Assessing the distribution of the Campanian-Maastrichtian oological record associated to titanosaur sauropods

Resumen

Two oofamilies have been directly linked to titanosaurian sauropods through embryo remains,Megaloolithidae and Fusioolithidae. Currently, the known record of these oofamilies iscircumscribed to European, North African, South American, and Indian Upper Cretaceouslocalities, ranging from Campanian to Maastrichtian in age. The distribution of these ootaxahas played a role in ongoing discussions on end-Cretaceous European dinosaur biogeographyas supporting evidence for a mid-Maastrichtian faunal turnover involving the arrival of dinosaurtaxa with Gondwanan affinities. In the present study, a preliminary Cluster Analysis conductedon the distribution data of those oofamilies found a clear dichotomy between the European andGondwanan records during the early Campanian–early Maastrichtian interval with the four testedpresence/absence similarity indexes (Simpson, Jaccard, Dice and Raup-Crick). Gondwananand European fossil sites from this interval show distinct sets of megaloolithid ootaxa, whilefusioolithids are common in Gondwana and mostly absent in Europe. Fusioolithus baghensismay be the only shared ootaxon known to date, as compatible remains have been found at theVillalba de la Sierra Fm (central Spain). This clear dichotomy between Europe and Gondwana isnonetheless not found during the middle–late Maastrichtian interval. Three main area clusters areidentified: Ibero-Armorica, central India, and the remaining Gondwanan sites. While central Indiansites are characterized by the presence of endemic fusioolithid ooespecies, other Gondwanansites are found closer to Ibero-Armorica, mainly due to the widespread distribution of Fusioolithusbaghensis. However, both the Hateg area and those that comprise this Gondwanan group includeseveral sites with scarce/outdated available data. New data from these regions would prove ofgreat value for further analyses and discussion.