The crater left by the ancient Nevada comet is now interpreted to have been at least one mile deep and 45 miles wide. It is comparable in size to one that struck the Chesapeake Bay area about 35 million years ago. On the basis of this comparison, the Nevada comet could have been as large as three miles in diameter, much larger than our initial calculation of one kilometer. It may have been part of the first of a series of comet showers that led to a mass extinction of many forms of life three million years later.
Conodonts are the microscopic teeth of primitive, boneless, eel-like animals.
The shape of these animals is similar to that of modern hagfish, best known from the fjords of Norway. The largest known conodont teeth, found near the town of Alamo in southern Nevada, measure nearly a half-inch in length, but most are not much larger than the head of a pin. Now, new conodont evidence for its dimensions has been found in small blocks of fallout debris from the impact crater. Iridium is an element found in asteroids and comets but not common on Earth. Shocked quartz grains are produced by the force of an impact on sandstone rocks.