Synapomorphy

A synapomorphy is a shared, unique trait that appears in all members of a particular group and evolved from a common ancestor. It helps scientists identify and classify related species by highlighting features that indicate a common evolutionary origin. For example, the ability to produce milk is a synapomorphy of mammals. These traits distinguish a group from other organisms and provide clues about their evolutionary history. Essentially, synapomorphies are important characteristics that link related species together through shared ancestry.