Lanthanotidae

The earless monitor lizard (Lanthanotus boreneensis) is a semi-aquatic, brown lizard native to northern Borneo

Borneo

Borneo is the third largest island in the world and is located at the centre of Maritime Southeast Asia. Administratively, this island is divided among Indonesia , Malaysia and Brunei . Indonesians refer to the island as Kalimantan...

. It is the only species in the family Lanthanotidae, a group related to the true monitor lizard

Monitor lizard

Monitor lizards also known as bayawak or goannas, genus Varanus, are members of the family Varanidae. Varanus is a group of carnivorous lizards which includes the heaviest living lizard, the Komodo dragon and the crocodile monitor which is the longest lizard in the world...

s, as well as to the beaded lizard

Heloderma

Heloderma, the only genus of the family Helodermatidae, consists of venomous lizards native to the southwestern United States, Mexico and as far south as Guatemala. It includes two separate species, with six subspecies...

s.

Earless monitor lizards are around 20 centimetres in length, and have reduced eyes and limbs, a thick body, and strongly keeled scales. Despite the name, it is capable of hearing, although it lacks a tympanum

Eardrum

The tympanic membrane , is a thin membrane that separates the external ear from the middle ear. Its function is to transmit sound from the air to the ossicles inside the middle ear. The malleus bone bridges the gap between the eardrum and the other ossicles...

 or other visible signs of ears.

The earless monitor lizard (Lanthanotus boreneensis) is a semi-aquatic, brown lizard native to northern Borneo

Borneo

Borneo is the third largest island in the world and is located at the centre of Maritime Southeast Asia. Administratively, this island is divided among Indonesia , Malaysia and Brunei . Indonesians refer to the island as Kalimantan...

. It is the only species in the family Lanthanotidae, a group related to the true monitor lizard

Monitor lizard

Monitor lizards also known as bayawak or goannas, genus Varanus, are members of the family Varanidae. Varanus is a group of carnivorous lizards which includes the heaviest living lizard, the Komodo dragon and the crocodile monitor which is the longest lizard in the world...

s, as well as to the beaded lizard

Heloderma

Heloderma, the only genus of the family Helodermatidae, consists of venomous lizards native to the southwestern United States, Mexico and as far south as Guatemala. It includes two separate species, with six subspecies...

s.

Earless monitor lizards are around 20 centimetres in length, and have reduced eyes and limbs, a thick body, and strongly keeled scales. Despite the name, it is capable of hearing, although it lacks a tympanum

Eardrum

The tympanic membrane , is a thin membrane that separates the external ear from the middle ear. Its function is to transmit sound from the air to the ossicles inside the middle ear. The malleus bone bridges the gap between the eardrum and the other ossicles...

 or other visible signs of ears. It is a burrowing, nocturnal animal, feeding on earthworm

Earthworm

Earthworm is the common name for the largest members of Oligochaeta in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening posterior to the female pores, even though the internal male segments are anterior to the female...

s and similar prey. In captivity, it has been known to eat squid,pieces of fish and liver.Like its closest relatives, it is oviparous, although little else is known about its reproduction.

This species is very rare, and most known specimens are preserved, though these, also, are rare. The species is primarily of interest to scientists, since it is an evolutionary outgroup for both varanid and helodermatid lizards.