The first multicellular animals first began to appear during the Precambrian Era, about 600 million years ago. About 540 million years ago, worms, mollusks, jellyfish and other invertabrates brgan to appear in the fossil record, followed by the earliest vertebrates about 500-440 million years ago. Fish began to appear, followed by arthropods that lived on land.
By the Devonian period, about 400-360 million years ago, amphibians began to evolve.
Reptiles came on the scene around 300 million years ago, followed by mammals around 250 million years ago. It was around this time that dinosaurs began to appear.
Dinosaurs were the dominate land creatures from the Triassic to Cretacious Periods. During this time, mammals and birds continued to evolve.
Mammals with more modern characteristics began to evolve and diversify around 65 million years ago. Primates can be traced back to 60 million years ago. The earliest of homosapiens did not appear until about 400,000 years ago, and modern humans only date back about 170,000 years.
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