Was this possum playing possum?

It was just sleeping. :-)

Well maybe. I thought of another possibility. Some people visit the park with their dogs. Maybe one of the dogs had frightened the possum.

^^ Very possible.

That’s how possums play possum. The more scared they become, the more dead they appear!!! Once you walked away, it jumped up & ran away before anybody else could mess with it.

Of course we can’t say for certain, but I’d wager @LadyMarissa is spot on.

There may be no predators, but there are certainly scavengers. Even deer eat carrion when hard pressed. A skunk could eat a possum in a single sitting. Just saying. It could be that other thing too.