Smithsonian.com

The giant sauropod Futalognkosaurus (at left) with some of its Cretaceous neighbors. Art by Maurilio Oliveira.

Which was the biggest dinosaur ever? We don’t know. Even though the size-based superlative draws a great deal of attention, paleontologists have uncovered so many scrappy sauropod skeletons that it’s difficult to tell who was truly the most titanic dinosaur of all. But, among the current spread of candidates, Futalognkosaurus dukei is one of the most complete giant dinosaurs yet found.

Discovered in 2000, and named in 2007 by Universidad Nacional del Comahue paleontologist Jorge Calvo and colleagues, Futalognkosaurus was one of many dinosaurs found in an exceptionally rich, roughly 90-million-year0old deposit in northwest Argentina. From fossil plants to pterosaurs, fish and dinosaurs, the one site entombed vestiges of a vibrant Cretaceous ecosystem. And, on that landscape, no dinosaur was as grand the newly named titanosaur.

Contrary to what you might expect given their skeletal sturdiness, the biggest sauropods are often found as partial skeletons. Our knowledge of Argentinosaurus, Puertasaurus, Supersaurus, Diplodocus hallorum and other giants is frustratingly incomplete, and figuring out how large they truly were relies on estimation from more complete representatives of other species.

The lack of complete tails from these dinosaurs makes the matter even more problematic. Dinosaur tails varied in length from individual to individual, and different subgroups had proportionally longer or shorter tails. In the case of Diplodocus hallorum, for example, a great deal of the dinosaur’s estimated  100-foot-plus length comes from the fact that other Diplodocus species had very long, tapering tails.

We don’t really know how long Futalognkosaurus was because, with the exception of a single vertebra, the dinosaur’s tail is entirely missing. Nevertheless, the sauropod that Calvo and coauthors described is remarkable for encompassing the entire neck, back and associated ribs, and the majority of the hips. Together, these elements represent over half the skeleton and comprise the most complete giant sauropod individual yet known.

Even if skeletal incompleteness keeps us from knowing exactly how big Futalognkosaurus was, the collected bones can leave no doubt that this was a truly enormous dinosaur. Calvo and coauthors estimated that the whole animal stretched between 105 and 112 feet in length, which would put it in the same class as the more famous (and less complete) Argentinosaurus. As the paleontologists at SV-POW! said when they posted images of Futalognkosaurus bones next to Juan Porfiri, who helped describe the dinosaur, there’s no doubt that the sauropod was “darned big.” The challenge is finding and filling in the parts of the dinosaur’s body that have not yet been found. There will undoubtedly be other challengers for the title of biggest dinosaur, but, for now, Futalognkosaurus remains our most detailed representative of the biggest of the big.

References:

Calvo, J., Porfiri, J., González-Riga, B., Kellner, A. 2007. A new Cretaceous terrestrial ecosystem from Gondwana with the description of a new sauropod dinosaur. Anais da Academia Brasileira de Ciências. 79, 3: 529-541

Calvo, J., Porfiri, J., González-Riga, B., Kellner, A. 2007. Anatomy of Futalognkosaurus dukei Calvo, Porfiri, González Riga, & Kellner, 2007 (Dinosauria, Titanosauridae) from the Neuquen Group, Late Cretaceous, Patagonia, Argentina. Arquivos do Museu Nacional 65, 4: 511–526.

Novas, F. 2009. The Age of Dinosaurs in South America. Bloomington: Indiana University Press. pp. 201-202

A graphic comparing the largest sauropods. The red giant in the back represents the estimated size of Amphicoelias (the blue speck to the lower left is a human for scale). By DinoGuy2, from Wikipedia.

My friend and fellow science writer Ed Yong recently met the biggest mammal of all time. During a trip to Sri Lanka, Ed was able to get quite close to some blue whales—the most massive animals on earth. But are they the largest animals ever? When I tweeted Ed’s story, noting that he met the most immense mammal that has ever lived, Ed picked up that I specified the blue whale as the largest mammal ever, rather than the largest animal. “Are you hedging your bets for a sauropod?” he asked. Well, yes and no.

As sauropod expert Matt Wedel once pointed out, there are two “semi-apocryphal” dinosaurs that may have been significantly larger than the biggest whales. One of these is a legend among paleontologists. In 1878, paleontologist Edward Drinker Cope named the 150-million-year-old dinosaur Amphicoelias fragillimus on the basis of a huge but partial piece of a vertebra called a neural spine. By itself, this fragment reportedly measured almost five feet high. The dinosaur it belonged to must have been absolutely gigantic. We may never know. The bone was lost, and efforts to locate additional bones of the dinosaur have failed. From the description of the single scrap, paleontologist Ken Carpenter estimated that the dinosaur may have been 190 feet long. This would make Amphicoelias about twice as long as the longest known sauropods, but without additional fossils from this titan, estimating Amphicoelias‘ size requires speculation.

