Size comparison: Argentinosaurus (green), Apatosaurus (blue), Triceratops (orange)

Bruce Chatwin begins his book In Patagonia with a description of a small piece of skin in a glass case in his grandmother’s dining room. When Chatwin was a young boy, his grandmother told him that this piece of skin, covered with coarse reddish hairs and pinned to a card, was from a Brontosaurus that her cousin Charley had discovered preserved in a glacier in Patagonia. This peculiar artifact so captured the boy’s imagination that decades later—long after his grandmother had died and the skin fragment had been discarded—Chatwin set out on his own adventure to Patagonia. One of his goals on this trip was to discover the true origin of the animal whose hide was such a familiar memory from his childhood—and with any luck, find another sample of skin and hair to replace the one that was lost.

An Apatosaurus by Any Other Name

In the mid-1970s, around the time Chatwin left on his six-month journey, scientists proved (or so they thought) that there had never been any such thing as a Brontosaurus. For nearly a century, a skeleton of a dinosaur known as the Apatosaurus had been displayed with the skull of an entirely different animal, the Camarasaurus. This odd combination of bones never should have been given a unique name, but the error persisted in popular usage, even decades after all references to Brontosaurus had been wiped from paleontological texts. (In 2015, those text had to be revised again, after evidence surfaced that the Brontosaurus was a unique species after all, the earlier mix-and-match error notwithstanding.) Chatwin may not have known this at the time, but he did at least discover before his journey that the skin fragment in his grandmother’s house belonged to another, more recent (but still prehistoric) creature: the Mylodon, or Giant Sloth. The last Mylodon expired perhaps 10,000 years ago, but some mylodon flesh was indeed preserved in a cave in a remote area of Patagonia. It was this creature whose remains his grandmother’s cousin Charley had found.

Nevertheless, Chatwin’s grandmother hadn’t been entirely off the mark. Argentina had, at least, been home to numerous large sauropods, the suborder of dinosaurs to which the Apatosaurus and Camarasaurus both belonged. In fact, just a couple of years before Chatwin’s death in 1989, an Argentinean rancher discovered some sauropod fossils that would soon be very big news in the world of dinosaurs. In 1993, paleontologists Rodolpho Coria and Jose Bonaparte classified the fossils as belonging to a hitherto unknown dinosaur, which they dubbed Argentinosaurus. It was the largest dinosaur—in fact, the largest land animal of any kind—to have been discovered at that time.

Thinking Big

The Argentinosaurus, which lived about 90 million years ago in the Upper Cretaceous period, weighed up to 100 tons and measured between 30 and 45 meters (100–150 feet) in length. As a plant eater, it was not the most fearsome creature, but I still wouldn’t want to meet one in a dark alley. Although only a small percentage of a full skeleton has been recovered so far, paleontologists have a pretty clear idea of what the entire creature must have looked like—enough to assemble a full-scale replica of the skeleton, which was recently installed in Atlanta’s Fernbank Museum of Natural History. (By law, dinosaur fossils cannot be removed from Argentina.)

Humongous dinosaurs turn up with remarkable frequency in Patagonia. This is also where the fossils of a Giganotosaurus, the largest known carnivore, were found. A number of years ago several vertebrae were unearthed belonging to a still-unidentified dinosaur that may well challenge Argentinosaurus for the record of largest lizard ever. Be that as it may, there’s no question that this creature was immense. At a museum of paleontology in Trelew, Argentina, the rear leg bones and one vertebra of an Argentinosaurus are affixed to a wall inside a painted outline of the body, giving visitors a dramatic picture of how tall this animal would have been—far too large, the staff said, for an entire skeleton to fit inside the museum.

I saw the bones myself on a trip to Patagonia in 2004. Before we entered the museum, our guide warned us, delicately, that what we would be seeing was a scientific presentation based on evolutionary theory. We all thought that disclaimer was pretty funny—what else would you see in a paleontological museum? I can only guess that earlier tourists with strong fundamentalist religious beliefs had taken offense at the suggestion that life as we know it evolved over billions of years. Personally, I lack the faith to accept a timeline that would have involved Argentinosaurus tromping around Patagonia a mere few thousand years ago. If they had, we might easily discover one, flesh intact, in the nearest glacier. I’ll be the first to lay a skin fragment on Bruce Chatwin’s grave.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on January 28, 2005.

Previous articleRoald Dahl Day
Next articleNational Cream-Filled Donut Day