A reevaluation of the enigmatic Permian synapsid Watongia and of its stratigraphic significance

The enigmatic synapsid Watongia, initially described on the basis of fragmentary remains from the Chickasha Formation of Oklahoma as an early therapsid (a gorgonopsian), is redescribed and is shown to represent the largest known varanopid synapsid. Its assignment to the Varanodontinae (Varanopidae: Synapsida) is supported by several diagnostic features, including a strongly recurved marginal dentition with both posterior and anterior, unserrated, cutting edges, quadratojugal with two discrete superficial rami, a large lateral tuberosity on the postorbital, short, deep excavations on the neural arches, and a broad, short radiale. The presence in Watongia of a posterolateral process of the frontal precludes therapsid or sphenacodontid affinities. The previously described preparietal that provided the strongest evidence of therapsid affinities for Watongia is shown to be based on misinterpreted skull fragments that were incorrectly assembled. The presence of a varanopid in the Chickasha Formation is consistent with a Guadalupian age (Middle Permian), and in the absence of large sphenacodontids and therapsids, Watongia was probably the top predator of its terrestrial vertebrate community.