THE HISTORY OF EARTH Geologic Time – Paleozoic Part IIc Carboniferous & Permian

1. THE HISTORY OF EARTHGeologic Time – Paleozoic Part IIc Carboniferous & Permian

2. THE HISTORY OF EARTHGeologic Time – Carboniferous (Mississipian) The Age of the Amphibians 360 mya to 325 mya • Euramerica & Gondwana continue to merge; much mountain building; other continent fragments drift closer • Vast forests and swamps form as sea levels fluctuate • Climate hot & humid but glaciated at the poles • Oxygen level 40% above today – abundant wildfires • Much of the world’s coal formed during the Carboniferous

3. THE HISTORY OF EARTHGeologic Time – Carboniferous (Mississipian) • Bark-bearing trees grew in vast lowland swamp forests. Vegetation included giant club mosses, tree ferns, great horsetails, and towering trees with strap-shaped leaves. • Over millions of years, the organic deposits of this plant debris formed the world's first extensive coal deposits. • The growth of these forests removed huge amounts of carbon dioxide from the atmosphere, leading to a surplus of oxygen. Atmospheric oxygen levels peaked around 40 percent (highest ever), compared with 21 percent today. • This excess oxygen may explain the giant insects emerging during this time. (The size reached by insects and similar creatures is thought to be limited by the amount of air they are able to breathe.) Lush Carboniferous Forest Coal Deposits

4. THE HISTORY OF EARTHGeologic Time – Carboniferous (Mississipian) Most impressive of all were dragonflies that grew to the size of seagulls. One exquisitely detailed fossil of a dragonfly that died 320 million years ago shows it had a wingspan of 2.5 feet. Deadly poisonous centipedes six feet in length scavenged in the company of mammoth cockroaches and scorpions as much as three feet long.

5. THE HISTORY OF EARTHGeologic Time – Carboniferous (Mississipian) Amphibians were also growing in size and diversity. There were predatory species that resembled modern-day crocodiles. Armed with vicious teeth, they reached lengths of almost 20 feet (6 meters). Remember the amphibian evolved from the lobe-finned fish Amphibians developed a thicker, scaly skin, solving the problem of them drying out if away from water too long.

6. THE HISTORY OF EARTHGeologic Time – Carboniferous (Mississipian) • They also reduced their reliance on wetland habitats through a crucial evolutionary adaptation known as the amniote egg. This protected the embryo inside with a fluid-retaining membrane while still allowing in air. • In time, the earliest reptiles appeared. Identified from remains found inside fossilized Carboniferous tree stumps, they were small, agile, lizard-like animals.

7. THE HISTORY OF EARTHGeologic Time – Carboniferous (Pennsylvanian) The Age of the Giant Coal Swamps 325 mya to 299 mya • Pangea supercontinent forms as all continents collide - significant mountain building worldwide • High sea levels form broad, shallow continental seas and vast coal swamps • Climate hot & humid but glaciated at the poles • Oxygen level 40% above today - abundant wildfires • Much of the world’s coal formed during the Carboniferous

8. THE HISTORY OF EARTHGeologic Time – Carboniferous (Pennsylvanian) Reptiles appear and diversify wildly • Reptiles were outnumbered by the amphibians, which were prosperous, diverse, and achieved lengths of up to 15 ft. First reptiles evolved during this period and were small (about a foot long). Hylonomus (left) and Archaeothyris (right) layed their eggs on land. In doing so they became the ancestor of every reptile, bird and mammal on the planet.

9. THE HISTORY OF EARTHGeologic Time – Carboniferous (Pennsylvanian) Scientist currently believe Hylonomus (Greek for forest mouse) may well have been first tetrapod to lay eggs and have scaly skin. These features would have allowed it to venture farther from bodies of water which amphibians were closely tied too. Scientists believe that the elevated oxygen levels of the Carboniferous period may have helped fuel the development of complex animals in general during this time.

10. THE HISTORY OF EARTHGeologic Time – Carboniferous (Pennsylvanian) • Insects also continued to thrive; dragonflies with 2.5-ft wingspans were common. Over 1,000 species of Pennsylvanian cockroach have been identified. Period also known as the "age of cockroach"

11. THE HISTORY OF EARTHGeologic Time – Carboniferous (Pennsylvanian) Giant, primitive horsetail, club moss and fern 'trees’ dominate. Dense layers of dead wood form coal beds. Amphibious tetrapodscontinue to flourish.