18,000-year-old stone tools are among the oldest found in the US, more evidence that humans lived in the Americas during the Ice Age

• Archaeologists found stone tools humans used to butcher animals in what's now Oregon.
• The tools were below ancient camel and bison tooth fragments that were over 18,000 years old. 
• It's among the earliest evidence of human occupation in the US. 

Ancient hunters used a rock-shelter in the Oregon desert to butcher camels, bison, mountain sheep, and horses during the Ice Age.