Info Bites: 10 Fascinating Facts about the Carboniferous Period

Carboniferous rain forestJohn Weinstein

A diorama depicting a typical Carboniferous rain forest scene.

359 million years ago, one of the five major extinction events that shaped the Earth’s evolution hailed in the end of the Devonian period. By this time, life had started to colonize the land from the sea. The Late Devonian mass extinction hailed in the next geological period, the Carboniferous period, which lasted from 354 to 290 million years ago, some 60 million years before the first dinosaurs even came to be.

The Carboniferous world was a remarkably different one to that we know today, but it is extremely significant nonetheless. The name Carboniferous is Latin for coal-bearing, which is appropriate given that much of the coal reserves we rely on today were formed during this time. Nonetheless, to today’s observer, the Carboniferous Earth would have looked and felt remarkably alien.

#1. The Air Was Completely Different

Carboniferous swampMary Evens Picture Library/Alamy

A nineteenth-century painting depicting the characteristic swamps of the early Carboniferous period.

The Carboniferous, as evidenced by air trapped in ice from that period, is known for having the highest percentage of oxygen in the atmosphere ever. If you were to visit the Carboniferous, you’d instantly notice that the air is ‘richer’ to breath, since it reached a peak of 35% oxygen as opposed to today’s 21%. This dramatic difference also allowed insects to grow to truly ungodly proportions, as you’ll find out later in this list.

#2. It Was a Time of Enormous Climate Change

Carboniferous marineFelix-Jean Gauchard

A nineteenth-century illustration depicting a typical coastal scenery of the Carboniferous.

The early Carboniferous saw lush jungles and swamps span vast stretches of the world, and the average global temperature was some 6 °C warmer than it is today. The atmospheric CO2 content was also three times higher than preindustrial levels, making for a far stronger greenhouse effect than that which concerns us today. However, from the middle of the period, the glaciers started to advance from the poles, and global temperatures decreased to bring about a severe ice age.

#3. Timekeeping Wasn’t Easy


Thanks partly to the Earth’s faster rotation , typhoons like this one, taken from the International Space Station, were particularly fierce during the Carboniferous.

If you were to be transported back to the Carboniferous, your alarm clock and calendar wouldn’t be much use. 350 million years ago, the day was only 22.4 hours long, and there were approximately 385 days in a year. The Earth’s faster rotation, combined with its thicker atmosphere, also made winds significantly stronger than they are today.

#4. The Map Was Unrecognizable

This is what the world map looked like 340 million years ago, in the middle of the Carboniferous period.

Since the Carboniferous was so long, the natural movement of the tectonic plates had ample time to change the map significantly, but at no time did it look anything like the one we’re familiar with today. By the end of the period, what is now Africa, the Middle East, India, Australia and South America were all joined together with Antarctica. The Eurasian tectonic plate was connected to this enormous southern content, named Gondwana, by a thick strip of land.

#5. Insects Ruled the Earth…

meganeuraAlexandre Albore

A fossil of the meganeura monyi, the largest known flying insect that ever lived.

Long before dinosaurs, birds or mammals existed, insects ruled the Earth, leading the Carboniferous to be dubbed the Age of Insects. Due to the much higher oxygen levels, insects were able to evolve to horror-movie sizes. The meganeura, for example, was a dragonfly sporting a 30-inch (75 cm) wingspan. Although not technically an insect, the arthropleura was another enormous creepy-crawly, a millipede that grew as long as a car. Adapted perfectly for the Carboniferous atmosphere, animals such as these would not be able to survive in today’s air.

#6. …and Scorpions

Measuring some 30 inches (75 cm) from claw to stinger, Pulmonoscopius was the largest arachnid that ever lived.

Scorpions are one of the oldest orders animals on Earth, having existed for some 430 million years. However, the early Carboniferous saw the most horrifying scorpion of all – the 28-inch (70 cm) long pulmonoscorpius, and the largest arachnid that ever lived. It’s likely that pulmonoscorpius lived on other arthropods and perhaps smaller amphibians. As is the case with Carboniferous insects, it is thought that the scorpion’s terrifyingly large size was also a due to the higher oxygen levels.

#7. Sharks Dominated the Seas

The stethacanthus was one of the many strange shark species that lived during the Carboniferous.

The early Carboniferous saw sharks at the top of the food chain in the seas, but they weren’t much like the sharks today. Among the stranger of the many species of that period was the akmonistion, characterized by its bizarre anvil-shaped crest and spines on the top of its head. Fortunately, however, at one metre (3 feet) long, it probably didn’t look particularly threatening. However, the helicoprion, which first appeared towards the very end of the Carboniferous, grew three times longer, and it sported a circular sawblade for jaw.

#8. Trilobites Started to Decline


Measuring up to 15 inches (37 cm) in length, Paradoxides was one of the largest species of trilobites.

Trilobites, a highly diverse class of marine arthropod, that ruled the Earth for hundreds of millions of years, started to decline rapidly towards the end of the Carboniferous period, likely due to competition with the explosion of versatile sea life. By the end of the period, only three families survived, which themselves became extinct some 250 million years ago.

#9. Amphibians Were Highly Successful

Petrolacosaurus was one of the many primitive reptiles that started colonising the land during the Carboniferous period.

Alongside insects, amphibians radiated to form the ancestors of the reptiles, birds and mammals that followed. These creatures made up the taxonomic clade of synapsida, which also includes all mammals. The earliest of these was the archaeothyris, a lizard-like creature that grew about 20 inches long and lived some 306 million years ago.

#10. It Was an Extremely Volatile Era

archaeothyrisArthur Weasley

The archaeothyris was one of the first synapsids, and a distant ancestor to all mammals and reptiles. It was also one of the few tetrapods to survive and thrive after the collapse of the Carboniferous rain forest.

One of the most important events of the period was the rainforest collapse towards the end of the Carboniferous, which caused countless extinctions along with the disappearance of most of the world’s rainforests. The Carboniferous ultimately ended with the Permian-Carboniferous Ice Age around 300 million years ago. Glaciers spread far and wide to cover some 50 degrees of latitude from the poles. Oxygen levels also dropped, a trend that sealed the fate of countless species, particularly arthropods. However, the world eventually recovered in the early Permian to bring in the birth of early mammals and many other lifeforms.

3 Responses

  1. Mike

    Regarding #1, the oldest ice found on earth is only about 2.7 million years old. We have deduced the oxygen percentages based on the fossil record, and perhaps air bubbles in amber, but definitely not ice.

    • Dick Riethmiller

      Add a zero Mike and I agree. No end Caboniferous ice exists, but ice started building up at the south pole about 30 mya that is likely still there. Antarctica has moved very little since.

    • Clint

      Amber air bubbles in themselves are not always a worthy oxygen reference for prehistoric times….over the eons, whatever trapped gases are contained in the amber often permeate the amber itself, generated by a temperature related exchanges between the two mediums, century after century till the results are often questionable….I’m really not sure how they’ve come to their conclusions


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