Reconstructing locomotion in fossil rodents using semicircular canal morphology
Date
2024-07-03
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Abstract
Anatomical structures vary among mammals with different locomotor behaviours, including sensory structures such as the semicircular canals (SCCs) in the inner ear. Recent research suggests that SCC morphology correlates with different locomotor behaviours in various extant and extinct mammalian taxa, but there is a lack of research on rodents, the most speciose and diverse mammalian group. In this thesis, an extant sample of rodent SCCs from 98 individuals across seven different locomotor behaviours (arboreal, fossorial, gliding, ricochetal, semiaquatic, semifossorial, terrestrial) was used to understand the correlations between SCC morphology and locomotion. The extant dataset was then used to create a Canonical Variates Analysis Model to predict probable locomotor modes in fossil rodents with unknown locomotor behaviours. Fossil rodent material consists mostly of craniodental remains; hence reconstructing fossil locomotion has been challenging. The fossil sample contains 7 specimens from four different rodent species from Napak, Uganda (site age: 20 Ma). This thesis provides the first micro-computed tomography scans of the SCCs from Diamantomys luederitzi, Paranomalurus bishopi, Paraphiomys pigotti, and one unidentified small thryonomyoid. The extant model predicted that Diamantomys luederitzi was semifossorial, Paranomalurus bishopi was semiaquatic, Paraphiomys pigotti was terrestrial, and the small thryonomyoid was terrestrial. While the model performed well with predicting specialized locomotor behaviours, the model should be complemented with postcranial and skull morphology for generalist forms of locomotion as it is difficult to distinguish the morphology between generalist locomotor categories.
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Keywords
Paleoanthropology, Inner ear, Locomotion, Geometric morphometrics, Rodentia
Citation
Hou, L. (2024). Reconstructing locomotion in fossil rodents using semicircular canal morphology (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.