Unusual theropod eggshells from the early cretaceous blesa formation of the Iberian Range, Spain

Abstract

Trigonoolithus amoae oogen. et oosp. nov. is described on the basis of abundant eggshell fragments from the La Cantalera 1 site in the Early Cretaceous (early Barremian) Blesa Formation, Teruel Province, northern Spain. The surface ornamentation, the most diagnostic feature of the new oogenus, consists of closely spaced sub-triangular or rounded protuberances that have not previously been reported in any other ootaxon. The eggshells present three distinct layers, with a gradual transition between prismatic and mammillary layers, and a poorly developed external layer with progressive prismatic to external layer transition, a combination of characters that allows them to be assigned to Prismatoolithidae. Phylogenetic analyses based on oological characters place Trigonoolithus at the base of Prismatoolithidae.