In Brazil, just north of the border with Bolivia, you might stumble across some enormous caves. Yet while they’re big enough for a man to stand upright in them, they weren’t created by any geological process. And scientists now think they’ve discovered exactly what it was that carved these incredible holes into the ground.
In a Brazilian state called Rondonia, deep in the Amazon, researchers found an enormous complex of strange caverns. In fact, it stretches more than 2,000 feet into the ground, with the roof standing 6 feet from the floor – and this discovery led to a heap of questions that scientists are only starting to get their heads around.
For one, it isn’t just the size of the caves that’s strange; indeed, their composition is nothing like that of other caverns which have been discovered in the region. The floors are smooth, while the tunnels are round. And scientists have inspected other caves in the area that were created by water and can see that they’re completely different. Then there are the marks on the walls.
These marks in fact gave the researchers their first clue as to what had created the mammoth underground structures. Gouged into the walls of the incredible caves are deep gashes, and closer examination showed that they could only have been made in one way. By the claws of a now-extinct giant animal.
However, even this theory posed far more questions than it answered. These so-called “paleoburrows” are, after all, enormous. So the first question that researchers had to ask themselves was just what creature had made them. And the explanations they came up with centered on creatures that are long-since dead yet have ties to animals still living today.
Some scientists believe that the enormous burrows were dug by giant ground sloths. These massive creatures, much larger than today’s tree-dwelling sloths, died out around 9,000 years ago. However, other experts have suggested that it was another beast which took it upon itself to create these underground lairs.
Scientists believe that giant armadillos could have been responsible for the burrows. For while these creatures weren’t as large as the giant ground sloths, they were still more than capable of digging into the ground. Either way, though, there are other questions that scientists still can’t answer – and these might be even more intriguing.
Indeed, there are species of giant armadillos still alive in South America now, and while they’re much, much smaller than their extinct cousins, they still make burrows. These underground hideaways are far smaller than the paleoburrows, though. And even comparatively, relative to the surviving armadillos’ size, they’re of nowhere near the same dimensions.
Speaking to Discover, Heinrich Frank, one of the team who found one of the paleoburrows, said, “So if a 90-pound animal living today digs a 16-inch by 20-foot borrow, what would dig one 5 feet wide and 250 feet long? There’s no explanation – not predators, not climate, not humidity. I really don’t know.”
In other words, these gigantic burrows are still incredibly difficult to explain. They’re much larger than would have been necessary to shelter even the enormous animals that scientists believe built them. Indeed, the spaces would have provided far more protection than a giant armadillo or ground sloth would ever have needed.
And this isn’t the only problem facing researchers who are, sometimes literally, looking into the caves. Right now, one of the biggest issues they have is figuring out just when the paleoburrows were made – in other words, determining how old they are – and this is thanks to a combination of circumstances.
What scientists do know is when the giant creatures that they think built the caverns disappeared. However, their research has yet to yield any firm conclusions. They could date material in the sediments found in the burrows, although that would only reveal when those sediments entered the burrow. Meanwhile, they could also get an approximate date from mineral deposits in the walls of the caves.
As it stands right now, though, neither of those tests have yet been completed. So the age of these incredible structures remains yet another of the various mysteries that surround them. What’s more, if that weren’t enough confusion, there is a third important question that’s baffling scientists as well – and if anything, this one is even stranger.
Right now, the geographical positioning of the paleoburrows is also leaving scientists confused. They seem to only exist in a narrow band of territory in Brazil, and there are hardly any of them further north in the country. It doesn’t look like there are any deeper south in Uruguay, either, and yet some may have been discovered in Argentina, which is to the south of both countries.
Furthermore, even though there were giant megafauna in North America, none of the paleoburrows have been discovered there, either. Why? It could be because the soil types in different areas have led the burrows to collapse over time. Yet there may be another, even simpler explanation for why scientists haven’t found burrows elsewhere.
There’s a chance that no paleoburrows have been found in these other areas because people just haven’t been looking. This particular field of research is in its infancy, and that means the paleoburrows could be hiding in plain sight. So the thinking is that no one has seen any of the structures simply because they’ve not yet tuned in to the possibility that they are there.
As more and more burrows are discovered, though, researchers are increasingly likely to understand the patterns behind them. And while some of the structures are small, there are many other massive ones. These spread out across multiple levels, too, and sometimes even open out into huge chambers deep under the soil.
There are so many questions about the paleoburrows that it will certainly be intriguing to see where the information that scientists can extract from them leads us. For example, the biggest paleoburrows were obviously dug over multiple generations, and right now we have no idea why.
