Veiled chameleon (Chamaeleo calyptratus), like other chameleons, captures insects at great 

 distances with its tongue, which in this individual extends about ten inches. Chameleons are 

 iguanians, most of which manipulate prey with the tongue, though a few are vegetarians. 

 Members of the other major group of squamates, the scleroglossans, capture prey with their jaws. 



snakes have all descended from terrestrial snakes. 



What a snake can find is limited only by the size 

 of crevice or hole that it can stick its head into; 

 what a snake can eat is limited in size only by how 

 tar it can disarticulate one of the most flexible skulls 

 known in vertebrates. As a result, snakes have be- 

 come top predators, coming back to haunt such 

 close evolutionary relatives as the lizard autar- 

 choglossans as well as iguanians and gekkotans. 

 Many snakes produce venoms, with which they kill 

 large prey and retaliate against would-be predators. 

 So do some lizards, such as the Gila monsters [see 

 Venomous Lizards of the Desert," by Daniel D. Beck, 

 July/August 2004]. Some snakes (including pit 

 vipers, many boa constrictors, and some pythons) 

 have heat-sensing pits in one or more scales along 

 the jaw, wired directly into the optic neural system, 

 which essentially enable them to see in the dark by 

 detecting changes in the thermal landscape. 



Many venomous snakes have brightly colored 

 rings (as do Gila monsters) that warn potential 



predators that they are dangerous. A host of non- 

 venomous snakes have evolved color patterns that 

 mimic those of venomous species, thereby taking 

 advantage of the protection a venomous reputation 

 affords against potential predators. People are 

 among the many large animals that instinctively 

 give snakes a wide berth. The threat of a ven- 

 omous snake, not to mention the dangers posed by 

 large constrictors, probably ingrained that instinct 

 in our early mammalian ancestors. 



Whether we are attracted or repelled by snakes 

 and other squamates, we owe the group respect for 

 its evolutionary success. Along with turtles and croc- 

 odilians, they are the reptiles that we see around us 

 today. Dinosaurs, ichthyosaurs, plesiosaurs, and 

 pterosaurs were impressive in their time, but all (ex- 

 cept for birds) were long gone before humans came 

 along, as much as we might fantasize about "lost 

 worlds." Squamates, on the other hand, watched the 

 dinosaurs come and go. Chances are they will be 

 around to watch humans exit as well. 



July/August 2006 NATURAL H1STOU.Y 



35 



