Tupinambis teguixin (Merram 1820) extant, commonly referred to as a tegu, primarily carnivorous, but one species is herbivorous. Described as convergent with Varanus. Hatchlings are miniatures of the adults. Able to lose the tail. A sister to Eolacerta, Tupinambis is derived from a sister to Acanthodactylus.
Distinct from Eolacerta, the skull of Tupinambis has a narrower skull roof and larger upper temporal fenestra. The orbit is not taller than long. The teeth are larger and the jawline is convex and notched.
The neural spines are all narrower. The dorsal ribs are shorter, creating a longer, shallower, more sinuous torso. The cheverons are deeper.
The clavicles are narrow medially, having lost the posterior fork.
The pubis is longer ventrally, nearly contacting the ventral ischium which curves anteriorly to meet it. The fibula is more robust, nearly equal to the tibia in diameter. Metatarsal IV is the longest and mt V is longer than in Eolacerta.