A new species of yunnanozoan with implications for deuterostome evolution.
Yunnanozoans are a distinctive clade of Lower Cambrian metazoans. Although widely accepted as deuterostomes, their exact placement within this superphylum is controversial. Here we describe a new species of Haikouella (H. jianshanensis) from the Chengjiang Lagerstätte (Yunnan, China) with exceptional preservation of a number of features. These include external gills, which suggest that the origin of the pharyngeal clefts was independent of the gills. The diagnostic branchial arches of chordates may, therefore, be composite structures. No evidence was found for the chordate-like structures that have been described in other yunnanozoans. We propose that yunnanozoans are stem-group deuterostomes, allied to the vetulicolians.
Shu
Degan
D
Early Life Institute and Department of Geology, Northwest University, Xi'an 710069, China. elidgshu@nwu.edu.cn
Morris
Simon Conway
SC
Zhang
Z F
ZF
Liu
J N
JN
Han
Jian
J
Chen
Ling
L
Zhang
X L
XL
Yasui
K
K
Li
Yong
Y
D000818:Animals; D005075:Biological Evolution; D002681:China; D002816:Chordata, Nonvertebrate / Q000033:anatomy & histology* / Q000145:classification*; D004064:Digestive System / Q000033:anatomy & histology; D005580:Fossils; D005880:Gills / Q000033:anatomy & histology; D009055:Mouth / Q000033:anatomy & histology; D010802:Phylogeny