Reptiles were the first true land-dwellers to evolve among the vertebrates. Their horny skins, almost always divided into scales and plates, protect them from dessication, and the amnion formed during larval development as well as the yolky eggs, with their parchment-like or calcareous shells, obviate the need for a free-living aquatic larval stage. Because of these adaptations, the predominance of the reptiles in the Galapagos is not surprising. These supposedly antediluvian creatures are not relics of "the age of dinosaurs" but are creations of past and present selective forces in the Galapagos.
Reptiles are "ectothermic" creatures. They can not regulate their body temperature physiologically by sweating or panting but are generally more tolerant to body temperature changes. During cold days or nights, they must seek up the warmth of the sun retained on the black lava boulders or just by getting "close," which explain why they are behaving in such a friendly way in the picture shown here.
