Understanding Evolution

Classifying Cambrian critters

After your investigation of five Cambrian animals, it should be clear that you canít judge a fossil by first impressions. Paleontologists had a tough time classifying many of these Cambrian animals. Some of the animals you studied were unfamiliar, but turned out to be arthropods (Sanctacaris, for example, was a chelicerate). Others looked like one animal, but turned out to be another (Pikaia, for example, looked like a worm, but was actually a chordate). And the characteristics of animals like Opabinia revealed that they didnít belong to any group alive today.

Cambrian critters


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