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Discovery of the oldest bilaterian from the Ediacaran of South Australia.
Proc Natl Acad Sci U S A. 2020 04 07; 117(14):7845-7850.PN

Abstract

Analysis of modern animals and Ediacaran trace fossils predicts that the oldest bilaterians were simple and small. Such organisms would be difficult to recognize in the fossil record, but should have been part of the Ediacara Biota, the earliest preserved macroscopic, complex animal communities. Here, we describe Ikaria wariootia gen. et sp. nov. from the Ediacara Member, South Australia, a small, simple organism with anterior/posterior differentiation. We find that the size and morphology of Ikaria match predictions for the progenitor of the trace fossil Helminthoidichnites-indicative of mobility and sediment displacement. In the Ediacara Member, Helminthoidichnites occurs stratigraphically below classic Ediacara body fossils. Together, these suggest that Ikaria represents one of the oldest total group bilaterians identified from South Australia, with little deviation from the characters predicted for their last common ancestor. Further, these trace fossils persist into the Phanerozoic, providing a critical link between Ediacaran and Cambrian animals.

Authors+Show Affiliations

Department of Earth Sciences, University of California, Riverside, CA 92521; EvansSD@si.edu.Section of Ecology, Behavior and Evolution, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093.Department of Palaeontology, South Australia Museum, Adelaide, SA 5000, Australia.Department of Earth Sciences, University of California, Riverside, CA 92521.

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

32205432

Citation

Evans, Scott D., et al. "Discovery of the Oldest Bilaterian From the Ediacaran of South Australia." Proceedings of the National Academy of Sciences of the United States of America, vol. 117, no. 14, 2020, pp. 7845-7850.
Evans SD, Hughes IV, Gehling JG, et al. Discovery of the oldest bilaterian from the Ediacaran of South Australia. Proc Natl Acad Sci U S A. 2020;117(14):7845-7850.
Evans, S. D., Hughes, I. V., Gehling, J. G., & Droser, M. L. (2020). Discovery of the oldest bilaterian from the Ediacaran of South Australia. Proceedings of the National Academy of Sciences of the United States of America, 117(14), 7845-7850. https://doi.org/10.1073/pnas.2001045117
Evans SD, et al. Discovery of the Oldest Bilaterian From the Ediacaran of South Australia. Proc Natl Acad Sci U S A. 2020 04 7;117(14):7845-7850. PubMed PMID: 32205432.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Discovery of the oldest bilaterian from the Ediacaran of South Australia. AU - Evans,Scott D, AU - Hughes,Ian V, AU - Gehling,James G, AU - Droser,Mary L, Y1 - 2020/03/23/ PY - 2020/3/25/pubmed PY - 2020/7/17/medline PY - 2020/3/25/entrez KW - Ediacara Biota KW - Ediacaran KW - bilaterian KW - phylogenetics KW - trace fossil SP - 7845 EP - 7850 JF - Proceedings of the National Academy of Sciences of the United States of America JO - Proc Natl Acad Sci U S A VL - 117 IS - 14 N2 - Analysis of modern animals and Ediacaran trace fossils predicts that the oldest bilaterians were simple and small. Such organisms would be difficult to recognize in the fossil record, but should have been part of the Ediacara Biota, the earliest preserved macroscopic, complex animal communities. Here, we describe Ikaria wariootia gen. et sp. nov. from the Ediacara Member, South Australia, a small, simple organism with anterior/posterior differentiation. We find that the size and morphology of Ikaria match predictions for the progenitor of the trace fossil Helminthoidichnites-indicative of mobility and sediment displacement. In the Ediacara Member, Helminthoidichnites occurs stratigraphically below classic Ediacara body fossils. Together, these suggest that Ikaria represents one of the oldest total group bilaterians identified from South Australia, with little deviation from the characters predicted for their last common ancestor. Further, these trace fossils persist into the Phanerozoic, providing a critical link between Ediacaran and Cambrian animals. SN - 1091-6490 UR - https://www.unboundmedicine.com/medline/citation/32205432/Discovery_of_the_oldest_bilaterian_from_the_Ediacaran_of_South_Australia_ L2 - http://www.pnas.org/cgi/pmidlookup?view=long&pmid=32205432 DB - PRIME DP - Unbound Medicine ER -