El grupo de Biología Evolutiva de la UNED defendió, en las XXXIX Jornadas de la Sociedad Española de Paleontología, varios trabajos relativos a algunas de las investigaciones sobre tortugas fósiles actualmente en curso. Entre ellas se incluye el análisis de las primeras formas de Pleurodira registradas en Europa. Para ello, se expusieron los principales resultados relativos al hallazgo de un caparazón de Algorachelus en niveles depositados junto a la transición entre el Cretácico Inferior y el Cretácico Superior, recientemente publicado. El resumen de esta contribución, con el título “Implications of the discovery of a pelomedusoid turtle in the Boundary Marls Unit (Utrillas Group) of Estercuel (Teruel, Spain)”, es el siguiente:
The recent discovery of a turtle shell at La Dehesa mine, in Estercuel (Teruel Province, northeastern Spain) is documented here. This discovery is the first reptile remain recovered in the mine. It corresponds to an articulated partial shell, preserving most of the plastral plates but only some osseous elements of its carapace. However, the internal cast of the other carapacial areas is also recognized. Its discovery occurred in shallow marine deposits of the Boundary Marls Unit of the Utrillas Group, deposited during the late Albian (latest Early Cretaceous) or earliest Cenomanian (earliest Late Cretaceous). Several characters of this shell, especially the presence of mesoplastra and that of the pelvic girdle sutured with the shell allow its attribution to the crown group Pleurodira. It is identified as a representative of Pelomedusoides and, more specifically, attributed to Bothremydidae. This systematic attribution has important paleobiogeographic repercussions, since it represents the oldest evidence of this successful lineage, of Gondwanan origin, outside this region. In fact, it is also the oldest fossil of a pelomedusoid turtle in Laurasia. The precise systematic attribution of this specimen is discussed.
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