A huge network of 10,000 year old tunnels called “paleoburrows” were discovered in the Amazon rainforest. The dinosaur experts are pretty sure they were dug by some equally huge animals. The alternative that a prehistoric cousin of the armadillo made them isn’t as promising but hasn’t been ruled out.
Paleoburrows the size of a cave
Geologist Amilcar Adamy was out of his specialty when he stumbled on a cavernous network of what were later identified as “paleoburrows.” New archaeological discoveries aren’t easy to come by these days, since all the Indiana Jones types have been scouring the planet with a paintbrush for a couple hundred years.
In 2010 the geologist discovered a “cave” that turned out not to be natural. He didn’t get a better look at it until years later.
While working on a general study of the Amazonian state of Rondonia for the Brazilian Geological Survey, Adamy heard rumors of “an impressive cave” in southern Brazil. Locals were kind enough to direct him to “a gaping hole on a wooded slope a few miles north of the Bolivian border.” The owner of the property wouldn’t answer his phone, so he couldn’t do much more than take a quick look.
He didn’t know at the time it was a network of paleoburrows but it didn’t take long for him to determine it wasn’t a cave. His “preliminary inspection revealed it wasn’t the work of any natural geological process.” He’d been lots of other caves having the same geology. “Those caves looked nothing like this large, round passage with a smooth floor.”
Adamy had “never seen anything like it before. It really grabbed my attention. It didn’t look natural.” He also didn’t know that a “few years earlier, and about 1,700 miles to the southeast, another Brazilian geologist happened upon a different, equally peculiar cave.”
Heinrich Frank never heard of paleoburrows either. A hole poked in a freeway embankment exposed by construction excavation caught his eye while “zipping down the highway on a Friday afternoon.”
Never heard of them
Frank, a professor at the Federal University of Rio Grande do Sul, knew that local geology “doesn’t yield such a sight.” He went back to investigate and crawled inside. “It was a single shaft, about 15 feet long.” When he hit the end, he was laying on his back looking up.
That’s when he saw the claw marks on the ceiling. In the process of solving the mystery, the professor learned something new. “I didn’t know there was such a thing as paleoburrows. I’m a geologist, a professor, and I’d never even heard of them.”
He wasn’t alone. Until the early 2000s, “hardly any burrows attributed to extinct megafauna had been described in the scientific literature.” The professor’s discovery in Novo Hamburgo became the first of several as Heinrich Frank started a new hobby.
“Surveying a 45-mile stretch of highway construction near the city of Porto Alegre, for example, Frank and his students identified paleoburrows in more than 70 percent of road cuts.” None of them are nearly as impressive as the one Adamy found.
In 2015, Amilcar Adamy finally got his chance to return to the “strange cave in Rondonia.” It turned out to be the first network of paleoburrows “discovered in the Amazon, which is notable, but not the coolest part,” Discover magazine writes.
“It also turned out to be one of the largest ever measured, with branching tunnels altogether tallying about 2,000 feet in length. The main shafts — since enlarged by erosion — were originally more than six feet tall and three to five feet wide; an estimated 4,000 metric tons of dirt and rock were dug out of the hillside to create the burrow.” The experts believe that it’s too big for one critter to make, even one as big as a ground sloth. “This wasn’t made by one or two individuals. t was made by many, over generations.”
