Explanation of map symbols. Ordovician Period. Devonian Period. There was a rapid recovery of biodiversity after the great extinction event at the end of the Ordovician. A warm climate and high sea level gave rise tolarge reefs in shallow equatorial seas. Tabulate corals and stromatoporid sponges were the main builders of these first coral based reefs, but rugose corals and recepticulite algae also contributed.
Invertebrates remained dominant because vertebrates were relatively rare. Sea scorpions euryptids reached their maximum diversity.
These predators were commonly 5—9 inches long, see the Eurypterus remipes in case but could be as large as 4.
Alife- model is shown below:. Mollusks, bryozoans, and especially brachiopods flourished, but trilobites and graptolites were on the decline. Invertebrates remained dominant, vertebrate fossils are rare. Fish with moveable jaws appear, and the first bony fish osteichthyans evolved.
Fishes and some invertebrate groups, such as eurypterids, invaded freshwater habitats during the Silurian period.
Simple vascular plants emerged on land with moss forests growing along streambeds and lakeshores. The Silurian is the first period with fossils of extensive non-microscopic life on land. During the Silurian period Earth's continents joined together, closing the Iapetus Ocean and forming two supercontinents: Laurasia in the north, and Gondwanaland to the south.
At the same time the northern continents moved together and began forming Laurasia. Glaciers retreated and nearly disappeared as continental warming began. Much of the equatorial land mass was covered by warm shallow seas. There were dramatic worldwide sea-level changes and oceanic turnovers exchanges of bottom waters and surface waters resulting in a moderate level of extinctions during the Period.
The Silurian ended with a series of relatively minor extinction events linked to climate change. Trilobites were on the decline in the Silurian, but still abundant locally. Environment Planet Possible India bets its energy future on solar—in ways both small and big Grassroots efforts are bringing solar panels to rural villages without electricity, while massive solar arrays are being built across the country.
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Strauss, Bob. Prehistoric Life During the Paleogene Period.
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