It didn’t take long for Pascal Godefroit
to realize 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 approached by a German
collector who’d come into possession of some Mongolian dinosaur fossils that had changed
hands multiple times, traveling from Central Asia to Japan and then all the way 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 had come from a large-bodied
animal. But the one thing that really caught Godefroit’s
attention were the bones of the creature’s hands. To him, they looked pretty darn familiar. They reminded him of the huge hands of a mysterious
dino that was first discovered in the Gobi Desert back in 1965. The dinosaur in question was a big theropod
that, at the time, was known mostly from fossils of its most distinctive feature: its enormous
arms. From end to end, the forelimbs alone measured an incredible 2.4 meters long and were tipped
with big, comma-shaped claws. Scientists had called the newfound dinosaur
Deinocheirus, which means “horrible hand.” But other than its bizarre arms, very little
material from this dinosaur had been found: no skull, no feet, almost nothing that could
give experts a fuller picture of what this dinosaur actually was. So for more than 40 years, nearly everything
about Deinocheirus was a mystery: how big it was it? What did it eat? How was it related to other
species? And just … what did it looked like. The bones Godefroit recognized in that chance
encounter in France would be the first big break in this scientific cold case. But before the mystery of Deinocheirus could
be solved, paleontologists would have to contend with the darker side of their science: things
like vandalism, poachers, and the black market fossil trade. And in the end, the creature they would discover
would turn out to be, from head to tail, one of the weirdest dinosaurs ever known. Deinocheirus was first described by a Polish
paleontologist who had been prospecting in the Gobi Desert for fossils from the Late
Cretaceous Period. There, she and her team discovered three fragmented
backbones, some ribs, and several of the stomach-lining bones called gastralia that dated to around
70 million years ago. And then there were, of course, the arms. Each one was found with shoulder bones intact. And although the right arm was missing its
claws, the left arm was basically complete. Even so, 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 noticed
that the hands and upper arm bones of Deinocheirus looked a lot like those of Ornithomimus, a
dinosaur from the Late Cretaceous of North America. Ornithomimosaurs, also known as “ostrich mimics,”
were a group of beaked theropods with long necks, long legs, and long arms. But there’s long, and then there’s loong. Deinocheirus’ arms would’ve dwarfed those
of Ornithomimus. Your typical ornithomimosaur ranged from around
2.5 to 7 meters long. And the biggest Ornithomimus had an overall
body length of about 3.8 meters. So the entire animal wasn’t much bigger
than a single Deinocheirus forelimb. But without the rest of the body, paleontologists
couldn’t say whether Deinocheirus fit the typical mold of an ornithomimosaur. These dinos had long, narrow beaks, and most
species were toothless. They also tended to have huge eye sockets. And just like real ostriches, many of the
ostrich mimics had long, powerful hindlimbs. Scientists estimate that certain ornithomimosaurs
might’ve had a top running speed of anywhere from 35 to 60 kilometers per hour! As far as feeding goes, it’s been hypothesized
that some ornithomimosaurs used their long arms and slender fingers to grasp fern fronds
and tree limbs. And plant-eating in these dinos has been supported
by the discovery of a dozen skeletons of Sinornithomimus with clumps of gastroliths inside their body
cavities. Gastroliths are tiny rocks that get some animals
swallow to help grind up food inside their digestive tracts. And in modern birds, gastroliths are usually
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 likely omnivorous. But again, without more fossils, paleontologists
couldn’t be sure about what Deinocheirus ate--or where it belonged on the family tree. Still, as time went by, most experts agreed
that Deinocheirus was probably an ornithomimosaur--just an exceptionally big one. Now, fast-forward to 2006. That year, scientists involved with the Korea-Mongolia
International Dinosaur Project seemed to hit the jackpot. At a new dig site in the Gobi’s Nemegt Basin,
they found fresh material from a different Deinocheirus, including elements from the
hips, hind legs, and vertebrae. And better still, an incomplete arm, more
backbones, and other parts of a third Deinocheirus turned up at yet another new quarry in 2009. But unfortunately, both of the new sites had
already been ravaged by fossil-poachers - a serious problem in the Gobi. Raiders had smashed up many of the fossils,
and it looked like other bones--including a skull--had been taken and 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 were left that the experts
could identify the two new specimens as Deinocheirus, based on comparisons with the material found
in 1965. And after word of all the new discoveries
got out, the paleontologists caught a lucky break, in that meeting with the fossil trader
in France. After seeing the German collector’s fossils,
Godefroit got in touch with the team that had been working in the Gobi. He told them he’d seen the bones of a strange
- and familiar - Mongolian dinosaur. The hand bones from this specimen had definitely
came from a Deinocheirus. And there was more: A right foot included
with the collector’s specimens was missing a toe bone; there was just an empty impression
in the rock where it should’ve been. But that little bone wasn’t lost forever. A toe bone that had just been recovered in
2009 fit the empty impression perfectly: the missing toe and the fossil-collector’s bones
came from same individual! Like a dinosaur Cinderella. Clearly, the specimens in France were the
very bones that had been poached from one of the new Deinocheirus sites. And that meant 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 plundered bones, he donated them to Godefroit’s museum. There, they were studied, and eventually returned
