We now know where giraffes get the emblematic long neck from, thanks to a recently published study featuring in the Royal Society Open Science journal.
It might sound like a remake of an old joke starting with ‘which came first’, but different theories on how giraffes got their emblematic long neck have been splitting the scientific community until now. Which came first, the neck or the giraffe?
The researchers handling the puzzling questions reached the conclusion that the neck was first. Giraffe ancestors that roamed around 16 million years ago already presented the neck elongation.
11 species and 71 fossils spanning the spectrum have been included in the diligent study. Modern giraffes and their ancestors, as well as more distant relatives have provided the proof needed to demonstrate that the necks elongated in time.
Both a more recent ancestor of modern giraffes, dubbed the Canthumeryx sirtensis that lived approximately 16 million years ago and the more distant relative Prodremotherium elongatum that lived approximately 25 million years ago had the same long neck. Neither of these two species are considered part of the modern giraffe family.
As the researchers wrote:
“the most distinguishing and popular attribute is apparently not a defining feature of the family”.
Two of the 11 species are still living. The modern giraffe and the okapi, found in the Democratic Republic of Congo.
The vertebrae of the two modern species were compared to the third cervical vertebra of their ancestors. Just as we do, giraffes also have seven cervical vertebrae, albeit larger. Canthumeryx was one of the species from which two branches of the family evolved. One branch of the family, including four species didn’t develop the long emblematic necks. The modern-day okapi is part of this branch.
But the second branch increasingly developed longer vertebrae and thus necks in time. Approximately seven million years ago marked a turning point in the evolution of the vertebrae. Each one’s front side became increasingly longer. Over time, this led to the elongation of the neck, already present with the Samotherium major, a species that is now extinct but is included in the modern giraffe family.
The process followed by the fossil trail indicates that another turning point took place approximately 1 million years ago. At this point, it was the back part of the vertebrae that lengthened, bringing the neck elongation to almost what it is now.
Now that we know where giraffes get their emblematic neck from, the next step is to understand what led to this physiological change in the cervical vertebrae.
Photo Credits: Flickr