Showing posts with label Evolution.. Show all posts
Showing posts with label Evolution.. 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.

PERMIAN EXTINCTION.

Evolution along the time has not followed a linear increase. The diversity and number of species and individuals increase and decrease depending on the environment of each historical moment and sometimes abruptly. Evolution has had many ups and downs and as at some times, the Earth could be proud of the number of animals that lived in the past in this life has been about to disappear altogether. We are talking about the great extinctions. Surely you know the extinction that ended the hegemony of big lizards, which ended with the T-Rex or Triceratops, perhaps because the nearest extinction and we have seen in many documentaries. This extinction which is popularly known as the extinction of the dinosaurs, and occurred in the Cretaceous 65 million years ago, exterminated 40% of life on Earth. Maybe we think a lot, 40% of human life on Earth would end up with almost 3,000 million people, with for example, all people living in the southern hemisphere, but if we look at the mass extinctions that have occurred , there is a very important extinction: the mass extinction of Permian-Triassic. This was the extinction that nearly destroyed of life on Earth.


The Permian extinction wiped out more than 70% of life on earth, and 95% of marine life. To continue with absurd comparisons, it is as if they disappeared all people in the world, except those who live in Mexico ... for example.
Disease, starvation, earthquakes, catastrophic weather events were the survivors had to endure 250,000,000 years ago.

And what were the largest causes of extinctions on Earth?

There are several theories about the causes of extinction, and as we discuss all take a long time, we discuss only the experts think that possible: Meteorite and Volcanism Theory.

250 million years ago, there were on Earth, exactly in which today is Siberia a continuing series of Mega volcanoes spewing material from the bowels of the planet for thousands and thousands of years (80,000 years). These surface megavolcanes threw 4 million km3 of lava. About 40,000 times the Krakatoa.


The CO2, lava, pyroclastic flows from volcanoes and other gases could increase the temperature of the Earth, it is estimated that in 5th.

Now comes the second part of the theory ... rather the first. A few years ago discovered a large crater on Antarctica, exactly what is known as Wilkes Land. This crater has a diameter of 450 km and it is estimated that the meteorite that caused it could measure almost 50 km (nearly 5 times more than the meteor that killed the dinosaurs.)


The meteorite discovered, made ​​a great impact on our planet, for example, separated Australia from Antarctica when they were together and formed the Gondwana continent 250 million years ago ... 250 million years, precisely the date on which occurred the volvanes. That's why many experts geologists attribute the origin of these supervolcanoes the ripple effect that could produce the meteorite on Earth.

Of course, along with supervolcanoes, the effect of the meteorite caused further increase in global temperature. It is thought that up to 12 degrees to increase the temperature of sea water, produced from melting methane hydrate deposits, which by pressure and cold were in solid state. Following this event was intoxicated marine life slowly almost to extermination.

This is summarized and anyone interested will easily find more information about it. Finally, say that the Permian extinction wiped out some prehistoric animals known as Scutosaurus, the DIMETRODON or Inostrancevia or insects as Meganeuropsis.



But thanks to what is perhaps the fate, life continued and developed further evolution to what we know today: the human species ... the last great extinction.

Archaeopteryx




Archaeopteryx is the oldest known bird. While the Microraptor is considered a dinosaur with feathers like a bird, Archaeopteryx is already a bird. The first bird ... Jurassic.
They are very similar, are common features of other theropods: bone thing, sharp claws, beak with small but sharp teeth and feathers, both forelimbs and hind.

But unlike Microraptor, Archaeopteryx flew better, not only was involved in planning from branch to branch. Perhaps its flight is not elegant as the an albatross or as fast as a swift, but was the first to fly. and that is a lot. Possibly its fly mode would seem very strange if we saw now. Archaeopteryx also had long feathers on the hind legs, along with feathers front, it flew in a strange mode. Some think that because of this, was more agile in flight modern birds, but their ability to fly long distances would be less.

Not very big, measuring just 35 cm, and weighed just under 500 gr. Its brain was proportionally greater than other theropods and structure of his ear and was similar to that of modern birds.

We could say that its size was similar to that of a magpie .... Consider the differences:


Incidentally, the Velociraptor, is a close relative.

From Miacis to the hyena.


A few days ago, I was watching the documentary typical of Africa, with its eternal battles between lions and hyenas, when something caught my attention. Early in the documentary, the narrator describing for the umpteenth time the hyenas, he said these were animals that were closer, evolutionarily speaking, a cat than a dog. I found it very funny because hyenas are very similar to dogs, even as they live in herds, ... that's when I started researching, from the beginning (or almost).

We talked of Miacis, the "animal mother", the ancestor of both dogs and cats (both as feliforms Caniformes. Following the storyline, we find gender Prionodon a split where the two genera of felids (where is the Smilodon or saber-toothed tiger and) and barbourofélidos, coming at last to viverrids (the picture above). This name is very important, viverrids developed at the end of the Eocene and they are the ancestors of hyenas and genets (Hyaenidae, Herpestidae, Eupleridae).
I imagine that no need to explain the differences between  Caniformia and Feliformia , shaped like a dog or cat shaped, with long snouts and claws fixed or short snouts and retractable claws ... but really, the peculiarity that differentiates these two groups is that the auditory bullae have their feliforms (bony capsules enclosing the middle and inner ear). This is a key to the diagnosis in the classification of species as Feliforme versus Caniforme. In the auditory bullae are feliforms dual chamber composed of two bones joined by a partition. The Caniformes has a single chamber or partially divided auditory bullae, composed of a single bone.

So it is true that the hyena (like all such) come from Miacis, and that is nearer to a big cat than a wolf. Although it is true that is nearer to a genet, a ferret or a tiger. Certainly within the family Hyaenidae we can also find the Hyena giant extinct.

The appearance of the viverrids was like a genet but more slender, had the sharp nose, long neck, tail as long as the rest of the body and dentition hipercarnívora (carnassial teeth, which cut the flesh the way scissors) which is not known is if your hair was streaked, spotted or brown uniform color. It lived in the Eocene and the two species are present linsang striped and spotted linsang.

I present a video of one of a genet, a representative living with an appearance similar to the first Feliformia  ... (precursors of the hyenas, cats, tigers or genets and weasels), perhaps this is greater.
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