22 juillet 2015

Saison des amours préhistorique

Les mâles s'affrontent pour les femelles depuis très, très, très longtemps:

Discovered four years ago, and following an updated and more in-depth study of the herbivorous mammalian ancestor, Tiarajudens eccentricus, researchers from Brazil and South Africa can now present a meticulous description of the skull, skeleton and dental replacement of this Brazilian species.

They also learned that 270 million years ago, the interspecific combat and fighting we see between male deer today were already present in these forerunners of mammals.

(...) When Tiarajudens eccentricus was discovered it had some surprises install: Despite large protruding saber-tooth canines and occluding postcanine teeth, it was an herbivore.

(...) In deer today enlarged canines are used in male-male displays during fighting. The long canine in the herbivore T. eccentricus is interpreted as an indication of its use in a similar way, and is the oldest evidence where male herbivores have used their canines during fights with rivals.

"It is incredible to think that features found in deer such as the water deer, musk deer and muntjacs today were already represented 270 million years ago," says Cisneros.

(...) In another group of mammal fossil relatives, dinocephalians -- that lived at the same time as anomodonts, some of the bones in their foreheads were massively thickened. This can be interpreted as being used in head-butting combat, a modern behaviour displayed by several deer species today.

"Fossils are always surprising us. Now they show us unexpectedly that 270 million years ago two forms of interspecific combat represented in deer today, were already present in the forerunners of mammals," says Cisneros.



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