Cacops,extinct amphibian genus found as fossils in Early Permian, or Cisuralian, rocks in North America (the Early Permian Period, or Cisuralian Epoch, lasted from 286 299 million to 258 271 million years ago). Cacops reached a length of about 40 cm (16 inches). The skull was heavily constructed, and the otic notch, the region in the hind part of the skull that housed the hearing mechanism, was extremely large and closed behind by a bony bar, indicating that Cacops probably relied heavily upon its sense of hearing and might have been nocturnal. With its strongly developed legs and limb girdles, the animal was well equipped to move about on land. The tail was relatively small, and the thick plating of bony armour on the back was probably an adaptation against attack. It is likely that Cacops spent more of its time on land than any other amphibian known in the fossil record.