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Evidence for Cnidaria-like behavior in ca. 560 Ma Ediacaran Aspidella

Latha R. Menon, Duncan McIlroy and Martin D. Brasier
Evidence for Cnidaria-like behavior in ca. 560 Ma Ediacaran Aspidella
Geology (Boulder) (June 2013) 41 (8): 895-898


The first appearance of animals in the geological record is a matter of continuing debate: how deep were the roots of the Cambrian explosion? Molecular clock estimates indicate that the deepest divergences of the Metazoa had occurred by the Ediacaran Period (635-541 Ma), yet evidence of animal activity from well below the Ediacaran-Cambrian boundary has been rare and often questionable. Meanwhile, the Ediacaran macrobiota has remained enigmatic, as emphasized by recent controversial claims that South Australia Ediacaran forms were not marine animals at all, but land-based lichens and microbial colonies. Here we report evidence for animal-like behavior in a submerged setting in a key Ediacaran form, Aspidella terranovica Billings 1872, a discoidal fossil from the ca. 560 Ma Fermeuse Formation of Newfoundland (Canada). We describe sedimentary fabrics indicating progressive vertical movement of an organism through sediment in response to an aggrading sediment-water interface. Such equilibrium traces are familiar from the Phanerozoic and are observed in partially buried marine animals such as tube anemones today. Furthermore, horizontal trails closely comparable to trails previously described from approximately 565 m.y. old Mistaken Point (Newfoundland) are now linked to Aspidella. Our findings constitute evidence of both vertical and horizontal movement in a key Ediacaran taxon, consistent with an animal of cnidarian grade. Moreover, because Aspidella is also reported from the Rawnsley Quartzite of South Australia, our evidence conflicts with the proposed radical interpretation of that Ediacaran fossil assemblage. We demonstrate that at least some Ediacaran forms were probably early animals, and that they lived underwater.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 41
Serial Issue: 8
Title: Evidence for Cnidaria-like behavior in ca. 560 Ma Ediacaran Aspidella
Affiliation: University of Oxford, Department of Earth Sciences, Oxford, United Kingdom
Pages: 895-898
Published: 20130606
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 35
Accession Number: 2013-054282
Categories: Invertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2013246
Illustration Description: illus. incl. strat. col., sketch map
N46°30'00" - N48°10'00", W54°15'00" - W52°30'00"
Secondary Affiliation: Memorial University of Newfoundland, CAN, Canada
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201333
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