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.

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