|Ancestors of Living Creatures Edition: The Ordovician Age|
We meet again with me to continue writing the prehistoric edition. In this third part, we are in the Ordovician Age.
This period lasts from 488 to 443 million years. As the Cambrian ended, the Earth's surface began to cool. And, it wasn't as hot as it was in the Early Ages I've discussed, where all the dirt tasted like barbecue grills.
This is the second time the earth has cooled to this snow. But no, we haven't reached the ice age yet. Soil formation is still ongoing. Melted basalt and rhyolite can appear anywhere. So, glacier hot springs were abundant at that time.
Due to the abundance of volcanic activity, carbon dioxide on earth is also increasing. Even up to a dozen times from today.
It turned out that upon further investigation, this very high CO2 level only occurred in the late Ordovician. After this ascension, the previously formed ice began to melt and disappeared completely in the Silurian period which I will discuss in my next article.
Entering life in the Ordovician, animals still use the sea as a nest. While the land is still a little inhabited. If anything, it's probably just microbes. In the rocks found today, there are many microfossils in the form of plankton, which indicate growth.
Funny trilobites also still existed in the Ordovician, though not as much as in the Cambrian. Plants in the sea are also dominated by species of algae, sponges, and also some bryozoans.
Let's start with an explanation session about the selected creatures that are the topic of this Ordovician era.
The Ordovician is still full of invertebrates, one of which is the Nautiloid (close to the Squidward family, but shelled). And this one is a top tier predator named Cameroceras. The size can be up to 9 meters. With this size, he swam slowly. But when hungry, the beak behind the tentacles can advance quickly.
Have you heard of the intelligence of the octopus? From camouflage to the use of marine debris for homes, the brain power of the octopus (cephalopod) family has been proven since Ordovician times.
And this Cameroceras is one of those animal innovators who take his home with him when he goes everywhere. From the Ordovician to the present, their shells have continued to evolve. Just imagine carrying a long and big house everywhere. Well, that long straight shell, following the evolutionary path, will eventually become more curved and become like a slug.
After Mollusca, it belongs to the Arthropoda family. Its name became Aegirocassis, the same genus as Anomalocaris and is the largest in the genus. What distinguishes them from the others is that they have fins that grow on the underside of the abdomen.
So, there are four groups of fins on the body. This makes the Aegirocassis able to swim more easily than its predecessor. His body is also increasingly modern, similar to today's shrimp.
Unfortunately, Aegirocassis is the only eurypterid that can survive in the Ordovician. Abandoned by their genus, they live alone on the high seas.
Judging from their large bodies, they are filter feeders (animals whose way of eating suck whatever is in the water, one of which is plankton), seen from their mouths.
One of the first eureptyd (sea scorpion) species, the forerunner of another scorpion, Megalograptus. They were the first creatures to use spiked legs. The body is soft and the tail is not poisonous, only serves as a swimming aid.
The only weapons that make them look (quite) fierce as carnivores are their claws. But even if they tried to look at their images, it was as if their claws were still unable to grip firmly. As a result, they only eat small animals. From any point of view, this Megalograptus is far behind when compared to today's scorpions.
It still lacks jaws, but its shape is more complex than Haikouichtys. Let's welcome, Astrapis. they were one of the first placoderms (shielded fish, tough skin). Astraspis is a companion of the Trilobites in the Ordovician.
As the animal most often hunted and harassed by Ordovician carnivores. To protect themselves, Astraspis didn't need to roll like the Trilobites. they are just silent, because all the skin is already hard. But because of that, they couldn't swim fast enough. If they encountered Cameroceras, those Astraspis would be instantly devoured.
Major Extinction Event
Ending the Ordovician period, there was the first Major Extinction Event, a massive extinction event of living things. This Major Extinction Event (so far in the Ordovician era) occurred five times. As many as 75% of living things died and became extinct at the end of the Ordovician.
This incident happened for two reasons. First, the Gondwana shift which caused many earthquakes and tsunamis. Second, the formation of glaciers which causes sea water to decrease. Due to these shifts and formations, the shallow seas are getting wider but the water is getting less and less. As a result, many living things have lost their homes.