Reassessing the endemic European Upper Cretaceous dinosaur egg Cairanoolithus

Abstract

The fossil record of dinosaur eggs and eggshells from the uppermost Cretaceous strata of south-western Europe is composed of both worldwide-distributed and endemic egg types. In this study, we are reviewing the enigmatic European oogenus Cairanoolithus, which after analysing abundant material from classic and new localities it is reassigned to a new oofamily (Cairanoolithidae oofam. nov.) in the light of the unique combination of structural characters. The new oofamily includes one oogenus and two oospecies. Cairanoolithid eggs share several features with other ornithopod egg types indeed. Furthermore, our phylogenetic analysis places Cairanoolithus as the sister ootaxon of the ornithopod ootaxa, being considered the most basal ornithischian egg type known so far. Although neither embryonic nor bones remains are known in association with cairanoolithid eggs so far, several taxonomic attributions have been proposed for this egg type over time. On the basis of microstructural features, phylogenetic results and anatomical constrains, we discuss in this paper previous taxonomic attributions and provide new evidence for suggesting a plausible nodosaurid affinity.

Keywords::

• Dinosauria
• Ornithischia
• egg
• Late Cretaceous
• Europe

Acknowledgements

This paper is a contribution to the project CGL2011-30069-C02-01,02/BTE subsidised by the Ministerio de Ciencia e Innovación of Spain), and part of the unpublished PhD dissertation of AGS supported by a FI [grant number 2008FI-AGAUR]. We thank Jean Le Loeuff (Musée des Dinosaures, Espéraza, France), Monique Vianey-Liaud (Univertite Montpeller II, France), Frankie D. Jackson, David Varricchio (Montana State University, USA) and staff members of CRARC (Masquefa, Spain) for providing comparative material. The authors thank Ashu Khosla (Panjab University) and an anonymous reviewer for their helpful reviews of this paper, Bernat Vila (Universidad de Zaragoza, Spain) for his comments and useful suggestions in early versions of the manuscript, and the assistance of staff members of CCiTUB in ESEM analyses. The Generalitat de Catalunya (Departament de Cultura) provided legal fieldwork permissions and supported research and fieldwork.

Notes

^1. Email: [email protected]