title: A precocial avian embryo from the Lower Cretaceous of China.
abstract: An embryo of an enantiornithine bird has been recovered from the Lower Cretaceous rocks of Liaoning, in northeast China. The bird has a nearly complete articulated skeleton with feather sheet impressions and is enclosed in egg-shaped confines. The tucking posture of the skeleton suggests that the embryo had attained the final stage of development. The presence of well-developed wing and tail feather sheets indicates a precocial developmental mode, supporting the hypothesis that precocial birds appeared before altricial birds.
authors.affiliation: Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Post Office Box 643, Beijing 100044, China. zhonghe@yeah.net
authors.forename: Zhonghe
authors.initials: Z
authors.lastname: Zhou
authors.forename: Fucheng
authors.initials: F
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001717:Birds / Q000196:embryology*; D002681:China; D004625:Embryo, Nonmammalian / Q000033:anatomy & histology*; D005241:Feathers / Q000196:embryology; D005580:Fossils; D014921:Wings, Animal / Q000196:embryology