Kryostega was discovered in beds of the upper Fremouw Formation at Gordon Valley in the central Transantarctic Mountains. This portion of the Fremouw Formation consists largely of a 300-meter thick series of crossbedded, volcaniclastic sandstones. Kryostega was found in a thin siltstone cobble conglomerate within these strata, about 70 meters from the base of the upper member. The same bed has produced remains of Cynognathus, along with a kannemeyeriid dicynodont, a gomphodont cynodont, and a second species of large temnospondyl. Sidor et al. (2008; p. 661-662) conclude that the ...inferred high paleolatitude of Gordon Valley during deposition would have subjected it to long periods of continuous darkness during the winter months, and that the discovery of a large, semi-aquatic amphibian in these beds is ...evidence for unsuspected ecological diversity with the Polar Circle during the Triassic.