Craniomandibular biomechanics

Congratulations to Alec Wilken and Chelsie Snipes for publishing their new paper, “Biomechanics of the mandibular middle ear of the cynodont Thrinaxodon and the evolution of mammal hearing”, along with Dr. Ross and frequent collaborator Zhe-Xi Luo! This paper uses finite element analysis to show that the 250-million-year-old synapsid Thrinaxodon already possessed tympanic hearing similar to modern mammals, relying primarily on a soft-tissue eardrum for airborne sound detection. The results indicate that the functional shift toward a mammalian middle ear—detached from the jaw and specialized for sensitive hearing—occurred very early in mammalian evolutionary history. This paper was covered in UChicago’s Biological Sciences Division newsletter- see the coverage here!

Emily McParland, Dr. Ross and colleagues, including lab alumni JD Laurence-Chasen and Kazutaka Takahashi, have published a new paper on the kinematics of chewing in the Wistar brown rat (Rattus norvegicus). This paper arose out of the fruitful collaboration between Dr. Ross’s lab at the University of Chicago and Dr. Nicholas Gidmark’s lab at Knox College. Because this species has an unfused mandibular symphysis, the kinematics are quite complex. The paper finds that due to the complexity, the rat is an unsuitable species in many cases for studying general mammalian chewing evolution or human chewing.