Small bilaterian fossils from 40 to 55 million years before the cambrian.
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.
Chen
Jun-Yuan
JY
Nanjing Institute of Geology and Paleontology, Nanjing 210008, China. chenjunyuan@163.net
Bottjer
David J
DJ
Oliveri
Paola
P
Dornbos
Stephen Q
SQ
Gao
Feng
F
Ruffins
Seth
S
Chi
Huimei
H
Li
Chia-Wei
CW
Davidson
Eric H
EH
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