Showing posts with label Pikaia.. Show all posts
Showing posts with label Pikaia.. Show all posts

HAIKOUICHTHYS


The name "Haikouichthys" comes from the Greek: "Ichthys" which means fish "Fish of the Chinese city of Haikou". And you put that name is very characteristic. I mean, a fish is a fish, and you do not name it except that fish being fish special. And here it is ... because the Haikouichthys is the first fish of evolution. Not only that, it is also one of the first vertebrates that existed, and which all others come from trout, shark, elephant, hen, you and me.

Anyway, this post, the first vertebrate, the first fish of prehistory, he shares with his contemporary, the Pikaia. Both of others lived in the Cambrian, appeared at the beginning of the famous Cambrian explosion of life. 530 million years ago.

The Haikouichthys, was not a giant of the oceans, in fact, was about 2.5 cm (3 in). With your thumb we could have ended the life of one of the most important animal in the history of evolution.

(It occurs to me cuanticocosmictemporal dysfunction, if we traveled back in time to 530 million years ago and we killed the fish in Haikou that evolved in all vertebrates, we would not exist, and therefore we could not kill the Haikouichthys, so he would survive and we too .... anyway ... I do not follow me head implodes and the blog is not about that).


A further feature is that Haikouichthys had a distinct head of the body. Until then, prehistoric animals seemed tubes, it was not known or where to eat or where defecated ... at first glance. And far fewer had a clear center differential that controlled the other body part. But with the Haikouichthys this was more evident. Had a head, eyes and mouth of millimeters. And then a "long" body with dorsal and pectoral fin that served to move like fish in water.

The movement is really important. We must bear in mind that at the beginning of the Cambrian, most of the oceans was occupied by large arthropods, sponges or slow and slimy worms. And suddenly, a small chordate appears, a young vertebrate with a capacity that others had: was agile and quick. And though not great, thanks to its speed and agility, he could escape their large predators and become the main protagonist in the formation of large animal phyla: vertebrates.

Pikaia



The Pikaia beings is one of the most important and that we should highlight, if we get an overall idea of ​​the exciting topic of evolution and prehistoric animals, I mean ...

Cambrian, 540 million years ago, at the beginning of the explosion of life that happened and all the various forms that appeared in the ancient seas. Appears then a small might just measuring 2 in (5 cm) long.  We're talking Pikaia.

This little creature would become the source of one of the major groups of animals to would be more successful throughout the history of Earth and ... where we also are included: vertebrates.

Lions, hyenas, falcons, whales, sharks, Allosaurus, Triceratops, Sabertooth, armored fish, gorillas and we owe our existence to this small, first vertebrate. We all come from it and was its advantageous morphology characteristic of vertebrates, which helped them survive, although it was a small animal compared to others of his time.


Well, Pikaia was not a colossus  or an apex predator in fact measured about 2 in (5 cm) long.

His body was flattened, hydrodynamic, which used to navigate near the ground where it fed, probably, filtering water particles.
Most characteristic of this small, prehistoric fish was that, unlike molluscs, which are invertebrates and some shelled, and arthropods with exoskeletons, the pikaia possessed the notochord, which is considered the evolutionary precursor of the column spine in all vertebrates.

This feature provided a fast, elasticity, speed with no other animals. Thanks to this feature, so it survived and was able to escape predators. Because the evolutionary experiment went well and that the Pikaia survived ... we are here.

A bit of prehistory.

Everyone knows the prehistory of the mind in which the dinosaurs disappeared about 65 million years. But few people know another story even more fascinating and more importance for what is life on land, but especially and more specifically, to us humans. It was not an isolated event but a chain of events, a struggle between forces of evolution among prehistoric creatures that ended with one victor, our ancestor ......... The story begins:

500 million years ago.


So far life in the prehistoric seas, oceans before the beginning of the Cambrian period,
consisted of single-celled or multicellular creatures (many
cells, but all the same) soft body, which they obtained their food by filtering the water around them, or feeding on bacterial mats (dense colonies of bacteria) on the ocean floor.

I will not go into details but then gave a very important place, which is known as the Cambrian Explosion, say it is from this date (500 thousand years) when the three-edged mother will result in all other species we know and that interaction
between them, set up, the situation now is the arthropods, molluscs and vertebrates (the group we belong to).

