Telmasaurus

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Telmasaurus is an extinct genus of varanoid lizard from the Late Cretaceous of Mongolia. Fossils come from the Djadokha and Barun Goyot Formations and are dated to about 80 to 71 million years ago. The type species, Telmasaurus grangeri, was named in 1943 and is known from several fossils, though only two skulls are preserved and the snouts are missing.

From the skulls, Telmasaurus appears to have been larger than many other Cretaceous varanoids and was approaching the size of modern monitor lizards. Its skull is relatively flat, and the frontal bones are fused, a feature shared with other early varanids like Paravaranus. The lacrimal bone has a single hole, a trait seen in early varanoids. The vertebrae are known and connect to adjacent bones in a way that is different from living monitor lizards. A small crest between the eye sockets helps distinguish Telmasaurus as a genus.

Telmasaurus was initially classified in the Varanidae family, making it a distant relative of living monitor lizards. Later analyses place Telmasaurus in a very basal position within Varanoidea, meaning it is an early member of the group, intermediate between helodermatids and the clade that includes monitor lizards and snakes. In different phylogenetic studies, Telmasaurus appears near other early varanoids such as Saniwides, and it is considered more primitive than some other Cretaceous relatives like Cherminotus and Aiolosaurus.