Abstract
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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Acknowledgments
This work was supported by the TRF-CNRS Special Programme for Biodiversity Research and Training, the Thai Department of Mineral Resources, the ECLIPSE 2 Programme of CNRS, the Jurassic Foundation, the Danish Natural Sciences Research Council, the Carlsberg Foundation, the Thai National Science Centre for Education, the Espéraza Dinosaur Museum, the exchange programme between CNRS and the Slovenian Academy of Arts and Sciences, the Department of Earth Sciences of the University of Southern California, the Natural History Museum of Los Angeles County, and the Geological Society of America. Thanks to Patrick De Wever (Muséum National d'Histoire Naturelle, Paris), Anne-Marie Lézine (CNRS, Gif-sur-Yvette) and F. Corsetti (Los Angeles) for their help with microscopical studies, to Luis Chiappe (Natural History Museum of Los Angeles County) for his support, to Rodolphe Gromberg (Paris), Didier Descouens and Jacques Treil (Toulouse) for their attempts at scanning the Phu Phok eggs, and to the three anonymous referees for their useful comments.
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Buffetaut, E., Grellet-Tinner, G., Suteethorn, V. et al. Minute theropod eggs and embryo from the Lower Cretaceous of Thailand and the dinosaur-bird transition. Naturwissenschaften 92, 477–482 (2005). https://doi.org/10.1007/s00114-005-0022-9
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DOI: https://doi.org/10.1007/s00114-005-0022-9