title: Zheng et al. reply.
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origin, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China. jingmai.oconnor@gmail.com
authors.forename: Jingmai
authors.initials: J
authors.lastname: O'Connor
authors.forename: Xiaoting
authors.initials: X
authors.lastname: Zheng
authors.forename: Zhonghe
authors.initials: Z
authors.lastname: Zhou
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000033:anatomy & histology* / Q000502:physiology*; D005260:Female; D005580:Fossils; D006080:Ovarian Follicle / Q000033:anatomy & histology* / Q000502:physiology*; D012098:Reproduction / Q000502:physiology*