Atlas Bone of White-tailed Deer

On one of my tracking study calls a photo was presented and everyone was asked to identify the bone that was shown. Somehow a few people were able to identify it rather quickly. I had never heard of the bone before but took note. I love learning about the skeletal structures of animals and spend a lot of time on it, but how did I miss a bone that so is so important to an animal, and that so many others knew? I needed to learn more about this bone.