The rise of bilaterians: a few closing comments

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.