Your browser does not seem to support JavaScript. As a result, your viewing experience will be diminished, and you have been placed in read-only mode.
Please download a browser that supports JavaScript, or enable it if it's disabled (i.e. NoScript).
from or referring to the period of time between about 543 and 490 million years ago, in which many different types of invertebrates (= animals with no back bone) first appeared:
the Cambrian period (= the period between about 543 and 490 million years ago) :
Share your knowledge with the community
Browse our collection of 300,000+ community-written definitions
