Parietal eyes in lizards: zoogeographical correlates.
Lizards without parietal eyes tend to be restricted to low latitudes, whereas lizards with parietal eyes are successful at higher latitudes also. These zoogeographical data, along with current theories of parietal eye physiology, strongly suggest that the overall significance of the parietal eye to lizards as a group is that it facilitates survival at higher latitudes, thus making possible the exploitation of a wider variety of habitats.
D000220:Adaptation, Biological; D000818:Animals; D004777:Environment; D005123:Eye / Q000033:anatomy & histology; D008116:Lizards / Q000033:anatomy & histology*