National Geographic News
Half of the tail belonging to a Sauropod found in Patagonia.

Ken Lacovara is shown with 22 tail vertebrae (out of 32 collected) of the massive sauropod Dreadnoughtus schrani. The dinosaur has the largest calculable weight of any known land animal.

Photograph by Robert Clark, Excel Magazine, Drexel University

Brian Switek

for National Geographic

Published September 4, 2014

After nine years of excavation and study, paleontologists have unveiled one of the largest creatures ever to walk the Earth. The most complete skeleton of a giant titanosaur will provide new insights into how these giants lived large.

The new dinosaur is named Dreadnoughtus schrani, a reference to the armored battleship and a tribute to the dinosaur's perceived fearlessness. Details on the dinosaur are announced Thursday in the journal Scientific Reports.

Illustration of Dreadnoughtus schrani.
Art: Emily M. Eng, NG Staff Source: Matthew C. Lamanna, Carnegie Museum of Natural History

In life, Dreadnoughtus would have been about 86 feet (26 meters) long and weigh nearly 60 tons, heavier than a Chieftan tank, Drexel University paleontologist Ken Lacovara and colleagues calculate. That's so big, the scientists write, that adults of the species would have been "nearly impervious to attack" by predators that stalked the same floodplains between 84 million and 66 million years ago.

Among the largest of dinosaurs, titanosaurs like Dreadnoughtus were hefty herbivores with tiny heads, long necks, and tapering tails. This body type marks titanosaurs as part of a group called sauropods, to which classic dinosaurs such as Apatosaurus also belonged. Sauropods spent their days feeding high and low, plucking greens from patches of ferns and trees alike, as they browsed the prehistoric salad bar.

What makes Dreadnoughtus a remarkable new addition to this prehistoric family is the amount of material recovered from the dinosaur. The remains, representing two individual animals, include both the humerus and femur of Dreadnoughtus, and Lacovara and colleagues used the circumference of these bones to estimate the dinosaur's weight.

So far, Lacovara says, "Dreadnoughtus has the largest calculable mass of any land animal."

Detail of the top of a Humerus from a Souropod sound in Patagonia.
The humerus, or upper arm bone, of Dreadnoughtus shows muscle scarring.
Photograph by Robert Clark, Excel Magazine, Drexel University

A Big Find

At first, though, Dreadnoughtus didn't seem so impressive. "In 2005, we were prospecting in the desert [of southern Argentina]," Lacovara says, "and the first day of that field season I found a collection of bones." They just looked like a pile of fragments, but when Lacovara and collaborators returned to the site, they started uncovering big limb bones.

"By the end of the day we had ten bones exposed," Lacovara says. "At that point we were pretty excited." Four field seasons later, the team had excavated 145 bones.

Altogether the bones represent about 45 percent of a complete skeleton, and because some of the bones have mirror images on the other side of the body, Lacovara and colleagues were able to reconstruct about 70 percent of a Dreadnoughtus skeleton. The best large titanosaur find previously, Futalognkosaurus, was only about 27 percent complete.

"Now we can start talking intelligently about the body proportions of these giant titanosaurs," says Western University of Health Sciences paleontologist Mathew Wedel.

Dreadnoughtus schrani on a football field for scale.
Emily M. Eng, NG Staff

And Dreadnoughtus could have grown even bigger than the new estimate. "Since the authors provide data that illustrate that Dreadnoughtus was still growing when it died," says Macalester College paleontologist Kristi Curry Rogers, "we can be fairly certain that there were other heavier dinosaurs out there."

Mysterious Lives

But size isn't everything. "If we want to really begin to understand how these big dinosaurs grew, and how long it took them to reach their massive sizes, these are the perfect kinds of data to begin with," Curry Rogers says. Having two individuals is a good start, she says, but scientists will need to find more of the dinosaurs to begin piecing together their lifestyles.

"There are so many fundamental things we don't know about sauropods," Lacovara says, such as the arrangement of their muscles and how they moved. Turning to muscle scars on the bones of Dreadnoughtus, Lacovara and others are figuring out the dinosaur's muscle anatomy and how those soft tissues translated to movement.

