MARK A. NORELL, JAMES M. CLARK, LUIS M. CHIAPPE
American Museum Novitates 2001 (3315), 1-20, (30 January 2001) https://doi.org/10.1206/0003-0082(2001)315<0001:AEODTF>2.0.CO;2
An embryonic oviraptorid skeleton is described within an egg from the Late Cretaceous Djadokha Formation of Ukhaa Tolgod, Mongolia. The specimen comprises the ventral part of the skull and most of the mandible, a poorly preserved axial skeleton missing most of the tail, and portions of the forelimbs, shoulder girdles, pelvis, and hindlimbs. The skull is readily referable to the theropod dinosaur clade Oviraptoridae on the basis of several skull specializations (edentulous, vertically oriented premaxilla, a sinusoidally shaped lower jaw, and an unusual articulation of the vomer and premaxilla), and the postcranial skeleton is consistent with this identification. The egg is equivalent in overall shape and microstructure to those found beneath several oviraptorid skeletons recovered from the same formation. The skeleton is well ossified and, in comparison with ossification patterns in living Aves, the evidence suggests that this species was closer to the precocial end of the precocial-altricial spectrum of developmental patterns.