title: Small bilaterian fossils from 40 to 55 million years before the cambrian.
abstract: Ten phosphatized specimens of a small (<180 micrometers) animal displaying clear bilaterian features have been recovered from the Doushantuo Formation, China, dating from 40 to 55 million years before the Cambrian. Seen in sections, this animal (Vernanimalcula guizhouena gen. et sp. nov.) had paired coeloms extending the length of the gut; paired external pits that could be sense organs; bilateral, anterior-posterior organization; a ventrally directed anterior mouth with thick walled pharynx; and a triploblastic structure. The structural complexity is that of an adult rather than a larval form. These fossils provide the first evidence confirming the phylogenetic inference that Bilateria arose well before the Cambrian.
authors.affiliation: Nanjing Institute of Geology and Paleontology, Nanjing 210008, China. chenjunyuan@163.net
authors.forename: Jun-Yuan
authors.initials: JY
authors.lastname: Chen
authors.forename: David J
authors.initials: DJ
authors.lastname: Bottjer
authors.forename: Paola
authors.initials: P
authors.lastname: Oliveri
authors.forename: Stephen Q
authors.initials: SQ
authors.lastname: Dornbos
authors.forename: Feng
authors.initials: F
authors.lastname: Gao
authors.forename: Seth
authors.initials: S
authors.lastname: Ruffins
authors.forename: Huimei
authors.initials: H
authors.lastname: Chi
authors.forename: Chia-Wei
authors.initials: CW
authors.lastname: Li
authors.forename: Eric H
authors.initials: EH
authors.lastname: Davidson
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002681:China; D004064:Digestive System / Q000033:anatomy & histology; D004707:Endoderm; D005580:Fossils; D007448:Invertebrates / Q000033:anatomy & histology / Q000145:classification; D008648:Mesoderm; D010802:Phylogeny; D013995:Time