National Geographic : 2017 Jun
97 clubs, but they too wielded thorny armor to deter predators. As it lumbered across the landscape between 110 million and 112 million years ago, almost midway through the Cretaceous period, the 18-foot-long, nearly 3,000-pound behemoth was the rhinoceros of its day, a grumpy herbivore that largely kept to itself. And if something did come calling—perhaps the fearsome Acrocan- thosaurus—the nodosaur had just the trick: two 20-inch-long spikes jutting out of its shoulders like a misplaced pair of bull’s horns. T he western Canada that this di- nosaur knew was a very different world from the brutally cold, wind- swept plains I encountered this past autumn. In the nodosaur’s time, the area resembled today’s South Florida, with warm, humid breezes wafting through conifer forests and fern-filled meadows. It’s even possi- ble that the nodosaur gazed out on an ocean. In the early Cretaceous, rising waters carved an in- land seaway that blanketed much of what’s now Alberta, its western shore lapping against eastern British Columbia, where the nodosaur may have lived. Today those ancient seabeds lie buried un- der forests and rolling fields of wheat. One unlucky day this landlubbing animal end- ed up dead in a river, possibly swept in by a flood. The belly-up carcass wended its way downriver— kept afloat by gases that bacteria belched into its body cavity—and eventually washed out into the seaway, scientists surmise. Winds blew the car- cass eastward, and after a week or so afloat, the bloated carcass burst. The body sank back-first onto the ocean floor, kicking up soupy mud that engulfed it. Minerals infiltrated the skin and ar- mor and cradled its back, ensuring that the dead nodosaur would keep its true-to-life form as eons’ worth of rock piled atop it. The creature’s immortality hinged on each link in this unlikely chain of events. If it had drifted another few hundred feet on that ancient sea, it would have fossilized beyond Suncor’s property line, keeping it entombed. Instead Funk stumbled upon the oldest Albertan dinosaur ever found, frozen in stone as if it had gazed upon Medusa. “ That was a really exciting discovery,” says Victoria Arbour, an armored-dinosaur pale- ontologist at Canada’s Royal Ontario Museum. Arbour has seen the fossil at various stages of preparation, but she’s not involved in its study. “It represents such a different environment from today and such a different time, and it has great preservation.” (Arbour has begun studying a similarly well preserved ankylosaur found in Montana in 2014, much of which remains hid- den within a 35,000-pound block of stone.) The Canadian specimen literally defies words, in more ways than one. As this article went to press, museum staff were finalizing the creature’s scientific description and hadn’t yet settled on a common name for it. (“Mrs. Prickley,” a reference to a Canadian sketch comedy character, didn’t stick.) But already the fossil is providing new insights into the structure of nodosaurs’ armor. Reconstructing armor usually requires educated guesswork, as the bony plates, called osteoderms, scatter early in the decaying process. Not only did the osteoderms on this nodosaur preserve in place, but so did traces of the scales in between. What’s more, sheaths once made of kera- tin—the same material that’s in human finger- nails—still coat many of the osteoderms, letting paleontologists see precisely how these sheaths exaggerated the armor’s size and shape. “I’ve been calling this one the Rosetta stone for armor,” says Donald Henderson, curator of dinosaurs at the Royal Tyrrell Museum. Freeing this Rosetta stone from its rocky tomb, however, proved a herculean task. After word of the discovery raced up the lad- der at Suncor, the company quickly notified the Royal Tyrrell Museum. Henderson and Darren Tanke, one of the museum’s veteran techni- cians, scrambled aboard a Suncor jet and flew to 3-D EXPERIENCE Rotate, zoom, and examine every detail of this remarkable fossil using our 3-D model at ngm.com/June2017.