to Mongolia. And--after their long, strange journey--they
were reunited with the rest of the skeleton. Between the material taken from the 2006 and
2009 sites, and from the original 1965 site, scientists now had samples of almost
every single bone in Deinocheirus’ body. And, it must’ve been a sight to behold. With a maximum length of about 11.5 meters,
the creature would’ve rivaled some tyrannosaurids in size. And some anatomical clues--like the toothless
beak--showed that scientists were right in thinking that Deinocheirus was a gigantic
ornithomimosaur. But it was the weirdest-looking ostrich mimic
that anybody had ever seen. For starters, the skull - which was over a
meter long - had a broad, duck-like bill. And some of its back bones had tall neural
spines, supporting a strange, triangle-shaped sail. At the end of the tail, the last few vertebrae
were fused together into a structure called a pygostyle. In living birds, the pygostyle is an attachment
point for tail feathers. So Deinocheirus probably had a tuft of feathers
at the end of its tail. These have been seen in a few other non-avian
dinosaurs, but nobody had ever found one on an ornithomimosaur before! And, unlike some of the speedier ornithomimosaurs,
Deinocheirus had relatively short legs, tipped with blunt claws that resembled hooves because
of their squared-off tips! Last but not least, there were the stomach
contents. The Deinocheirus from the 2009 site had a
belly filled with over 1,000 tiny gastroliths! And sprinkled among the stomach stones were
fish scales and vertebrae. Clearly, this dinosaur had enjoyed a fishy
meal before it died. Taken altogether, this weird combination of
features revealed a lot about Deinocheirus and how it lived. Judging by the geology, experts already knew
that, about 70 million years ago, the Nemegt Formation was a seasonal floodplain, covered
by a network of lakes and braided rivers. It may have resembled the Okavango Delta in
modern-day Botswana, which has a mixture of permanent swamps and grasslands that flood
periodically. And the local rock record shows that this
formation was just full of predatory dinosaurs. The theropod Tarbosaurus is well-represented. At 9.5 meters long, and with an estimated
weight of four metric tons, it would’ve been an awesome hunter. There was also Alioramus, a smaller tyrannosaurid
species with an elongated skull. With so many tyrannosaurids to contend with,
some experts have hypothesized that the massive proportions of Deinocheirus might have been
an adaptation that helped it fend off would-be predators. After all, we know Tarbosaurus munched on
Deinocheirus from time to time. Some Deinocheirus gastralia have been found
covered in bite wounds that match up with the size, shape and placement of Tarbosaurus
teeth. But we don’t know if Tarbosaurus hunted
or scavenged that Deinocheirus. Nevertheless, being big might’ve given Deinocheirus
an edge against potential tyrannosaurid attacks on the Cretaceous floodplains. But there was a trade-off: Because of its
size, Deinocheirus wasn’t as fast as some other ornithomimosaurs. And huge bodies require lots of food. Here, its broad beak gives us a major lifestyle
clue. The dimensions of its lower jaw suggest that
the creature had a powerful tongue, which it could’ve used in aquatic foraging to
create a vacuum that would help it suck up lake or river plants. As for the “horrible hands” themselves,
recent research suggests that they were adaptations for digging up plant matter or raking in aquatic
vegetation. And maybe those specialized, hoof-like toes
helped keep it from sinking into muddy riverbanks. The sail, however, is a bigger puzzle. 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 sails might’ve been used to help regulate body temperature. Others said they supported lots of fatty tissue,
much like the humps on living bison. Both hypotheses were later criticized, though. It’s also possible that the sails were used
for display, making the animals look bigger and/or more attractive to mates. The jury’s still out. Regardless, while Deinocheirus was an ornithomimosaur
through and through, it didn’t just look like a scaled-up Ornithomimus. And in hindsight, Deinocheirus’ bizarre
anatomy kind of makes sense. Instead of speed, it went for size to avoid
being preyed upon. And its broad beak helped it snack on the
abundant aquatic resources of its seasonal floodplain home. Deinocheirus reminds us that the fossil record
is full of surprises, but also that it’s a precious resource - and paleontologists
aren’t the only ones out there prospecting it. Without a well-connected fossil-dealer, a sharp-eyed paleontologist,
and a little luck, we’d still be asking ourselves what is up with those
horrible hands? So now that we know what Deinocheirus looked
like - what do you think that sail was for? Fat storage, display, or something else? Let us know in the comments what your hypothesis
is and why! Also long armed high-fives to 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 in
the Konstantin Haase Studio. Subscribe at youtube.com/eons for more adventures
in time!
Like many people in those YouTube comments, I grew up reading about this mysterious Deinocheirus whose arms were the only part we knew. And they were massive! If it was like an Allosauroid-proportioned dinosaur, it was probably the largest carnivore to ever walk the Earth. As an ornithomimosaurid, it also dwarfed Gigantoraptor (which we discovered many years later).
So when I learned that we finally got a bodyshape to put next to those arms, I was thrilled. I didn't know the black market helped, it seems like "Irritator Part II" even lol.
There's a really cool documentary on curiosity stream about this dinosaur. You should check it out.
Omg. Thanks so much for posting. When I was younger (I’m 55 now) I saw a picture of “terrible claw” and was amazed. It has always been in my thoughts.
To know that we finally know more about it is amazing and so bizarre too.
So sad that bone poachers destroy the other bones. That part really upset me but a million thanks to the collector for donating his bones
One of the weirdest dinos out there, with an appropriately weird and wild story to go along with it! Hahaha, I love it!