The type specimen of the enigmatic marine reptile Omphalosaurus is reexamined to test its postulated affinity with the Ichthyopterygia. Some of the specimens that have been assigned to the genus cannot be linked to the type specimen, and the rest fails to establish any of the basal ichthyopterygian synapomorphies in the genus. The similarities between the genus and some ichthyopterygians are either symplesiomorphies or common convergences; none of them are unique to the two. The genus also possesses characters that do not exist in any ichthyopterygians, such as a splenial jaw symphysis. Although the affinity of Omphalosaurus is inconclusive at this point, there is insufficient reason to prefer ichthyopterygians as its sister group among others.