The Largest Dinosaur that Ever Existed?

A titanosaur skeleton as it appears in the American Museum of Natural History. I believe this reconstruction is a generalized giant titanosaur, which means it is a good example of how massive these dinosaurs could get.

Fair warning, this is a long post. However, it details an interesting story, so I hope that you stick along for the whole thing. There are plenty of illustrations to break up the text.

Officially, Dreadnoughtus is the largest known dinosaur. Dreadnoughtus is a titanosaur. The official name of this group is Titanosauria, which is a group of sauropods (long-necked dinosaurs) that includes other gigantic dinosaurs such as Argentinosaurus and Futalognkosaurus. The titanosaurs also included some smaller sauropods, such as Rapetosaurus and Saltasaurus. Regardless of size, however, the titanosaurus were all heavy, stocky animals. Thus, even though Dreadnoughtus had a mass of 59,300 kilograms (about 130,700 pounds), it was “only” 26 meters long (85 feet long).[1] To help put this in perspective, the largest familiar dinosaur is Giraffatitan (which is similar to, and often confused with, Brachiosaurus), which has an estimated mass of of around 35,000 kilograms (about 77,000 pounds)[2] and a length of 23 meters (75 feet).[3] 

A reconstruction of Dreadnoughtus. Modified from Lacovara, Kenneth; Matthew Lamanna; Lucio Ibiricu; Jason Poole; Elena Schroeter; Paul Ullmann; Kristyn Voegele; Zachary Boles; Aja Carter; Emma Fowler; Victoria Egerton; Alison Moyer; Christopher Coughenour; Jason Schein; Jerald Harris; Rubén Martínez; and Fernando Novas (2014) “A Gigantic, Exceptionally Complete Titanosaurian Sauropod Dinosaur from Southern Patagonia, Argentina” Scientific Reports 4:6196

Now, Dreadnoughtus was likely not thee largest dinosaur to have lived. It is considered to be the largest dinosaur known simply because it is the most complete large dinosaur. Other titanosaurs, such as Argentinosaurus, are thought to have been even larger, but as their remains are fragmentary, it is impossible to get good estimates of their sizes.

As large as Dreadnoughtus was, there is another dinosaur that, if its size estimates are accurate, would dwarf Dreadnoughtus. That dinosaur is Amphicoelias fragillimus.[4] It is estimated to have been 190 feet long and weighed around 122,400 kilograms (around 269,800 pounds).[5] Such a size not only dwarfs the next largest dinosaur, it rivals the largest of whales (such a mass would make Amphicoelias fragillimus larger than the average but less than the maximum size of a blue whale). That is a phenomenal size!

A Diplodocus model next to a human. The Diplodocus is scaled to be the size of Diplodocus hallorum. Note the long neck and very long tail. These were very long giant dinosaurs.

Let us put Amphicoelias fragillimus in perspective. Unlike Dreadnoughtus, Amphicoelias fragillimus is classified as a diplodocid (family Diplodocidae).[6] Diplodocids are represented by Diplodocus, Apatosaurus, and Brontosaurus. As a group. they are some of the longer, leaner dinosaurs. Their bodies are relatively small, but they have long necks and very long, whip-like tails. To give an example of their size, one of the longest of the diplodocids, Diplodocus hallorum (formerly called Seismosaurus hallorum[7]) has an estimated length of 33 meters (108 feet).[8] Despite being longer than Dreadnoughtus, it probably weighed less, and would thus be considered a smaller animal. As such, diplodocids are some of the longest of dinosaurs but are not the largest.  

The same model, but this time scaled to the size of Amphicoelias fragillimus. It would be nearly twice as long as Diplodocus hallorum.
To help put the massive size of Amphicoelias fragillimus in perspective, here is Diplodocus hallorum (on the left) and Amphicoelias fragillimus (on the right) scaled to the Ark. As a note, I have seen at least one person mock the Ark account because Amphicoelias fragillimus simple could not have fit on it. It has been said time and again, but it bears repeating, Noah brought kinds on the Ark, not species. Noah did not take the largest species on the Ark, but smaller species of the same kind.

The reason I am calling Amphicoelias fragillimus by its full name (genus and species) rather than by its genus name alone is because Amphicoelias fragillimus is the second named Amphicoelias species. The first named species, Amphicoelias altus, was large, but more typical in size of a large diplodocid. In fact, some paleontologists believe that Amphicoelias altus is just a type of Diplodocus,[9] and would thus be a relatively normal animal. Thus, it is important to distinguish the two species of Amphicoelias as only one of them (A. fragillimus) is a controversial giant.

