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14 March 2019 Unusually variable paleocommunity composition in the oldest metazoan fossil assemblages
Seth Finnegan, James G. Gehling, Mary L. Droser
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Recent excavations of Ediacaran assemblages have revealed striking bed-to-bed variation in diversity–abundance structure, offering potential insight into the ecology and taphonomy of these poorly understood early Metazoan ecosystems. Here we compare faunal variability in Ediacaran assemblages to that of younger benthic assemblages, both fossil and modern. We decompose the diversity of local assemblages into within-collection (α) and among-collection (β) components and show that β diversity in Ediacaran assemblages is unusually high relative to younger assemblages. Average between-bed ecological dissimilarities in the Phanerozoic fossil record are comparable to within-habitat dissimilarities typically observed over meter to kilometer scales in modern benthic marine habitats, but dissimilarities in Ediacaran assemblages are comparable to those typically observed over 10–100 km scales in modern habitats. We suggest that the unusually variable diversity–abundance structure of Ediacaran assemblages is due both to their preservation as near snapshots of benthic communities and to original ecological differences, in particular the paucity of motile taxa and the near lack of predation and infaunalization.

© 2019 The Paleontological Society. All rights reserved. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Seth Finnegan, James G. Gehling, and Mary L. Droser "Unusually variable paleocommunity composition in the oldest metazoan fossil assemblages," Paleobiology 45(2), 235-245, (14 March 2019).
Accepted: 6 January 2019; Published: 14 March 2019

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