Ordovician

[ awr-duh-vish-uhn ]

adjective

1. 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

1. the Ordovician Period or System.

Ordovician

/ ˌɔːdəʊˈvɪʃɪən /

adjective

1. 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

1. the Ordovician
   the Ordovician the Ordovician period or rock system

Ordovician

/ ôr′də-vĭsh′ən /

1. 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.
2. See Chart at geologic time

Other Words From

• post-Or·do·vician adjective

Word History and Origins

Origin of Ordovician¹

1879; after the Ordovices (plural) (< Latin ) an ancient British tribe in N Wales, where rocks characterizing the period were found; -ian

Word History and Origins

Origin of Ordovician¹

C19: from Latin Ordovices ancient Celtic tribe in N Wales

Example Sentences

We have a precedent for such an event back in the Ordovician period—over 400 million years ago—when there were numerous impact events in a short period of time.

From Singularity Hub 

The North Welsh area gives two different developments of the Ordovician strata, one of which is much less volcanic than the other.

From Project Gutenberg

The beds belonging to the Ordovician system are divided into two series, the Glenkiln shales below and the Hartfell shales above.

From Project Gutenberg

The trilobites belong to few genera though these are mostly more highly organised than those of the Ordovician period.

From Project Gutenberg

In the Cambrian, Ordovician, and Silurian the invertebrates were represented in all their subkingdoms by a varied fauna.

From Project Gutenberg

The Ordovician was closed by a deformation whose extent and severity are not yet known.

From Project Gutenberg