Rosasia is distinguished by a skull with a moderately obtuseV-shape, less so than in Bothremys cooki. The orbits are less reduced than Bothremys, though the external nostril is unusually narrow for the group. The maxillae are greatly enlarged, and there is a strong ventral expansion of the quadratojugal. The first vertebra of the carapace largelyu covers the entire nuchal, as in Bothremys parva. The vertebrae themselves are relatively narrow.