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.

Walking cactus (Diania cactiformis)


Today we are going to go back in time, we will go to the origin of complex life, until 520 million years ago when the first groups of animals (arthropods, mammals and molluscs) appeared on Earth.
In ancient seas, in the emergence of complex life (Cambrian Explosion) we find a rare animal, a creature that looks like a sketch of the creation ... as if evolution had thought - I'm going to put this together with this, to see what happens.
This prehistoric animal that seems from another planet, called Diania cactiformis, cactiformis means in the form of cactus, so its common name: The walking cactus.
The truth is that there is no plant. The experts believe that this curious animal occupies a far evolutionary empty, It is between worms and arthropods. With the discovery of this animal is evidence that the big group of arthropods evolved from worms. Among arthropods and worms, is walking cactus. Among the prehistoric arthropods more "famous" can find the Arthopleura, the Hurdia Victoria, the Anomalocaris or pulmonoscopius ... and now, the walking cactus, which is the oldest arthropod found yet.

The Diania cactiformis was small, measuring about 6 cm long and had a long, thin body, vermiform (worm-shaped elongated). His body was segmented with hard covering (exoskeleton), and body of arthropod born 10 pairs of spiny legs hard, sharp and thorny (hence the name of cactus). And you do not think it was like a starfish elongated, no. The walking cactus had jointed legs, was fast, and even experts think that could jump with some agility: he was a ruthless predator ... maybe I exaggerated when using the word "ruthless".



Anyway, walking cactus, it was a prehistoric ocean that lived 520 million years. It lived on the seabed of what is now the province of Yunnan in the Himalayas. Its marine fossils found in the higher mountain formation of the Earth. Another curious fact of which I speak.
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