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The Carboniferous Period
280 million to 325 million years ago
325 million to 345 million years ago
Molluscs increase, many brachiopods and amphibians die out, coal swamps develop widely. Conifers, insects, amphibians, and reptiles evolve
Crinoids abundant. First seed ferns, ammonoids
The Lower Carboniferous (also known as the Mississippian in North America) was a time when crinoids became widespread and common enough to be the main limestone-forming fossils.
By the Upper Carboniferous (Pennsylvanian) the crinoids were declining; molluscs increased, as did some brachiopods, especially the productids.
On land, or in coastal swamps, there were large forests, whose buried remains now make up vast beds
of coal. The largest trees were lycopods, or scale trees. Another important group on land were the seed ferns, for these developed into flowering plants.
On land, insects diversified and the largest insects ever to have lived, flourished. Dragonflies with a wing span of
75 centimetres were common, and cockroaches reached 10 centimetres in length. Amphibians were, by now,
much more common. Also, the first reptiles developed watertight eggs; they no longer had to return to the water to breed, and so they could reach all of the land, while the amphibians had to remain close to water.
The Permian Period
(Above) Upper Carboniferous seed fern Neuropteris.
(Below) Permian tree.
225 million to 280 million years ago
The world’s greatest known mass extinction occurs at the end of the Permian with many Palaeozoic Era species becoming extinct, including trilobites; many others reduced greatly in numbers, including ammonoids, brachiopods, crinoids and amphibians
In the seas, brachiopods developed long spines,
and crinoids were abundant, but the increasingly
dry climate over much of the world’s land meant
that plants declined and many became extinct.
One of the more successful were the conifers,
since they were more able to adapt to dry conditions.
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