Parataxonomía de los restos de huevos de dinosaurio procedentes del yacimiento de Poyos en las XXXVI Jornadas de la SEP

Durante las pasadas XXXVI Jornadas de la Sociedad Española de Paleontología, Fernando Sanguino presentó una discusión preliminar sobre la parataxonomía de los restos oológicos (fósiles de huevos) del Campaniense (Cretácico Superior) del yacimiento de Poyos, en Guadalajara. Este yacimiento, de la misma Formación geológica que Lo Hueco (y aproximadamente de la misma edad) ha proporcionado numerosísimos restos que van desde fragmentos de cáscara hasta grupos de huevos. Todos los restos estudiados hasta el momento de realizar esta comunicación parecen pertenecer a un único ootaxón, diferente al identificado en el yacimiento de Portilla, también de la misma Formación. Mientras que los restos de Portilla concuerdan con restos encontrados en Pirineos y la cuenca de Hateg (Rumanía), los restos de Poyos son claramente distintos y se asemejan mucho más a los conocidos en el yacimiento de Auca Mahuevo (Argentina). A continuación dejamos el resumen:

The Upper Cretaceous (Campanian-Maastrichtian) outcrops of the Margas, Arcillas y Yesos de Villalba de la Sierra Fm. have provided abundant fossils of fishes, amphibians, squamates, turtles, crocodylomorphs and dinosaurs. Among them, dinosaur eggshells found in Portilla (Cuenca) were preliminarily assigned to Megaloolithus siruguei. 

In recent years, abundant eggshells and large, subspherical eggs, often grouped in clutches and distributed in different stratigraphic layers have been found in Poyos (Sacedón, Guadalajara). The studied material seems to represent a single ootaxon different from the one recognized at Portilla due to its different microstructure, larger size and lower shell thickness. A preliminary discussion on the parataxonomic attribution of the egg remains from Poyos and their potential dinosaurian producers is proposed.

These remains can be attributed to a dinosauroid-spherulitic type with almost completely fused eggshell units and very few pore channels, strongly undulating but uniform growth lines, a prolatospherolitic-like microstructure and a dispersituberculate ornamentation. Although the prolatospherulitic  microstructure is typical of Spheroolithidae (ornithopod eggs), ootaxa from this family present very smooth undulations on their growth lines and exterior margin, and a sagenotuberculate ornamentation. Conversely, some discretispherulitic (tubospherulitic) ootaxa from Megaloolithidae (usually attributed to titanosaur sauropods) also display heavily fused eggshell units that may resemble the prolatospherulitic configuration, and an undulation of their growth lines akin to that of the Poyos’ specimens.

Additionally, the inferred palaeoecology and taphonomy of the eggs seem to favour a sauropod productor rather than an ornithopod, as the clutches from Poyos suggest that the eggs were laid in shallow grooves and then buried similar to other clutches attributed to titanosaur sauropods, a group with abundant skeletal remains in this Formation.

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Más información:

• Sanguino, F., Gascó-Lluna, F., Pérez-García, A., Ortega, F. 2021. Ootaxonomy of the Upper Cretaceous dinosaur eggs from Poyos (Sacedón, Guadalajara, Spain). Lucas Mallada, Revista de Ciencias (XXXVI Jornadas de la Sociedad Española de Paleontología. Huesca), 23: 223-224.