Showing posts with label The evolution of vertebrates.. Show all posts
Showing posts with label The evolution of vertebrates.. Show all posts

Arandapis

If retrocediéramos in time 475 million years to the Ordovician, we would see that our planet Earth is totally different as we know. It is very hot, and it's easy to find places with temperatures exceeding 50 º. The continents were all together and formed what is known as Gondwana, an enormous supercontinent, and therefore, if there was a supercontienente also had a superocéano called Panthalassa, meaning "all the seas".

Most would find animal life in the sea, and of course, we would not find, orcas, whales or sharks, or even, similar animals. Arthropods and vertebrates ruled the prehistoric seas and began to emphasize vertebrate species timidly, promised much for its featuresin particular the spine.

One of the first was the Arandaspis marine arthropods, one of the first fish that descended from Pikaia and that would lead to the wide range of armored fish as Dunkleosteus.

This aquatic fish, just have information. It was found some 60 years ago in Alice Spings, Australia and its name comes from the tribe that inhabited those lands (Aranda). It was about 15 cm and started having bony plates on the body that gave some protection, began to form the shield would then armoured prehistoric fish.

These fish were small, and a feature of them was that they had jaw (some experts think they did have), only a small, hard lips that helped him to swallow everything that was while prospecting in search of food. In our view, it would seem a tadpole, but bigger and harder. Anyway, as I introduce you to one of the first vertebrates to have lived on Earth and apparently, succeeded because it appeared a large number of new species.

Acanthostega



The Acanthostega is the oldest known tetrapod. Is Ichthyostega predecessor and successor of Tiktaalik. It is of the first vertebrates that poked their heads out of the water to see what had out and hunt insects and arthropods near water. Remember that a tetrapod is one animal that has four legs, and who uses them.

It is the oldest known tetrapod. It was the first animal that had the bone structure needed to walk out of the water. A structure, perfected, was the basis for all other tetrapods (amphibians, reptiles, mammals and birds).

How was this prehistoric animal?


Similar to Ichthyostega, no more than a meter in length and its legs were 8 fingers. And like Tiktaalik, the Acanthostega had a disembodied skull that could move while the body ... Unlike fish.

Like early amphibians, the first ones out of the water, his breathing was a simple combination of lungs and gills.

This evolution firstborn old, lived in the shallow waters of the Devonian, 370-360 million years ago.

A curious animal right?

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.

Tiktaalik



Tiktaalik was primarily the characteristics of a fish, but with the tips forming skeletal structures similar to an arm, similar to those of crocodiles, including shoulder, elbow and wrist. He had the sharp teeth of a predator, and his neck could move independently of his body, it is not possible in other fish. The animal also had a flat skull like the crocodile eyes on the top of the head, suggesting that spend much time looking up, neck and ribs like those of tetrapods, which will serve to support the body and help to breathe through lungs, a long snout can catch prey on land, and a gill opening, in higher animals, would subsequently become heard. Its discoverers felt that, in all likelihood, Tiktaalik flexed its proto-limbs in the main river bed and could have pushed himself to the shore for brief periods. These specimens reached a size of 1.2 to 2.75 meters.

He lived in the Devonian period about 375 million years.

Excellently preserved remains of Tiktaalik in 2004 were found on Ellesmere Island in Canada.

Along with Ichthyostega, Coelacanth and Acanthostega is one of the prehistoric animals that show as was the transition from fish to tetrapod.

For more information:
Wikipedia.
http://www.nodo50.org.
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