What was the Ordovician Period?

The Ordovician Period (Ordovician, symbol O), the name of the geological age, is the second age of the Paleozoic (primitive vertebrate appearance), beginning before 488 geological units (480 million years ago) ~ 444 Before geological units (440 million years ago), it lasted 42 million years. There was a large-scale species extinction between the Ordovician and Siluriangamma-ray bursts. In this species extinction, 60% of the species are extinct. The main extinct animals are: Crescent-shaped sickle, comet, and primitive creatures. The Ordovician began at an isotope age of 485.4 ± 1.9Ma (Million Anniversary, million years), and ended at 443.4 ± 1.5Ma.

Ordovice

Ordovician profile

The first mass extinction on Earth occurred in the late Ordovician 449 million years ago, which caused the extinction of 60% of the species on the planet.

Ordovician specific process

449 million years ago, the Earth entered the late Ordovician. The earth at this time is very different from what it is today: the pan-continent has not yet formed, and today South America, Australia, Southern Europe, Africa, India, and Antarctica form the Gondwana continent, and the rest of the land is divided into a series of islands distributed around the world. The Ordovician era was the worst invasion of Shanghai in the history of the earth. The sea level was 400 meters higher than it is now, and one third of the land today is covered by shallow seas.

There were no animals on the Ordovician land, and plants did not appear at that time. All animals live in the ocean. The animals at that time were also very different from the current ones. There were only a few species of vertebrates, and the arthropod species were less than 1/10 of the present. There are some lesser-known animals in the oceans.

The top predator in the sea is a nautilus. It is 6 meters long and weighs 150 kg. It is the ancestor of cephalopod mollusks such as nautilus and octopus. It eats almost everything, including animals such as trilobites, star turtles, and plate-footed pheasants. The straight-shelled nautilus also has competitors: the largest arthropod ever: the 3.6-meter-long board foot salamander. It looks like a huge scorpion without a tail hook. It is one of the oldest arthropods. It is common for scabies to compete for food with straight-shell nautilus, but it is always impossible to defeat them.

The marine animals lived leisurely, and no one realized that the calamity was coming.

The culprit in this disaster was a gamma ray storm. A distance of 6000 light years away from the earth, a neutron star collided with a black hole for unknown reasons, generating several beams of gamma-ray bursts, one of which hit the earth impartially. In fact, the probability of a gamma ray hitting the earth is very small, less than 1 / 100,000,000. This time the earth is really unlucky.

One day 449 million years ago, a beam of gamma rays from 6000 light-years passed through the atmosphere and hit the earth. The rays shattered the gas molecules, and the earth's atmosphere suddenly became fragmented.

The animals in the ocean only felt the violent shaking of the earth, and did not know that the calamity had come.

The rays destroyed 3/1 of the ozone layer, and the ultraviolet rays in sunlight directly penetrated the atmosphere, killing a lot of plankton, destroying the foundation of the marine food chain, and famine began to spread around. The radiation from the rays also kills a lot of corals and destroys the habitat of marine life.

One year after the disaster, famine has spread to the world, no matter living creatures are at the top or bottom of the food chain, they are struggling with hunger. Predators need to kill their kind to get enough food.

Decades after the disaster, the broken gas molecules regrouped to form a toxic gas called nitrogen dioxide. Nitrogen dioxide covers up to 50% of the sun. The earth lost its sunshine and the temperature began to drop rapidly. Animal eggs cannot develop normally at low temperatures, resulting in a significant decline in the population.

With the sudden drop in sunlight, the climate became very unstable. The sea produced huge waves that disturbed the animals. Straight-shelled nautilus wants to take refuge in the deep sea, but the water pressure in the deep sea is very high. High water pressure crushes the sturdy shell of the nautilus, so that they have only a dead end. And their close relatives, the nautilus, have a sturdy shell that allows them to survive.

Ten years after the disaster, the water temperature dropped from 25 degrees Celsius to 10 degrees, killing more plankton, which accelerated the collapse of the food chain, but small animals with less food requirements did not feel hungry, so they were in famine. Small animals are easier to survive.

500 years after the disaster, one third of the life on the planet has disappeared, and the remaining life is still struggling with hunger. Due to the lack of sunlight, the global average temperature dropped from 22 degrees Celsius to 10 degrees, which caused a large amount of sea water to freeze, and marine animals once again lost a lot of habitat. The spread of glaciers is unimaginable fast. After a few years, more than 10% of the sea water is frozen. Glaciers consume a lot of seawater, causing sea levels to drop by about 100 meters, and many of the original oceans became land.

The glacial events are getting more and more serious. A large number of icebergs have appeared in the ocean. Icebergs are like runaway cars that run rampant and a large number of creatures are killed by it.

150,000 years after the disaster, the average global temperature has dropped to 5 degrees Celsius, and more than half of the living things have become extinct in the severe cold. Can the remaining living things survive?

Two hundred thousand years after the disaster, the ice age is finally over. However, almost all signs of life on the earth have disappeared, and it will take hundreds of thousands of years for the earth to restore its former vitality. Mr. Yuan's vibrant ocean became deadly, but the remaining plankton continued to multiply, repairing the food chain.

It has been 400,000 years since the gamma-ray storm hit the earth, and the disaster has basically ended. The catastrophe that swept the globe was the first mass extinction in Earth's history, causing 56% of species to become extinct. The straight-shell nautilus miraculously survived, but with a bad genetic mutation, its size was reduced to 2 meters. After the disaster, it was quickly replaced by the nautilus and became a top predator. There is also a beneficiary in this disaster-one of the earliest vertebrates: the star turtle. Star turtles are cephalocephalous fish without jaws. One of their branches evolved after the disaster into the earliest vertebrate with jaws: the spiny fish.

Deadly rays, severe famine, toxic gases covering the sky, and severe ice ages constitute the first mass extinction of the species-a gamma - ray storm hit the earth .