Both A. altus and A. fragillimus were named by the same person: Edward Drinker Cope. Cope was one of the combatants in the Great Bone Wars. He fought this war against Othniel Charles Marsh. Both men worked frantically to one-up each other with their paleontological discoveries. The story goes that the war began when Cope described Elasmosaurus. Elasmosaurus is the most well known of the large, long-necked plesiosaurs. In Cope’s original paper describing the animal, he illustrated Elasmosaurus with a long tail and a short neck. He did this because he put the head on the tail and mistook the long neck as a long tail. Marsh pointed out Cope’s error, which embarrassed Cope so much that he attempted to find every copy of his humiliating paper, to wipe out the memory of what happened. The truth is, Cope and Marsh were starting to get on each other’s nerves before the Elasmosaurus incident, but that broke the proverbial camel’s back. It was all out war at that point, with each man trying to out do each other and name more new species than the other.

As childish as the Great Bone Wars sounds, it greatly expanded the knowledge of fossils in America. Many, many new species, some of which have become classics, were discovered during this time. Creatures such as Allosaurus, Stegosaurus, Ceratosaurus, Brontosaurus, Apatosaurus, Diplodocus, Camarasaurus, Triceratops, Pteranodon, Elasmosaurus, Edaphosaurus, and others were named by Marsh or Cope. However, such eagerness to name new species did lead to errors. For example, a single animal, Uintatherium anceps, was given 29 different species names, all but four given by Marsh or Cope.[10] The point is, Cope and Marsh were certainly capable of making errors in their rush to one-up each other.

Which brings us back to Amphicoelias fragillimus. Even though it is reputed to be the largest dinosaur that ever lived, it is based on a single drawing of a partial vertebra by Cope. Technically, Cope found two bones: a partial vertebra and a fragment of a femur.[11] In his description of the dinosaur, Cope described and illustrated the vertebra but the femur got little more than a mention. Unfortunately, both bones disappeared. The reason is unknown, though it is suspected that the bones were badly damaged and destroyed. After all, the species (fragillimus) is named after how fragile the remains were. The point is, the one and only thing we have to show us what Amphicoelias fragillimus was is Cope’s illustration and description of the vertebra.

Cope’s illustration of the vertebra of Amphicoelias fragillimus. This is the only remains we have of this controversial giant. Illustration taken from Carpenter, Kenneth (2006) “Biggest of the Big: A Critical Re-Evaluation of the Mega-Sauropod Amphiocoelias fragillimus Cope, 1878″ in Paleontology and Geology of the Upper Jurassic Morrison Formation, New Mexico Museum of Natural History and Science Bulletin, 36, Foster, J. R. and S. G. Lucas, eds., pg. 131-137

While some paleontologists accept that Amphicoelias fragillimus was a real animal,[12] others suggest that the dimensions of the vertebra given by Cope were in error.[13] Let me detail this critique a little bit.

In his description, Cope gives four specific dimensions of the vertebra: the height of the remains of the vertebra, which was given as 1500 mm; the neural arch height, which is 190 mm; the transverse expanse of posterior zygapophyses, which is 585 mm; and the elevation of the posterior zygapophyses, which is 390 mm.[14] If these dimensions don’t mean anything to you, that is okay. The points I want to make are these: notice that the height of the vertebra is not given. That is because the vertebra is so incomplete, an accurate height cannot be given. Roughly half of the height of the vertebra is actually preserved. The rest had to be reconstructed by Cope, and every other paleontologist after him. The second thing to note is that there was scant detail about the vertebra from Cope, aside from his illustration. There is simply not a lot to go on with the single illustration and description of Amphicoelias fragillimus.

Now, here comes a key criticism of the accuracy of Cope’s illustration: it has been noted that if one uses a height of 1500 for the illustrated vertebra and measures the other three dimensions given by Cope, then the dimensions of the illustration are all too large compared to the dimensions given in the text. However, if one assumes that Cope made a transcription error and instead uses a height of 1050 mm for the remains of the vertebra, then the other dimensions in the illustration get closer to the dimensions described in the text.[15] If the vertebra remains are indeed only 1050 mm tall, instead of 1500 mm, the vertebra remains big, but it is only a little bit larger than a typical diplodocid, rather than being gigantic.

Other paleontologists insist that there is no need to question the accuracy of Cope’s dimensions and illustrations. It is claimed that Cope’s illustrations have stunning accuracy and that other paleontologists confirmed that Cope indeed found a gigantic vertebra.[16] I want to comment about both of these arguments. First, I don’t think it matters how accurate someone usually is: everyone, even the most meticulous person, can make a mistake. The fact remains that the dimensions of the illustration do not match the dimensions given in the text. That has to be reconciled somehow, regardless of how accurate Cope’s illustrations usually are. Second, the paleontologist who confirmed Cope’s discovery did not confirm a height of 1500 mm for the height of the vertebra remains. He instead confirmed a reconstructed height of six feet for the whole vertebra. Thus, we don’t have any real confirmation that the crucial bit of information, a height of the actual remains of 1500 mm, was accurate or not.

