Double stretch for giraffe’s neck
5 Nov 2015 by qwwqdccwwm.d qwwqdccwwm.d
Scientists have discovered that the long neck of modern-day giraffes evolved in two stages.
Scientists have discovered that the long neck of modern-day giraffes evolved in two stages.
A research team at the New York Institute of Technology (NYIT) used fossilised caudal and cranial vertebrae of giraffe species and found that neck evolution occurred in stages. The team think a segment of the neck first stretched toward the head and then toward the tail.
“Within the family, cranial vertebral elongation is the first lengthening stage observed followed by caudal vertebral elongation, which accounts for the extremely long neck of the giraffe,” the researchers reported in their paper.
The researchers studied 71 fossils of nine extinct and two living species of the giraffe family and used a computational model to track the evolutionary elongation of their necks. The model showed them that elongation of part of the backbone – C3 – occurred disproportionately. After analysing the anatomical features of the fossils they compared the C3 fossils and found the elongation of the neck occurred in two stages.
Professor Nikos Solounias, a palaeontologist at NYIT said: “It’s interesting to note that that the lengthening was not consistent. First, only the front portion of the C3 vertebra lengthened in one group of species. The second stage was the elongation of the back portion of the C3 neck vertebra. The modern giraffe is the only species that underwent both stages, which is why it has a remarkably long neck.”
The results, published in Royal Society Open Science, also showed that the cranial end of the backbone fossil stretched initially around 7 million years ago in an extinct relative of today’s modern giraffe known as Samotherium. The scientists believe the second stage of elongation on the back or caudal portion occurred around one million years ago.
More, the palaeontologists found that the most primitive giraffe started off with a slightly elongated neck. They suggest that the lengthening started before the giraffe family was even created 16 million years ago.
Next, the team will study the evolution of the giraffe’s long leg bones.
Paper: http://rsos.royalsocietypublishing.org/content/2/10/150393
