It turns out the secret to the evolution of the giraffe’s long neck has been sitting in museums for the last hundred years. In a recent study published in the journal Royal Society Open Science, scientists collected and analyzed 71 ancient fossils, originally discovered in the late 19th and early 20th centuries, and dispersed throughout museums in England, Austria, Germany, Sweden, Kenya, and Greece.

Using fossilized vertebrae from nine extinct and two living species in the giraffe family, they charted out the process of neck elongation, which they discovered occurred in two stages, millions of years apart. They found that the first stage of elongation occurred around seven million years ago in a now-extinct genus of giraffe called the Samotherium

They also found that the animal’s neck vertebrae stretched first toward the head, then several million years later, toward the tail. The evolution, however, wasn’t consistent. That is, not all ancient species within the giraffe family experienced both stages of elongation. 

Giraffe anatomy expert Nikos Solounias explained in a press statement, “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 researchers also discovered that the earliest giraffe specimens started out with a slightly elongated neck. Melinda Danowitz, a medical student who participated in the project, said in the statement, “The lengthening started before the giraffe family was even created 16 million years ago.” 

Interestingly, the okapi, which is the only other living member of the giraffe family, underwent the opposite transformation: As the giraffe's neck was stretching, the okapi's neck got shorter. Now, according to Danowitz, it's one of four species with a "secondarily shortened neck."  

[h/t: Science Daily]