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PaleoStories Fundamentals Part 4: Jackpot today? Fossilize!

I know that is not put on the blog and I have broken my good intention of the at least one post per week. You can scold him on. I could stand here and tell you how and the why of my absence (single quote, a great stay in Brussels), but it probably will not interest anybody.
But now, it's time to revive this blog, possibly to gain a greater frequency.
Today's theme, which is part of the basics of Paleostories (for the last time, I promise), concerns the extraordinary and rare biogeologist process that is called fossilization.

Generally, they are all considered fossil petrified remains of organisms that lived in the past (or rather, a period of time in the past that it can be quite dead, buried and fossilized) and possibly also any type of track which suggested their existence ( footprints, remains of excrements, traces of habitation, meal, eggs, deposits secretions, etc.).. A fossil therefore rapprendente something that was once alive (or connected to life) and, for reasons quite extraordinary, has been preserved in the form of rock.
For a living organism, becoming a fossil is by no means an easy task. This is because the inexorable fate of almost all (about 99.9%) of the organic matter in the world is to decompose and eventually disappear. On the death of an organism, cells and organic matter that makes up his body is used by other organisms (decomposers, predators) as a source of livelihood or taken from some other system. In nature, nothing lasts forever and everything is recycled. Can hurt, but it is.
also part of what you did qual'ora 0.01% escaped the action of the composition, your chances of fossilization would in any case very small.

reducing everything to the bone, you could say that fossilize requires very, very lucky: we must die in the right place (or be transported), be buried in time and in the right way, and, finally, be lucky enough to escape all destructive processes imposed on the rock strata of the earth, including one in which, fortunately before, you have found.
Only 15% of the rocks can preserve fossils. Igneous rocks of magmatic origin, obviously not conducive to the preservation any organic material, as well as those metamorphic (maybe even worse). To fossilize, it is necessary to happen in rock quite compact and safe to allow your remains to avoid the decomposition and transformation, through for example, chemical substitutions in mineral material in order to create a copy of the original Rocky.
Later, your loved ones sediments, guardians of what is left of you (already petrified), must bend, twist, press, without which you lose your shape and come broken, broken or crushed by the force of these processes.
And finally, if you want some 'of reputation (and do not have fossilized, say, human activities, "for nothing "), you should have the great fortune (perhaps even greater than all that had previously) to be recovered by any person and said the subject of scientific interest, because cestinaggio or indeterminate sleep in a drawer.
As you can see (and I've explained things very simply), fossilize is absolutely not a simple thing. A fossil, therefore, is something very rare. If in your life you will have the opportunity to pick up a fossil, regardless of their age, do you think are holding the remains of a creature that has had more luck than it would you if you win the lottery every year . Obviously, you have to multiply all for several million years.

For this, we know very little about the life of the past and its amazing forms. Almost all organisms lived on Earth up to now have left no trace of itself. And those who did, few have been discovered, thanks to the work (often poorly supported by the proper authorities to deal with large scale) of paleontologists.
It is believed that less than one case per 10,000 have left no fossil traces. The message is clear: what we have is just a taste of life developed on Earth. Moreover, often possess only a few remains of some animals (some fossil taxa, for example, are described on the basis of a few bones, or a few flakes, or indirect traces of activity). And, to make us even more evil, about 95% of more than 250,000 fossil species known so far belong to organisms that lived in the sea, so dangerously distort our picture of life on Earth.

In conclusion, we think for a moment this sentence: "quell'osso about 150 million years ago." Well, we are able to quantify 150 million years ago?
Someone like me, who does not remember what he ate for breakfast two days ago, is terribly far away that time.
Yet all the fossils in the world belong to a past much more remote than we can imagine. Much more than the life of our life. Sometimes the Romans seem far the Egyptians, the Sumerians. Yet, the ancient Egyptian hieroglyphs, dating to 5,000 years ago (more or less), are 30,000 times the most recent of our dear bone. The depth of time is the basis of paleontological research seriously, which implies the absence of reckless speculation on things that none of us will ever occur (such as a Tyrannosaurus eating as much meat per day, or how much distance travels in one year, a trilobite or whether it was the strongest guy or Dick, and other imaginative applications from TV).
True, many of the stories will later Paleo supposition of past events. A past in which no one can go back.

However, we give a little 'to honor those who have been lucky enough to fossilize, thanks to these we now know some (albeit poor) aspect of life in the past. And, in a rational, rigorous and conscientious attempt to analyze the aspects and groped to understand how things went.
Good.

Now we are ready to go.
PaleoStoria you at first.

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PaleoStories Fundamentals Part 3: taxon that has quite a good temper!

INTRODUCTION: The topics treated her in this third post on the basics of PaleoStories represent only an introduction to a topic that is far more complex and that, for a insight to 360 'degrees, deserves much more than a single post ( probably more than just a blog). However, since its basic concepts and then understand some of the stories, I will try to explain some of these things as clearly and simply as possible. But know that this is only a small crumb.

