A relative of the giraffe with a shorter neck was found in China. It attacked its adversaries by using the head of its helmet.

16.9 million years ago, animals inhabited the earth.

The recently discovered D. xiezhi possessed a head shield for defense and a shorter neck than its giraffoid relatives, but it still had a head shield.

A relative of contemporary giraffes that roamed northern China over 17 million years ago had a thick, stumpy neck and a big skull, making it ideal for clashing with rival males in headbutting fights.

The newly discovered giraffe relative is a now-extinct species called Discokeryx xiezhi. It had a bony, disk-like shield on top of its skull and was covered in a protective layer of keratin. Keratin is the same type of tissue found in the horns of headbutters such as bulls and rams. According to the findings of a recent study of multiple D. xiezhi fossils, published on June 2 in the journal Science, the hard disk resembled a sort of squat helmet that perched atop the animal's head. This finding was made public by the scientists.

The researchers concluded that D. xiezhi likely fought over mates by forcefully thwacking their necks together in a method of fighting known as "necking." This is similar to how modern male giraffes battle over females by fiercely thwacking their necks together in a method of combat.

Robert Simmons, an honorary research associate at the FitzPatrick Institute of African Ornithology at the University of Cape Town, who was not involved in the study, said that the researchers have provided "unequivocal evidence" that the Discokeryx fossil is beautifully adapted to intense head clashes. Simmons was not a part of the research team. Simmons stated in an email to Live Science that this characteristic must have been the result of sexual selection "because head-to-head collisions are intimately involved in male-male combat."

That is to say, fierce rivalry over mates most likely pushed D. xiezhi to evolve its thick neck and built-in helmet to protect its head. This theory, which Simmons and other researchers have referred to as the "necks-for-sex hypothesis," proposes that the contemporary giraffe's long neck and ossicones, or the bony projections that stick off its head, evolved as a result of the animal's need to compete with other giraffes for mates.

Discokeryx xiezhi (a), a relative of giraffes that was just named, lived approximately 16.9 million years ago. It is believed that the other creatures are shown in this scene (b-g) once inhabited the Junggar Basin in China during the same historical period as the one portrayed here. (Wang et al., Science (2022) are credited with the image.)

Designed to deliver blows to the skull,

The researchers found the newly identified fossils of D. xiezhi in the Junggar Basin, a huge depression filled with sediment and located in the Xinjiang area of northwestern China. A full braincase and the first four vertebrae of the animal's spine were found in one of the specimens. The braincase is the portion of the skull that contains the brain.

"Because these, along with the skull, were employed for headbutting," said research author Jin Meng, a vertebrate paleontologist and the curator-in-charge of fossil mammals at the American Museum of Natural History. These spinal bones, known as cervical vertebrae, are rather big. According to what he shared with Live Science, each neck bone "is quite robust, very thick in terms of the cross-section, so it can withstand this sort of force."

According to the researchers' findings, two of the D. xiezhi specimens had teeth that had "quite high crowns," making them well-suited for the consumption of grass. The team concluded that the creature was most likely an open-land grazer that shifted its habitat depending on the time of year based on the shape of its teeth and the presence of isotopes, which are variants of an element that contain a different number of neutrons, in the enamel of its teeth.

According to what Meng told Live Science, based on the sizes of all the fossils, the team reckons that D. xiezhi stood roughly as tall as a modern sheep and had a neck of similar length to other comparably-sized terrestrial animals. And the team concluded, after examining the fossilized bones and teeth, that this stocky, extinct animal, albeit linked to the towering giraffes of today, is not a direct progenitor of living giraffes. This was discovered based on the examination of fossilized bones and teeth.

Meng explained that this particular offshoot of the giraffe family tree is distinct from the others.

After that, the group matched the bones to those of live giraffes and their relatives that have since become extinct. Within this group, they found 14 distinct forms of "headgear," some examples of which include the ossicones of modern giraffes and the helmets of D. xiezhi. They also saw a vast diversity of head and neck shapes, and in particular, they discovered that the animals' highest vertebrae radically differed in length and thickness. Along with this great variety of headgear, they also observed various head and neck shapes.

According to what the research team wrote in their report, just as D. xiezhi appears to be made for headbutting and modern giraffes are built for necking, all of these giraffe relatives may have evolved their distinctive headgear and necks, at least in part, to suit their specialized combat methods. This is consistent with the necks-for-sex hypothesis for modern giraffes, which posits that at some point in evolutionary history, males with long, sinewy necks prevailed in conflicts with females. This hypothesis applies to modern giraffes as well. Their increased chances of having healthy offspring over time led to the evolution of animals with longer and longer necks.

The concept of trading necks for sex was initially proposed by Simmons and Lue Scheepers, a zoologist working at the Etosha Ecological Institute in Namibia. They did so as co-authors of a study published in 1996 in the journal, The American Naturalist. At the time, their hypothesis ran counter to the widely held conception of how the necks of giraffes evolved. Charles Darwin famously proposed that giraffes evolved their long necks due to food competition; by being absurdly tall, the animals could consume foliage that was out of reach of other species. According to National Geographic, there is a continuing discussion about whether the evolution of giraffe necks was mostly due to rivalry over subsistence or sex. This discussion continues to this day.

Simmons told Live Science that it is quite likely that the extended necks of giraffes were sculpted to some degree by both the selective pressures of evolution and natural selection.

Simmons stated that it is now difficult to differentiate between the "feeding competition" notion and the "necks for sex" idea. "At the present time," he remarked. Both of these factors have likely contributed to the evolution of the amazing animals that we see today. However, in the future, the finding of more ancient giraffoid fossils could help clarify how modern giraffes get to appear the way they do, he added. The discovery of short-necked D. xiezhi does not end the argument over whether or not neck length is related to a giraffe's gender. 

Article source : https://www.livescience.com/extinct-giraffe-relative-fossils

Image source  : https://pixabay.com/id/photos/jerapah-matahari-terbenam-2233366/

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