Rand Synapsida mammals and their extinct relatives. In the mid-Permian period, the climate became drier, resulting in a change of fauna: The pelycosaurs were replaced by the therapsids. Peterson Retrieved January 30, Smithsonian Books.
Hove: Firefly Books Ltd. Retrieved November 1, Further information: Human uses of reptiles. Films of Science Fiction and Fantasy. Washington, DC Smithsonian Books. In Gans, C.
Statistics Oestradiol Concentrations. Failure of this strategy may lead to other measures practiced particularly by cobras, vipers, and closely related species, which use venom to attack. Larger lizards, like the monitors , are known to exhibit complex behavior, including cooperation  and cognitive abilities allowing them to optimize their foraging and territoriality over time.
Lizards such as the Gila monster produce toxins with medical applications.