More Info about the Devonian World
By middle Paleozoic time, approximately 400 million years ago, the Iapetus Ocean had closed bringing Laurentia
and Baltica crashing together. This continental collision, preceded in many places by the obduction of marginal island arcs,
resulted in the formation of the Caledonide mountains in Scandinavia, northern Great Britain and Greenland, and the
Northern Appalachian mountains along the eastern seaboard of North America.
It is also likely that by middle Paleozoic times, North China and South China had rifted away from the Indo-Australian
margin of Gondwana, and were headed northwards across the Paleo-Tethys Ocean. Throughout the Early and Middle
Paleozoic, the expansive Panthalassic Ocean covered much of the northern hemisphere. Surrounding this ocean was a
subduction zone, much like the modern"ring-of-fire" that surrounds the Pacific Ocean.
The Devonian was the Age of Fishes. Fish evolved jaws early in the Devonian and became the top predators by the
end of this Period.
Plants took over the land and became so abundant that the first coal deposits formed in the tropical swamps that
covered much of the Canadian Arctic Islands, northern Greenland, and Scandinavia.