The last of the woolly mammoths may have suffered serious birth defects, say scientists

Fossils of mammoths found near the North Sea and dating to the late Pleistocene, about 12,000 years ago, frequently sported extra ribs along their neck vertebrae. Though harmless on their own, these cervical ribs are often signs of development gone awry. A 2006 study of extra cervical ribs in humans published in the journal Evolution found that about 78 percent of fetuses with cervical ribs die before birth; 86 percent of fetuses that develop with these extra ribs won't make it to their first birthday.

The mammoth rib study began with the discovery of three neck vertebrae in the North Sea during a construction project in the Rotterdam Harbor. Two out of the three vertebrae showed signs that ribs had once been attached: smooth surfaces where bones once joined and a lack of normal openings for blood vessels and nerves. [Image Gallery: Stunning Mammoth Bones Unearthed]

Source: Here