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Researchers are now closer to explaining how giraffe’s long neck came to be, after discovering evidence of this evolutionary trait in fossils from more than 16 million years ago.
The study was conducted by a team of experts from the New York Institute of Technology’s College of Osteopathic Medicine, led by paleontologist Nikos Solounias and anatomist Melinda Danowitz.
The analysis included 71 cervical (neck) vertebrae from 11 giraffe species and their ancestors, spanning from more than 16 million years ago to modern days. The samples, belonging to 2 living species, and 9 extinct ones, had come from museums in England, Austria, Sweden, Greece, Germany and Kenya.
It was discovered that the most ancient giraffe fossils already had an elongated neck, before the actual Giraffidae family came to be. A species called Prodremotherium elongatum displayed this trait around 25 million years ago, and another giraffe ancestor named Canthumeryx sirtensis also had this feature 16 million years ago.
According to researchers, the lengthening which preceded the Giraffdidae subgroup didn’t unfold in a consistent pattern. Initially, the C3 vertebra, which is the third from the top of the spine, started to extend among one branch of the Canthumeryx, named Samotherium.
The lengthening took place towards the animals’ head, approximately 7 million years ago. Another branch of the species didn’t suffer this change, and eventually mammals like Giraffokeryx or Sivatherium actually evolved shorter necks.
Subsequently, around one million years ago, the back of the C3 vertebra also started to elongate among some species, and due to this, the neck grew longer, towards the tail.
Modern-day giraffes are the only such species where the lengthening happened in both sections of the C3 vertebra. This is how they have come to possess such an incredibly long and thin neck. The mammals have seven cervical vertebrae, just like humans, but of much more astounding dimensions, at up to 10 inches long.
It may be that the elongated neck was an adaptive advantage, allowing mammals to reach food more easily and graze on leaves that other herbivores found inaccessible. It may also be that this trait gave male giraffes better chances of mating, by fighting off their competitors.
Another theory is that the elongation allowed them to dissuade predators from attacking them, by appearing more threatening. Thanks to this evolution, modern-day giraffes are now the world’s tallest mammals, reaching heights of up to 18 feet.
There is also however another less-known species in the Giraffidae family, called the okapi, which is native to the Democratic Republic of Congo. Although these mammals’ necks are much shorter and their stripes make them resemble zebras, in fact their closest relative is the giraffe.
However, evolution occurred differently among these animals, and their cervical vertebrae elongation wasn’t as spectacular. They are actually considered to be living fossils, since their morphology is much more similar to that of ancient species like the Samotherium.
Image Source: Pixabay
