Carboniferous Period

 The Carboniferous Period spanned 358.9 million years ago to 298.9 million years ago. On a time table, it sits behind the Devonian Period and before the Permian Period.

In the Early Carboniferous Period, average global temperatures were approximately 68 F (20 C). During the Middle Carboniferous, they dropped to about 54 F (12 C). Carbon dioxide levels fell during the period from roughly 8 times today's level at the beginning to about the same as today's level at the end. Lack of growth rings of fossilized trees suggest a lack of seasons, or a tropical climate. Glaciations in Gondwana were triggered by its southward movement, and continued beyond this time period.

Also, there was mountain building as continents collided to form Pangaea. There was a minor extinction event at the end of the period, caused by climate change.

Now, the last we heard, pieces of Gondwana had broken off and were sitting at the equator or slightly north, while the rest of Gondwana drifted south to the south pole.

During the Carboniferous Period, the land was covered by vast forests, which would eventually become the coal beds characteristic of this period's stratigraphy. Some of the Early Carboniferous land plants were very similar to those of the Late Devonian, but new groups also appeared. The main plants of the early period were horse-tails, scrambling plants, club mosses, scale trees, and ferns. The club mosses of this period are cousins to today's tiny club-moss, but not ancestors; and they had trunks 30 meters high and up to 1.5 meter in diameter. Another type of large tree was ancestor of today's ferns. These continued throughout the period, but late in the period, they were joined by cycads (a new form of 'seed fern') and plants related to conifers.

At least one tall plant (6 to over 30 meters tall) was related to cycads (often mistaken for palm trees) and conifers and are thought to have lived in swamps. True conifer trees appeared later in the period and preferred higher, drier ground.

During this period, animals and bacteria had great difficulty processing the lignin and cellulose that made up the gigantic trees. After the trees died, they piled up on the ground, occasionally becoming part of long-running wildfires after a lightning strike. Others very slowly degraded into coal. White rot fungus was the first living creature that could process these trees and break them down.

Animal life was well established by now. Amphibians were diverse and common by the middle of the period, the dominant type of land vertebrates. Some were as long as 6 meters, but most were probably about 6 in (15 cm) in length. Some were aquatic and lived in rivers, while others may have been semi-aquatic. One branch of amphibians would eventually evolve into the first solely terrestrial vertebrates. The cooling climate slowed the evolution of amphibians, who could not survive as well in the new conditions.

Insects, spiders, crustaceans, and others were also very common, and many were much larger than those of today. The atmospheric content of oxygen reached its highest level in Earth's history—35% compared to today's 21%—which allowed the land invertebrates to get so large. There was a millipede-like creature that grew to 8.5 ft (2.6 m) long. Startling to come across, but if you could kill it, there should be some meat on all those legs. This was the largest known land invertebrate of all time. Among the insects, there were the griffinflies, which included a dragonfly-like insect with a wingspan of 30 in (75 cm). This was the largest flying insect ever to roam the planet. Many other insects flew and crawled about, including cockroach ancestors.

Reptiles, however, prospered due to specific adaptations, such as the amniote egg, which allowed the laying of eggs in a dry environment. Some of the small lizard-like animals gave rise to many descendants, including reptiles, birds and mammals.

I wanted to include a statement about the marine animals of the time, but that section of the article was mostly full of names and little else. I did gather than sponges were fairly prolific and diverse. Also sharks evolved into a multitude of shapes and sizes. Although sharks were mostly sea creatures, there was one type that would sometimes visit swamps. At least one marine fish explored river outlets, and fresh-water fish were common in rivers.

During the latter half of this period, there were glaciations, which meant low sea levels. The cooling and drying of the climate led to a minor extinction event at the end of the period. The tropical rainforest fragmented and then was devastated by climate change.

 

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