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published on 18 May 2009 in earth

Sauropods

40 meters long and 17 high, huge but peaceful, the Branchiosaurus were a masterpiece in genetic Engineering. Survival machines in the difficult prehistoric world.
Branchiosaurus are the real lords of prehistory. Their huge size and extraordinary weight ( equal to that of 10 African elephants) have always amazed researchers. How could it be that they were so big and yet so resistant that they dominated the earth for over 100 million years, from the mid Jurassic to the Cretaceous era? According to P. Martin, a paleontologist from the University of Bonn, in Germany, and Marcus Clauss from the University of Zurich, in Switzerland, it is a lucky mix of four characteristics.

Successful characteristics?
No chewing
First of all, sauropods didn’t chew their food. Generally it is considered a bad habit, but in this case it has been vital. Swallowing without chewing actually allowed these prehistoric herbivores to develop just a small set of teeth, consequently they had small and light heads, which were suitable to fit between branches to reach the greener leaves, with the higher energetic content.  On the other hand, if they had had heavier heads they would not have been able to develop such a long and “strategic” neck to help feed themselves.
Variable metabolism
But that is not enough. Branchiosaurus may not have had powerful jaws, but they did have enormous stomachs, suitable to accumulate tons of ingested food while waiting to digest it. Although there is no way to verify this, the two researchers assume that, in order to grow so much and so quickly, sauropods had to have a very fast metabolism which, once they reached adulthood, would have slowed down. If it had continued at the same rate, because of their huge size it would have produced too much heat, causing their body temperature to rise excessively.
Complex breathing system
Another thing that puzzled scientists was: how could such large bodies take in sufficient oxygen and dispose of the excess body heat produced by all their vital functions? With such a long neck, the air had to travel down several meters of trachea before reaching the lungs… These dinosaurs solved the problem with a breathing system similar to that of birds. Instead of flexible lungs that would expand and contract, sauropods (just like birds nowadays) had an “air bag” system which pumped oxygen into rigid lungs. The air bags that started off from the lungs, were inserted between the cervical bones, creating a pneumatic support effect: an efficient system to carry excessive heat out of the body and to hold up the neck.
Sauropod eggs
If these dinosaurs survived so long it is also thanks to an evolution system that make them different from mammals: while the latter have only one baby at a time, sauropods laid multiple eggs. A statistically efficient way to give a chance to more individuals to survive. Besides, the speed at which the young grew, defended them from predators that soon became fearful of their size.
written by Videoscienza

Written by Videoscienza

With the sponsorship of the Italian Ministry of Education, Universities and Research
 
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