Rodents of Unusual Size?

I believe then that the Fire Swamp is in South America:

Long Ago, a Rodent as Big as a Bull Lurked in South America - New York Times: "LONDON — Imagine a rodent that weighed a ton and was as big as a bull.

Uruguayan scientists say they have uncovered fossil evidence of the biggest species of rodent ever found, one that scurried across wooded areas of South America about four million years ago, when the continent was not connected to North America.

A herbivore, the beast may have been a contemporary, and possibly prey, of saber-toothed cats — a prehistoric version of Tom and Jerry.

Its huge skull, more than 20 inches long, suggested a beast more than eight feet long and weighing between 1,700 and 3,000 pounds."