The rise of bilaterians: a few closing comments |
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Authors: | Shuhai Xiao Micha? Kowalewski Bing Shen Lin Dong Marc Laflamme |
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Institution: | 1. Department of Geosciences , Virginia Polytechnic Institute and State University , Blacksburg, VA, 24061, USA xiao@vt.edu;3. Department of Geosciences , Virginia Polytechnic Institute and State University , Blacksburg, VA, 24061, USA;4. Department of Earth Science , Rice University , Houston, TX, 77005, USA;5. BP America Production Co. , Houston, TX, 77079, USA;6. Department of Geology and Geophysics , Yale University , New Haven, CT, 06520, USA |
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Abstract: | Freeman (2009, 2010) argue that Ediacara “faunas” should be analysed using “promorphologies” of extant animals, that rangeomorphs and erniettomorphs are colonial animals, and that Vernanimalcula is a bilaterian animal. Recent studies of Ediacara fossils have provided multiple lines of evidence that these fossils represent a sample of phylogenetically diverse marine organisms that included crown-group animals as well as stem-group animals and non-animals. Thus, it is inappropriate to analyse Ediacara fossils using “promorphologies” of extant animals. The interpretation of rangeomorphs and erniettomorphs as colonial animals is inconsistent with the functional morphologies of these Ediacara fossils. Although Vernanimalcula is a fossil, the purported germ layers of Vernanimalcula are of diagenetic origin and there is no morphological evidence in support of its bilaterian affinity. |
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Keywords: | Ediacaran Period Ediacara fossils bilaterian animals morphospace |
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