In life, it probably resembled lizards of the genus Heloderma to a large degree, though its skull was more elongated than lizards of that genus.
The type species is Heloderma horridum, which was first described in 1829 by Arend Weigmann.
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Members of the genus Heloderma have many extinct relatives in the Helodermatidae whose evolutionary history may be traced back to the Cretaceous period, such as Estesia.
Knuckle pads (also known as "Heloderma", meaning similar to the skin of the Gila monster lizard for which it is named) are circumscribed, keratotic, fibrous growths over the dorsa of the interphalangeal joints.
The teeth are similar to those of living venomous squamates such as Heloderma and venomous snakes.