A large temnospondyl mandible from the Lystrosaurus Assemblage Zone (Early Triassic) of
South Africa is referred to the higher-level taxon Trematosauridae. The mandible is remarkably similar
to that described for Trematosaurus from the Middle Buntsandstein of Germany, a genus closely
related to the South African Trematosuchus, for which the mandible is unknown. However, the
mandible cannot be referred unequivocally to either of these taxa. Trematosuchus is considered to be
restricted to the lowermost subzone of the overlying Cynognathus Assemblage Zone, which, based
principally on the temnospondyl and therapsid fauna, is considered to be of Upper Olenekian age.
The mandible described here extends back the range of the Trematosauridae to the underlying
Lystrosaurus Assemblage Zone and argues against the long-held notion of a sharp palaeontological
break between the faunas of the Lystrosaurus and Cynognathus Assemblage zones. It also supports the
hypothesis that the Lystrosaurus Assemblage Zone extended up to the Upper Olenekian.