In further proof that size matters, the giraffe likely developed a long neck so males could battle each other for mates. If you've ever seen a male giraffe whip its foes, you'll know the neck can be an nasty weapon, with the added benefit that giraffes can reach vegetation others cannot, an animal behaviorist writes at the Arizona Daily Sun. But while scientists know why giraffes have long necks, how they got them has been somewhat of a mystery. Now, a study suggests the giraffe didn't simply grow its long neck suddenly, or even steadily over millions of years. Rather, two bursts of evolution created the animal we know today. A researcher who studied 71 fossils of nine extinct and two living giraffe species says in a release that "the most primitive giraffe already started off with a slightly elongated neck" around 16 million years ago. Then 7 million years ago, the end of the third cervical (C3) vertebra near the head of extinct relative Samotherium began to stretch.
The neck was elongated, but it didn't compare to that of the modern giraffe. Then around one million years ago, the back end of the same C3 vertebra started to stretch so that the vertebra reached the length it is today—about as long as the bone that runs from your shoulder to your elbow and nine times longer than its width. Interestingly, around the time of this evolution, another giraffe relative known as okapi—still found in central Africa today—set off on a different evolutionary path as its neck began to shorten, researchers say. "It's interesting to note that that the lengthening was not consistent," says a paleontologist. "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." (Think giraffes are silent? You're wrong.)