title: Growth patterns in brooding dinosaurs reveals the timing of sexual maturity in non-avian dinosaurs and genesis of the avian condition.
abstract: The timing of sexual maturation in non-avian dinosaurs is not known. In extant squamates and crocodilians it occurs in conjunction with the initial slowing of growth rates as adult size is approached. In birds (living dinosaurs) on the other hand, reproductive activity begins well after somatic maturity. Here we used growth line counts and spacing in all of the known brooding non-avian dinosaurs to determine the stages of development when they perished. It was revealed that sexual maturation occurred well before full adult size was reached-the primitive reptilian condition. In this sense, the life history and physiology of non-avian dinosaurs was not like that of modern birds. Palaeobiological ramifications of these findings include the potential to deduce reproductive lifespan, fecundity and reproductive population sizes in non-avian dinosaurs, as well as aid in the identification of secondary sexual characteristics.
authors.affiliation: Department of Biological Science, Florida State University, Tallahassee, FL 32306-1100, USA. gerickson@bio.fsu.edu
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Erickson
authors.forename: Kristina
authors.initials: K
authors.lastname: Curry Rogers
authors.forename: David J
authors.initials: DJ
authors.lastname: Varricchio
authors.forename: Mark A
authors.initials: MA
authors.lastname: Norell
authors.forename: Xing
authors.initials: X
authors.lastname: Xu
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000502:physiology*; D025061:Dinosaurs / Q000033:anatomy & histology / Q000254:growth & development*; D012098:Reproduction; D012741:Sexual Maturation