Browsing by Subject "Paleontology -- Pennsylvanian"
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Item Middle-late Pennsylvanian fusulinid faunas from Midcontinent North American and the Paradox Basin, Utah and Colorado(Texas Tech University, 1996-05) Nail, Robert SThe utility and limits of using fusulinids for biostratigraphy in cyclical depositional sequences are evaluated in two studies on Middle-Late Pennsylvanian strata in North America. The first study concentrates on the fusulinid succession in Missourian-Virgilian transitional strata within the type region of the North American Midcontinent. The fusulinid faunas from the Captain Creek Limestone Member, Stanton Limestone Formation through the Amazonia Limestone Member, Lawrence Formation are described and illustrated. The fusulinid succession consists dominantly of Triticites species, and nine new species and subspecies are recognized. Species oí Kansanella constitute a minor part of the flisulinid succession, and one new species is recognized. Fusulinid distribution is analyzed in six depositional cycles (cyclothems): the Stanton, South Bend, latan, Westphalia, Haskell, and Amazonia cycles. The transgressive limestone facies of each cycle extends throughout the study area, but the regressive limestone facies is not always present. Fusulinid faunas are not only cycle specific, but some species are restricted to the transgressive or regressive phase. Thus, flisulinid faunas may delimit time intervals less than the duration of a cyclothem. Many biostratigraphic datums can be defined by diagnostic species and are intimately associated with glacioeustatic cycles, which enables a high level of correlation within the Midcontinent region. Unfortunately, few of the biostratigraphic datums defined by Midcontinent fusulinid species can be recognized in other geographic regions due to provincialism. The second study documents Middle-Late Pennsylvanian fusulinids from the Paradox Basin in Utah and Colorado. Detailed biostratigraphic data for Paradox Basin strata do not exist due to the dominance of shallow-water depositional environments, and a paucity of significant biostratigraphic fauna. Several outcropping and subsurface fusulinid horizons from the Hermosa Group yielded species of Triticites, Beedeina, Fusulinella?, and Oketaella. The fusulinid faunas indicate the presence of Desmoinesian, Missourian, and Virgilian age strata. The flisulinid succession provides data with which to assign ages to depositional sequences, and permit the correlation of these cycles within the basin and with major eustatic events in the Midcontinent region.Item Paleontology and geology of an upper Pennsylvanian tetrapod locality from the Ada Formation: Seminole County, Oklahoma(Texas Tech University, 1999-12) Kissel, Richard AnthonyThe paleontology, taphonomy, stratigraphy, depositional setting, and paleozoogeographic significance of an Upper Pennsylvanian tetrapod-bearing fossil locality is presented. The site, OMNH Locality V1005, is located within the Virgilian Ada Formation in southcentral Oklahoma, north of the town of Ada. The fossiliferous outcrop represents a meandering stream deposit, with the majority of the exposure consisting of fine-grained overbank (floodplain) deposits. The fossil material is found within a single horizon that stretches 11 meters along the face of the outcrop. This horizon is located within a gray mudstone unit and is 22.4 meters above the contact between the Ada Formation and the imderlying Vamoosa Formation. The bone-bearing interval is further characterized by the presence of granule-sized carbonate rock clasts and carbonized plant material. Tetrapod fossils recovered fi-om the Ada locality include the remains of at least six taxa, with remains of the pelycosaurian-grade synapsid Ophiacodon cf O. mirus constituting the majority (90 percent) of the fossil material collected and identified. Other taxa include the diadectid Diasparactus zenos, the temnospondyl ?Eryops sp., and three unidentified taxa known only from jaw fragments. An absolute minimum of five Ophiacodon individuals were recovered from the site, including the remains of both mature and immature individuals. Moreover, the material recovered from the Ada locality suggests, for the first time, the presence of size-based sexual dimorphism within the genus Ophiacodon. Linear measurements of the larger dimorph are approximately 1.5 times as great as those of the small form. No gender assignment is suggested. Of the five remaining taxa, no evidence supports the presence of more than one individual of each taxon. Except for four articulated vertebral segments, all of the fossil material collected in situ was disarticulated. The presence of articulated vertebral sequences, while all other skeletal elements are isolated and disarticulated, suggests that the vertebral column represents the last stage of the disarticulation sequence of an Ophiacodon corpse. The vertebral segments are straight and relaxed, which indicates that the corpses decomposed in water. All of the in situ bones are complete except for the anterior margin of a scapulocoracoid and the puboischiadic plate of a pelvic girdle. The bone surfaces exhibit no indication of cracking or flaking and, thus, were not exposed to prolonged periods of weathering at the surface. All fractures are indicative of post-burial breakage. The hypothesis that the bones were buried relatively quickly after the individuals' deaths is also supported by the lack of tooth marks and other evidence of scavenging. The fossil material represents a transported assemblage and the orientation of the long bones indicates that flow direction was either northwest or southeast during the time of deposition. Furthermore, the dip of several bones relative to the stratification suggests rapid deposition under flood conditions. OMNH Locality VI005 significantly extends the paleozoogeographic range of the taxa recovered. Diasparactus zenos is no longer restricted to the Upper Pennsylvanian deposits of El Cobre Canyon, New Mexico, and, thus, can no longer be considered endemic to that region. The Ada locality records the first Late Pennsylvanian report of Eryops outside of Pennsylvania. It also presents the first occurrence oi Ophiacodon within the Upper Pennsylvanian units of Oklahoma. Furthermore, O. mirus has been positively identified fi-om only the Lower Permian of New Mexico. If the Ada Ophiacodon is indeed referrable to O. mirus, then OMNH Locality VI005 extends both the stratigraphic and geographic range of this species to include the Upper Pennsylvanian of central Oklahoma.