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The Arthropod Story Table of Contents   

A closer look at the arthropod branches

Arthropods can be divided into five major groups, each with its own distinctive characteristics.

the arthropod tree

The first land animal wasn't a slippery amphibian or a giant dragonfly, but a myriapod. Fossil evidence suggests that these wriggly critters climbed out of the water 490-443 million years ago — about 200 million years before the first dinosaurs evolved!
To explore these groups, just click on the names below:
insects (including moths)
chelicerates (including spiders and scorpions)
crustaceans (including crayfish and barnacles)
myriapods (including millipedes)
trilobites (which are now extinct)

Despite their differences, these groups inherited certain "arthropod traits" from a common ancestor, and they are all part of the arthropod lineage.

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What's with that weird caterpillar-like onychophoran? Check out the Almost Arthropod.