Large dinosaur egg accumulations and their significance for understanding nesting behaviour

Abstract

The accurate identification of dinosaur egg accumulations as nests or clutches is crucial for understanding the reproductive behaviour of these extinct species. However, existing methods often rely on the presence of complete eggs and embryo remains, and sedimentological criteria that are only applicable to well-structured sediments. In this study, we introduce an innovative approach to characterize egg accumulations in structureless sediments, where traditional nest structures may not be preserved. Our methodology employs a unique combination of sedimentological, taphonomic, geochemical, and geophysical proxies for the study of egg accumulations. We applied this approach to the egg accumulation from Paimogo (Jurassic, Portugal), traditionally interpreted as a nest. Our findings reveal that the Paimogo egg assemblage is a secondary deposit, resulting from a flooding event in a fluvial plain that dismantled several allosauroid and crocodylomorph clutches. The eggshell vapor conductance results, coupled with sedimentological evidence, suggest that allosauroid dinosaurs buried their eggs in the dry terrain of overbank areas close to a main channel during the breeding season, likely during the dry season to prevent the embryos from drowning. This research underscores the necessity of multidisciplinary approaches in interpreting egg accumulations and offers a novel methodology for studying these accumulations in structureless sediments. Our findings provide new insights into the breeding behaviour and nesting preferences of these extinct organisms, contributing to our understanding of dinosaur ecology.

Keywords

Breeding behaviour / Theropod / Taphonomy / Stable isotopes / Magnetic susceptibility / Jurassic

CRediT authorship contribution statement

L. Ezquerro: Conceptualization, Data curation, Investigation, Methodology, Supervision, Writing – original draft, Writing – review & editing. R. Coimbra: Data curation, Investigation, Methodology, Writing – original draft, Writing – review & editing. B. Baulúz: Data curation, Investigation, Methodology, Writing – original draft, Writing – review & editing. C. Núñez-Lahuerta: Data curation, Investigation, Methodology, Writing – original draft, Writing – review & editing. T. Román-Berdiel: Data curation, Investigation, Methodology, Writing – original draft, Writing – review & editing. M. Moreno-Azanza: Data curation, Investigation, Methodology, Writing – original draft, Writing – review & editing.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported the PLEC2021-008203 project and RYC2021-034473-I, funded by MCIN/AEI/10.13039/501100011033 and by the European Union “NextGenerationEU”/PRTR”; Fundação para a Ciência e Tecnologia (FCT-MCTES) of Portugal (projects PTDC/CTA-PAL/31656/2017 and PTDC/CTA-PAL/2217/2021), and Research Unit GeoBioTec UIDB/04035/2020. Also, the work is part of the Carmen Nunez-Lahuerta is supported by FJC2020-044561-I-; MCIN, co-financed by the NextGeneration EU/PRTR.

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