There are other arguments that have been put forth to argue that Amphicoelias fragillimus could not be as large as it was originally reconstructed. One of these is that it is too big. Not necessarily too big of a body for an animal to be able to move or breathe, but too big of body to be fed on a day to day basis.[17] Basically, the argument is that the animal would not be able to eat enough food to sustain a body of that size.

A model of Nigersaurus scaled to the model of a human. Nigersaurus is one of the best known members of the family Rebbachisauridae. It was a relatively small sauropod, but other members got larger. Note that the proportions of this model are not entirely accurate. For example, the head should be smaller. Nevertheless, it shows what a typical rebbachisaurid would look like.

Which brings us to our final, interesting wrinkle in the debate over Amphicoelias fragillimus. It has recently been renamed as Maraapunisaurus fragillimus and reclassified as a rebbachisaur.[18] Certain details of the vertebra have been noted that are more similar to rebbachisaurs (family Rebbachisauridae) than they are to diplodocids. Rebbachisaurs are similar to diplodocids: they both belong to the same subgroup of sauropods, but they have notably shorter necks and tails. Thus, a reconstruction of Maraapunisaurus as a rebbachisaur gives it a length of “only” 32 meters (104 feet).[19] That would still likely make it the largest sauropod known, but it puts it in the same league as the titanosaurs, rather than being an order of magnitude larger. Plus, it helps answer the argument that Amphicoelias fragillimus would not be able to eat enough to stay alive.

The same model as the previous illustration, but scaled to the size of Maraapunisaurus.
The Ark with Diplodocus hallorum, Amphicoelias fragillimus, and Maraapunisaurus. Note that Maraapunisaurus is a more reasonable size compared to Amphicoelias fragillimus, though it is still colossal.

I believe that the information for Maraapunisaurus is a little too fragile (pun intended) to accept. As already explained, regardless of what one thinks of Cope and the accuracy of his drawings, there is a discrepancy between his illustration and the dimensions he described in the text of his paper. Plus, and this is a significant argument for me, no new remains of anything that large has been found in the Morrison Formation since.[20]  The Morrison Formation is the layer of rock where the remains of Maraapunisaurus were found. Since the remains were found in 1878, there has been close to 150 years time for more remains of this giant to be found. Yet, nothing more has turned up, despite the fact that the Morrison Formation is one of the most researched and best accessed dinosaur-bearing strata in the world. As rare as fossils of Maraapunisaurus may be, it should be found again eventually. Until such a time may happen, I am going to treat the existence of a gigantic diplodocid or rebbachisaur in the Morrison Formation with skepticism.

Now, why go through all of this? Why spend all this time to describe a missing fossil just to say that I doubt it represents anything special? First of all, because it is an interesting story. While I don’t accept that there was a colossal sauropod in the Morrison Formation, the slight possibility that it may be there is intriguing. Second, Amphicoelias fragillimus and Maraapunisaurus are not that familiar to people (the truth is, most paleontologists just ignore it because of is fragmentary remains and sketchy reconstructions) but you can find references to it occasionally. So, if you every ran across a reconstruction of a truly massive sauropod, you now know where it is coming from. Thirdly, the entire story is a lesson in why paleontology, and any science, for that matter, needs to be conducted with the utmost care. Do you know what could put to rest the debate of Maraapunisaurus? Actually having the remains preserved today. To his credit, Cope tried to do just that, but despite his efforts, the remains went missing and now we are left wondering what it was that he found. Recording, documenting, and preserving remains is crucial for science to prevent this kind of confusion from happening.

Finally, not all controversies are driven by ideology. This last purpose of the story may seem odd, so let me explain. Creationists often question the reconstructions of dinosaurs, other extinct animals, and past life in general because our worldview of history is radically different from that of secular scientists. Thus, when we focus on debatable topics, we often focus on a subject that is colored by the creation/evolution controversy. Doing so can sometimes leave the impression that the controversial topics in science only exist because evolutionists deliberately confound the subject to promote their ideology. Such is not the case. Science, any subject in science, is riddled with controversial topics for the simple reason that there is still a lot we do not know about the world in which we live. I believe I have said it before, but science is messy. Science is not made messy by evolutionists, it is messy by its nature. Sure, evolutionists are able to insert their ideology into the various gaps left in science, but those gaps exist regardless of what worldview we espouse. Maraapunisaurus reminds us that science and its interpretation is never as easy as we wish it would be.

