The Great Dying
The Paleozoic Era
The Permian period lasted from 299 to 251 million years ago. It was the last period of the Paleozoic Era. An era distinguished by the formation of the supercontinent Pangea, and the evolution of certain animals and insects (ancestors of the ones that exist today). Life flourished in the seas and the first vertebrate animals colonized the Land.
The event that made the distinction between the Paleozoic and the Mesozoic era was the Permian-Triassic Extinction (The Great Dying) which killed most of the species on Earth, which then led to the end of the Permian period and the beginning of the Triassic period.
Pangea During The Permian Period
Characteristics Of The Permian Period
Overall, the global geography of the Permian Period contained massive areas of land and water. Like I mentioned before, all the continents we know today met in Pangea. Only asia was slightly separated at the time. The rest of the surface of the planet was occupied vy a single giant ocean known as "Panthalassa".
By the end of the period, Pangea was nearly fully assembled. This created a few new shallow seas.
The Permian world was warm in climate. It was dry with few variatiosn in seasonality, while the polar regions were tundras.There were also swampy tropical forests.
Helicoprion (Permian Shark)
Life During The Permian Period
There is not much known about marine life during this time because there is very little fossil evidence available. Sharks and rays were abundant throughout the Panthalassic ocean. There was also lobed finned and spiny fishes that made way for amphibians.
Some insects were similar and related to the modern day beetle, grasshopper, dragonfly etc.
Two Groups of animals were dominant on land.Synapsids and Sauropsids.There were reptile like animals and true reptiles.More forms evolved later on in the permain period such as the rodent like theriodonts, mammal like therapsids and cow like herbivorous dicynodonts.
Dimetrodon was a synapsid and apex predator that was about 11.5 feet long (3.5m) and weighed 550 pounds (250 kg). It had sharp teeth and clawed feet, and a large flap of skin along its back, dense with blood vessels. It was also a very fast runner, and a dominant carnivorous pelycosaur.
The Sphenacadon was also a synapsid carnivore that weighed about 100 pounds and was around 2.5 meters long (maybe even more). It possessed enlarged neural spines rising from its vertebrae,supports for its powerful dorsal muscles that would allow Sphenacodon to undertake powerful strikes on its prey, overpowering it by brute force.
The Great Dying: Causes And Effects
The Permian Period ended in the largest mass extinction the Earth has ever known. It is estimated to have wiped out more than 90 percent of all marine species and 70 percent of all land animals.
The cause of The Great Dying is still unknown due to the fact that it happened so long ago (251 million years ago).There are still many theories.
Scientists have suggested different causes, like enviromental changes caused by the formation of Pangea, the eruption of several volcanos, a nearby supernova or the collison of an asteroid or a combination of all of these. Most of the evidence has been destroyed, so to prove exactly which actually ocurred is difficult.
Some scientists think a series of volcanic eruptions pumped so much debris in the atmosphere that led to months or even years of darkness which caused a significant drop in temperature and prevented proper plant photosynthesis , which then caused food chains to collapse.
Other scientists think global climate change was the cause , pointing out evidence for periods of sudden warming and cooling. They suggest most species weren't able to adapt to these rapid changes. and perished. The climate change would have altered weather patterns so that regions normally rainy became dry and vice versa.
Other theories include earthquakes triggering the release of methane gas from underneath the seabed with catastrophic consequences.
Recently, a team of scientists went to sites in Hungary, Japan, and China where there are still rocks that date back to 250 million years ago. They found telltale signs of a collision with Earth and a nearby asteroid about 12 km across.
Although some scientists used to think that this extinction happened over a period of millions of years and not all of a sudden.
Thanks to numerous methods developed over the years to help investigate, estimates have shrunk to between 8,000 and 100,000 years. Which apparently is a very short amount of time in geological terms. Scientists now argue that it takes something catastrophic to cause life to vanish so quickly.
The Triassic Period: Characteristics
After the end of the Paleozoic Era due to The Great Dying, came the The Triassic Period, the first period of The Mesozoic Era which is distinguished by the first apppearances of dinosaurs. Somewhere near 251 million years ago.
It was a time for change on Earth. The few species that had survived began to repopulate the planet. Around this time, Pangea finished forming and already started to separate by the late triassic.
The climate in Triassic was overall warm and dry, while the interior of Pangea was very arid. Animals and plants continued to evolve. The first corrals appeared in the seaand the first mammals and dinosaurs appeared near the end of the Triassic.
Crocodiles, turtles, frogs and snakes roamed the Triassic lakes and rivers.
The icthyosaur was dominant throughout the oceans (at this time Panthalassic, Tethys and Paleo Tethys Ocean). Ichthyosaurs weren't actually fish, they were in fact reptiles.
There were spiders,scorpions ,milipedes and centipedes. Grasshoppers first appeared in the Triassic. Infact, many of the animal groups alive today made their first appearances in the Triassic.
Therapsids had become extinct by the mid Triassic. Archosaurs dominated the land and were ascendants of some dinosaurs.
They were a group of carnivourous archosaurs generally large in size measuring 13 to 20 feet (4 to 6 meters) in length. They were quadrupedal and active predators.
Prestocuchus was a rasuichian archosaur that measured between 5 and 6 meters long. It was an apex predator that targeted other large animals. It had a deep skull and sharp serrated teeth.
Mammals played an important role in the Triassic, though they remained mostly small and some of them were nocturnal.
One of the first mammals was the Eozostrodon (shrew like animal) that measured 3 feet long and laid eggs but fed its young with its own milk.
The earliest dinosaurs include predatory theropods and herbivorous ornithischians. The most abundant dinosaurs at the time were small theropods like the Coelophysis from North America which grew up to 9 feet (2.7 meters) tall and weighed up to one hundred pounds. It fed on small reptiles and amphibians.
There was also the Plateosaurus from Europe. This one was a herbivore that measured between 4.8 and 10 meters long (16 and 33 feet). It weighed between 600 and 4,000 kilograms (1322 and 8818 pounds).
End Of Triassic Period
The Triassic Period ended in a smilar way to how it began. With a series of events triggering another mass extinction. This one being much smaller than The Great Dying.
Scientists theorize that massive volcanic eruptions caused an increase in latmospheric CO2 which led to an acidification of the oceans and global warming that killed many of the species on Earth.
The dinosaurs however managed to survive and went on to dominate the Jurassic and Cretaceous periods (rest of the Mesozoic Era) before facing their own extinction.
It is fascinating to see how the Earth evolves and changes over the course of the years due to different events, and how mass extinctions affect the planet. Also, how the animals and species manage to adapt, evolve, or perish alongside. Most people agree that humans will face the same fate. The interesting thing here will be how the human race goes extinct.
What do you think will cause the next mass extinction?
© 2015 Ivan Chavez