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The Carboniferous period, lasting 60 million years, saw the evolution of abundant terrestrial life, including reptiles and mammals. High oxygen levels allowed for giant arthropods, while lignin-rich trees and swamps created vast carbon deposits. Marine life was recovering from extinctions, but the period was not great for marine genres.
The Carboniferous period is a geological period extending from 359 to 299 million years ago. It takes its name from the huge deposits of oil and gas left over from decaying plant matter during this time. The Carboniferous, lasting about 60 million years, is among the longest of geological periods, surpassed in length only by the Cretaceous of 80 million years.
The Carboniferous is the first full period during which there was abundant terrestrial life, including numerous plants, arthropods, and amphibians. The first sauropsids (reptiles) and synapsids (ancestors of mammals) evolved during the mid-Carboniferous, about 420 million years ago. Both resembled small lizards in appearance. These species fossilized when they became trapped in decaying tree stumps and could not find their way out.
The bark fiber lignin first evolved shortly before the Carboniferous. These early trees make such extensive use of bark, that the “bark” was actually the bulk of the tree, making up 80-95% of the tree’s volume, with traditional wood making up the rest. It is thought that the large deposits of carbon created during the Carboniferous (which fueled the Industrial Revolution) were due to two causes: first, the bacteria and animals capable of effectively breaking down lignin had not yet evolved, and the vast low-lying low-lying forests and swamps during the mid-period.
Although there were a number of different amphibians in the early period, including amphibians larger than humans, terrestrial fauna was mostly dominated by arthropods such as insects. Oxygen levels were so high during the Carboniferous that arthropods could grow to gigantic sizes. Two of the most spectacular examples were the 0.3–2.6 m (1–8.5 ft) myriapod (millipede and centipede relative) Arthropleura, the largest land invertebrate ever, and the griffins, order Protodonata (dragonfly relatives), with wingspans up to 75 cm (2.5 ft), the largest flying invertebrates ever. Arthropleura had a mixed diet that would have included a ton of plants per year, while griffins were predators, eating other insects and even small amphibians, in a reversal of the roles of modern species.
The shallow oceans were populated by a variety of fish and invertebrate species, especially brachiopods (a phyla of filter feeders that superficially resemble bivalves) and crinoids (echinoderms called sea lilies). The deep seas of the Devonian disappeared as the poles froze and water was withdrawn from the oceans. Marine life was recovering from a 15-million-year series of extinctions that wiped out about three-quarters of marine species, including important groups of fish like placoderms. During the mid-Carboniferous, there was another minor extinction event. Like the Permian after it, the Carboniferous was not a great time for marine genres and much of the action took place on land.
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