359-299 million years ago

amphibian with insect

The anthracosaurs were a group of amphibians which developed additional adaptations for terrestrial environments and are thought to have given rise to reptiles.

Anthracosaurs are known from the early Carboniferous, but they were never very common or diverse. They developed a deep skull, a shorter snout, a short body, large eyes, and strong legs. Silvanerpeton was a small anthracosaur whose skull measured 4 cm. Its ribs were long and slender. In anthracosaurs, the postparietal bone was reduced and the tabular contacted the parietal. Anthracosaurs possessed a joint where skull the met cheek called kinetic line which had been inherited from the osteolepiforms. This group of amphibians is thought to have given rise to the reptiles. In the labyrinthodonts and anthracosaurs, the back of the skull is not solid and therefore the stapes (a middle ear bone in humans) was still large to function in the support of the skull and would not have functioned well in hearing.