Southern Franklin Mts. at El Paso (Ordovician of the United States)

Where: El Paso County, Texas (31.8° N, 106.5° W: paleocoordinates 15.0° S, 87.6° W)

• coordinate based on nearby landmark

• small collection-level geographic resolution

When: Scenic Drive Formation (El Paso Group), Cassinian (478.6 - 468.1 Ma)

• " [...] from the upper part of the dolomites, bed 8 of Cloud & Barnes [1946, Univ. Texas Publ. 4621], in the lower part of the Cassinian (unit B2b) [...] " (p. 104)

•B2B means "submember" b of "member" 2 of "formation" B of El Paso Group. This interval corresponds to the Scenic Drive Fm. or to the Cindy Fm. and lower Ranger Peak Fm., respectively (see fig. 4 in Goldham et al., 1993, J. Sedim. Petr. 63(3))

• member-level stratigraphic resolution

Environment/lithology: shallow subtidal; black dolomite

• "The southern Franklin Mountains [...] in west Texas [...] form the southeastern part of the Cambro-Ordovician Diablo Platform [...], which presents a thick Lower Ordovician shallow-marine carbonate section that accumulated as part of a huge, gently dipping carbonate platform that rimmed the North American continent. The Lower Ordovician is a passive-margin sequence resting unconformably on a rifted Precambrian succession." (Goldhammer et al., 1993)
• "two 8- to 12-inch layers of black dolomite [...] contain silicified fossils"

Size class: macrofossils

Preservation: recrystallized, replaced with silica

Reposited in the USNM

• RHF = collection of Rousseau H. Flower, transferred to the Smithsonian Institution/U.S. National Museum (see Wolberg, 1990, J. Paleont. 64(3, 5, 6))

Primary reference: R. H. Flower. 1964. The Nautiloid Order Ellesmeroceratida (Cephalopoda). State Bureau of Mines and Mineral Resources New Mexico Institute of Mining and Technology, Memoir 12:234 p. [B. Kröger/T. Liebrecht/P. Wagner]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 88838: authorized by Björn Kröger, entered by Torsten Liebrecht on 22.04.2009

Creative Commons license: CC BY (attribution)

Taxonomic list

Cephalopoda
 Ellesmerocerida - Rioceratidae
Rioceras dartoni n. sp. Flower 1964
RHF 866 (holotype), 867-869 (paratypes)
Rioceras wellsi n. sp. Flower 1964
RHF 876 (holotype), 877-880, 881 (part?) (all are paratypes)
Rioceras tubulare n. sp. Flower 1964
RHF 881 (part?, holotype)
 Ellesmerocerida - Protocycloceratidae
Cyptendoceras richardsoni n. sp. Flower 1964
RHF 870 (holotype), 871-875 (paratypes)
Catoraphiceras sp. Ulrich and Foerste 1936
RHF 399