Not all legs are the same or are they?
SMALL animals have SHORT, THIN legs ... LARGE animals have LONG, THICK legs.
From the quail to the cow, from the rabbit to the pig, measure the length and section area of the largest bone in their legs, the FEMURES, and construct the graph below.
MEASURING THE LENGTHS
To each of the half bone, find the missing part.
To which ANIMAL does it belong?
What is its length?
Giants and Dwarfs
Since Newton we know that any two bodies attract each other in direct proportion to their masses and inverse to the square of the distance they are located. Any body on the surface of the Earth is therefore inevitably attracted by the Earth. WEIGHT is the name we give to this force of attraction. It is therefore evident that the greater the mass of a body, the greater will be its weight. However, there is no direct relationship between the increase in size and the increase in weight; a man who is 1,90 m weighs more than twice as much as a boy who is 90cm tall. In fact, for similar bodies, when we double the linear measurements, the areas increase squarely and the volume is a cubic increase.
This is one of the causes of the animosity between the Lilliputians against Guliver, because, on realising that his stature exceeded their own by a ratio of 12 to 1, concluded, based on the similarity of their bodies, that the capacity of Guliver´s stomach would be 1728 times (12 3) that of their´s....
The fact that size variations in similar objects implies different volume (and therefore weight) increments than increment in area, has an important consequence on the characteristics of the living beings that inhabit the surface of the continents.
If you think of small creatures (e.g. insects) you would expect them to have a high surface to volume ratio compared to a larger being (e.g. most mammals), this explains why most insects can easily fly, unlike mammals.
Giants and Dwarfs
A QUESTION OF PHYSICS
The Earth attracts all bodies to its surface, WEIGHT is the name we give to this force of attraction. For the same material, the larger the body size the greater its weight. However, there is no direct relation between size and weight increase; an adult man who is 1.80m tall weighs more than a boy who is 90cm in height. In fact, for similar bodies, when we double the linear measurements, the areas increase squared and the volumes increase cubically.
This differential variation has important consequences in the characteristics of living things that inhabit the surface of the continents. For example, small creatures such as insects have a larger surface-to-volume ratio than larger creatures such as many mammals, and this explains why most insects fly, unlike mammals.
Why are we the way we are?
3500 million years of seemingly insignificant transformations, separate the first life forms on Earth from the living beings that inhabit it today. We are used to seeing this long evolutionary history as the sum of small victories of the fittest, we often forget that there are physical limits to this evolution. Certainly Stephen Jay Gould's analogy that if it were possible to replay the evolution of life on Earth we would get completely different life forms is correct. In fact, there is an endless series of acidents that lead to the fact that the evolution of Life on our planet has been a unique process, impossible to repeat in exactly the same way. However, if the forms of the living beings could be quite different, there are other aspects, such as size, where the possibility of variation would be much more limited.
If a 4 meter high apple tree has 10cm apples, why doesn't a 40 meter high tree have fruits of 1 meter?
Why don't the large fruits (watermelons, pumpkins, and melons) grow hanging down, but flat on the ground?
Why are the feet of elephants, rhinos and hippos abnormally thick? Why is the neck of elephants abnormally short?
The resistance of a body is a function of the stress applied to it. When the stress exceeds a certain limit, which depends on the material, it begins to deform. But tension is the result of a force divided by the area on which it is applied. The example of a tree the stress that is applied to its base is the result of its weight divided by the trunk section. Since the increase between similar bodies leads to a greater increase in volume than in area, the state of stress that exists in a large tree is much greater than that in a small tree. If we think of an animal, the reasoning is identical; what determines its resistance is its weight divided by the section to which it is applied.
There is therefore a limit to the growth of any living being on the surface of the Earth, which is a function of the materials that compose it (for example, bones, wood, or muscles). The existence of this limit has direct implications on the forms that oversized animals can take, in order to be viable from a mechanical point of view. With lifeforms in water, the mechanical problems associated with their growth disappear. Indeed, propulsion is opposed to the action of gravity, so whales can easily reach weights equal to 30 elephants or the Tyrannosaurus.
A special kind of reptile…
In 1842 Sir Richard Owen coined the term dinosaur (from the Greek DEINOS, meaning terrible, and SAUROS, meaning lizard) to refer to some fossil reptiles from Great Britain with particular characteristics. The name and the terrifying appearance of some dinosaurs as well as certain movies made this group of animals extremely popular. But if very few people are not familiar with the famous Tyrannosaurus rex, there are less that know WHAT differentiates dinosaurs from other reptiles...
