A study suggests that the ancestral mammal was a small, whole-footed walker whose descendants evolved into toe-walkers and hooved animals. In mammals, foot postures reflect successful adaptations spanning a wide range of ecological niches. For example, the limb morphologies and biomechanics of whole-foot walkers, such as humans and mice, closely track underlying differences in their evolutionary trajectories, compared with toe-walkers, such as cats and dogs. Tai Kubo, Manabu Sakamoto, and colleagues applied Bayesian statistical methods to a dataset spanning 880 extant species and reconstructed the evolutionary histories of foot postures in mammals. The authors' analysis suggests that the ancestral mammal was likely a plantigrade, or flat-footed walker, whose descendants evolved digitigrade, or tip-toed postures, and later unguligrade, or hooved postures. Further, the reconstructions revealed that transitions from one posture to another coincided with sharp increases in rates of body size evolution, suggesting links between foot posture and the emergence of large descendants. Although the current findings do not establish that foot posture drove increases in body size or vice versa, the macroevolutionary statistical approach can be applied to datasets spanning broader ranges of living and extinct terrestrial tetrapods to address this question, according to the authors.
Article #18-14329: "Transitions between foot postures are associated with elevated rates of body size evolution in mammals," by Tai Kubo, Manabu Sakamoto, Andrew Meade, and Chris Venditti
MEDIA CONTACT: Tai Kubo, University of Tokyo, JAPAN; e-mail: taikubo@hotmail.com; Manabu Sakamoto, University of Reading, UNITED KINGDOM; e-mail: m.sakamoto@reading.ac.uk
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