Biggest.... sauropod.... ever (part.... I)

Hope you had a good Christmas - I did! Here's an old article from Tet Zoo ver 1, apologies if you recall it from its first airing in 2006. The article is now a bit dated - sorry about that (I've added one or two new bits).


Even if you're not an expert on dinosaurs, it's likely that you've heard - firstly - that some sauropods were rily, rily big and - secondly - that these biggest of the big included such whoppers as Seismosaurus, Supersaurus and Argentinosaurus. It's always helpful that their names are easy to remember. Recent work has not only resulted in the publication of reasonably accurate size estimates for these dinosaurs, it has also clarified their taxonomy and phylogenetic positions.


Supersaurus vivianae from the Morrison Formation of Colorado is, despite its name, a valid taxon - specifically it's a diplodocid diplodocoid, and apparently an apatosaurine (the image at the top of page shows a new skeletal mount of this taxon). Recent estimates put its total length at 33 m. The most oft-figured bit of Supersaurus is its enormous scapulocoracoid: it's usually depicted with the late Jim Jensen, its discoverer and describer, lying alongside it. For a change, here (at left) is a curious new take on the theme (borrowed from here). Oh, and if you're wondering about Ultrasauros (originally informally named Ultrasaurus: note the spelling difference), it's no longer regarded as a valid taxon as the type material - a posterior dorsal vertebra - was shown by Brian Curtice and colleagues (Curtice et al. 1996) to belong to Supersaurus (come back Brian, all is forgiven!). The famous Ultrasauros scapulocoracoid doesn't belong together with the vertebra, and has mostly been regarded as belonging to Brachiosaurus (either to Brachiosaurus sp. or to Brachiosaurus altithorax. In the most recent appraisal of the specimen, Taylor (2009) supported the latter referral). Below, you can see dead fish expert Graeme Elliott standing alongside the Ultrasauros scapulocoracoid (go here for hilarious caption, sorry Graeme).


Moving on, Seismosaurus hallorum (originally described as S. halli), from the Morrison Formation of New Mexico, is also a diplodocid diplodocoid, but recent work indicates that it is not generically distinct from Diplodocus and should thus be renamed Diplodocus hallorum. Originally claimed to be over 40 m long, new estimates put it between 30 and 35 m. Supersaurus and Diplodocus hallorum, being relatively gracile diplodocids, probably weighed between 25 and 50 tons (Paul 1994a, b, 1997).

A few more super-sauropods have been added to the list in recent years. Most are titanosaurs, the predominantly Cretaceous sauropod clade originally thought to be late-surviving relatives of diplodocoids but now known to be close kin of the short-skulled brachiosaurs. Argentinosaurus huinculensis, named in 1993, is a huge titanosaur from the Upper Cretaceous RÃo Limay Formation of Argentina: it was perhaps 30 m long. Paralititan stromeri is another massive titanosaur, this time from the Upper Cretaceous of Egypt. Estimated by its describers as having been around 30 m long, it has more recently been down-sized to a mere 26 m (the image below is Todd Marshall's painting of Paralititan, taken from here). Puertasaurus reuili, named in 2005 and from the Upper Cretaceous Pari Aike Formation of Argentina, was similar in size to these forms. Finally, Turiasaurus riodevensis is a gigantic Spanish form, and it's not a titanosaur, belonging instead to a hitherto unrecognised clade termed Turiasauria. It was described at the end of 2006 (go here for more) and is one of the biggest sauropods known, with an estimated length of 36-39 m.


Exactly how heavy these mega-sauropods were is mildly controversial. Accurate mass estimates generally agree that they were on the order of 80-90 tons, but Royo-Torres et al. (2006), the describers of Turiasaurus, put this animal at half this. However, they used a notoriously unreliable method of estimating weight.

While you might have heard of Supersaurus, Seimosaurus or Argentinosaurus - and perhaps even Turiasaurus and Paralititan - have you heard of... Amphicoelias fragillimus? Well, ok, if you're a dinosaur ubernerd then the answer will be yes, but not if you're a normal person. Though described as long ago as 1878, this sauropod has remained decidedly obscure and hardly heard of until pretty recently. I've done my part for the cause, having mentioned it at every opportunity: in both Dinosaurs of the Isle of Wight, and Walking With Dinosaurs: The Evidence, it's discussed and touted as, possibly, the biggest sauropod of them all. Naish & Martill (2001), for example, stated 'What has recently been claimed as the biggest of all sauropods and, indeed, the biggest of all land animals, is actually a specimen discovered in 1878. Based only on a single enormous vertebra, now lost, Amphicoelias fragillimus has been estimated to have reached a length of 60 m and may have attained a weight of 150 tons!' (p. 230). If these estimates are valid, then this animal was twice as long as Supersaurus and Diplodocus, and perhaps over four times heavier. Err, gosh.

