Neck mobility, Grazing habits, and intraspecific combat behaviour in the Giant Pleistocene horned Turtle Meiolania Platyceps

Abstract:

Meiolania platyceps is the stratigraphically youngest, and osteologically best-known members of the enigmatic Paleogene-Holocene testudinatan clade Meiolaniidae. This study generated digital reconstructions of intervertebral mobility using the complete cervical series of M. platyceps as a functional model for inferring feeding habits in giant meiolaniid taxa. A combined photogrammetric and CT data approach was used to compile surface meshes for each individual vertebra, which were then scaled, articulated, and animated to visualise maximal movement through segments radiating from the dorsoventral and mediolateral planes. The results show that M. platyceps was incapable of any kind of neck retraction, which is not surprising given the massive skull and prong-like squamosal horns. In addition, impeded dorsal flexibility via the vertebral processes and projecting anterior margin of the carapace suggests that browsing would have been difficult. Indeed, the neck of M. platyceps was best capable of downward mobility allowing the skull to tilt forward. This presumably brought the muzzle into a grazing position and allowed the animal to feed upon low growing herbaceous vegetation, ferns and palm fruits. Because of the insularity and the skull configuration of this aberrant turtle, an intraspecific combat behaviour has also been suggested in the reconstruction of the lifestyle of M. platyceps.