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The Cambrian Explosion of Animal Life
![Trilobites](../../../../../../../../../figures.boundless-cdn.com/20659/full/figure-27-04-04abcd.jpeg)
Trilobites
These fossils (a–d) belong to trilobites, extinct arthropods that appeared in the early Cambrian period 525 million years ago and disappeared from the fossil record during a mass extinction at the end of the Permian period about 250 million years ago.
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"OpenStax College, Biology. November 14, 2013."
http://cnx.org/content/m44660/latest/?collection=col11448/latest
OpenStax CNX
CC BY 3.0.