An order and clade of elongate lepospondyls with highly reduced limbs and a lightly built, open skull known from the Middle Pennsylvanian to Lower Permian (305–270 million years ago) of North America and the British Isles. Unlike other lepospondyls, no lysorophians have been found in continental Europe. The vast majority of specimens come from two localities: the coal deposits of Linton, Ohio, and the Clear Fork redbeds of north central Texas. They were aquatic in their lifestyle, and are frequently found in large numbers curled in burrows. These burrows are believed to be estivation chambers, structures constructed by animals for periods of dormancy associated with suboptimal living conditions.