Eocene Paleoecology of Adapis parisiensis (Primate, Adapidae): From Inner Ear to Lifestyle.

European adapids, especially Adapis parisiensis, have been extensively studied over the past two centuries, essentially for taxonomic and phylogenetic purposes. Analyses of dental, cranial, and postcranial morphology have led to various hypotheses about the diet, locomotion, and lifestyle of this fossil primate species. As the morphology of Adapis parisiensis is not directly comparable to any extant species, some interpretations are still debated. The inner ear is crucial to several functional parameters, such as auditory acuity, balance, agility, orientation, and head motion speed during locomotion. We examined the inner ear morphology of Adapis parisiensis in order to make some functional inferences, using μCT techniques to access the internal morphology without damaging the fossil specimens. We analyzed the length and shape of the cochlea, the size of the oval window, and the size and orientation of the semicircular canals of seven Adapis parisiensis crania. Results indicate that the species was more sensitive to high frequencies than low frequencies. Results for locomotion style are different, depending on the method used. Results about the coefficient of agility are in good agreement with previous studies, proposing a slow/medium slow locomotion for the fossil species. In contrast, angular velocity magnitude (AVM) results show a great range of variation in the locomotor repertory for Adapis parisiensis, probably indicating that the model used is not adapted to the study of the fossil record. A comparison to measurements of extant strepsirhines leads us to conclude that Adapis parisiensis was probably monogamous and solitary, with a small home range. Anat Rec, 300:1576-1588, 2017. © 2017 Wiley Periodicals, Inc.
(© 2017 Wiley Periodicals, Inc.)