This is just the sort of effort other paleontologists are hoping to see. "It's all about building toward a more complete picture of the living animal," Wedel says.

The 1.7m scapula of Dreadnoughtus schrani is the longest yet reported for any titanosaur.
The 5.6-foot (1.7-meter) scapula of Dreadnoughtus is the longest yet reported for any titanosaur.
Photograph by Robert Clark, Excel Magazine, Drexel University

For now, though, Lacovara is glad to see Dreadnoughtus finally emerge after all the years of fieldwork and study. "This is like Christmas and my birthday and my wedding combined."

Read Brian Switek's blog Laelaps on NationalGeographic.com. Follow him on Twitter, Facebook, and Instagram.

RELATED:

— "Catching a Titanosaur By a Tooth"
— "From Punting to Tromping"
— "Uncovering Patagonia's Lost World"

31 comments
BK Jeong
BK Jeong

Sorry, but Amphicoelias was much bigger than even this beast. it was 300 feet long and weighed 250 tons, as much as a blue whale.

Jay Bhatt
Jay Bhatt

Simply wow. Ken, proud of you and your team's outstanding achievements!

Saketh Upadhya
Saketh Upadhya

A great find.  It is cool that almost the whole skeleton was retrieved which is quite difficult for such a huge dinosaur. 

Pat Kelley
Pat Kelley

Very cool, if only Jurassic Park was real!

Stanley Yelnats
Stanley Yelnats

"Largest calculable weight of any known land animal"?  As in, if it were any larger, we couldn't calculate its weight?  Good type...

Badrinith Badrinath
Badrinith Badrinath

As human's we are way beyond what we are yet to explore or discover. Its good to see atleast we are inching towards finding atleast 0.01% what we have on this planet

Charlene Carney
Charlene Carney

Okay, here's the $60,000 question:  Why do animals not grow so large anymore? It would obviously be a plus so don't evolution me. What is it about our environment that will not grow an animal that large? 

Bonus question:  If there were animals so large why is it so hard for people to believe we also had people much larger than now?

JOHN MULHOLLAN
JOHN MULHOLLAN

the amazement will never stop.  our knowledge is a grain of sand on a desert 

Wes Smith
Wes Smith

This is, by far, the most Metal dinosaur name ever. What an incredible find, and amazing to think of these titans actually walking around at one point in time. Hopefully more finds pop up soon so we can get a better picture of how these guys actually grew.

Philip Olson
Philip Olson

More soft tissue would be nice.  Nerve impulse travel time is dependent on diameter of the nerve and whether or not myelin  sheaths are present.  Either way the best rate would give over a two second transmission time from head to tail.

Some dinosaurs were found to have secondary brains in their aft section to coordinate control of the rear quarters with the front halves.  This giant could have used a couple extra brains, one for  the tail and another just for the legs.

Without the myelin sheaths the travel time for nerve commands could be in the four to five second range, too long for coordination.  The inability of giraffes to articulate comes from a half second difference in travel time to the halves of it's larynx, and the giraffe owns a high speed modern nerve system.

Questions to be answered only with more research, what a great age we live in. 

Jerry Cohen
Jerry Cohen

Big bones are really great, but a minute amount of well preserved frozen DNA...then wow!

Seth Bucholz
Seth Bucholz

Amazing to wonder what other massive land animals remain to be discovered under the the layers of rock and sediment. Congrats to Lacovara and his team!


Dreadnoughtus will probably get mass public attention once Scifi produces a film, starring it as a man eating abomination. :P




JOHN LONGENECKER
JOHN LONGENECKER

Sept 5. I saw that documentary film about some dinosaurs running around in a park shot on a island off the coast of Mexico I think. So, at least on that island there are still some alive dinosaurs. Maybe there are other parks like the one you mention that they should make films about. If you had enough money to buy a bunch of GoPro cameras I bet you could strap on the GoPros and see how they live. I think the documentary I saw was made before there were GoPros or even Flip cameras. Now in 2014 it will be lots simpler to film dinosaurs running around. You could even use those Amazon drone helecopters to film in the parks. I bet somebody is working on stuff like that now. Way cool.

