GEOLOGY

Detailed explanation-1: -The Ordovician saw some of the most varied climates and sea level variations of the whole Phanerozoic (Fig. 3). At the beginning of the Ordovician the Earth was very warm with tropical sea surface temperatures of around 45 °C or more, and by  450 Ma sea levels were so high (Fig.

Detailed explanation-2: -For the most part the Earth’s climate was warm and wet, with sea levels rising as much as 1, 970 feet (600 meters) above those of today. But once Gondwana took up its polar position in the late Ordovician, massive glaciers formed over Africa at the supercontinent’s center.

Detailed explanation-3: -For most of the Ordovician period, global conditions were as stifling as during the preceding Cambrian; air temperatures averaged about 120 degrees Fahrenheit worldwide, and sea temperatures may have reached as high as 110 degrees at the equator.

Detailed explanation-4: -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, cephalopods, corals, crinoids, and gastropods.

Detailed explanation-5: -Despite high carbon dioxide levels in the Ordovician Period, evidence of cooler climates in higher latitudes is seen by the presence of unweathered mica in sedimentary rocks from North Africa, central and southern Europe, and much of South America.