Abstract
Azzabaremys moragjonesi, from the Paleocene of Mali, is a member of Nigeremydini. This is a clade of bothremydid pleurodiran turtles that includes large putatively marine forms which inhabited the African Trans-Saharian Seaway from the Maastrichtian to the Paleocene. This work represents the first neuroanatomical reconstruction of a putative sea pleurodire. Some of the neuroanatomical modifications observed for Azzabaremys moragjonesi differ from those in the other lineages of Bothremydidae in which these structures have been documented, corresponding to freshwater instead of pelagic marine forms. In fact, the primitive condition for Pleurodira is the adaptation to freshwater environments, as is the case with all extant representatives, but also with most documented extinct forms. The neuroanatomy of Azzabaremys moragjonesi shows convergences with that of the members of Pan-Cryptodira with adaptations to marine environments (i.e., Chelonioidea, including Cheloniidae and Dermochelyidae), but also with other clades of marine turtles exclusive to the fossil record (i.e., several Mesozoic and Palaeogene clades with uncertain affiliations: Plesiochelyidae, Sandownidae, and Protostegidae). Thus, aspects such as the position of the geniculate ganglion into the canalis cavernosus, the absence of an anterior vidian canal piercing the pterygoid, and the possession of wide semicircular canals of the endosseous labyrinth, as well as the possible presence of enlarged lacrimal glands, are recognized here as convergent modifications developed in Cryptodira, extinct clades with uncertain affiliations, and Pleurodira in response to adaptation to marine environments.
Published Version
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