title: PALEONTOLOGY: Homoplasy in the Mammalian Ear.
abstract: The separation of the middle ear bones from the mandible is considered a defining feature of all modern mammals. But did this event happen once in a primitive mammalian ancestor or independently in the monotreme lineage and therian (marsupial and placental) lineage? As Martin and Luo discuss in their Perspective, a new fossil-the dentary bone of an ancient toothed monotreme-suggests that the middle ear bones formed independently in these two mammalian lineages, providing a remarkable example of homoplastic evolution.
authors.forename: Thomas
authors.initials: T
authors.lastname: Martin
authors.forename: Zhe-Xi
authors.initials: ZX
authors.lastname: Luo