Crotalus viridis
The Prairie Rattlesnake usually grows up to the length of around 100 centimeters (3.3 ft). Prairie Rattlesnakes in Montana can sometimes grow up to the length of 120 centimeters (3.9 ft), but the longest ever found was 151.5 centimeters (4.97 ft) long. They are usually light brown in color with some patches of dark brown.