A cousin of the giraffe was fond of headbutting

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A cousin of the giraffe liked headbutts

The finding supports the thesis that the initial driver of giraffe neck elongation was sexual selection.

The giraffe did not always have a long neck, but she always favored headbutting to defend her position, as evidenced by the discovery of a fossil specimen of a giraffoid with a real skull shield.

This finding supports the thesis that the initial driver of giraffe neck elongation was sexual selection.

Uncovered in northern China, the Discokeryx xiezhi fossil belongs to a previously unknown species that lived 17 million years ago, reports a study published in the journal Science.< /p>

This ruminant the size of a large deer had a thick bony disc at the top of the skull and a neck with formidable cervical vertebrae allowing it to withstand violent frontal shocks, according to paleontologist Shi-Qi Wang, Chinese Academy of Sciences, first author of the paper.

This particular morphology was most likely adapted to head-butting behaviors between males, the researchers speculate, who compare this behavior to the fighting of male giraffes with their necks. The latter – the current species – engage in domination struggles by swinging their heads, equipped with small horns, at all their strength against the opponent.

The discovery of Chinese paleontologists pours a decisive piece to a debate as old as that of paleontology: why does the giraffe have such a long neck?

Paleontologists have long defended the thesis of ecological advantage, according to which this long neck gave its holder a decisive advantage in reaching high foliage. More recent and much disputed, the other theory postulates that a long and powerful neck influences the outcome of fights between males, and has therefore favored its growth.

The study by Shi-Qi Wang and his colleagues agrees with this last thesis: this kind of fighting is probably the first reason why giraffes developed long necks, which then provided them with an advantage for grazing on animals. foliage in height.

This is a perfect example of exaptation, that is, of an advantage provided by an organ that will prove useful later for another use, explains to AFP the paleontologist Grégoire Metais, of the National Museum of Natural History, who welcomes a very beautiful study.

According to him, giraffids have embarked on a race for a long and reinforced neck. This shows once again that sexual competition is one of the driving forces of evolution, which leads to morphological innovations that can be used for other purposes.

In In the case of Discokeryx xiezhi, its morphology represented the most optimal adaptation for head-butting, when compared with current species engaging in this practice, according to the ;study.

As evidence, computer modeling of the impact of headbutts, applied to other combative ruminants, such as the muskox, suggests that the very special head and neck morphology of Discokeryx xiezh i was linked to an intense practice of headbutting. And that this morphology gave it an incomparable ability to absorb the energy of the shock and protect its brain.

The study also clearly establishes that this fossil was a giraffoid, which appeared about 20 million years ago, of which the only two extant species are the giraffe and the okapi.

But then why Discokeryx xiezhi develop a long neck too? First because he didn't need it: he lived through a remarkable episode of the Miocene, which saw a marked warming of the climate, allowing him to graze to his heart's content. Then, because it was only the beginning of the history of giraffids, recalls Mr. Metais. And that of the growth of their long necks.

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