Diplovertebron,genus of extinct amphibians of North America and Europe known from fossils in Late Carboniferous rocks (from 320 to 286 million years ago). Diplovertebron represents a late surviving form an early representative of the anthracosaurs, a group of primitive amphibians that probably included the ancestors of the more advanced reptilestetropods with some reptile traits. Since they could not produce an amniotic egg, which is a defining characteristic of true reptiles, anthracosaurs are classified as reptilelike amphibians. Diplovertebron and other primitive anthracosaurs are characterized by a distinctively constructed vertebral column and skull pattern and five-toed feet.