Eggshell taphonomy: environmental effects on fragment orientation

Abstract

Dinosaur eggshell is abundant in the fossil record but only during the last several decades has this reproductive product been considered more than a novelty. Recent work has provided evidence that both whole eggs and fragmented eggshell represent a rich source of information related to paleoecology and dinosaur reproductive biology. In this paper, we report the effects of environmental variables on modern eggshell fragment orientation. Non-transported eggshell fragments at hatching and predation sites favoured concave-up over concave-down orientations. Trampled fragments and fragments transported by wind and water favoured concave-down over concave-up orientations. Although differences in orientation between non-transported and transported eggshell fragments were usually obvious and significant under the chosen experimental conditions, paleontologists are cautioned to interpret the taphonomy at fossil eggshell sites with care and within their sedimentological context.

Keywords:

• dinosaur
• eggshell
• experiments
• taphonomy
• transport

Acknowledgements

We are grateful for the encouragement to study eggshell taphonomy by our late friend Karl F. Hirsch (1921–1996). We thank David Varricchio and Frankie Jackson for their helpful critiques of an earlier draft of this paper and, who along with Jack Horner, hosted the Fourth International Symposium on Dinosaur Eggs and Babies where this paper was presented. Research funds were provided by Andrews University Faculty Grants program, Andrews University Department of Biology, and the McGregor Foundation. Logistic support was provided by Rosario Beach Marine Laboratory, Anacortes, Washington. The last four authors participated in this research as undergraduate members of the Andrews University Honors Program.

Notes

^† Email: [email protected]

^‡ Email: [email protected]

^§ Email: [email protected]

^¶ Email: [email protected]

Additional information

Notes on contributors

Kristin M. Dickson

† † Email: [email protected]

Susan R. Gamble

‡ ‡ Email: [email protected]

Adam W. Owen

§ § Email: [email protected]

Kimberly C. Owen

¶ ¶ Email: [email protected]