Frogs

Frogs and their ancestors are among the most ancient of terrestrial vertebrates. A frog-like fossil animal more than 240 million years old is known from early Triassic rocks of Madagascar. This ancient amphibian, named Triadobatrachus, differs from true frogs in having more vertebrae in its spinal column (14, rather than 5-9) and in having a tail made up of six additional vertebrae. For these and several other differences, it is classified in a different order, the Proanura. By Jurassic times, 208-146 million years ago, such ancestral amphibians had evolved into true frogs, whose skeletal remains are little different from those living today.