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Law of fossil succession strata dating

law of fossil succession strata dating-38

From a purely practical point of view, it is incomprehensible that a turtle should swim, a horse run, a person write, and a bird or a bat fly with forelimb structures built of the same bones.

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The similarities are less between mammals and birds than they are among mammals, and they are still less between mammals and fishes.In some cases the succession of forms over time has been reconstructed in detail.One example is the evolution of the ), is much larger in size, is one-toed, and has teeth appropriate for grazing.Not one but many creatures intermediate between living apes and humans have since been found as fossils.The oldest known fossil had an upright human stance but a cranial capacity of less than 500 cc (equivalent to a brain weight of about 500 grams), comparable to that of a gorilla or a chimpanzee and about one-third that of humans.The oldest known animal fossils, about 700 million years old, come from the so-called Ediacara fauna, small wormlike creatures with soft bodies.

Numerous fossils belonging to many living phyla and exhibiting mineralized skeletons appear in rocks about 540 million years old.

But if it is accepted that all of these skeletons inherited their structures from a common ancestor and became modified only as they adapted to different ways of life, the similarity of their structures makes sense.

Homologies of the forelimb among vertebrates, giving evidence for evolution.

Paleontologists have recovered and studied the fossil remains of many thousands of organisms that lived in the past.

This fossil record shows that many kinds of extinct organisms were very different in form from any now living.

It also shows successions of organisms through time ( When an organism dies, it is usually destroyed by other forms of life and by weathering processes.