Saturday, September 24, 2005

Transitional Dinosaur - Bird Eggs

Evolutionary trends in eggs and egg-laying from basal archosaurs to modern birds

An interesting new article is available from Naturwissenschaften reporting the discovery of eggs with dinosaur-like and bird-like characteristics. This is of course exactly what you would expect to find if birds had evolved from dinosaurs.

Minute theropod eggs and embryo from the Lower Cretaceous of Thailand and the dinosaur-bird transition

Eric Buffetaut, Gerald Grellet-Tinner, Varavudh Suteethorn, Gilles Cuny, Haiyan Tong, Adrijan Košir, Lionel Cavin, Suwanna Chitsing, Peter J. Griffiths, Jérôme Tabouelle1 and Jean Le Loeuff.


We report on very small fossil eggs from the Lower Cretaceous of Thailand, one of them containing a theropod embryo, which display a remarkable mosaic of characters. While the surficial ornamentation is typical of non-avian saurischian dinosaurs, the three-layered prismatic structure of the eggshell is currently known only in extant and fossil eggs associated with birds. These eggs, about the size of a goldfinch's, mirror at the reproductive level the retention of small body size that was paramount in the transition from non-avian theropods to birds. The egg-layer may have been a small feathered theropod similar to those recently found in China.

Link - journal website

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