Sobre la validez de la tortuga británica “Pleurosternon portlandicum”

El Grupo de Biología Evolutiva de la UNED acaba de publicar un nuevo artículo en la revista Journal of Iberian Geology, dentro del número especial de las VIII Jornadas Internacionales sobre Paleontología de Dinosaurios y su Entorno. El trabajo titulado “On the validity of the British Upper Jurassic turtle “Pleurosternon portlandicum” (Paracryptodira, Pleurosternidae)”, hace una evaluación de la validez específica del taxón apenas conocido “Pleurosternon portlandicum” y de su atribución al género Pleurosternon.

Os dejamos el resumen del artículo a continuación:

Pleurosternidae is a clade of North American and European Mesozoic turtles known from the Late Jurassic to the Early Cretaceous. The knowledge about the European record of this group has significantly being improved during the last decade, both by the description of new taxa as well as by the detailed study of several poorly known members. However, phylogenetic relationships within this clade still generate controversy, due to the scarce available information on several representatives. In that regard, the problematic “Pleurosternon portlandicum” is currently the worst known European pleurosternid. This taxon is represented by a single and partially preserved shell, from the Tithonian (Upper Jurassic) of the Isle of Portland (United Kingdom). Relatively limited information is provided by this individual, exclusively known in ventral view. In this study, the characters used by previous authors to distinguish “Pleurosternon portlandicum” from the type species of the genus Pleurosternon (i.e., Pleurosternon bullockii) are revised in detail given the intraspecific variation we recognized for the study of a large collection of adult specimens of Pleurosternon bullockii. In this way, both the specific validity of “Pleurosternon portlandicum” and its attribution to the genus Pleurosternon are evaluated. As a consequence, the validity of this species cannot be supported, being recognized as a senior synonym of the type species. Thus, Pleurosternon bullockii is identified not only as restricted to the lowermost Cretaceous (Berriasian) but its present during the Upper Jurassic (Tithonian) is demonstrated, not only being recognized in the Tithonian record of Great Britain but also in that of France.

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Más información:

• Referencia: Guerrero, A., Pérez-García, A. 2020. On the validity of the British Upper Jurassic turtle “Pleurosternon portlandicum” (Paracryptodira, Pleurosternidae). Journal of Iberian Geology. https://link.springer.com/article/10.1007%2Fs41513-020-00136-x
• Imágenes (de arriba abajo): Holotipo de “Pleurosternon portlandicum” del Titoniense (Jurásico Superior) de la Isla de Portland (Dorset, Reino Unido), reasignado aquí a Pleurosternon bullockii; Comparación entre “Pleurosternon portlandicum” (a) y algunos ejemplares de Pleurosternon bullockii (b-e).