Los huevos de dinosaurio de la Formación Villalba de la Sierra tuvieron su hueco con la charla “Titanosaur eggs from the Villalba de la Sierra Formation (Upper Cretaceous, Castilla-La Mancha, Spain” de Sanguino et al. En esta contribución se repasaron los avances realizados en el último año sobre este registro, que aparece en forma de cáscaras aisladas, huevos más o menos completos y puestas parciales. Cada una de ellas aporta distintas capas de información para diferentes líneas de trabajo, entre los que se encuentran la parataxonomía con el reconocimiento de al menos dos ootaxones nuevos; la tafonomía y patrones de eclosión con el modelado 3D y segmentación de huevos completos; patrones de puesta mediante la disposición de los grupos de huevos; y paleoecología y bioestratigrafía al combinar las evidencias obtenidas del registro oológico con otras fuentes de información.
The titanosaurian affinities of the Campanian-Maastrichtian oological remains at the Villalba de la Sierra Formation have been discussed since the study of the Megaloolithus siruguei eggshells from the Portilla fossil site (Cuenca). Since then, additional eggshells have been collected in several outcrops of the Formation, such as those around Zafra de Záncara and Buendía (Cuenca), and at the Poyos fossil site (Sacedón, Guadalajara) and its surroundings, where partial and complete eggs and clutches have also been found. These findings have significantly improved the knowledge of the oological record from the Villalba de la Sierra Formation. The shape, size, .0and microstructure of the newly found eggs and eggshells have allowed, on one hand, the identification of the oofamily Fusioolithidae represented by at least two ootaxa. This oofamily has been attributed to titanosaur sauropods with Gondwanan affinities through the identification of preserved in ovo embryos at the Argentinean site of Auca Mahuevo, and its appearance in the European record has been interpreted as evidence of the arrival of Gondwanan faunas in the lower Maastrichtian. On the other hand, the characteristics of the eggs and eggshells have allowed the assessment of optimal incubation conditions for the eggs from Poyos through comparison with extant avian and non-avian reptilian species. Partial and complete eggs from Poyos have been CT-scanned in search for embryo remains and hatching patterns. Taphonomical evidence obtained from these patterns suggests that the eggs where originally covered by sediment and later filled as the hatchling dug upward, preventing them from collapsing and facilitating their 3D preservation. This taphonomical interpretation, along with the egg disposition among the recovered partial clutches and the inferred optimal incubation conditions, is compatible with the nesting behaviour inferred for titanosaurs through complete clutches from other sites.
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