Rochdale (Ordovician of the United States)

Also known as cephalopod localities D and F of Dwight (1884); Rochdale Fm., "Fort Ann Fm."; Dutchess Co.

Where: Dutchess County, New York (41.7° N, 73.8° W: paleocoordinates 32.7° S, 69.3° W)

• coordinate based on nearby landmark

• small collection-level geographic resolution

When: Rochdale Formation (Beekmantown Group), Stairsian (485.4 - 478.6 Ma)

• "As concluded by Landing & Westrop (2006, p. 967), the Rochdale Formation is the senior synonym of the ‘Fort Ann Formation’, a unit for which a type section was never specified and which was named for a village that is actually located on Late Ordovician synorogenic flysch. Further north in western Vermont, the Bascom Formation (Cady, 1945) includes three divisions that indicate lateral equivalency and junior synonymy with the upper Tribes Hill, Rochdale and Fort Cassin formations (Landing, Westrop & Van Aller Hernick, 2003)." (Kröger & Landing, 2008 p. 492)

• formation-level stratigraphic resolution

Environment/lithology: shallow subtidal; stromatolitic, shelly/skeletal reef rocks

• "These thrombolitic- and intraclast dominated horizons are very similar to the cephalopod bearing beds of the underlying upper Tribes Hill Formation (Kröger & Landing, 2007) and represent the shoaling interval of a highstand systems tract."
• " [...] interbedded sucrosic dolostone and fossil wackestone beds, with Bassleroceras conchs noted at 6.0 m. The top of the Rochdale (15.7–16.6) is a massive thrombolitic limestone with abundant basslerocerids and endocerids."

Size class: macrofossils

Preservation: cast

Collected by W. B. Dwight; reposited in the NYSM

• "Dwight’s collections, including his illustrated types (Dwight, 1884), were

•transferred from Vassar College in Poughkeepsie, New York, to the New York State Museum (NYSM) Paleontology Collection, probably in the first half of the

•20th century."

Primary reference: B. Kröger and E. Landing. 2008. Onset of the Ordovician cephalopod radiation - evidence from the Rochdale Formation (middle Early Ordovician, Stairsian)in eastern New York. Geological Magazine 145(4):490-520 [B. Kröger/B. Kröger]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 89492: authorized by Björn Kröger, entered by Torsten Liebrecht on 26.05.2009, edited by Björn Kröger

Creative Commons license: CC BY (attribution)

Taxonomic list

Cephalopoda
 Ellesmerocerida - Ellesmeroceratidae
"Cyrtoceras vassarina n. sp." = Bassleroceras vassarina Dwight 1884
NYSM 10367, 10370, 11423 (type, originally numbered 117), 17480 to 17482
Bassleroceras spissiseptum Dwight 1884
USNM 109443
 Ellesmerocerida -
"Orthoceras henrietta n. sp." = Vassaroceras henrietta
"Orthoceras henrietta n. sp." = Vassaroceras henrietta Dwight 1884
no number of specimens and catalogue numbers given
 Multiceratoidea - Bassleroceratidae
 Tarphycerida - Tarphyceratidae
Campbelloceras sp. Ulrich and Foerste 1936
NYSM 17518 (originally labeled by W. B. Dwight as "Eurystomites armilla n. sp.")
 Endocerida - Proterocameroceratidae
Paraendoceras depressum, "? Endoceras wappingerense n. sp." = Paraendoceras wappingerense
Paraendoceras depressum Kröger and Landing 2008
NYSM 17514 (paratype)
"? Endoceras wappingerense n. sp." = Paraendoceras wappingerense Ulrich et al. 1944
NYSM 10371 (holotype), 17504 (hypotype of Kröger & Landing, 2008); both were originally numbered 301