Meeting Abstract
Facial muscles are a distinctively mammalian feature responsible for daily activities such as communication, sensory exploration, and feeding. Examination of the fossil record suggests that at least a subset of facial muscles – those responsible for the mobilization of mystacial vibrissae – may have been present in stem-mammalian ancestors as far back as the Mid-Triassic. From their deep evolutionary origins, facial muscles in modern mammals have subsequently diversified into an incredible array, including extreme modifications such as the elephant’s powerful trunk and the subtle expressive landscape of the human face. In this study, we compare the ontogeny of facial muscles in various marsupial and placental mammal species using both confocal images of fluorescent immunostained and reconstructed microCT scans of iodine contrast-stained embryos and neonates. Our exploration of the sequence of facial muscle differentiation shows some of the conserved as well as the more clade-specific variations in the developmental process, providing insight on the evolution and diversification of this muscle system.
