Skip to main content
×
Home
    • Aa
    • Aa

Onset of the Ordovician cephalopod radiation – evidence from the Rochdale Formation (middle Early Ordovician, Stairsian) in eastern New York

  • BJÖRN KRÖGER (a1) and ED LANDING (a2)
Abstract
Abstract

The Rochdale Formation of eastern New York (= Fort Ann and lower Bascom formations, designations abandoned) is now recognized to record the earliest stages of the Great Ordovician Radiation of cephalopods. The earliest Bassleroceratidae, Tarphyceratidae and endoceridans on the east Laurentian shallow carbonate platform occur in the upper, thrombolite-bearing member of the Rochdale. This fauna demonstrates that the earliest radiation of Ordovician nautiloids took place in the late Tremadocian and is best recorded in tropical platform facies. Revision of this cephalopod fauna based on approximately 190 specimens collected along a 200 km, N–S belt in easternmost New York has provided new information on inter- and intraspecific variation of earlier described species. The ellesmerocerid Vassaroceras and the endocerids Mcqueenoceras and Paraendoceras are emended. New taxa include Bassleroceras champlainense sp. nov. and B. triangulum sp. nov., Mccluskiceras comstockense gen. et sp. nov., Exoclitendoceras rochdalense gen. et sp. nov. and Paraendoceras depressum sp. nov. A rank abundance plot of 146 specimens from a locality in the Lake Champlain lowlands provides information on the community structure of a nautiloid fauna in which the longiconic cyrtoconic Bassleroceras is shown to dominate strongly. The nautiloid community structure of the Rochdale Formation is similar to that of the underlying Tribes Hill Formation (late early Tremadocian) with respect to the depositional setting, diversity and evenness but displays a remarkably increased taxonomic distinctness.

Copyright
Corresponding author
*Author for correspondence: bjoekroe@gmx.de
Linked references
Hide All

This list contains references from the content that can be linked to their source. For a full set of references and notes please see the PDF or HTML where available.

W. M. Cady 1945. Stratigraphy and structure of west-central Vermont. Geological Society of America Bulletin 56, 515–58.

K. R. Clarke & R. M. Warwick 1998. A taxonomic distinctness index and its statistical properties. Journal of Applied Ecology 35, 523–31.

K. R. Clarke & R. M. Warwick 1999. The taxonomic distinctness measure of biodiversity: weighting of step lengths between hierarchical levels. Marine Ecology Progress Series 184, 21–9.

B. Kröger 2003. The size of siphuncle in cephalopod evolution. Senckenbergiana lethaea 83, 3952.

B. Kröger 2004. Large shell injuries in Middle Ordovician Orthocerida (Nautiloidea, Cephalopoda). GFF 126, 311–16.

B. Kröger & R. Mapes 2007. On the origin of bactritoids (Cephalopoda). Paläontologische Zeitschrift 81 (3), 316–27.

B. Kröger & H. Mutvei 2005. Nautiloids with multiple paired muscle scars from Lower–Middle Ordovician of Baltoscandia. Palaeontology 48, 781–91.

E. Landing & S. R. Westrop 2006. Lower Ordovician faunas, stratigraphy, and sea-level history of the middle Beekmantown Group, northeastern New York. Journal of Paleontology 80, 958–80.

E. Landing , S. R. Westrop & L. Van Aller Hernick 2003. Uppermost Cambrian–Lower Ordovician faunas and Laurentian platform sequence stratigraphy, eastern New York and Vermont. Journal of Paleontology 77, 7898.

R. I. Murchison 1859. On the succession of the older Rocks in the northernmost counties of Scotland; with some observations on the Orkney and Shetland Islands. The Quarterly Journal of the Geological Society of London 15, 353418.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Geological Magazine
  • ISSN: 0016-7568
  • EISSN: 1469-5081
  • URL: /core/journals/geological-magazine
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×

Keywords:

Metrics

Altmetric attention score

Full text views

Total number of HTML views: 1
Total number of PDF views: 6 *
Loading metrics...

Abstract views

Total abstract views: 71 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 25th May 2017. This data will be updated every 24 hours.