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writes of fine-grained greenish sandstones deposited in freshwater in which land plant fossils are well preserved.
"Among the most attractive of these" tree-fern once called Cyelopteris (Round-leaved Fern), re named Palasopteris Hibernicus (Primitive Irish Fern). It was the "monarch of the primeval forests" whose "graceful fronds bent over the clear waters of a lake".
Three strata of toadstone had been found, and the limestone under the third was as far as miners had reached. The map project describes the "shallow tropical sea surrounded by coral reefs" in which the limestones were laid down and how "subterranean volcanoes erupted spasmodically through the sea floor, covering the limestones with ash and lava" which formed the toadstone.
The end-Frasnian extinction was most pronounced in tropical environments, particularly in the reefs of the shallow seas.
Reef building sponges called stromatoporoids and corals suffered losses and stromatoporoids finally disappeared in the third extinction near the end of the Devonian.
) 13,800,000,000 (13.8 billion) years ago The creation of the universe according to present estimates of "big bang" - "Stephen Hawkings and others...
estimate between 18 and 11 billion with 13.8 being the closest estimation".
All plants were responsible for the transformation, but Archaeopteris was important because it made up 90 percent of the forests during the last 15 million years when these changes accelerated" ...