Out of the five major mass extinction, one is Cretaceous-Tertiary extinction (K-T extinction). It happened 66 million years ago marked by the end of the Cretinous period.
Answer: 1741289L
Explanation:
1 gallon = 3.78541 L
4.6×10^5 gallons = 4.6×10^5 x 3.78541 = 1741289L