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Biol Lett. 2017 May;13(5). pii: 20170033. doi: 10.1098/rsbl.2017.0033.

Inference of facultative mobility in the enigmatic Ediacaran organism Parvancorina.

Author information

1
Vanderbilt University, Nashville, TN 37235-1805, USA simon.a.darroch@vanderbilt.edu.
2
Oxford University Museum of Natural History, Oxford OX1 3PW, UK.
3
Vanderbilt University, Nashville, TN 37235-1805, USA.
4
Natural History Museum of Los Angeles County, Los Angeles, CA 90007, USA.
5
University of Toronto Mississauga, Mississauga, Ontario L5 L 1C6, Canada.

Abstract

Establishing how Ediacaran organisms moved and fed is critical to deciphering their ecological and evolutionary significance, but has long been confounded by their non-analogue body plans. Here, we use computational fluid dynamics to quantitatively analyse water flow around the Ediacaran taxon Parvancorina, thereby testing between competing models for feeding mode and mobility. The results show that flow was not distributed evenly across the organism, but was directed towards localized areas; this allows us to reject osmotrophy, and instead supports either suspension feeding or detritivory. Moreover, the patterns of recirculating flow differ substantially with orientation to the current, suggesting that if Parvancorina was a suspension feeder, it would have been most efficient if it was able to re-orient itself with respect to current direction, and thus ensure flow was directed towards feeding structures. Our simulations also demonstrate that the amount of drag varied with orientation, indicating that Parvancorina would have greatly benefited from adjusting its position to minimize drag. Inference of facultative mobility in Parvancorina suggests that Ediacaran benthic ecosystems might have possessed a higher proportion of mobile taxa than currently appreciated from trace fossil studies. Furthermore, this inference of movement suggests the presence of musculature or appendages that are not preserved in fossils, but which would noneltheless support a bilaterian affinity for Parvancorina.

KEYWORDS:

Ediacaran; Parvancorina; computational fluid dynamics; paleobiology

PMID:
28515329
PMCID:
PMC5454237
DOI:
10.1098/rsbl.2017.0033
[Indexed for MEDLINE]
Free PMC Article

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