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| Chordata :: amphibia
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Frogs
Imagine traveling back through time millions of years to the age of the dinosaurs. Pterodactyls glide above a soggy marsh. Nearby, a colossal 80-ton Brachiosaurus munches on a tree. On the ground at its feet, something strangely familiar hops by: a frog.
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Toads
Although there is no scientific distinction between TOADs and frogs, frogs are typically smooth-skinned, have long hind limbs for leaping, and live in water, where TOADs have warty, drier skin, with shorter hind limbs for hopping, and live on land.
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Amphibia: Fossil Record
Fossil caecilians are very rare; until recently the oldest known caecilians were Cenozoic in age (that is, less than 65 million years old), but recent finds have pushed back the ancestry of the legless caecilians to Jurassic ancestors that had short legs. |
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Life History and Ecology
The name amphibian means "double life", and is given to members of this group for the double life that they lead. For while adult amphibians usually live on land, their soft eggs must be laid in the water. |
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Sea Turtle
Air-breathing reptiles, sea turtles are well-adapted to their marine environment. Their size varies greatly, depending upon species-from the small Kemp's ridley, which weighs between 80-100 pounds, to the enormous leatherback, which often weighs more than 1,000 pounds. |
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Systematics
One problem in establishing the main lines of amphibian evolution is the relatively sparse fossil record; key groups such as the caecilians have very few fossils, and the early history of modern amphibian groups is not well known. |
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