title: New evidence on the anatomy and phylogeny of the earliest vertebrates.
abstract: We report the discovery of a new agnathan specimen from the Lower Cambrian Chengjiang Lagerstätte of China and thereby provide new evidence on the myomeres (V-shaped), the branchial apparatus (gill filaments and arches), the dorsal fin and the gonads (24-26) of the earliest vertebrates. The new specimen and the co-occurring Myllokunmingia fengjiaoa and Haikouichthys ercaicunensis represent a single species, which is a primitive member of the crown group craniates (vertebrates) and post-dates the origin of the myxinoids (hagfish). The origin of the vertebrate clade is at least as old as Early Cambrian.
mesh_terms: D000818:Animals; D001934:Branchial Region / Q000033:anatomy & histology; D002681:China; D004064:Digestive System / Q000033:anatomy & histology; D005399:Fishes / Q000033:anatomy & histology*; D005580:Fossils; D005880:Gills / Q000033:anatomy & histology; D006066:Gonads / Q000033:anatomy & histology; D006257:Head / Q000033:anatomy & histology; D009672:Notochord / Q000033:anatomy & histology; D010802:Phylogeny