The Origin of Lizard Species

Study of the origin of lizard species takes us back millions of years to a time when animal life moved out of the primordial waters and onto land. The first land animals were divided into two phylum: amphibians and reptiles. Reptile characteristics -- tough, scaly body covering and reproduction through laying and incubating hard-shelled amniotic eggs -- made it possible for reptilians to take advantage of the ecosystems found on land. Reptiles thrived so well that the Mesozoic period of history is known as "the age of reptiles."

  1. Evolution from Reptile to Lizard

    • The age of reptiles came to an end due to climactic changes or other catastrophic events. This marked the end of the Mesozoic Era. Giant reptiles disappeared, leaving only fossil remains as testimony to their existence. However, smaller reptiles survived. These reptiles were represented by four groups: crocodiles, birds, tautaras and squamates. Squamates evolved into three subgroups: lizards, snakes and worm-lizards.

    Lizard Characteristics

    • Lizard scales shed in patches, allowing the lizard's skin to grow.

      Lizards evolved into thousands of species. At this time, there are more than 4,500 species of lizards living in all parts of the earth except Antarctica and the deep oceans. Lizard species include iguanas, monitors, Gila monsters, skinks, geckos and chameleons. Lizards are covered with scaly skin. They have external ear openings and eyelids. Each species of lizard is uniquely suited to the ecosystem in which it lives.

    Lizard Habitat

    • Chameleons have tree-climbing toes and prehensile tails.

      Lizards live in every type of terrain and ecosystem, except the very cold or the deep ocean. Certain lizards, such as the ground gecko, survive in desert areas by sleeping under the sand during the day and coming out at night. Marine iguanas spend most of their time in the water. Chameleons live in temperate to desert regions, and skinks live in a variety of different habitats, from tropical forests to deserts to home gardens.

    Lizard Diversity

    • The Komodo dragon is a member of the monitor family.

      Lizards range in size from the tiny jaragua lizard, a Caribbean gecko that can stand on a dime, to the Komodo dragon, reaching a length of 10 feet and a weight of 176 pounds. Lizards exhibit a variety of survival tactics, from break-away tails to the venomous bites of the Gila monster and the Mexican Bearded Lizard. Perhaps most unique is the horned lizard with its ability to squirt blood out of its eye to thwart predators.