The Giant Dinosaur That Was Missing a Body

It didn't take long for Pascal Godefroit to realize that he was looking at a stolen

dinosaur

. The year was 2011. And Godefroit, a paleontologist at the Royal Belgian Institute of Natural Sciences, had been called to France by an acquaintance who was a fossil dealer. The dealer had been contacted by a German collector who had come into possession of some Mongolian

dinosaur

fossils that had changed hands several times, traveling from Central Asia to Japan and then to Europe. And the bones looked, well, strange. There was a skull measuring over a meter long, as well as a variety of hand and foot bones.

Clearly, these came from a large animal. But the only thing that really caught Godefroit's attention were the bones in the creature's hands. To him, they seemed quite familiar. They reminded him of the enormous hands of a mysterious dinosaur first discovered in the Gobi Desert in 1965. The dinosaur in question was a large theropod that, at the time, was known primarily from fossils of its most distinctive feature: its enormous arms. From tip to tip, the forelimbs alone measured an incredible 8 feet long and were tipped with large, comma-shaped claws. Scientists had named the newly discovered dinosaur Deinocheirus, which means "horrible hand." But apart from its strange arms, very little material of this dinosaur was found: no skull, no legs, almost nothing that could give experts a more complete picture of what this dinosaur really was.

So for more than 40 years, almost everything about Deinocheirus was a mystery: how big was it? That ate? How did it relate to other species? And just…what did it look like? The bones Godefroit recognized in that chance encounter in France would be the first major break in this unsolved scientific case. But before the mystery of Deinocheirus can be solved, paleontologists would have to deal with the darker side of their science: things like vandalism, poachers, and the black market for fossils. And in the end, the creature they would discover would turn out to be, from head to tail, one of the strangest dinosaurs ever known.

Deinocheirus was first described by a Polish paleontologist who had been exploring the Gobi Desert in search of fossils from the Late Cretaceous period. There, she and her team discovered three fragmented spinal columns, some ribs, and several of the bones that line the stomach, called gastralia, dating back to about 70 million years ago. And then there were, of course, the arms. Each was found with shoulder bones intact. And although the right arm was

missing

claws, the left arm was basically complete. Still, for a long time scientists couldn't do much more than speculate about what the rest of the owner of those

giant

arms looked like.

As early as 1969, paleontologists had noted that the hand and upper arm bones of Deinocheirus closely resembled those of Ornithomimus, a dinosaur from the Late Cretaceous of North America. Ornithomimosaurs, also known as "ostrich imitators," were a group of beaked theropods with long necks, legs, and arms. But there is a lot of time and then there is a lot of time. The arms of Deinocheirus would have eclipsed those of Ornithomimus. The typical ornithomimosaur measured between 2.5 and 7 meters long. And the largest Ornithomimus had a total

body

length of about 3.8 meters. So the entire animal was not much larger than a single forelimb of Deinocheirus.

But without the rest of the

body

, paleontologists couldn't say whether Deinocheirus fit the typical mold of an ornithomimosaur. These dinosaurs had long, narrow beaks and most species did not have teeth. They also tended to have enormous eye sockets. And like real ostriches, many of the ostrich imitators had long, powerful hind legs. Scientists estimate that certain ornithomimosaurs may have had a maximum running speed of between 35 and 60 kilometers per hour! Regarding feeding, it has been hypothesized that some ornithomimosaurs used their long arms and thin fingers to grasp fern leaves and tree branches. And plant consumption in these dinosaurs has been supported by the discovery of a dozen Sinornithomimus skeletons with clusters of gastroliths within their body cavities.

Gastroliths are small rocks that some animals swallow to help crush food within their digestive tracts. And in modern birds, gastroliths are often associated with a plant-based diet. However, most experts think that, in addition to plants, ornithomimosaurs probably ate insects and small animals. In other words, many, if not all, of these ostrich dinosaurs were probably omnivores. But again, without more fossils, paleontologists couldn't be sure what Deinocheirus ate or where it belonged on the family tree. Still, as time went on, most experts agreed that Deinocheirus was probably an ornithomimosaur, but an exceptionally large one. Now, fast forward to 2006.

That year, scientists involved in the Korea-Mongolia International Dinosaur Project seemed to hit the jackpot. At a new excavation site in the Nemegt Basin of the Gobi, they found fresh material from a different Deinocheirus, including elements of the hips, hind legs and vertebrae. And better yet, an incomplete arm, more columns and other parts of a third Deinocheirus turned up at another new quarry in 2009. But unfortunately, both new sites had already been devastated by fossil poachers, a serious problem in the Gobi. The raiders had smashed many of the fossils and it appeared that other bones, including a skull, had been smuggled out of the country.

Poachers often take skulls, hands and feet and then destroy or leave behind the rest of the skeleton. But enough fossils remained for experts to identify the two new specimens as Deinocheirus, based on comparisons with material found in 1965. And after word spread of all the new discoveries, paleontologists had a stroke of luck, in that meeting with the fossil dealer in France. After seeing the German collector's fossils, Godefroit contacted the team that had been working in the Gobi. He told them that he had seen the bones of a strange and familiar Mongolian dinosaur. The hand bones of this specimen definitely came from a Deinocheirus.

