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The evolutionary significance of a Lower Cambrian trace-fossil assemblage from the Meguma Terrane, Nova Scotia

Murray K. Gingras, John W. F. Waldron, Chris E. White and Sandra M. Barr
The evolutionary significance of a Lower Cambrian trace-fossil assemblage from the Meguma Terrane, Nova Scotia
Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre (January 2011) 48 (1): 71-85

Abstract

We report a diverse assemblage of trace fossils from the Lower(?) Cambrian High Head member of the Church Point Formation near Yarmouth, Nova Scotia. Based on the presence of sharp-based beds, load casts, and flute casts, along with other sedimentological criteria, the strata are interpreted to have a turbidite origin. Other characteristics, including wrinkle structures and high fidelity of trace-fossil preservation, suggest that the inter-episode biotope was influenced by the presence of biomats. The trace-fossil assemblage includes (in approximate order of abundance) Planolites, Helminthopsis, Oldhamia, Chondrites, Gordia, Cladichnus, Psammichnites gigas, Treptichnus, Phycodes, Lorenzinia, Palaeophycus, and Teichichnus. Trace fossils are increasingly abundant upwards in the section, but they are ultimately mitigated by an increase in (inferred) sedimentation rates. The trace-fossil assemblage, which bears many similarities to other Lower Cambrian locales (e.g., Puncoviscana Formation of northwest Argentina, Chapel Island Formation of southeastern Newfoundland), and the distribution of ichnofossils strongly support an earliest Cambrian age for the studied strata. More importantly, evolutionary trends can be interpreted from the trace-fossil assemblage, namely (1) an increase in size and diversity of animals in deep water; (2) an expansion of motile strategies used to coexist with biomats; and, (3) increasingly complex mining strategies below the sediment-biomat interface.


ISSN: 0008-4077
EISSN: 1480-3313
Coden: CJESAP
Serial Title: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre
Serial Volume: 48
Serial Issue: 1
Title: The evolutionary significance of a Lower Cambrian trace-fossil assemblage from the Meguma Terrane, Nova Scotia
Affiliation: University of Alberta, Department of Earth and Atmospheric Science, Edmonton, AB, Canada
Pages: 71-85
Published: 201101
Text Language: English
Summary Language: French
Publisher: National Research Council of Canada, Ottawa, ON, Canada
References: 79
Accession Number: 2011-019879
Categories: Invertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. col., geol. sketch maps
N44°00'00" - N44°00'00", W66°00'00" - W66°00'00"
Secondary Affiliation: Nova Scotia Department of Natural Resources, CAN, CanadaAcadia University, CAN, Canada
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 201112
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