Fossil eggshells from the Upper Cretaceous (Campanian) Fruitland Formation, New Mexico

Abstract

Approximately 1500 eggshell fragments were recovered from a vertebrate bonebed (NMMNH L-4010) in the late Campanian Fruitland Formation in northwestern New Mexico, a locality that represents one of the few southern occurrences of fossil eggshells in North America. Here, we present the first description of Campanian eggshells from New Mexico and identify six different eggshell types (Continuoolithus sp., Porituberoolithus sp., Testudoolithus sp., Prismatoolithus sp., krokolithid, indeterminate type) among the well-preserved fragments, which are attributable to dinosaurs, crocodilians and turtles. The taxonomic diversity of eggshells is comparable to the taxonomic diversity of animals represented by skeletal remains in the bonebed, which would have laid rigid-shelled eggs (i.e. dinosaurs, crocodilians and turtles). Eggshells of theropod dinosaurs are the most common and comprise approximately 85% of the eggshells, whereas those of crocodilians and turtles form the remaining 15%. Although bones of hadrosaurs and ceratopsians are well represented by skeletal remains at the locality, their eggshells have yet to be identified. The relative abundance of the taxa represented by eggshells at NMMNH L-4010, with those of theropods being by far the most common, is comparable to that observed in the more northern late Campanian microsites of Dinosaur Provincial Park, Alberta.

Keywords:

• eggshell
• theropod dinosaur
• turtle
• crocodilian
• vertebrate microsite
• Fruitland Formation

Acknowledgements

Funding for research was provided by the Natural Sciences and Engineering Council of Canada Discovery Grant to DKZ. The authors thank Dr Donald Brinkman of the Royal Tyrrell Museum for his help with the photography of some of the specimens. KT is grateful to his parents (Takahiko and Makiko Tanaka) for their support while he was overseas in Canada working on this project, and to Dr Yoshitsugu Kobayashi for discussions on the manuscript. The manuscript was improved by reviews of Dr Frankie Jackson of Montana State University and of an anonymous reviewer.

Notes

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Additional information

Notes on contributors

Darla K. Zelenitsky

† † Email: [email protected]

Thomas Williamson

‡ ‡ Email: [email protected]

Anne Weil

§ § Email: [email protected]

François Therrien

¶ ¶ Email: [email protected]