Silurian Period

After the Ordovician Period came the Silurian Period, lasting 24.6 million years, from 443.8 million years ago to 419.8 million years ago. It began approximately the same time as the major series of extinction events mentioned at the end of the Ordovician Period, when a large number of marine fauna were wiped out.

The Silurian saw wide-spread diversification of jawed fish as well as bony fish. Multi-cellular life also appeared on land as small plants similar to liverworts, hornworts, and mosses, which grew besides lakes, streams and coastlines. Invertebrate animals with an exoskeleton also found land during this time period. This includes insects, spiders and crustaceans. However, terrestrial life would not greatly diversify until later.

With the supercontinent Gondwana still covering much of the southern hemisphere, a large ocean occupied most of the northern half of the globe. High sea levels and relatively flat land (there were few significant mountain belts) produced a number of island chains, meaning there was a rich diversity of environmental settings.

What was left of Gondwana remained intact and continued to drift south, but there is evidence that the icecaps were less extensive than those of the late-Ordovician time period. The smaller continents of Avalonia, Baltica, and Laurentia drift together near the equator, starting the formation of a second supercontinent known as Euramerica.

When proto-Europe (Baltica) collided with proto-North America (Laurentia), the collision folded coastal areas from modern New York State through Europe and Greenland to Norway. At the end of the Silurian Period, sea levels dropped again, and the new mountain ranges were rapidly eroded.

The Silurian period enjoyed relatively stable and warm temperatures, in contrast with the extreme glaciations of the period before it, and the extreme heat that would follow it. Sea levels rose during the first half of this period, and fell during the second half.

Climate was warm because high CO₂ levels and warm shallow seas produced a greenhouse phase. Glaciers at the South Pole nearly disappeared entirely. There is strong evidence of a climate dominated by violent storms generated by warm sea surfaces.

The Silurian was the first period to have megafossils in the form of moss-like miniature forests along lakes and streams. The first fossil records of vascular plants (land plants with tissues that carry water and food) appeared in the second half of the Silurian period.

Fish reached considerable diversity. A diverse fauna of sea scorpions (some of them several meters in length) prowled the shallow Silurian seas of North America. Leeches made their appearance.

About the middle of the Silurian, the earliest-known animals fully adapted to terrestrial conditions appeared, including a millipede. There is also some evidence of predatory spiders and millipedes and centipedes. Predatory invertebrates indicate that simple food webs were in place that included prey animals. These may have included those who grazed on micro-organisms.

Yes, we are getting closer and closer modern Earth. That is what happens when you start at the beginning and work your way towards today. I'm still not seeing any fauna that would be worth hunting. Although a millipede several meters in length might have enough meat to make a stew. Is the ground fertile enough to grow carrots and potatoes to put in that stew? And just how bad did those storms get? Maybe I'll keep going before I try to colonize.

 

https://en.wikipedia.org/wiki/Silurian