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The lizard

10 October 2013

The lizards are an artificial grouping of vertebrate animals of the Orde Squamata and there are at least 338 species in southern Africa, including the chameleons. They occur on all the continents of the world except Antarctica and have their highest diversity in the semi-desert parts of Australia and southern Africa. Lizards differ from snakes in that the two halves of the lower jaw of a lizard are fused and the upper jaw bones are firmly attached to the skull. Some lizards have greatly reduced legs or the legs have been lost totally to allow them to burrow. Most lizards also have movable eyelids while those of geckos and snakes are fused. Many lizards can shed their tails as an anti-predator strategy but the tail regenerates rapidly. Some lizards are habitat-specific or are limited to a particular substrate.

Lizards first appear as fossils that are some 195 million years old. The early lizards were air-breathing swimmers and some that lived 98 to 66 million years ago near Amman in Jordan had tails like sharks. These ancient lizards lived during a warm period on the Earth, co-existed with the early mammals and were up to 3 m long. The Waterberg with its unique geological origin forms an excellent habitat for lizards.

The chameleons are an ancient group of specialized lizards of some 160 species that originated some 100 million years ago in East Africa or Madagascar. They are specialized lizards and have characteristic skulls that usually form a bony casque with prominent crests and tubercles and no external ears. The common flap-neck chameleon Chamaeleo dilepis is common in the Waterberg and has a body length of up to 150 mm with a ridge along the spine and a large flap on the back of the head. It usually occurs in trees and eats insects which it ambushes.

The agama lizards are found in Africa, south-eastern Europe, tropical and temperate Asia, New Guinea, Australia and the Solomon Islands, with 12 species occurring in southern Africa. They are medium to large lizards with a squat body and a large head with slightly rough scales. The body is covered with small, spiny scales and tubercles, there may be a crest of enlarged, raised scales along the spine and they have distinct throat patterns. The limbs have strong, recurved claws and the diet is mainly insects. The southern tree agama Acanthocercus atricollis with its blue head, Peter‘ ground agama Agama armata and Distant‘s ground agama Agama aculeata distanti occur in the Waterberg... (Become a subscriber for more)

article by: Prof J du P Bothma