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.
the Ordovician Period or System.
- post-Or·do·vi·cian, adjective
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How to use Ordovician in a sentence
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.The Asteroid That Wiped Out the Dinosaurs May Have Had a ‘Little Sister’ | Uisdean Nicholson | August 21, 2022 | Singularity Hub
The North Welsh area gives two different developments of the Ordovician strata, one of which is much less volcanic than the other.
The beds belonging to the Ordovician system are divided into two series, the Glenkiln shales below and the Hartfell shales above.
The trilobites belong to few genera though these are mostly more highly organised than those of the Ordovician period.
In the Cambrian, Ordovician, and Silurian the invertebrates were represented in all their subkingdoms by a varied fauna.The Elements of Geology | William Harmon Norton
The Ordovician was closed by a deformation whose extent and severity are not yet known.The Elements of Geology | William Harmon Norton
British Dictionary definitions for Ordovician
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
the Ordovician the Ordovician period or rock system
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Scientific definitions for Ordovician
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.
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