Ordovician
[ awr-duh-vish-uh n ]
/ ˌɔr dəˈvɪʃ ən /
adjective
noting or pertaining to a geologic period of the Paleozoic Era, from 500 million to 425 million years ago, notable for the advent of fish.
noun
the Ordovician Period or System.
Origin of Ordovician
1879; after the
Ordovices (plural) (< Latin) an ancient British tribe in N Wales, where rocks characterizing the period were found; see
-ian
OTHER WORDS FROM Ordovician
post-Or·do·vi·cian, adjectiveExample sentences from the Web for ordovician
British Dictionary definitions for ordovician
Ordovician
/ (ˌɔːdəʊˈvɪʃɪən) /
adjective
of, denoting, or formed in the second period of the Palaeozoic era, between the Cambrian and Silurian periods, which lasted for 45 000 000 years during which marine invertebrates flourished
noun
the Ordovician
the Ordovician period or rock system
Word Origin for Ordovician
C19: from Latin
Ordovices ancient Celtic tribe in N Wales
Scientific definitions for ordovician
Ordovician
[ ôr′də-vĭsh′ən ]
The second period of the Paleozoic Era, from about 505 to 438 million years ago. During this time most of the Earth's landmasses were gathered in the supercontinent Gondwanaland, located in the Southern Hemisphere. Much of this continent was submerged under shallow seas, and marine invertebrates, including trilobites, brachiopods, graptolites, and conodonts were widespread. The first primitive fishes appeared; some evidence suggests the first land plants may also have appeared at this time. By the end of the Ordovician massive glaciers formed on Gondwanaland, causing sea levels to drop and approximately 60 percent of all known marine invertebrates to become extinct. See Chart at geologic time.