Walking narrow branches is a tough high-wire act for most lizards

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All today’s cold-blooded speed records are held by lizards. (animatronic dinosaur costume)The best lacertilian sprinters are long-legged bipeds, species that at high speed tuck their arms under the chest and stride on hindquarter power alone. In our own American West the mountain boomer, a short-bodied, wide-headed predator that gulps down big desert bugs and other lizards, has been clocked at eighteen miles per hour. (walking dinosaur costume)Lizard feats of arms and legs span the entire range possible for a land vertebrate, a complete evolutionary decathalon: burrowing by wormlike amphisbaenid lizards; sand-swimming by Kalahari skinks; snakelike grass-slithering by legless glass lizards; crocodilelike swimming by monitors; leaf-leaping by anolis lizards (Florida chameleons); claw-propelled digging; bipedal sprints; and the incredible slow branch stalk by the Old World tree chameleons. And there are even some lizards that can glide, using rib-supported wings.

 

Walking narrow branches is a tough high-wire act for most lizards, difficult to master because the basic lacertilian posture is a sprawl, with elbows and knees held far out beside the body and the paws held far apart. (realistic dinosaur costume)Gripping a narrow branch is awkward with such a wide-track gait. The prizes for the successful branch walker are enticing: hordes of insects and other juicy prey teem among the leaves, twigs, and stems. The Old World chameleons have solved this problem with a suite of limb adaptations rarely matched elsewhere. Most lizards have broad chests, which separate left and right shoulder sockets widely. (animatronic dinosaur)Chameleons have deep chests, very narrow from side to side, like that of a cat. So the chameleon arms can swing fore and aft directly under the body. And the chameleon’s forepaws can grip the narrowest of perches. Most lizard hands are rather crude five-fingered devices incapable of a precise grip. Chameleon hands are cleft—two fingers are separated from the other three at the wrist—and the chameleon can use the two as a sort of scaly thumb for gripping a branch. Hind limbs are similarly cast into a narrow-striding, gripping mode. With four precision grippers and a narrow stride, the true chameleon on the hunt makes all the slender vines and branches of the tropical forest unsafe for butterflies and beetles.