Geological Society of America

T77 Topics in Paleoecology: Modern Analogues and Ancient Systems (Posters)

Sunday, 25 September 2016
9:00 AM - 5:30 PM
Exhibit Hall E/F

WESTERMANN MORPHOSPACE METRICS APPLIED TO COEXISTING UPPER CRETACEOUS NAUTILIDS AND AMMONITES

Paper number: T77-15
Program: Technical Sessions
Time: 9:00 AM – 5:30 PM

Authors

Nicholas Hugo Presenting Author
North Dakota State University, Fargo, ND
Lydia Tackett
North Dakota State University, Fargo, ND
Joyce Grier
Hawley, MN
James W. Grier
North Dakota State University, Fargo, ND
Neil H. Landman
American Museum of Natural History, New York, NY

Abstract

As an alternative to previous techniques for analyzing shell shapes of fossil cephalopods, such as principle component analysis of multiple shell measurements, geometric morphometric Procrustes analyses, and elliptical Fourier analysis of cross sections, we used scaled ternary diagrams or Westermann Morphospace Metrics (WMM). WMM were previously tested for planispiral ammonites. We extended the technique to nautilids (Eutrephoceras). We compare WMM results for nautilids and ammonites (Hoploscaphites, Rhaeboceras) coexisting, and indeed sometimes found in the same fossil concretions, from the Upper Cretaceous (lower Maastrichtian) Pierre Shale on the Cedar Creek Anticline in east-central Montana. We discuss the possible implications of the Westermann Morphospace positions of these related but different cephalopods in terms of their possible swimming abilities, habitat, and potential ecological competition.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-281914

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