GSA Annual Meeting in Indianapolis, Indiana, USA - 2018

Paper No. 88-7
Presentation Time: 9:45 AM


SPRINKLE, James, Department of Geological Sciences, Jackson School of Geosciences, University of Texas, 1 University Station C1100, Austin, TX 78712-0254, GUENSBURG, Thomas E., IRC, Field Museum, 1400 South Lake Shore Drive, Chicago, IL 60605, RUSHLAU, William, 2706 North 382, Wetumka, OK 74883, MCCALL, Linda J., 132 Mallard Court, Reidsville, NC 27320, THEISEN, Leon, P. O. Box 795, Ardmore, OK 73402-0795, MCKINZIE, Mark G., 11 Enmedio Place, Santa Fe, NM 87508 and VANLANDINGHAM, Steve, 907 W. Eufala, Norman, OK 73069

The Bromide Formation in southern Oklahoma contains one of the largest Late Ordovician echinoderm faunas ever collected from a single formation. When monographed in 1982, the ~11,500 available echinoderms had mostly been collected from three thin intervals in the Bromide: the Lower Echinoderm Zone (LEZ), a 1-2 m shaly interval in the middle Mountain Lake Member; the Upper Echinoderm Zone (UEZ), a 1-4 m shaly and limy interval near the top of the Mountain Lake Member; and the Pooleville Echinoderm Zones (PEZ) in the top 15 m of the thin-bedded, limy, Pooleville Member. An estimated 4,000 additional Bromide echinoderms have now been collected from these three prolific zones, including 8 new genera or species based on 64 type (or more complete) specimens.

Seven new or more complete specimens have been found in the LEZ since 1982, including a new genus of cleiocrinid crinoid (1 specimen figured in a 2008 GSA poster); 4 specimens of a new myeinocystitid solute species not previously found in this zone; 2 slabs with specimens of the camerate Bromidocrinus nodosus with complete arms and partial stems; and a new specimen of the eocrinoid Bromidocystis bassleri with a complete stem and attached holdfast. Most of these came from the ditches on McLish Ranch road, but the cleiocrinid came from Fittstown Quarry.

Thirty-eight new or more complete specimens have been found in the UEZ since 1982, including 9 specimens of a new genus of large camerate crinoid; 13 new specimens of the smaller camerate Paradiabolocrinus stellatus, including several with arms, vs. the single cup known before; an uncrushed specimen of Pleurocystites toddi (named in 1985), showing its highly domed profile; and 15 specimens of a new rhipidocystid genus, the first ever found in the Bromide. Most specimens came from the North I-35 Roadcut or nearby localities, but the rhipidocystids came from Rock Crossing in the Criner Hills.

Nineteen new specimens have been found in the PEZ since 1982, all from Dunn (now Theisen) Quarry in the Criner Hills. These include 2 specimens of Bromidechinus rimaporus (named in 2001); 13 partial specimens of a new “giant echinoid” genus figured in a 2014 GSA poster as a possible edrioasteroid; 2 specimens of a new crinoid genus resembling the British disparid Pandoracrinus; and 2 specimens of a new cyclocystoid genus.