Crocodylomorph eggs and eggshells from the Adamantina Formation (Bauru Group), Upper Cretaceous of Brazil |
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| Authors: | CARLOS E M OLIVEIRA RODRIGO M SANTUCCI MARCO B ANDRADE VICENTE J FULFARO JOSÉ A F BASÍLIO MICHAEL J BENTON |
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| Institution: | 1. Departamento de Geologia Aplicada, Instituto de Geociências e Ciências Exatas, IGCE‐UNESP, Avenida 24‐A 1515, Rio Claro, S?o Paulo 13506‐900, Brazil;2. e‐mails edumaiaoli@yahoo.com.br;3. vfulfaro@rc.unesp.br;4. Funda??o Educacional de Fernandópolis, FEF, Campus Universitário, Avenida Teot?nio Vilela, PO Box 120, Fernandópolis, S?o Paulo 15600‐000, Brazil;5. e‐mails edumaiaoli@yahoo.com.br;6. jabasilio@gmail.com;7. Universidade Camilo Castelo Branco, Unicastelo, Campus Universitário, Estrada Projetada s/n, Fazenda Santa Rita, PO Box 121, Fernandópolis,S?o Paulo 15600‐000, Brazil;8. e‐mail edumaiaoli@yahoo.com.br;9. Universidade de Brasília, Faculdade UnB Planaltina, Brasília, Distrito Federal 73300‐000, Brazil;10. e‐mail rodrigoms@unb.com.br;11. Departamento Nacional de Produ??o Mineral, S.A.N. Q 01 Bloco B, Brasília, Distrito Federal 70041‐903, Brazil;12. Palaeobiology and Biodiversity Research Group, Department of Earth Sciences, University of Bristol, Queens Road, Wills Memorial Building, Clifton,Bristol BS8 1RJ, UK;13. e‐mails marcobranda@yahoo.com.br;14. mike.benton@bris.ac.uk;15. Departamento de Paleontologia e Estratigrafia, Universidade Federal do Rio Grande do Sul, Avenida Bento Gon?alves 9500, PO Box 15001, Porto Alegre, Rio Grande do Sul 91501‐970, Brazil;16. Funda??o Educacional de Fernandópolis, FEF, Campus Universitário, Avenida Teot?nio Vilela, PO Box 120, Fernandópolis, S?o Paulo 15600‐000, Brazil |
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| Abstract: | Abstract: Compared with crocodylomorph body fossils, the record of fossil crocodiloid eggs is scarce and poorly understood, a gap partially attributed to their typically thin eggshell, which is not conducive to preservation. A remarkable new association of well‐preserved eggs and eggshells from the Adamantina Formation (Bauru Group, Upper Cretaceous) is described and compared to other known materials, while the significance of their unique oological features is discussed. These eggs constitute a new ootaxon, Bauruoolithus fragilis oogen. et oosp. nov., diagnosed by the following characteristics: elongate and elliptical egg with blunt ends; length‐to‐diameter ratio of 1:0.55; outer surface slightly undulating; shell thickness ranging from 0.15 to 0.25 mm; pore openings elliptical or teardrop‐shaped, ranging from 30 to 80 μm in diameter; and shell units wider than higher, with the interstices forming an obtuse triangle. Specimens of Bauruoolithus also show only slight signs of extrinsic degradation that, coupled with the evidence that some of them constitute hatched eggs, suggests that the egg‐laying taxon had a different pattern of egg incubation, in which the hatchling could break through the rather thin eggshell relatively easily and that the extrinsic degradation of the eggshell was not necessary. This contrasts with the pattern of incubation for all other known crocodylomorphs and crocodiloid eggs, where extrinsic degradation is a key component of the hatching process. |
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| Keywords: | eggs crocodylomorphs Upper Cretaceous Bauru Basin Adamantina Formation extrinsic degradation Baurusuchus |
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