Archaeovaranus lii

Overview

Archaeovaranus lii is an Eocene lizard that connects the distant history of monitor lizards. It was studied as an ancient branch close to the group containing today’s Komodo dragon. Different structures survive within a similar-looking head.^[1]

Key facts

A distinctive feature is that the upper and middle segments of the forelimbs and hindlimbs were almost equal in length. Living monitors generally have longer hindlimbs. Even similar-looking lizards differed in the body proportions involved in movement.^[3]

Time and place

It is known from Early Eocene China, within a range of approximately 56–48 million years ago. An important skeleton was found in the Liguanqiao Basin of present-day Hubei Province. It reveals the appearance of an East Asian lizard of that time.^[1][3]

The time range describes source context, not the complete duration of this species.

Size, form and skeleton

The research institution gives a total length of approximately 1 m. An elongated snout and posteriorly placed nostrils evoke monitor lizards. In contrast, features such as bone closing the region behind the eye and small teeth on the palate differ from modern monitors.^[3]

Habitat and reproduction

The proportions of forelimbs and hindlimbs raise questions about movement. Living monitors use the ground, trees, and watersides in varied ways, but Archaeovaranus is not a direct copy of one of them. Researchers compare limbs and trunk together to investigate its way of life.^[3][2]

Fossil discovery

A skeleton discovered during fieldwork in 2008 underwent careful preparation and CT scanning before being introduced as a new genus and species in 2022. Its specimen number is IVPP V22770. Reading scattered bones within a block revealed connections between the head and body.^[3][2]

References

1. Dong et al. (2022), “A new stem-varanid lizard (Reptilia, Squamata) from the early Eocene of China,” Philosophical Transactions B 377:20210041.
2. Dong et al. (2022) — A new stem-varanid lizard from the early Eocene of China
3. IVPP — 中国巨蜥科化石新属种支持巨蜥科的亚洲起源说
4. Dong et al. (2022), “A new stem-varanid lizard (Reptilia, Squamata) from the early Eocene of China,” Philosophical Transactions B 377:20210041.
5. IVPP — 中国巨蜥科化石新属种支持巨蜥科的亚洲起源说
6. Mo, Xu & Evans2010 — Evolution of the lower temporal bar in lizards

Research questions

Where did the early evolution of monitor lizards unfold? This East Asian fossil occupies an important position in comparisons between ancient lizards and living monitors. Comparing bones behind the eyes and teeth on the palate also helps trace changes in the head.^[1][3]

Observation

Examine the nostril positions, the region behind the eyes, and the proportions of the forelimbs and hindlimbs.^[3]