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

• publication
• 01-10-2005

Buffetaut, E., Grellet-Tinner, G., Suteethorn, V., Cuny, G., Kosir, A., Cavin, L., Chitsing, S., Griffiths, P., Tabouelle, T., Le Loeuff, J.. Die Naturwissenschaften, 92(10), 477–482. https://doi.org/10.1007/s00114-005-0022-9

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.

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