Their enormous size? Certainly not, for some were smaller than chickens...
Are they warm-blooded? This is a subject still far from consensus ....
What covered their body? certainly not, because in the eighteen hundreds, in Owen's time one had no idea that, for example, dinosaurs were covered with feathers...
THE EVOLUTION OF WALKING
In the reptiles, the forelimbs and hind limbs develop SIDEWAY from the body, which leads to the characteristic walk, reptiles move by undulating the body; this is called REPTATION. In the DINOSSAURS, the evolution of the shape of the bones that connect the forelimbs (humerus) and hind limbs (femur) to the body, led to the legs being located underneath the body. This more ERECT POSTURE of dinosaurs was an advantage when moving on land, it was not at all favorable for dinosaurs to have evolved to swim or fly ... The seas and the atmosphere were closed environments to these beings... until a small group of dinosaurs evolved into the BIRDS...
LETS PRETEND WE ARE A PALEONTOLOGIS
Paleontologists are SCIENTISTS who study FOSSEIS !!! To find the fossils the palentologists HAVE TO ESCAVATE the rocks !!! be a palentologist by digging the sand and searching for fossils… good luck…
Do you know the name of the fossils you found? No? Then pay attention to the exhibit to see if you can find out.
What is 4 550 000 000 years?
How many stars are there?
What is the difference between a bilion and a milion?
How many grains of sand are there on a beach?
Used to counting in units, by the dozen and in hundreds, or at best in thousands, man has no ability to truly understand large numbers. However, in history almost everything is measured in millions: millions of years, millions of degrees, millions of kilometers, millions of dead... Who is able to recognize a million?
HOURGLASS OF A MILION
This hourglass lets you see a million... objects pass by. Imagine that each object took a year to fall... that's a million years. A long time...and yet only one instant in the History of our Planet formed some 4,550 million years ago.
The experience acquired in day-to-day life is one of the main obstacles to understand how our Planet works, it is what serves to calibrate the referentials, where we tend to classify every situation. However, it is clearly insufficient when we want to study the rhythms of the Earth.
Used to a world where time is money and the faster the better, Man tends to overvalue fast and short-duration phenomena such as Volcanoes, Earthquakes or Storms. However, these catastrophic phenomena only reveal a small part of the way our Planet works.
Only when we are able to understand the importance of the repetition of seemingly insignificant actions over millions of years, such as the fall of a drop of water or the formation of a stalactite, can we hope to better understand how the Earth works.
The detailed knowledge of any history always implies the interpretation of forms of writing.
Oral tradition, besides being lost with the passing of generations, is easily influenced by those involved in it; "He who tells a tale ..."
Reading the newspapers gives us a daily knowledge of what has happened in the last 100 to 150 years.
More remote but still recent events in human history are still well documented in the form of other written texts.
but writing does not allow us to go back beyond 4 or 5 thousand years ... and even then only in some civilizationsWords of a different kind
Man's most remote past is read in the various forms that result from his activity; pottery, stone utensils, and cave paintings are the "words" used by archaeologists to try to find out what happened over the last hundreds of thousands of years.
And before Man?
To try to understand the countless mysteries surrounding the Earth's history, it was important to find other forms of "writing" where all these events were recorded. Rocks thus appear as the "words" that geologists use to learn about our planet's most remote past, while fossils and minerals are the "letters" of this strange language.
Basalt from the Lisboa Volcanic Complex
" there was a volcano about 65 million years ago"
Trilobite of the Devonian Period, from Morocco
" I am over 300million years old"
When the rocks are no longer read one by one, but as a whole, they come together to form a wonderful storybook ....
The Book of Earth's History.
Geologic time scale
Just as man needed to divide the 365 days of the year into 12 months to better situate the events surrounding him, so did Geologists, dividing the approximately 4550 million years of the Earth's history to made it easier to understand the complex evolution of our planet.
From this need came the scale of geological time, also known as the statigraphic column. On this scale is marked the main events that define the evolution of living beings , the complex and wonderful path that links the first cells to Man begins to acquire its true dimension.
single-celled organisms evolve into soft-bodied multi-celled organisms. First invertebrates
oldest fossils; bacteria and other single-celled organisms
Cretaceous flowering plants become more and more common; great extinction, including dinosaurs and ammonoids.
Diniosaurs are abundant; birds appear.
Diniosaurs and mammals appear. Reptiles begin to fly and conifers are abundant.
Present day man
Diversification of mammals; first hominids.