Confirming the Metazoan Character of a 565 Ma Trace-Fossil Assemblage from Mistaken Point, Newfoundland

Liu, Alexander G. and Mcilroy, Duncan and Matthews, Jack J. and Brasier, Martin D. (2014) Confirming the Metazoan Character of a 565 Ma Trace-Fossil Assemblage from Mistaken Point, Newfoundland. Palaios, 29 (8). pp. 420-430. ISSN 0833-1351 DOI 10.2110/palo.2014.011

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Abstract

Surface locomotory trace fossils from the Mistaken Point Formation of Newfoundland, dated at ∼ 565 Ma, suggest that organisms capable of controlled locomotion and possessing muscular tissue may have existed among Avalonian Ediacaran macrofossil assemblages. Here we describe the Mistaken Point trace-fossil assemblage in full, discuss its stratigraphic context within the Mistaken Point Formation, and explore the competing hypotheses for the formation of the traces. We find that the trace fossils, preserved within a turbidite succession in a deep-marine depositional environment, are not attributable to abiogenic structures, to Ediacaran tubular or filamentous body fossils, to rangeomorph stems, or to a host of late Ediacaran and early Phanerozoic ichnofossils. Specimens within the assemblage show some similarities to the ichnogenera Helminthoidichnites and Archaeonassa, but discrepancies in certain aspects of their structure mean that we do not formally attribute them to these ichnotaxa at this time. The Mistaken Point ichnofossils possess morphological characteristics indicative of formation by an organism with a round base. Comparison with traces formed by modern organisms of such character appears to rule out formation by protistan, echinoderm, or annelid styles of movement, but is consistent with organisms moving via muscular controlled locomotion in a similar way to some modern mollusks and actinian cnidarians. We suggest therefore that the Mistaken Point trace-fossil assemblage reveals the presence of muscular metazoans in late Ediacaran deep-marine ecosystems. Such organisms cannot yet be attributed to specific phyla, but their inferred locomotory mechanisms share closest similarities with those utilized by extant actinians.

Item Type: Article
Uncontrolled Keywords: 2014AREP; IA68;
Subjects: 04 - Palaeobiology
Divisions: 04 - Palaeobiology
Journal or Publication Title: Palaios
Volume: 29
Page Range: pp. 420-430
Identification Number: 10.2110/palo.2014.011
Depositing User: Sarah Humbert
Date Deposited: 23 Feb 2015 15:28
Last Modified: 27 Feb 2015 17:08
URI: http://eprints.esc.cam.ac.uk/id/eprint/3244

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