And there was more: a right foot included in the collector's specimens was

missing

a bone; there was only an empty impression in the rock where it should have been. But that little bone was not lost forever. A toe bone that had just been recovered in 2009 matched the empty impression perfectly: the missing toe and the fossil collector's bones came from the same individual! Like a Cinderella dinosaur. Clearly, the specimens in France were the same bones that had been poached from one of the new Deinocheirus sites. And that meant that the skull the fossil collector had was a Deinocheirus head!

After so many years of searching, scientists finally knew what this dinosaur's face looked like. Once the situation was explained to the collector who owned the looted bones, he donated them to the Godefroit museum. There they were studied and eventually returned to Mongolia. And, after their long and strange journey, they were reunited with the rest of the skeleton. Between the material taken from the 2006 and 2009 sites, and the original 1965 site, scientists now had samples of almost all the bones in Deinocheirus's body. And it must have been a sight to behold. With a maximum length of about 11.5 meters, the creature would have rivaled some tyrannosaurids in size.

And some anatomical clues, like the toothless beak, showed that scientists were right to think Deinocheirus was a gigantic ornithomimosaur. But it was the strangest looking imitation ostrich anyone had ever seen. For starters, the skull, which was more than a meter long, had a wide duck-like beak. And some of the bones on its back had tall neural spines that held up a strange triangle-shaped sail. At the end of the tail, the last vertebrae were fused into a structure called the pygostyle. In living birds, the pygostyle is an attachment point for the tail feathers. So Deinocheirus probably had a tuft of feathers at the end of its tail.

These have been seen in some other non-avian dinosaurs, but no one has ever found one in an ornithomimosaur before! And unlike some of the faster ornithomimosaurs, Deinocheirus had relatively short legs, tipped with blunt claws that looked like hooves because of their square tips. Last but not least was the contents of the stomach. The Deinocheirus from the 2009 site had a belly full of over 1000 tiny gastroliths! And scattered among the stomach stones were fish scales and vertebrae. Clearly, this dinosaur had eaten fish before it died. Taken together, this strange combination of characteristics revealed a lot about Deinocheirus and how he lived.

Judging by geology, experts already knew that about 70 million years ago the Nemegt Formation was a seasonal alluvial plain, covered by a network of intertwined lakes and rivers. It may have resembled the Okavango Delta in modern-day Botswana, which has a mix of permanent swamps and periodically flooded grasslands. And the local rock record shows that this formation was full of predatory dinosaurs. The theropod Tarbosaurus is well represented. At 9.5 meters long and weighing an estimated four metric tons, it would have been an incredible hunter. There was also Alioramus, a smaller species of tyrannosaurid with an elongated skull. With so many tyrannosaurids to contend with, some experts have hypothesized that Deinocheirus' enormous proportions could have been an adaptation that helped it defend itself from potential predators.

After all, we know that Tarbosaurus ate Deinocheirus from time to time. Some Deinocheirus gastralia have been found covered in bite wounds that match the size, shape and location of Tarbosaurus teeth. But we don't know if Tarbosaurus hunted or scavenged that Deinocheirus. However, being large could have given Deinocheirus an advantage against possible tyrannosaurid attacks on the Cretaceous floodplains. But there was a trade-off: Due to its size, Deinocheirus was not as fast as other ornithomimosaurs. And huge bodies require a lot of food. In this case, its wide beak gives us an important clue about its lifestyle. The dimensions of its lower jaw suggest that the creature had a powerful tongue, which it could have used in searching for aquatic food to create a vacuum that would help it suck plants from lakes or rivers.

As for the "ugly hands," recent research suggests they were adaptations for digging up plant matter or raking aquatic vegetation. And perhaps those specialized, hoove-like fingers helped keep it from sinking into muddy river banks. The candle, however, is a major enigma. Other sail-backed dinosaurs have come to light over the years, including the predatory Spinosaurus and Ouranosaurus, a large herbivore. In decades past, some paleontologists argued that these candles could have been used to help regulate body temperature. Others said they held a large amount of fatty tissue, much like the humps of living bison. However, both hypotheses were later criticized.

It is also possible that the candles were used for display, making the animals appear larger and/or more attractive to their mates. The jury is still out. Anyway, while Deinocheirus was an ornithomimosaur through and through, it didn't just look like an enlarged Ornithomimus. And in retrospect, Deinocheirus' strange anatomy makes sense. Instead of speed, he opted for size to avoid being attacked. And its broad beak helped it take advantage of the abundant aquatic resources of its seasonal floodplain home. Deinocheirus reminds us that the fossil record is full of surprises, but also that it is a precious resource, and paleontologists are not the only ones exploring it.

Without a well-connected fossil dealer, a perceptive paleontologist, and a little luck, we'd still be wondering what's up with those horrible hands? Now that we know what Deinocheirus looked like, what do you think that candle was used for? Fat storage, display or something else? Let us know in the comments what your hypothesis is and why! Also high-five this month's eontologists: Patrick Seifert, Jake Hart, Jon Davison Ng, Sean Dennis, Hollis, and Steve. Pledge your support at patreon.com/eons and become an Eonite! And as always, thank you for joining me at the Konstantin Haase Studio. Subscribe at youtube.com/eons for more adventures through time!