The Ordovician (/ ɔːrdəˈvɪʃi.ən, - doʊ -, - ˈvɪʃən / or-də-VISH-ee-ən, -⁠doh-, -⁠VISH-ən) [9] is a geologic period and system, the second of six periods of the Paleozoic Era, and the second of twelve periods of the Phanerozoic Eon.

2024年12月24日 · Ordovician Period, in geologic time, the second period of the Paleozoic Era. It began 485.4 million years ago and ended 443.8 million years ago. The interval was a time of intense diversification (an increase in the number of species) of marine animal life in what became known as the Ordovician radiation.

2023年4月28日 · Rocks from the Ordovician Period contain evidence that plants began colonizing dry land at this time. Most experts agree that the ancestors of land plants first evolved in a marine environment, then moved into a freshwater environment and finally onto land.

The Ordovician is best known for its diverse marine invertebrates, including graptolites, trilobites, brachiopods, and the conodonts (early vertebrates). A typical marine community consisted of these animals, plus red and green algae, primitive fish, …

2012年8月10日 · The Ordovician ended with the second greatest extinction event of the Phanerozoic Eon. Two massive reductions, a million years apart, created this event—resulting in the extinction of more than 60% of invertebrates.

During the Ordovician period, part of the Paleozoic era, a rich variety of marine life flourished in the vast seas and the first primitive plants began to appear on land—before the second largest...

2023年1月23日 · The Ordovician Period is the second period of the Paleozoic Era (the first and longest era of the Phanerozoic eon). The era began about 541 million years ago with the Cambrian explosion, which saw the rise and diversity of many of earth’s organisms.

The Ordovician is the second period of the Paleozoic era and the Phanerozoic eon. It lasted from about 485.4 million years ago (mya) to 443.4 mya. [ 1 ] It follows the Cambrian period and is followed by the Silurian period.

The Ordovician is best known for the presence of its diverse marine invertebrates, including graptolites, trilobites, brachiopods, and the conodonts (early vertebrates). A typical marine community consisted of these animals, plus red and green algae, primitive fish, cephalopods, corals, crinoids, and gastropods.

Ordovician Period, Interval of geologic time, 485.4–443.4 million years ago, the second oldest period of the Paleozoic Era. It follows the Cambrian and precedes the Silurian Period. During the Ordovician, many of the landmasses were aligned in the tropics.