One pattern that is evidence that reptiles and amphibians share the same ancestor is the presence of similar skeletal structures and patterns in both groups. For example, both reptiles and amphibians have similar skull structures, including a lower jaw composed of multiple bones that are joined by sutures. This similarity suggests that these groups share a common ancestor with a similar skull structure that has been retained through evolution. Additionally, both reptiles and amphibians have similar limb structures, with five digits on their limbs arranged in a similar pattern. This shared trait indicates that these groups have a common evolutionary origin.
