shales from Dale Hollow Lake in Pickett County. The Stewart Co. assemblage has low species diversity and is dominated by Graphiadactyllis fernglensis Benson, 1955. The Baker’s Station fauna has low diversity and is dominated by Graphiadactyllis lineatus (Ulrich & Bassler), 1932. The Dale Hollow assemblage comprises a highly diverse assemblage with an equitable distribution of individuals among some 16 species. The most prominent among these species are Ectodemites warei (Morey),1935, Cavellina congruens (Cooper), 1941, Bairdia cestriensis (Ulrich), 1891, and two species of Bairdiacypris.