Amphicoelias fragillimus, giant of giants


In August 1878 the famous and prolific scientist* Edward Drinker Cope (1840-1897), shown here, described a new super-sauropod, Amphicoelias fragillimus, from the Garden Park quarries of the Morrison Formation of Colorado. It was represented only by an incomplete dorsal vertebra and the distal end of a femur (contra Naish & Martill above: whoops!). A good drawing of the vertebra was provided (Cope 1878), showing that this sauropod was clearly a diplodocoid: a member of the same sauropod clade as Diplodocus, Apatosaurus and their relatives (the name Diplodocimorpha is also sometimes used for these animals: see Taylor & Naish 2005: free pdf). The big deal is how, err, big these remains were. The partial vertebra had a preserved height of 1.5 m and, when reconstructed on the basis of comparison with complete diplodocoid vertebrae, has a total height of 2.7 m. Again... gosh (or words to that effect) [Amphicoelias fragillimus compared to a person below, from wikipedia].

* Though usually described (by palaeontologists) as a palaeontologist, Cope was also an accomplished herpetologist and ichthyologist, which explains the name of the journal Copeia.

i-44e1985034973e204dceb3f8f3cd8517-Human-amphicoelias_size_comparison_wikipedia-Dec-2009 copy.jpg

If history were fair, we would all have grown up familiar with Cope's hyper-enormous Amphicoelias fragillimus, and we would be less impressed by Brachiosaurus and Balaenoptera, let alone with paltry little 20-m long sauropods like 'Angloposeidon' (go here). But it was not to be, and it was to sink into the morass of obscurity. In a major 1921 review of Cope's sauropods, Henry Fairfield Osborn and Charles Mook noted that they were unable to locate the immense vertebra in Cope's sauropod collection (Osborn & Mook 1921), today at the American Museum of Natural History (New York). It was lost.

And... I'll have to stop there. The rest of the story will come in part II. It concentrates on those recent studies that have looked at this species, and one of the most-asked questions about this remarkable dinosaur: was it a hoax? Stay tuned, all will be revealed.

For previous Tet Zoo posts on sauropods see...

And - if you're serious about sauropods - you really should be spending more time at SV-POW!

Refs - -

Cope, E. D. 1878. A new species of Amphicoelias. American Naturalist 12, 563-565.

Curtice, B. D., Stadtman, K. L. & Curtice, L. J. 1996. A reassessment of Ultrasauros macintoshi (Jensen, 1985). In Morales, M. (ed) The Continental Jurassic. Museum of Northern Arizona Bulletin 60, 87-95.

Davidson, J. P. 2002. Bonehead mistakes: the backround in scientific literature and illustrations for Edward Drinker Cope's first restoration of Elasmosaurus platyurus. Proceedings of the Academy of Natural Sciences of Philadelphia 152, 215-240.

McIntosh, J. S. 1998. New information about the Cope collection of sauropods from Garden Park, Colorado. Modern Geology 23, 481-506.

Naish, D. & Martill, D. M. 2001. Saurischian dinosaurs 1: Sauropods. In Martill, D. M. & Naish, D. (eds) Dinosaurs of the Isle of Wight. The Palaeontological Association (London), pp. 185-241.

Osborn, H. F. & Mook, C. C. 1921. Camarasaurus, Amphicoelias and other sauropods of Cope. Memoirs of the American Museum of Natural History, n.s. 3, 247-287.

Paul, G. S. 1994a. Is Garden Park home to the world's largest known land animal? Tracks in Time 4 (5), 1.

- . 1994b. Big sauropods - really, really big sauropods. The Dinosaur Report Fall 1994, 12-13.

- . 1997. Dinosaur models: the good, the bad, and using them to estimate the mass of dinosaurs. In Wolberg, D. L., Stump, E. & Rosenberg, G. D. (eds) Dinofest International: Proceedings of a Symposium Sponsored by Arizona State University. Academy of Natural Sciences (Philadelphia), pp. 129-154.

