Across 1. The class of land-dwelling vertebrates that possess scales, lay amniotic eggs, and are ectothermic. 6. A series of changes young animals undergo at some point to become adults. 7. An order of amphibians that includes salamanders and newts. 9. An ectothermic vertebrate animal that is well adapted to both life in water and on land. 11. The reptilian order that includes the largest living reptiles on Earth. 12. Large reptiles that have a relatively flat snout and long, powerful tail. 13. The larval form of frogs and toads; possess a tail and gills.

Down 1. A small order of reptiles that includes only two living species of tuataras. 2. A characteristic of amphibians and reptiles in which their core body temperature fluctuates according to environmental conditions. 3. An order of reptiles that includes lizards and snakes. 4. The amphibian order that includes frogs and toads. 5. Watertight, multi-layered structure within which the reptilian embryo develops. 8. The largest reptiles to have lived on Earth; are now extinct. 9. The amphibian order that includes worm-like animals, many of which live in the ground. 10. Sea turtles, tortoises, and freshwater turtles are members of this order.