Of, relating to, or being the era of geologic time from about 542 to 251 million years ago. The Paleozoic Era includes the Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, and Permian Periods and is characterized by the appearance of marine invertebrates, primitive fishes, land plants, and primitive reptiles. The end of this era is marked by the largest recorded mass extinction in the earth's history, in which 90 percent of marine life forms were wiped out. See Table at geologic time.
The Paleozoic Era.
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Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.