Nick Porter
Nick Porter

@Stanley Yelnats  Suspect you might be joking there, but if not: it's about the completeness of the skeleton. Argentinosaurus and several other sauropods were probably larger, but they're only known from a tiny number of bones, so we don't really know enough about their proportions to make a remotely accurate measurement.

Nick Porter
Nick Porter

@Charlene Carney  Saurischian dinosaur skeletons were constructed in such a way that they were unusually light, without sacrificing strength (it's believed they incorporated air sacs like birds and crocodiles, which would also have improved their respiration). So structurally speaking, it was easier for them to achieve giant sizes than mammals or ornithischian dinosaurs.


As for *why* sauropods grew so huge, it was probably to increase the efficiency of their digestive system. A larger gut means more bacteria, more gastric juices, and being able to store and process food for longer. The bigger animal could extract more nutrition from the same amount of food.

Mesozoic plants tended to be extremely hard to digest - ferns, horsetails, conifers, cycads, ginkgos; the sort of plants that few modern grazers can subsist on. Sauropods flourished on them.

Michon Scott
Michon Scott

@Charlene Carney It's hard to believe there were people so much larger than now because, unlike sauropods, nobody has found credible remains of giant humans. That doesn't mean it's impossible. It does mean that you need to find evidence to support your argument.

Larger size is not a plus in every instance. Larger animals tend to need more food and are therefore more vulnerable to disruptions in the food chain.

Joem Costes
Joem Costes

@Charlene Carney When the dinos reigned there was a lot more Oxygen in the atmosphere. (ref. Cosmos w/ Neil deGrasse Tyson 

Lexi Gardiner
Lexi Gardiner

@Seth Bucholz You mean Discovery Channel.  They'll 'creatively' fill in the blanks and we'll be presented with a steaming load of dino doo...

Thomas Wise
Thomas Wise

@Nick Porter  When you speak about "why" something happens, in advance, you're talking about an intelligent decision.  The genetic anomalies create a menu.  The real question is why anything should survive at all.  The real question is why variety ought to spring forth at all.


It was a good question, why dinosaurs grew so large, and the real answer is, because nothing stood in their way.  Then, we believe they were wiped out by a disease and/or asteroid.  What was left on Earth then needed to grow again.


BUT.. mammoths.  Why did they get SMALLER and become elephants?  And.. Eohippus... why did they BIGGER and become horses?  There is no "necessity."  That means God did it.  There is only happenstance.  And the variety of happenstances is sooooo great that it too looks like God.


Why don't insects grow to gigantic proportions anymore?  Not about oxygen or plant life.  And if you invoke that, explain why any species ought to grow larger?  Or is it a natural consequence of the oxygen content of the atmosphere?  If so, why can't we grow large vegetables in oxygen tents?  Or large insects? Or large viruses?


Sorry to go on and on, but it irks me when evolutionists have to cover their ignorance of "why" with speculation on "need."  Evolution doesn't fill needs.  Evolution is a mechanism of survival among genetic anomalies.  The WONDER is twofold: 1) why is a menu of anomalies provided at all, and 2) why is that menu filled with likelihoods of survival rather than of decimation?  The FITTEST ought to be that which is already living.  The fact that anomalies can be BETTER is NOT from need - needs unmet creates death, and death does not permit genetic transmission.

Jayce Ha
Jayce Ha

@Joem Costes @Charlene Carney Neil was talking about giant insects, not animals let alone dinosaurs. Plus the period he was talking about was WAY before the jurassic age.


Philip Olson
Philip Olson

@Mike McMahon @Philip Olson

I was a child back in the sixties when I learned about the second brain, a time when dinosaurs named Brontosaurus had the wrong head attached and dragged their tails on the ground.

Some things I just want to believe just because It made sense when I was young.

Oh well.

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