It is a close relative of the family Xenosauridae, which includes living knob-scaled lizards.

Fossils of the type and only species Carusia intermedia come from the late-Campanian age Barun Goyot Formation and have been found in the Flaming Cliffs, Ukhaa Tolgod, and Kheerman Tsav fossil localities.

[1] Carusia had initially been known from fragmentary skull material, complicating efforts to determine its evolutionary relationships with other lizards; it had variously been described as an indeterminate scincomorph, a xenosaurid, or some other type of autarchoglossan lizard convergent with xenosaurids.

However, the discovery of 35 complete skulls in the 1990s, three of which were described in a detailed 1998 monograph, revealed that Carusia was the sister taxon (closest relative) of Xenosauridae, compelling the authors of the monograph to create a new clade called Carusioidea to include both taxa.

[2] Like xenosaurids, Carusia has a skull roof covered in large rounded osteoderms (bony plates embedded in the skin).