Two new theropod egg sites from the Late Jurassic Lourinhã Formation, Portugal

Abstract

Two new Late Jurassic (uppermost Late Kimmeridgian) dinosaur eggshell sites are described, Casal da Rola and Porto das Barcas, both near Lourinhã, central-west Portugal. Casal da Rola yields eggshells with an obliquiprismatic morphotype comparable to those from a nest with the associated fossil embryos from Paimogo, tentatively assigned to the theropod Lourinhanosaurus antunesi. The Porto das Barcas eggshells have a dendrospherulitic morphotype with a prolatocanaliculate pore system. This morphotype was also recognised in eggshells from a clutch with associated Torvosaurus embryos at the Porto das Barcas locality. A preliminary cladistic analysis of eggshell morphology suggests theropod affinities for the Casal da Rola eggs, but is unable to resolve the phylogenetic position of the Porto das Barcas eggs. The eggshells at both sites are preserved in distal flood plain mudstones and siltstones. Carbonate concretions within the deposits indicate paleosol development.

Keywords::

• Late Jurassic
• Portugal
• theropods
• dinosaur eggs

Acknowledgements

We would like to T.S. Myers (SMU) for the revision. We also thank Nuno Leal (FCT, UNL) for kindly assisting with SEM imaging. Many thanks also to Nury López (Museu da Lourinhã), Verónica Duarte (Museu da Lourinhã), João Russo (Museu da Lourinhã, UNL) and Emanuel Tschopp (Museu da Lourinhã, UNL) for energetic fieldwork. This research is part of Project Dinoeggs – dinosaur eggs and embryos in Portugal: paleobiological implications and paleoenvironmental settings (PTDC/BIA-EVF/113222/2009) funded by the Fundação para a Ciência e Tecnologia (FCT), Portugal.