Nuevos datos sobre las tortugas de Riodeva (Teruel) en las X Jornadas Internacionales de Salas de los Infantes

Un único individuo de tortuga había sido, hasta ahora, documentado en la bien conocida localidad del Jurásico Superior de Barrihonda-El Húmero, en Riodeva (Teruel). Se trataba del holotipo de Riodevemys inumbragigas, el primer pleurostérnido definido en el registro español. Hasta ahora esta especie era conocida exclusivamente mediante ese espécimen, correspondiente a un espécimen adulto. Un ejemplar hasta ahora inédito de Pleurosternidae de esa misma localidad ha sido presentado en las X Jornadas Internacionales sobre Paleontología de Dinosaurios y su Entorno, recientemente celebradas en Salas de los Infantes (Burgos). Al igual que el individuo previamente documentado, se trata de un esqueleto parcial, destacando, por su preservación, el caparazón. Su potencial atribución a una misma especie y, por tanto, las posibles implicaciones para conocer la ontogenia de un miembro de este linaje, son evaluadas. El resumen de esta contribución, titulada “The second individual of Pleurosternidae from the Tithonian Barrihonda-El Humero site (Riodeva, Teruel)”, es el siguiente:

One of the main lineages of stem turtles (i.e., Testudinata not attributable to the crown group Testudines) identified in the Iberian record is that of Paracryptodira. In this region, it is exclusively represented by members of the Pleurosternidae. Pleurosternidae is the only group of freshwater turtles identified in the Upper Jurassic record of both North America and Europe, showing a relatively high diversity in both regions. The North American record of this lineage is restricted to the Upper Jurassic. However, Pleurosternidae shows a notably wider temporal distribution in Europe, surviving at least until the last stage of the Lower Cretaceous (i.e., the Albian).
The information on the European members of Pleurosternidae was, until a few years ago, very limited. However, recent studies and, especially, the description of several new forms, allowed improving the knowledge on the diversity, systematic, and stratigraphic and palaeobiogeographic distributions of the forms that inhabited this continent. Although several forms are currently known for the Spanish record, the first described there was Riodevemys inumbragigas. It comes from the Kimmeridgian or Tithonian Barrihonda-El Humero fossil site, located in Riodeva, in the Teruel Province (South Iberian Basin). Other vertebrates found at this site include the sauropod Turiasaurus, the stegosaurid Dacentrurus, and the ornithopod Oblitosaurus.

Riodevemys inumbragigas was defined by a partial skeleton of an adult individual, including the almost complete shell, as well as several bones of the scapular and pelvic girdles. No other specimen has been attributed to it so far.
An unpublished partial skeleton of a turtle from the type locality of Riodevemys inumbragigas is presented here. It corresponds to a juvenile individual. Its attribution to Pleurosternidae is justified here. In fact, it is probably attributable to Riodevemys inumbragigas. However, differences in several shell characters relative to the holotype of this species are recognized. The possibility that some of these differences are due to ontogeny, but others to individual variability, are evaluated here considering the intraspecific variability known for Pleurosternidae.