Thoughts from Steven


[1]Lacovara, Kenneth; Matthew Lamanna; Lucio Ibiricu; Jason Poole; Elena Schroeter; Paul Ullmann; Kristyn Voegele; Zachary Boles; Aja Carter; Emma Fowler; Victoria Egerton; Alison Moyer; Christopher Coughenour; Jason Schein; Jerald Harris; Rubén Martínez; and Fernando Novas (2014) “A Gigantic, Exceptionally Complete Titanosaurian Sauropod Dinosaur from Southern Patagonia, Argentina” Scientific Reports 4:6196. Note that the estimation of a dinosaur mass can be difficult, so there are other estimates of the mass of Dreadnoughtus. See Bates, Karl; Peter Falkingham; Sophie Macaulay; Charlotte Brassey; and Susannah Maidment (2015) “Downsizing a giant: Re-evaluating Dreadnoughtus body mass” Biology Letters 11:20150215 for a different estimate.

[2]Bates, Karl; Peter Falkingham; Sophie Macaulay; Charlotte Brassey; and Susannah Maidment (2015) “Downsizing a giant: Re-evaluating Dreadnoughtus body mass” Biology Letters 11:20150215

[3]Janensch, Werner (1950) ” The Skeleton Reconstruction of Brachiosaurus brancaiPalaeontographica Supp. 7:97-103

[4]Technically, it is now called Maraapunisaurus fragillimus, but we will get to that later.

[5]Carpenter, Kenneth (2006) “Biggest of the Big: A Critical Re-Evaluation of the Mega-Sauropod Amphiocoelias fragillimus Cope, 1878″ in Paleontology and Geology of the Upper Jurassic Morrison Formation, New Mexico Museum of Natural History and Science Bulletin, 36, Foster, J. R. and S. G. Lucas, eds., pg. 131-137

[6]With its reclassification as Maraapunisaurus, it would belong to a different family, but again, we will get to that later.

[7]Lucas, Spencer; Justin Speilmann; Larry Rinehart; Andrew Heckert; Matthew Herne; Adrian Hunt; John Foster; Robert Sullivan (2006) “Taxonomic Status of Seismosaurus hallorum, a Late Jurassic Sauropod Dinosaur from New Mexico” in Paleontology and Geology of the Upper Jurassic Morrison Formation, New Mexico Museum of Natural History and Science Bulletin, 36, Foster, J. R. and S. G. Lucas, eds., pg. 149-161

[8]Herne, Matthew and Spencer Lucas (2006) “Seismosaurus hallorum: Osteological Reconstruction from the Holotype” in Paleontology and Geology of the Upper Jurassic Morrison Formation, New Mexico Museum of Natural History and Science Bulletin, 36, Foster, J. R. and S. G. Lucas, eds., pg. 139-148

[9]Woodruff, D. Cary and John Foster (2014) “The fragile legacy of Amphicoelias fragillimus (Dinosauria: Sauropoda; Morrison Formation — latest Jurassic)” Volumina Jurassica 12(2): 211-220

[10]Wheeler, Walter (1961) “Revision of the Uintatheres” Peabody Museum of Natural History Yale University, Bulletin 14, pg. 1-128

[11]Woodruff, D. Cary and John Foster (2014) “The fragile legacy of Amphicoelias fragillimus (Dinosauria: Sauropoda; Morrison Formation — latest Jurassic)” Volumina Jurassica 12(2): 211-220

[12]See, for example, Carpenter, Kenneth (2006) “Biggest of the Big: A Critical Re-Evaluation of the Mega-Sauropod Amphiocoelias fragillimus Cope, 1878″ in Paleontology and Geology of the Upper Jurassic Morrison Formation, New Mexico Museum of Natural History and Science Bulletin, 36, Foster, J. R. and S. G. Lucas, eds., pg. 131-137

[13]Woodruff, D. Cary and John Foster (2014) “The fragile legacy of Amphicoelias fragillimus (Dinosauria: Sauropoda; Morrison Formation — latest Jurassic)” Volumina Jurassica 12(2): 211-220

[14]Ibid.

[15]Ibid.

[16]Carpenter, Kenneth (2018) “Maraapunisaurus fragillimus, N.G. (Formerly Amphicoelias fragillimus), A Basal Rebbachisaurid From the Morrison Formation (Upper Jurassic) of Colorado” Geology of the Intermountain West 5: 227-244

[17]Woodruff, D. Cary and John Foster (2014) “The fragile legacy of Amphicoelias fragillimus (Dinosauria: Sauropoda; Morrison Formation — latest Jurassic)” Volumina Jurassica 12(2): 211-220

[18]Carpenter, Kenneth (2018) “Maraapunisaurus fragillimus, N.G. (Formerly Amphicoelias fragillimus), A Basal Rebbachisaurid From the Morrison Formation (Upper Jurassic) of Colorado” Geology of the Intermountain West 5: 227-244

[19]Ibid.

[20]Woodruff, D. Cary and John Foster (2014) “The fragile legacy of Amphicoelias fragillimus (Dinosauria: Sauropoda; Morrison Formation — latest Jurassic)” Volumina Jurassica 12(2): 211-220