10 M.Y. EVOLUTIONARY STASIS OF EARLIEST CAMBRIAN (TERRENEUVIAN) MOLLUSK-RICH FAUNAS AND CAMBRIAN EVOLUTIONARY RADIATION CORRELATIONS

LANDING, Ed, New York State Museum, 222 Madison Avenue, Albany, NY 12230, KOUCHINSKY, Artem, Dept. of Palaeozoology, Swedish Museum of Natural History, Box 50007, Stockholm, SE-104 05, Sweden, WESTROP, Stephen R., Oklahoma Museum of Natural History and School of Geology & Geophysics, Univ of Oklahoma, Norman, OK 73072, GEYER, Gerd, Institut für Geographie und Geologie, Universität Würzburg, Am Hubland, Würzburg, 97074, Germany and BOWRING, Samuel A., Dept. of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, ed.landing@nysed.gov

Mollusk-rich assemblages with Watsonella crosbyi with or without Aldanella spp. represent a temporally problematical, earliest Cambrian interval. Although frequently regarded as Tommotian-equivalents (upper Terreneuvian), new biotic and carbon isotope data demonstrate a pre-Tommotian (middle Terreneuvian) age for early W. crosbyi-A. spp. assemblages. Both W. crosbyi and A. spp. occur below the I’ carbon isotope excursion in the Siberian “Manykayan/Nemakit-Daldynian” Stage. Roughly coeval (pre-Tommotian) W. crosbyi-bearing faunas with A. attleborensis (=A. yanjiaheensis) occur below a distinctive, positive δ¹³C excursion in the middle Meishucunian Stage (China; L4, P3, ZHUCE excursions) and correlatives (middle Chapel Island Formation, Avalonia; upper Bayan Gol Formation, Mongolia). Heraultia Limestone (Gondwanan France) faunas are also pre-Tommotian-equivalents. The δ¹³C excursion above early W. crosbyi-bearing faunas is a reliable Stage 2 basal marker that is older (ca. 530 Ma) than earliest Tommotian (ca. 525.5 Ma). Benthic faunas with W. crosbyi and A. spp. record a ca. 10 m.y. “slow down” in the Cambrian Evolutionary Radiation. A Stage 2 base defined by W. crosbyi or A. attleborensis FADs is discouraged; these FADs are diachronous; W. crosbyi Zone taxa also appear with exceptionally early Cambrian acritarchs (Baltica), and their ranges are bracketed by lithofacies changes and unconformities (SE Siberia, South China, Avalonia, France).

Handouts

BaltimorePPTPDF.pdf (4.0 MB)

Baltimore GSATalk.pdf (211.1 kB)

Session No. 3

Paleontology: Ancient Life in Deep Time: Temporal and Geographic Trends in Fossil Distributions

Sunday, 1 November 2015: 8:00 AM-12:00 PM

Room 316 (Baltimore Convention Center)

Geological Society of America Abstracts with Programs. Vol. 47, No. 7, p.27

© Copyright 2015 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.

Back to: Paleontology: Ancient Life in Deep Time: Temporal and Geographic Trends in Fossil Distributions

<< Previous Abstract | Next Abstract >>

2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

10 M.Y. EVOLUTIONARY STASIS OF EARLIEST CAMBRIAN (TERRENEUVIAN) MOLLUSK-RICH FAUNAS AND CAMBRIAN EVOLUTIONARY RADIATION CORRELATIONS