The tales of dolphins and crocodiles are different in structure but similar in function what are these kinds of structures called

 Homology refers to two things that have an equivalent role or relationship. Homology is important in comparative biology since it makes it possible to determine if two different animals or plants share a common ancestor. Essentially, homology in this context means that there are two species that have related parts that do similar things, but that are not exactly the same. 

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this age may represent the age of the earth's accretion, of core formation, or of the material from which the earth formed. this dating is based on evidence from radiometric age-dating of meteorite material and is consistent with the radiometric ages of the oldest-known terrestrial and lunar samples.