129-26 Paleobotany of the Mingus Shale (Desmoinesian, Pennsylvanian), Palo Pinto County, Texas

Abstract:

During the Middle Pennsylvanian, along the margins of the Eastern shelf of the Permian Basin, deltas prograded from the Ouchita Mountains in the east, into swampy lowland environments.  River channels and flood plains crossing these lowlands created a variety of wetland and drier habitats in close proximity to one another. Plant fossils have been collected from two outcrops of the Mingus shale located 15 miles southwest of Mineral Wells, Texas. The western locality, at the base of the Lake Palo Pinto Creek spillway (MSPP), is less than two miles away from the eastern locality, Ward Mountain (WMTN). Floral assemblages of marattialean ferns, filicalean ferns, lycopsids, cordaitaleans, sphenopsids, pteridosperms and coniferophytes have been recovered from these sites. Despite the short distance between the localities, the degree of preservation and floral diversity varies significantly. Fossils collected from WMTN are large, well-articulated and represent a diverse flora. MSPP has produced smaller fragmented plants dominated by marattialean ferns and lacks many of the species found to the east. Large, well-preserved mats of two species of Sphenophyllum are present at WMTN while MSPP specimens are fewer in occurrence and of a single species. Large fern pinna have been recovered at WMTN whereas MSPP fern specimens are only fragments of pinnules. Several species are found only at WMTN including Mixonera sp., Macroneuropteris sp., and Neropteris sp.. Restricted to WMTN are specimens of Walchia, Annularia, Cordaitanthus, Calamites, Sigillaria  and  Stigmaria. Fragment size, diversity, and preservation increase as depositional distance from the paleo-shoreline decreases. The MSPP floral assemblage is interpreted as allochthonous, while the WMTN assemblage is parautochthonous.

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