Remarkable insights into the paleoecology of the Avalonian Ediacaran macrobiota
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Liu, A., Kenchington, C., & Mitchell, E. (2014). Remarkable insights into the paleoecology of the Avalonian Ediacaran macrobiota. Gondwana Research, 27 1355-1380. https://doi.org/10.1016/j.gr.2014.11.002
Ediacaran macrofossils from the Avalon Terrane (primarily eastern Newfoundland and the central UK) record some of the earliest large and complex multicellular organisms on Earth. Perhaps the greatest unknown regarding these fossils is their relevance to the early evolutionary history of the Kingdom Animalia. In recent years, new data and discoveries have revealed insights into Ediacaran paleobiology, taxonomic relationships, paleoecology and taphonomy, significantly refining our understanding of Avalonian ecosystems. Here, we summarise recent observational and quantitative studies, and their bearing on the current understanding of Avalonian benthic marine ecosystems. A review of existing knowledge of the biological composition of Avalonian marine assemblages demonstrates that they record densely-populated ecosystems inhabited by a diverse range of organisms, likely representing multiple biological Kingdoms. Appreciation of this diversity, and of the complexities it introduces to paleoecological studies, is vital when considering the relationship between macroevolution and contemporaneous climatic, tectonic and geochemical events. We then summarise current understanding of Avalonian paleoecology. Studies into locomotion, reproduction, feeding strategies, and community structure and succession reveal that these ecosystems were considerably different to Phanerozoic settings. Furthermore, we suggest that Avalonian ecosystems witnessed the appearance of novel nutrient sources, offering new opportunities and niches for benthic organisms. The suggestion that the numerically dominant rangeomorphs were osmotrophic is reviewed and appraised in light of geochemical, morphological, and biological information. Finally, the use of modern ecological metrics in the study of Ediacaran fossil assemblages is assessed. Concerns regarding the interpretation of paleoecological data are outlined in light of current taphonomic and sedimentological understanding, and these cast doubt on previous suggestions that the Avalonian assemblages were largely composed of metazoans. Nevertheless, we emphasise that if treated with necessary caution, paleoecological data can play a significant role in assisting efforts to determine the biological affinities of late Ediacaran macroscopic organisms.
Ediacaran, Newfoundland, Avalonia, Paleoecology, Paleontology
Thanks are extended to the editors of Gondwana Research, T. Horscroft and M. Santosh, for inviting this review, and for their patience whilst we completed it. The Parks and Natural Areas Division, Department of Environment and Conservation, Government of Newfoundland and Labrador provided permits to conduct research within the Mistaken Point Ecological Reserve between 2008–2013, whilst the Department of Tourism, Culture and Recreation provided permits for paleontological research in other parts of the Province from 2012–2013. The support of the Portugal Cove South Visitor Center interpreters during our field research was greatly appreciated. This work has been supported by the Natural Environment Research Council [grant numbers NE/I005927/1 to CGK and NE/G523539/1 to EGM]; a Henslow Junior Research Fellowship from Cambridge Philosophical Society to AGL; and the National Geographic Global Exploration Fund [GEFNE 22-11 to AGL]. Field assistance from J. Matthews, J. Stewart, D. Collins, and T. Hearing has been invaluable, and we have enjoyed fruitful discussions on this topic with N. Butterfield, D. McIlroy, J. Hoyal Cuthill, M. Brasier, S. Conway Morris and P. Wilby. The work and support of past and current workers in this field is gratefully acknowledged. B. MacGabhann and one anonymous reviewer are thanked for providing detailed comments that have strengthened this manuscript, whilst S. Jensen and M. Friedman provided helpful feedback on parts of this manuscript assessed as a chapter of AGL's thesis.
Natural Environment Research Council (NE/L011409/2)
External DOI: https://doi.org/10.1016/j.gr.2014.11.002
This record's URL: https://www.repository.cam.ac.uk/handle/1810/247081
Attribution 2.0 UK: England & Wales
Licence URL: http://creativecommons.org/licenses/by/2.0/uk/
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