Some late Cretaceous? and Paleogene freshwater ostracoda from Central and Eastern Nevada

• F.M. Swain ^[1]
  1. [1] University of Delaware

     University of Delaware

     Estados Unidos

     
• Localización: Revista española de micropaleontología, ISSN 0556-655X, Vol. 19, Nº. 2, 1987, págs. 215-238
• Idioma: inglés
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• Resumen

  • A small fauna of 20 species of freshwater Ostracoda is described from the Late Cretaceous?, Paleocene and Eocene? Sheep Pass Formation of Eureka and Nye Counties, Nevada; from the Middle? and Late? Eocene Twin Bridges Limestone, and the Late Eocene and Oligocene ? Elko Formation of western Elko County, Nevada. Eight of the species are newly described; three species were previously described and eight species are given affinitive assignment or are left in open nomenclature. The new species are: Chlamydotheca? dixieflatensis, n. sp.; Paracypridopsis? fouchi, n. sp.; Herpetocypris? winfreyi, n. sp.; Cyclocypris? ketneri, n. sp.; Procyprois twinbridgensis, n. sp.; Cyprus whiteflatensis, n. sp.; Pontoniella? catlinensis, n. sp., and Timiriasevia? heylmuni, n. sp.

    The Sheep Pass ostracodes are represented by Late Cretaceous? and Paleocene deposits with Cypridea (Bisulcocypridea) bicostata and younger Paleocene and Eocene? deposits with C. (B.) nyensis.

    The Twin Bridges ostracodes differ from those described previously from the Sheep Pass Formation of east-central Nevada and from the Early and Middle Eocene Green River Formation of eastern Utah and western Colorado and are here suggested to be Late Eocene. The Elko oil shales contain a predominantly different ostracode assemblage from that in the underlying Twin Bridges Limestone and have several species that suggest a relationship to the younger Tertiary rocks of the region. The Elko fauna may be late Eocene or early Oligocene in age, as has been suggested by others.