The Mesozoic Era

What about insects? Yes, there were many insects during this time – and they were huge! Dragonflies and centipedes reached sizes that were nearly 5-7 meters in total length or wingspan. Four-legged animals are called tetrapods. These were possibly able to live on land because of the high oxygen levels in the atmosphere. They were mainly amphibians, but much larger than you would see today.

The Paleozoic era came to a screeching halt with the Permian-Triassic mass extinction event. It was far worse than the one that killed the dinosaurs, destroying about 95 percent of all species living at the time. No one knows why it occurred; the theories will be laid out next. This began the Mesozoic era.

THE MESOZOIC ERA

The Permian-Triassic extinction was rough on this planet. The causes were probably multifactorial. There was more carbon dioxide in the air due to burning after a giant eruption in the Siberian Traps region. The oceans then became too acidified and lacked oxygen to support life. This led to a 3-level series of extinctions over a brief time in geologic time, that is – the entire time period happened about 252 million years ago.

The Mesozoic era started with Europe and Asia colliding with North America. These continents formed a giant supercontinent we now called Pangea. The climate was warmer then, and most areas on earth were tropical by today's standards. The seas were much lower, allowing for more land mass. A few areas were dryer and were desert-like.

This era had three periods —the Triassic, the Jurassic, and the Cretaceous. Life needed a great deal of recovery time after the mass extinction events prior to this era. Plants made it through the extinction more than the animals did but there were wide temperature variations they needed to get through after the event. Ferns and plants called gymnosperms were able to spread through the air to allow for different reproductive methods and wider spread of these plants. Spore-forming plants were better able to get through droughts.

Corals, fish, and mollusks were widespread in the ocean. Reptiles were able to be on land and water to catch predators better. Mosasaurs and Plesiosaurs were the first of what we now call dinosaurs. Near the end of the Permian period, were animals called