title: A pair of shelled eggs inside a female dinosaur.
abstract: An oviraptosaurian specimen (Dinosauria, Theropoda) from an Upper Cretaceous formation in China retains a pair of shelled eggs in the pelvis, providing direct evidence that oviraptorosaurian dinosaurs laid paired elongatoolithid eggs. The presence of the paired eggs suggests that theropod dinosaurs had two functional oviducts (like crocodiles) but that each oviduct produced only one egg at a time and that an entire egg clutch was laid through multiple ovipositions (like birds). The orientations of the eggs inside the skeleton and in clutches indicate that the mother came to the center of the nest to lay eggs.
authors.affiliation: Canadian Museum of Nature (CMN), Post Office Box 3443, STN D, Ottawa, Ontario K1P 6P4, Canada. tsato@mus-nature.ca
authors.forename: Tamaki
authors.initials: T
authors.lastname: Sato
authors.forename: Yen-nien
authors.initials: YN
authors.lastname: Cheng
authors.forename: Xiao-chun
authors.initials: XC
authors.lastname: Wu
authors.forename: Darla K
authors.initials: DK
authors.lastname: Zelenitsky
authors.forename: Yu-fu
authors.initials: YF
authors.lastname: Hsiao
mesh_terms: D000818:Animals; D025061:Dinosaurs / Q000033:anatomy & histology / Q000502:physiology*; D004528:Egg Shell; D005260:Female; D005580:Fossils; D010057:Oviducts / Q000033:anatomy & histology / Q000502:physiology; D010058:Oviposition; D010063:Ovum