Varanidae

What are Varanidae?

The Varanidae, commonly known as monitor lizards, represent a distinct family within the lizard suborder Anguimorpha. This group is characterized by its members' carnivorous and, in some cases, frugivorous diets. The family encompasses the well-known Komodo dragon, recognized as the largest living lizard, along with species like the crocodile monitor and savannah monitor, as well as the goannas native to Australia and Southeast Asia. Their closest living relatives are the earless monitor lizard and the Chinese crocodile lizard.

Biology and Behavior

Monitor lizards are reputed to be among the most intelligent lizards, a trait that likely aids their survival. Most species are known to forage extensively and maintain large home ranges, demonstrating considerable stamina. While the majority are carnivorous, a notable exception exists in three arboreal species from the Philippines (Varanus olivaceus, Varanus mabitang, and Varanus bitatawa), which are primarily frugivores, subsisting mainly on fruits. Anatomically, varanids exhibit positive allometry in their limbs, meaning limb size increases disproportionately with body size, though their feet tend to become proportionally smaller as individuals grow larger.

Evolutionary History

The fossil record for the Varanidae family is substantial, with the oldest known members dating back to the Late Cretaceous period. These ancient specimens have been discovered primarily in Mongolia. The taxonomic classification of the Varanidae has seen some variation, particularly concerning the inclusion of the earless monitor lizard. Different researchers have proposed definitions that either include or exclude this species, leading to its placement within Varanidae or in a separate family, Lanthanotidae, depending on the classification system used.