The type locality, called Merkel's Quarry, is in east-central Germany at Bernburg an der Saale within the Bausandstein (Olenekian) and was collected for several decades from the 1840s into the early 20th century, producing extensive cranial remains, although the majority of these are preserved as internal molds (steinkerns) or natural molds.

This was remedied by subsequent workers who provided specimen illustrations for material reposited at numerous museums across Europe.

[9][10] Trematosaurus fuchsi is widely regarded as a junior synonym of T. brauni, while T. thuringiensis is tentatively considered to be valid with the caveat that poor preservation of the single specimen may account for some of the purported differences.

from Russia belong to Inflectosaurus,[11] but Trematosaurus galae is a recently described Russian species that remains valid to date.

[1] The more questionably valid T. thuringiensis differs only in having larger orbits and a narrower skull table than the type species.