Well, at that time, life beyond the seas was unknown, and the seas and oceans were then inhabited by beings of strange shapes as the famous trilobites and other less friendly as Anomalocaris (left) or Hurdia Victoria (the latter were the top predators of the time). These three species were among the arthropods. The dominant and most numerous group that reigned on molluscs (its variety was insignificant) and vertebrates.

In fact, the Cambrian vertebrates were a small and unimportant. For example, while Victoria Hurdia reach 50 cm or up to one meter Anomalocaris, the

representative of the larger vertebrates that was Pikaia (pictured right) did not exceed 5 cm
length. Come on, that our ancestor was a true miniature land of giants.


The pikaia our ancestor, was long, small, light having a backbone instead of shell but it was also the major arthropod prey. He devoted himself to hide in the care of arthropods and eat the waste and the remains of prey left by large predators battleships were mainly scavengers.

Nothing seemed likely to change, the arthropods dominate the land and seas over the millennia, eating and leaving decimated vertebrates, thus reducing the possibility of not only our species but also birds, dinosaurs, fish and other mammals, may appear in the future. But conditions changed.

450 million years ago.


In the late Ordovician period (the next to the Cambrian period) was the second largest extinction of life on Earth history, eliminating 85% of the species.

A global ice age that froze oceans and seas


covered them with a blanket of 800 meters of ice and snow had catastrophic consequences for the life of this era. The lack of light and the intense cold was killing larger species and more specialized, bone arthropods. This led to the other two groups (vertebrates and molluscs) may develop: vertebrates evolved and appeared larger scavengers such as conodont (about 10 cm, right image). But they were vertebrates which rose to the position of the dominant group, but molluscs. The supremacy of vertebrates was cut again, but in this case by the large mollusks.



Now the predators were large molluscs such as Ortocono (left)

and Nautiloidea. And they dominated the other groups until they took another step, one giant leap in the way of the evolution of arthropods came ashore.


On land they had no predators, and eventually took the opportunity to grow and multiply. There were big and strong and the seas again to reconquer. And they succeeded. Arthropods were Jaekelopterus rhenaniae most important ancestors of scorpions and giant like Pulmonoscorpius.

Over time, the move gave them the advantage on mollusks to arthropods and vertebrates (leaving ground) would also be a fatal mistake that would destroy them.

375 million years ago.

Gradually, over the millennia, vertebrates were going to land, a land that was populated with a number of plants that helps to oxygenate the atmosphere and produced the right conditions for our ancestors to develop.


Shellfish centuries ago who had returned to background. In contrast, on land, vertebrates were developed only arthropods and began to exceed the size, strength or agility of the arthropods. The last battle was about to begin.

On the one hand were the arthropods were strong but had a weakness: its outer armor. They had to grow as the animal grew. If the animal was too big armor, and thus increasing the animal's weight. Could weigh as much that came a moment that was counterproductive in an evolutionary sense. At best, could reach a size of 3 meters.

On the other side were the vertebrate ancestors. Animals that could grow larger without becoming too heavy to be sustained. Vertebrates, thanks to its design, its backbone, they could better adapt, develop better, evolve ... and all this without becoming heavy tanks.

250 million years ago.

The reign of the arthropods are gone forever. And with this came the dinosaurs, birds, fish ... y.

.. us HUMANS.

Anomalocaris.


During the Cambrian explosion of life (for about 525-510 millions years. Up to this point had not been very successful multicellular life) appeared the first predator to bite, was the Anomalocaris. The biggest predator of the Cambrian seas. Measure up to 1 meter and its name means "strange shrimp."

Possibly it was given this name because when they discovered the fossils were so strange that they thought of three different animals.

It had a segmented body, such as some crustaceans and a current "arms" armed with thorns, compound eyes (with a very developed on their prey, but not entirely confirmed). The mouth was circular and had 32 overlapping layers (four large and 28 small) equipped with small barbs which failed serrated rings around a central opening. With his arms gripping the defenseless Pikaia or trilobites and pounding and crushing.




Like trilobites, the Anomalocaris was an arthropod, bony internal skeleton had not, this was a protection mechanism, a cuticle or exoskeleton made of chitin and proteins such as cuticulina.



Curiosity: A recently described a new species closely related to Cambrian Anomalocaris the Hurdia victoria.
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