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

Eric Buffetaut (1) , Gerald Grellet-Tinner (2, 3) , Varavudh Suteethorn (4) , Gilles Cuny , Haiyan Tong (1) , Adrijan Košir , Lionel Cavin , Suwanna Chitsing , Peter J. Griffiths , Jérôme Tabouelle , Jean Le Loeuff

1 PEPS - PaleoEnvironnements et PaleobioSphere
2 Department of Vertebrate Paleontology, Natural History
3 Department of Earth Sciences [USC Los Angeles]
4 Department of Mineral Resources

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 egglayer may have been a small feathered theropod similar to those recently found in China.

Domaines: Paléontologie

Eric Buffetaut, Gerald Grellet-Tinner, Varavudh Suteethorn, Gilles Cuny, Haiyan Tong, et al.. Minute theropod eggs and embryo from the Lower Cretaceous of Thailand and the dinosaur-bird transition. The Science of Nature Naturwissenschaften, 2005, 92, pp.477-482. ⟨10.1007/s00114-005-0022-9⟩. ⟨hal-00178636⟩