Platyhystrix

Platyhystrix (from the membrane flat sort of fabric) is an extinct amphibian, from the Permian (around 300-280 million years ago). Its remains have been found in Texas. It was an amphibian suited for the drier climate of the Permian.

A salamander with a "sail"

Platyhystrix, measuring less than a meter, appeared rather unusual: the dorsal vertebrae were extraordinarily lengthened, and probably in life they formed a skin-covered sail. This structure perhaps served the function of thermal regulation, as other animals (such as the two pelycosaurs Dimetrodon and Edaphosaurus), that lived in the same environment were endowed with a similar “dorsal sail”. The back of the Platyhystrix had covered besides with thick hard plates, similar to that of its near relative, Cacops. The skull was big and strong with a frog-like face. Platyhystrix had a compact body and its short and strong legs indicate a mainly terrestrial life.

References

Vertebrate Palaeontology by Michael J. Benton and John Sibbick
The Simon & Schuster Encyclopedia of Dinosaurs and Prehistoric Creatures: A Visual Who's Who of Prehistoric Life by Barry Cox, Colin Harrison, R.J.G. Savage, and Brian Gardiner
Bibliography Of Fossil Vertebrates 1934-1938 by C. I. Camp