@VisualInspiration

So it turned out that sentient mammals were not as dumb as they pretended to be. The human stewardship of the planet was going so awry that they finally had to step in to avoid the total collapse of all ecosystems. The first to act were the coyotes, who out of necessity had infiltrated urban environments and knew human behavior well.

First they recruited the dogs to the cause. They said, "Give up your loyalty to humans, or we will hunt and eat you. Join the sentient mammal pact." The working dogs and hunting dogs quickly agreed. The little fluffy dogs said "What? We've got a good deal here." Most were eaten.

Cats were a different story. They said, "Our arrangements with humans were always transactional. We allowed ourselves to be petted as long as they fed us and gave us cat treats. What have you got for us?" Most cats ended up in trees and high places where coyotes couldn't climb. Some made deals and opened doors that coyotes couldn't open.

At sea, orcas began attacking boats, usually by removing the rudder. Seals and sea lions attacked any human they found near the water. Humans defended themselves with guns and other weapons, but their homes and businesses were neutralized by rats, who cut wires and dismantled electronics. Eventually, the few remaining humans were reduced to a hunter-gatherer existence in newly resilient forest environments.

The liberated mammals occupied human cities and structures, and took over many human institutions. They had learned from human ingenuity. But they never, ever, considered burning fossil fuels. Gradually, the Earth returned to a pristine state.

And what about monkeys, apes, and other primates? They were allowed to live, but carefully watched. No one wanted them to evolve into another monster.