| Named By: | Williston in 1911 |
| Time Period: | Late Carboniferous - Early Permian, 301-298 Ma |
| Location: | USA, Texas |
| Size: | 1 meter long |
| Diet: | Carnivore |
| Fossil(s): | Enough remains are known to enable reconstruction |
| Classification: | | Chordata | Amphibia | Temnospondyli | Euskelia | Dissorophoidea | Dissorophidae | |
Platyhystrix (meaning "flat porcupine") was a temnospondyl amphibian with a distinctive sail along its back, similar to the unrelated synapsids, Dimetrodon and Edaphosaurus. It lived during the latest Carboniferous and earliest Permian periods in Texas, about 300 million years ago.