5 years after people, the western diamondback rattlesnake are begining to thrive. In the time of humans, anual roundups were held to control the snakes numbers and protect cattle. On average, some 60 thousand rattlesnake were captured and killed every year. Now, without humans to control them, they begin to grow in numbers and move into urban areas, where they feed on city mice, rats and even small cats like baby kittens.
75 years after people, without their human predators, rattlesnakes are growing to enormous sizes. The largest western diamondback in the time of humans was over 7 feet long. Now, left alone to grow unchecked, many of these venomous snakes now reach more then 9 feet in length and have now become an apex predator like their southern relatives.
It seems 75 years after people, and 65 million years after the dinosaurs, the age of the reptiles has returned despite that there is still lots of large mammals.