Yet Frank isn’t deterred by the mass of questions that still surround the new discoveries. What’s more, he’s pinpointed other possible paleoburrow sites using web searches of pictures that people have taken in caves. There is, in fact, a chance that people have unknowingly discovered more examples of the phenomenon without even realizing it.
Finally, speaking to Discover, Frank said there’s an incredible atmosphere down in the caves. “In these burrows, sometimes you get the feeling that there’s some creature waiting around the next curve – that’s how much it feels like a prehistoric animal den.” Perhaps, then, the prospect of being in such an extraordinary environment will inspire other researchers to get out there and find even more of these remarkable structures.
But as some workers in southwest China discovered, you don’t need to be deep in the Amazon jungle to uncover incredible remnants left behind by prehistoric creatures. Yes, when they tried to build a new road, they found that an ancient relic was blocking their way – and it had lain buried there for 65 million years.
In April 2015 a road was being upgraded in Heyuan, a city in China’s Guangdong province. With a thriving economy that ranks among the biggest in the world, this region beside the South China Sea has seen much investment and development – and the city of Heyuan is no exception.
So, using heavy machinery on the streets of this city, workers made light work of the concrete covering the existing road. But as they uncovered the older earth and rubble beneath, they were in for an incredible shock.
Buried in a slab of red rock, the workers discovered a strange, round object. Then they spotted another. And another. There were 43 in total, all grayish-blue in color, and the biggest measured some 5 inches across.
Unsurprisingly, as workers pulled these mysterious objects from the ground, a crowd gathered to watch. But although the discovery was impressive, Heyuan locals may well have had some inkling as to the true nature of the finds.
Back in 2005, the city found its way into the Guinness Book of World Records with a rather singular claim. Yes, it was declared to be the home of the largest collection of fossilized dinosaur eggs in the world. Astonishingly, at the time more than 10,000 had been found, but the total unearthed there now stands closer to 14,000.
It all started in 1995 when a group of youths were playing on a building site. When one of them tripped over a rock, he took a closer look and realized that it bore a remarkable resemblance to an image of a dinosaur egg that he had once seen.
The boys told their parents and teachers about what they had found, and Huang Dong, a local dinosaur expert, was informed. Moreover, since that first discovery, thousands more eggs have been uncovered – earning Heyuan the nickname “Home of Dinosaurs.”
And as well as fossilized eggs, researchers have also discovered fossilized dinosaur skeletons and footprints. So, in 2008, local authorities allocated the equivalent of $7 million to build Heyuan’s own dinosaur museum.
In fact, Heyuan is so well known for its dinosaurs that it has a species named in its honor. Heyuannia, a type of oviraptorid, are known for their parrot-like beaks and large crests.
Authorities now estimate that around 17,000 whole or partial eggs have been discovered in Heyuan and its surroundings. Not all, however, have found their way to the museum or into scientific hands.
In 2004 a Heyuan farmer got into trouble with the police after failing to declare a stash of dinosaur eggs that he had found. And when they searched his home, they found 557 of the ancient relics.
Then, in summer 2015, a vast collection of fossilized eggs was discovered at a Heyuan construction site. However, before researchers could arrive to properly document the find, locals had stolen most of them.
Later that year, a police raid on a house in southern China revealed a hidden stash of 213 dinosaur eggs, and they were believed to be the same eggs as those stolen from the construction site. What’s more, police also uncovered a complete Psittacosaurus skeleton in the same house.
Now although the idea of keeping dinosaur fossils as souvenirs is clearly tempting, experts insist that the authorities should be notified of any finds. So when the Heyuan construction workers made their amazing discovery in April 2015, they got in touch with local officials.
Workers from the Heyuan Dinosaur Museum were subsequently sent to recover the objects, which were buried just a few inches beneath the road. As many must have suspected, they were indeed dinosaur eggs.
According to experts, the eggs are thought to date back to the late Cretaceous period, which occurred approximately 65 million years ago. And of the 43 eggs uncovered, 19 were in perfect condition.
Moreover, although dinosaur eggs had been discovered in the region before, this was the first time they’d been retrieved from a central, urban area. And with development in Heyuan showing no signs of slowing down, there could well be more finds to come.
Du Yanli, Heyuan Dinosaur Museum’s director, certainly believes that conditions are ripe for a similar discovery. “The eggs were found in the rock strata of red sandstone, [in] an environment in which other dinosaur egg fossils have previously been found,” he told CCTV news.
Now, experts at the Chinese Academy of Sciences are attempting to determine what species of dinosaur might have laid the eggs millions of years ago. So as Heyuan’s far-distant past continues to clash with its bright future, Yanli and his colleagues shouldn’t have too long to wait until the next prehistoric treasure trove reveals itself.