Unlike other members of the Iguanomorpha, however, Magnuviator bears a distinct articulating notch on its tibia for the ankle bones (astragalus and calcaneum), which has traditionally been considered a characteristic of non-iguanomorph lizards.

The morphology of its teeth suggests that its diet would have mainly consisted of wasps, like the modern phyrnosomatid iguanians Callisaurus and Urosaurus, although it also shows some adaptations to herbivory.

On the postorbital, the interior edge bears a projection around its midpoint, and forms the front margin of the supratemporal fenestra.

On the underside of the jaw, the palatine bone uniquely bears an opening near the front end that extends forward into the skull to connect to the infraorbital canal.

They are pleurodont, meaning that they extend out from the interior side of the jawbone, they are roughly equal in height, and they do not have V-shaped wear facets.

[1] Both known specimens of Magnuviator are known from the Egg Mountain locality of the Two Medicine Formation, which represents a nesting site.

[3] This locality is located in Teton County, Montana, and would have been at 48° N[4] in the Campanian age of the Cretaceous period; more specifically, it has been dated to 75.5 ± 0.4 million years ago.

[1] The genus name Magnuviator combines the Latin words magnus ("mighty") and viator ("traveller"), in reference to its large size and close affinities to the Asian Temujiniidae.

Three characteristics allow Magnuviator to be recognized as a member of the Iguanomorpha: the parietal eye being located at the frontal-parietal suture; the boss on the prefrontal; and the angular process in front of the jaw joint.

[1] Acrodonta Priscagamidae Ctenomastax parva Magnuviator ovimonsensis Saichangurvel davidsoni Temujinia ellisoni Isodontosaurus gracilis Polrussia mongoliensis Zapsosaurus sceliphros Pleurodonta As the oldest known North American iguanomorph, Magnuviator helps to complete the picture of the emergence of the Pleurodonta, a clade only definitely known from the Eocene forward due to scarcity of fossil remains in the southern parts of North America.

Also from Egg Mountain are unnamed varanoid lizards, as well as various non-body fossils, including wasp pupal cases, nests, and dinosaurian coprolites.

[21] Overall, the environment of the Egg Mountain locality more closely parallels that of the Mongolian Djadochta Formation[30] (from where temujiniids and other basal iguanomorphs are known),[2][31] than that of its contemporary non-iguanomorph squamates in North America (largely preserved in lowland systems of freshwater rivers).