But there’s another dinosaur that may have outstripped whales. Or maybe not. Bruhathkayosaurus, a more recent contender for largest dinosaur, also has a tortured history. The dinosaur was named in 1989 on the basis of limb, hip and backbone elements found in the 70-million-year-old strata of India. At first, the remains seemed to represent one of the biggest predatory dinosaurs of all time, but paleontologists later recognized that the bones had come from a sauropod. These bones might indicate a dinosaur even larger than the roughly 100 foot long Argentinosaurus—the creature often cited as being the current record-holder for the biggest dinosaur of all time.

Despite being discovered just a few decades ago, however, the size and characteristics of Bruhathkayosaurus are almost as mysterious as those of Amphicoelias. The original description represents all that is known about this dinosaur, and as far as I am aware, no one has formally published a reexamination of the dinosaur’s skeleton. Informal estimates have placed this dinosaur at between 90 and 145 feet long, with weight estimates varying as well.

For the moment, the biggest confirmed dinosaurs all seem to fall around the same upper limit: around 100 feet long. Whether any species grew considerably bigger than this remains to be seen. The fact that so many dinosaurs seem to fall around this length might indicate that it represented the rough upper boundary for sauropod size, yet huge sauropods are so rare that it is difficult to say whether this is real or a factor of sampling and estimation techniques.

So are blue whales the biggest animals ever? In terms of mass, almost certainly yes. The biggest whales weigh more than 200 tons, and as Matt Wedel pointed out in his post on this mammal vs. dinosaur competition, even fairly liberal mass estimates for the biggest dinosaurs don’t come close to this. But dinosaurs may have whales beat when it comes to length. Supersaurus—one of the many confirmed giants—might have been a little longer than the 110 foot benchmark set by whales, and perhaps Amphicoelias was even longer. If only someone could find a good skeleton of such a giant.

Dinosaurs 3D Inc.

What is it about dinosaurs that make them so compelling? Why do people, and in particular kids, throng to dinosaur exhibits and collect all manner of ancient reptile paraphernalia? Other than the bubbly, purple Barney, these creatures are fearsome with their incredible bulk, jagged teeth and armor-like plates. Yet kids love them, especially the young ones. Long before pre-schoolers have mastered more conventional vocabulary they can rattle off the multisyllabic names of these beasts. Whatever the explanation for their popularity, dinosaurs attract audiences and the IMAX movie Dinosaurs 3D: Giants of the Patagonia is doing just that.

Playing at Smithsonian’s National Museum of Natural History, the movie is pulling in streams of viewers eager to see a time when reptiles ruled the earth, and in particular when they roamed Patagonia in southern Argentina, a region where paleontologist Dr. Rodolfo Coria has been discovering the fossils of new dinosaur species. Narrated by Donald Sutherland, the movie focuses on the lives of simulated dinosaurs in their prehistoric ecosystem, with only passing reference to the painstaking paleontological spadework that led to the discoveries of these dinosaurs. The computer-generated images of the reptiles are impressive. The 3-D effects amplify the heft of these prehistoric creatures. And the featured dinosaurs are huge! The plant-eating Argentinosaurus, possibly the largest of all the dinosaurs, stretched 120 feet fully grown and the carnivorous upright Gigantosaurus was still imposing at 45 feet long and 8 tons.

Waiting to enter the theater, a young boy already sporting the 3-D glasses is barely able to keep still while sitting on a bench. Six-year-old Han from New Jersey has been enamored with dinosaurs since he was three and his favorite is the T. rex. “I know all about dinosaurs,” he says, “but some things I don’t know.” A sentiment the movie uncannily echoes when paleontologist Coria remarks that the number of questions about dinosaurs grows bigger than the number of answers. Apparently, Han is merely exhibiting the insight of a budding paleontologist. Coria’s work wins other converts. After a scene of the scientist examining a dinosaur footprint, a little boy stage whispers to his mother, “I want to become a paleontologist when I grow up.”

Dinosaurs 3D begins with a cosmic explosion that startles the audience, producing a group flinch. “I’m scared,” says a little girl. “You’re supposed to be,” says her older brother. The movie seems intended to elicit physical responses. There’s nothing like an immense dinosaur lunging at you to get the adrenalin surging. The 3-D heightens this effect. Flying reptiles zoom out at the audience. Younger viewers reach out to touch deceptively close dinos. An older man swats away a dragonfly hovering near his face despite knowing on some level that it’s only an image on the screen. Naturally, there’s a lot of teeth baring, tail whipping, foot stomping and aggressive roaring in encounters between species. The action even gets grudging respect from an older boy indifferent to the ancient reptiles—“That was almost cool.”

The movie ends with the arrival of an asteroid that sets in motion the extinction of the dinosaurs. “The movie made me sad,” said Jordan, age 6, from Houston, after seeing the demise of his favorite creatures. He’s not comforted by the upbeat, concluding note pointing out dinosaurs’ evolutionary connection to today’s birds. But if that’s small solace, at least the prehistoric creatures come staggeringly alive again onscreen.

– Lyn Garrity