Estudio neuroanatómico de Azzabaremys moragjonesi en las XXXIX Jornadas de la SEP

Aunque la mayoría de especies de tortugas pleurodiras extintas y la totalidad de formas actuales de este grupo son formas dulceacuícolas o de medios litorales, algunos miembros de Bothremydidae presentan adaptaciones a ambientes pelágicos, como es el caso de los Nigeremydini. En las XXXIX Jornadas de la Sociedad Española de Paleontología celebradas en A Coruña entre el 2 y el 5 de Octubre se presentó la primera reconstrucción del único cráneo conocido hasta la fecha de Azzabaremys moragjonesi, que corresponde al holotipo de esta especie del Paleoceno de Mali. En este trabajo se evaluaron las modificaciones neuroanatómicas en este taxón respecto al resto de botremídidos de los que se conoce su neuroanatomía, así como las posibles convergencias anatómicas en las cavidades craneales con otras formas de tortugas adaptadas a un modo de vida marino, principalmente con grupos de criptodiras y otras formas de tortugas mesozoicas basales. El resumen del póster se expone a continuación:

Although all extant side-necked turtles are freshwater forms, as was the case with most extinct pleurodires, some extinct podocnemididoid turtles (i.e., several bothremydid species and the Stereogenyini podocnemidids) have been interpreted as possible inhabitants of coastal or even open marine environments. This assumption is based on sedimentary evidence, rather than on anatomical modifications related to a coastal or pelagic way of life. In this context, Nigeremydini has been identified as a putative marine group of Bothremydidae, which inhabited the Trans-Saharian Seaway from the Maastrichtian to the Paleocene. Anatomical and physiological adaptations to pelagic environments in turtles are linked to the changes in salinity and density of this habitat in relation to freshwater environments, as well as the greater capacity for the locomotion in the open sea. Modifications in appendicular and shell osseous elements, but also the presence of well-developed salt glands related to an osmoregulatory function, have been reported from the representatives of Chelonioidea (including extant and extinct members of Cheloniidae and Dermochelyidae), as well as for some extinct groups of Mesozoic and Cenozoic turtles. Modifications of some neuroanatomical elements, as the pattern of the facial nerve system or the semicircular canals of the endosseous labyrinth, are also related with this pelagic lifestyle. The skull of the holotype and unique known specimen of the Malian Paleocene Azzabaremys moragjonesi was scanned through a high-resolution Micro-CT scan to reconstruct the internal cranial cavities and to analyze the neuroanatomical elements of this member of Nigeremydini. These structures will be compared with those known from marine forms of Cryptodira and other extinct lineages (i.e., Protostegidae, Plesiochelyidae, and Sandownidae) to identifying potential adaptive convergences to pelagic environments.

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Más información:

• Referencia: Martín-Jiménez, M., Pérez-García, A. Evaluating the potential development of neuroanatomical modifications for marine environment adaptations in Pleurodira. In Moncunill-Solé, B., Blanco, A., Grandal d’Anglade, A., González Fortes, G., Santos Fidalgo, L., Bao, R. (Eds.), Libro de Resúmenes de las XXXIX Jornadas SEP. Palaeontological Publications 5, 73.