We saw in the previous post the importance of a standard and universal method to describe and categorize the taxa living in an orderly and understandable to all. Once appointed living things in our consciousness, to describe, appreciate, understand and study the characteristics that distinguish them you need a method altrettando objective and precise, able to give an idea of \u200b\u200bthe concept of life and personal development free from any speculation . This is essential if we are to understand how have evolved certain structures, such taxa are more related to each other or to trace the evolutionary history of a certain line.

"In the mid-50's of last century, scientists began to realize that the only way, truth and objective, groped to study the evolution of life on Earth was to analyze the bodies simply studying the homologies between the their body parts. The fundamental point was to study these homologies for what they really were, not what they seemed, and in a perspective that takes into account the impossibility of knowing all taxa in the past (as we shall see in the next post) and the breadth of past time, to a depth as to make it somewhat difficult to interpret.
Creator of an innovative method was Willi Hennig, an expert on insects: Henning
showed how the most objective and accurate as possible to reason about the history of life on Earth was groped to understand the evolution of organisms to from the study of their shared features, regardless of time and without taking into account their history of ancestors and descendants. In this way he would deal with the study of the journey of life on earth without assuming anything about the causal and temporal component del'evoluzione. "
Henning's method, called phylogenetic analysis, or cladistics , is still used today and is stampatevelo in mind, the ONLY method trustworthy, objects and non-speculative to study the evolution of living taxa and in the past.

But what it is, in short, the cladistic method?
Before I talked about "character counterparts, the concept behind the cladisitca: What then are the characters counterparts?

If we look carefully the body and compare it with that of other animals we can see that we share with them some important characteristics, for example, if we take into account the animals with whom we have more to do (dogs, cats, birds, horses , cows, lizards, etc..) notice that everyone we have two legs, two arms, one head, two eyes, a mouth, etc.. Not only that, going into detail we can see that, for example, the bones that make up our arms are the same that are present in the wing of the pigeon, art front of the dog, cat, crocodile, cow, 's elephant, etc. This is because, as you will have understood by now, we humans share a common ancestor with them, and because these are our shared traits inherited from our common ancestor.
"In the case of morphologically similar anatomical structures, all derived from a single structure in this" common ancestor, we speak of homologies .
The homologous structures are therefore similarities due to the legacy and history reflect the sense of a line in the pedigree and, if correctly identified, allow to arrange the species in evolutionary trees. "

The concept of homology is contrasted with that of homoplasy (or equivalent), in which two structures, though similar in appearance or used for the same function (such as the fin of the fish or the limb pinniforme whales), but have a different structure or a different evolutionary history.

How can the concept of homology be used to understand the relationships between phyletic taxa? Well simple: the more features in common (homologous) have two species, the greater will be related to each other.
In this way, having a number of taxa and by recognizing the diagnostic characters (which identify the various taxa) and the homologies shared, we can reconstruct a diamagramma and linking these taxa. A diagram of this type is called cladogram, from the greek klados branch.
"In evolutionary terms, a clade represents a group of individuals who all have evolved from a common ancestor, and are therefore for-genealogy - more similar to each other than they are with all other creatures. "

Underlying this reasoning is the concept of sister group (sister group in English): since all the taxa derived from a common ancestor, and because the mechanism for the evolution of species differentiation, the different taxa will evolve a mechanism dichotomous, expressed by the node on the cladogram, or junction of two branches. Each node corresponds to one or more shared characteristics (called synapomorphies ) and taxa placed on branches that branch off from this are known sister - taxa (or sister grupo, is the same) and are part of a group monfiletico . "The monophyly is an important property of a group, as index of possession of a common ancestor exclusive. For this reason, groups that it excludes taxa derived from more than one ancestor (polyphyletic groups) or including only a few taxa derived from a single common ancestor (paraphyletic groups) can not be taken into account for understanding the evolution of organisms. "

A final note on some important terms to be used in upcoming posts, we have seen the importance of considering the characteristics of the various taxa as a means to understand their evolution. but it is fundamental to understand the nature of these characters, because not everyone can be helpful to our cause.
Since we are investigating for possible evolutionary events, will be useful Only the innovative features, derivatives, or, better said, apomorfici , while characters primitive ancestral plesiomorph , will not give us more information. For example, if we want to know the phyletic relationships within the mammalian characters such as the presence of a spine, four legs or two eyes, will not be useful, as in all our taxa, derived from evolutionary events occurred very before the onset of the common ancestor of mammals.

I know that these concepts may seem difficult, and it is for me difficult to explain these things clearly having so little space (it would take much more of a post, as mentioned above). I hope in any case to have you made as understandable as possible one of the cornerstones of this blog, the phylogenetic analysis.
If you have questions, you can ask without question in the comments.

The next and last post of "Fundamentals of PaleoStories), will talk about what's behind this blog, the first in importance: the fossils and paleontology.

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Images taken from Wikipedia (before fig.) and from the site of Florida International University.
Quotes from "In Dino Veritas, Castiello Lampugnani Broccoli, In press. "