Along with the similarly large dinocephalia, the bradysaurs constituted the herbivorous megafauna of the late Middle Permian Period.

Its large dimensions show that, even very early in their evolutionary history, these strange animals had already attained an optimal size.

The advantage of large size was to provide defense against predators and to maintain a stable body temperature (gigantothermy).

Boonstra 1969 distinguishes only four species on the basis of tooth structure, two of which Kuhn places in the genus Embrithosaurus.

B. baini (Seeley, 1892) is from the Tapinocephalus zone, Lower Beaufort Beds, Karoo basin, South Africa.

B. seeleyi (Haughton and Boonstra, 1929) is from the Tapinocephalus zone, Lower Beaufort Beds, Karoo basin, South Africa.