A new tiny rhytidosteid (Temnospondyli : Stereospondyli) from the Early Triassic of Australia and the possibility of hidden temnospondyl diversity

A new genus and species of stereospondyl temnospondyl, Nanolania anatopreti a, is described from the Early Triassic Arcadia Formation (Rewan Group) of Queensland, Australia. N. anatopretia has several character states that sug gest it belongs to the group of derived trematosaurian stereospondyls that include the Rhytidosteidae and Brachyopoidea. These include the absence of a lacrimal, an untwisted quadrate ramus of the pterygoid. and a shallow oti c notch. It is tentatively referred to the Rhytidosteidae. N. anatopretia i s the third temnospondyl taxon from the Arcadia Formation to be represented by a skull less than 50 mm long. The others are the basal stereospondyl La pillopsis nana. and juveniles of the capitosaurid Paratosuchus aliciae. Giv en that Lapillopsis nana and Nanolania anatopretia are not known from any l arger specimens, and that the temnospondyl fauna from the Arcadia Formation has been well sampled, it is suggested that they art: species that never g rew large. It seems quite likely that a diverse array of small temnospondyl s lived alongside the larger temnospondyls of the Triassic elsewhere in the world but have not been discovered due to biases working against the prese rvation and collection of small temnospondyl specimens.