Over 13,000 years ago, many great animals lived in North America, including mastodons, saber-toothed cats, and even American horses, but they all disappeared at the end of the Pleistocene period. The exact cause of this mass extinction has been a matter of debate for some time now. Researchers at the University of California, Santa Barbara however have new evidence that may solve the mystery.
Studies of prehistoric times often require looking at the many layers of materials beneath us. Each layer was deposited at a certain time and the materials of each layer can tell us about the Earth's situation at the time, and about certain events. Across what is called the Younger Dryas boundary, the researchers have found many nanodiamonds. These small carbon crystals are found in their cubic forms, like those we use for jewelry, and as hexagonal crystals. What makes these particular diamonds important though is that they could only have been formed by a massive event, such as a cosmic impact.
The only other barrier that has had more than one identification of nanodiamonds is the Cretaceous-Tertiary boundary. The nanodiamonds in this barrier are the result of the cosmic impact that killed off the dinosaurs and many other species on Earth, 65 million years ago.