Evolution and systematics

The Cordylidae is the only lizard family restricted to Africa, with one subfamily also occurring on Madagascar. The fossil history is very poor, although some fossils (Pseudolacerta and Palaeocordylus) from the early Eocene to the early Miocene of Europe are provisionally assigned to the family. Relationships to other lizards also remain problematic, but they appear to be close to the Scinicidae and less confidently with the lacertiforms (Teiidae, Gymnophthalmidae, and Lacer-tidae). The family is relatively ancient and evolved before the separation of the southern supercontinent Gondwana and the separation of Madagascar from Africa in the middle Cretaceous epoch (80-100 million years ago).

Two well-defined subfamilies are recognized, and have often been treated as separate families within a superfamily— the Cordyliformes.

The first subfamily is Cordylinae, or girdled lizards. The head has four parietal scales and the nostril is enclosed in a single, or between only two, scales. Cordylines are restricted to southern and tropical Africa. Within cordylines, the flat lizards (Platysaurus, 16 species) are the basal stock and retain oviparity. Crag lizards (Pseudocordylus) and grass lizards (Chamaesaura) evolve from within girdled lizards (Cordylus), and to reflect this evolutionary relationship these genera have recently been transferred to Cordylus. This large genus now contains more than 40 species.

The second subfamily is Gerrhosaurinae, or plated lizards. The head has two parietal scales and the nostril is surrounded by three to four scales. Two genera are restricted to Madagascar and another three genera inhabit savanna and semiarid regions of Africa south of the Sahel. The desert plated lizard, previously included in a separate genus (Angolosaurus), is now transferred to Gerrhosaurus.

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