Ruedemann's Spellman Ledge, Beekmantown Group, (=Spelman Ledge) (Ordovician of the United States)

Also known as NYSM locality 3327

Where: New York (44.8° N, 73.5° W: paleocoordinates 30.0° S, 61.0° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Oepikodus communis - Reutterodus andinus conodont zone, Ward Member (Fort Cassin Formation), Cassinian (478.6 - 468.1 Ma)

• corrected by Kröger 07/07/2009

• member-level stratigraphic resolution

Environment/lithology: shallow subtidal; lithified, sandy, carbonaceous sandstone

• As other Beekmantown Group units, the Fort Cassin includes two lithologically distinct divisions. The lower is a transgressive systems tract interval with a basal carbonate clast conglomerate succeeded by a thin-bedded, quartzose to dolomitic quartz arenite [Ward Member of Fisher (1977); formally defined in Fisher (1984)]. The 0–ca. 5.0 m-thick

•Ward Member is overlain by the carbonate-dominated, highstand facies of the Sciota Member [named in Fisher (1977); formally defined in Fisher (1984)]. We agree with Brett

•and Westrop (1996, p. 408) that Welby’s (1961) ‘‘Thorp Point’’ and ‘‘Emerson School’’ Members of the Fort Cassin Formation in Vermont should be abandoned. These unmappable divisions of the upper Fort Cassin (i.e., the Sciota Member) were distinguished by a ‘‘Calaurops bed’’ at the base of a reportedly less arenaceous ‘‘Emerson School Member’’— although Welby (1961, p. 77, sections 9, 10) reported Calaurops lituiformis Whitfield, 1890, in the ‘‘Thorp Point Member’’ and documented sandy beds in the ‘‘Emerson School.’

Size class: macrofossils

Preservation: mold/impression, original aragonite

Primary reference: R. Ruedemann. 1906. Cephalopoda of the Beekmantown and Chazy formations of the Champlain Basin. Bulletin of the New York State Museum, Paleontology 14:389-611 [P. Wagner/K. Koverman/M. Uhen]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 42782: authorized by Pete Wagner, entered by Kimberly Koverman on 05.08.2004, edited by Björn Kröger

Creative Commons license: CC BY (attribution)

Taxonomic list

Gastropoda
 Euomphalina - Ophiletidae
"Cyrtendoceras priscum" = Cyrtendoceras priscum1, "Beekmanoceras priscum" = Cyrtendoceras priscum3
"Cyrtendoceras priscum" = Cyrtendoceras priscum1 Ruedemann 1906 snail
"Beekmanoceras priscum" = Cyrtendoceras priscum3 Ruedemann 1906 snail
Cephalopoda
 Orthocerida - Baltoceratidae
 Ellesmerocerida - Ellesmeroceratidae
Bassleroceras kirbyi3 Whitfield 1889
Bassleroceras beekmanense3 Whitfield 1889
 Endocerida - Endoceratidae
Endoceras champlainense1 Ruedemann 1906
 Tarphycerida - Tarphyceratidae
Seelyoceras raei3 Whitfield 1889
 Orthoceratoidea - Protocycloceratidae
"Protocycloceras furtivum" = Protocycloceras furtivum2, "Orthoceras furtivum" = Protocycloceras furtivum3, "Protocycloceras lamarcki" = Protocycloceras lamarcki, "Orthoceras lamarcki" = Protocycloceras lamarcki3
"Protocycloceras furtivum" = Protocycloceras furtivum2 Billings 1865
"Orthoceras furtivum" = Protocycloceras furtivum3 Billings 1865
"Protocycloceras lamarcki" = Protocycloceras lamarcki Salter and in Murchison 1859
"Orthoceras lamarcki" = Protocycloceras lamarcki3 Salter and in Murchison 1859