Geologist uses radiometric dating
They have moist scaleless skin which is used to supplement the lungs in gas exchange.
The eggs are soft and vulnerable to drying, therefore reproduction commonly occurs in water.
Then, even if circumstances change such that it no longer provides any survival or reproductive advantage, the behavior will still tend to be exhibited -- unless it becomes positively disadvantageous in the new environment.
adaptive radiation: The diversification, over evolutionary time, of a species or group of species into several different species or subspecies that are typically adapted to different ecological niches (for example, Darwin's finches).
allopatric speciation: Speciation that occurs when two or more populations of a species are geographically isolated from one another sufficiently that they do not interbreed. There are 20 main amino acids in the proteins of living things, and the properties of a protein are determined by its particular amino acid sequence.amphibians: The class of vertebrates that contains the frogs, toads, newts, and salamanders.The amphibians evolved in the Devonian period (about 370 million years ago) as the first vertebrates to occupy the land.In a diploid cell there are usually two alleles of any one gene (one from each parent).Within a population there may be many different alleles of a gene; each has a unique nucleotide sequence.