Trematopidae is a family of dissorophoid temnospondyl spanning the late Carboniferous to the early Permian. Together with Dissorophidae, the family forms Olsoniformes, a clade comprising the medium-large terrestrial dissorophoids. Trematopids are known from numerous localities in North America, primarily in New Mexico, Oklahoma, and Texas, and from the Bromacker quarry in Germany.
The clade Trematopidae was first proposed by American paleontologist S.W. Williston in 1910, although it was named as "Trematopsidae" following the historical (but inaccurate) derivation from the genus "Trematops" (now synonymized with Acheloma).[1] British paleontologist D.M.S. Watson proposed a related clade in 1919, Achelomidae, for Acheloma, based on perceived differences separating the taxa;[2] this is now considered a junior synonym of Trematopidae following guidelines of historical precedent.
In 1882, American paleontologist Edward Drinker Cope named Acheloma cumminsi based on material collected from the early Permian of Texas.[3] This is technically the first trematopid to be named, although the holotype of Mordex calliprepes was named a year earlier as a species of Limnerpeton by Czech paleontologist Antonin Fritsch in 1881 (one year prior);[4] the status of Mordex as a trematopid remained debated however until the revision by Milner (2018).[5]
In the first half of the 20th century, American paleontologist S.W. Williston named a new genus from the early Permian of Texas, Trematops.[6] At the time, most workers regarded it as only distantly related to Cope's Acheloma.[7] Two additional species of Trematops were named in short order, Trematops thomasi from Oklahoma, named by American paleontologist Maurice Mehl,[8] and Trematops willistoni from Texas, named by American paleontologist E.C. Olson in 1941.[9] Both are now regarded as junior synonyms of Acheloma cumminsi. Olson also named two species of Acheloma, A. whitei and A. pricei; both are now regarded as belonging to Phonerpeton.[10] In the same paper that he named these taxa, Olson also provided the first review of the Trematopidae, synthesizing all of the known material and providing updated taxonomic frameworks.