Royo-Torres, R., Cobos, A. & Alcalá, L. 2006. A giant European dinosaur and a new sauropod clade. Science 314, 1925-1927.

Taylor, M. P. 2009. A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914). Journal of Vertebrate Paleontology 29, 787-806.

- . & Naish, D. 2005. The phylogenetic taxonomy of Diplodocoidea (Dinosauria: Sauropoda). PaleoBios 25, 1-7.

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Well, given the new weighing method for dinosaurs Amphicoelias may actually have weighed no more than 60 or 70 tons, about as much as Argentinosaurus and Sauroposeidon are now thought to have weighed. The length is still up in the air though.

By gray Stanback (not verified) on 28 Dec 2009 #permalink

I laughed my ass off when I saw that caption. Also, with regards to Seismosaurus, I've read that some scientists go even further with the lumping, classifying it as a large Diplodocus longus.

Dare I hope that there might be a new, giant sauropod-related reason to reposting this classic?

By Adam Pritchard (not verified) on 28 Dec 2009 #permalink

The Mamenchisaurus specimen shown at the recent exhibition in Chiba in Japan was reportedly 35m long.
This compares well with Supersaurus and D. hallorum.
It would be interesting to know more about this.
Was it a M. sinocanadorum or something else.
It would be a lightweight compared to some of the other sauropods mentioned but it must have had an insanely long neck if it had the proportions of other smaller Mamenchisaurus species.


It's great to see this classic Tet Zoo V1 article getting another outing, and I'm looking forward to seeing all the comments once people return after Christmas.

A few mistakes though:

Most obviously, you forgot to paste in the oh-so-hilarious image of the Supersaurus scap., so it seems like you're saying the "Ultrasaurus" scap. in the photo with Graeme belongs to Supersaurus. Just to confirm for anyone who was misled by this, Graeme is standing with BYU 9462, the large brachiosaurid scapulocoracoid that Jensen (1985) referred to his then-new genus "Ultrasaurus" (subsequently renamed Ultrasauros as there was already an Ultrasaurus, a Korean sauropod inadequately described by Kim (1983)). Throw in the fact that Jensen's paper (and subsequently Paul (1888)) used the temporary specimen number BYU 5001 for this element and the confusion would seem to be complete.

By the way, anyone who wants to see true Supersaurus scapulae should be able to slake their thirst at…

Regarding what the "Ultrasauros" scapulocoracoid actually represents, it's not really true that Taylor (2009) supported referral to Brachiosaurus altithorax. What I actually wrote (p789) was:

Curtice et al. (1996:95) referred this element to Brachiosaurus sp., citing the narrow scapular neck, distal blade expansion and irregular shape of the coracoid as brachiosaurid characters (Curtice et al., 1996:93), and Paul, (1988:6-7) referred it specifically to B. altithorax. Its coracoid, however, does not closely resemble that of the B. altithorax holotype, lacking the the latter's distinctively strong lateral deflection of the glenoid. Neither is the scapula very similar to that of B. brancai, having a less pronounced acromion process -- compare Curtice et al. (1996:fig. 1a) with Janensch (1961:pl. XV figs. 1 and 3a). As shown by Curtice et al. (1996:table 1), the coracoid of the "Ultrasauros" scapulocoracoid is smaller in both length and breadth than that of the Brachiosaurus altithorax holotype FMNH P 25107 (Riggs 1904:241); so the Dry Mesa brachiosaur, often cited as unusually large, was most likely rather smaller than the holotype. In conclusion, none of the Dry Mesa material described by Jensen can be confidently referred to Brachiosaurus altithorax.

(Since we know coracoid shapes and sizes can be pretty variable between individuals, I do think it's perfectly possible that BYU 9462 might indeed by B. altithorax, but we don't yet have enough evidence to support that claim at anything more than the level of a suggestion.)

Ian (comment #2) is right that Lovelace et al. (2008) considered Seismosaurus hallorum not merely a species of Diplodocus, but synonymous with Diplodocus longus, having found (pp538-539) that is was scored identically with that species in their matrix. This corroborates the tentative suggestion of Lucas et al. (2006), and seems to put the tin lid on the resonant name Seismosaurus.

Finally, I am not sure what "new weighing method for dinosaurs" gray Stanback has in mind (comment #1), but I assure you that if Amphicoelias fragillimus really was as big as it's recently been credibly reconstructed, then there is absolutely no way on Earth that it massed as little as 60 or 70 tonnes. It just isn't possible. I'll say no more for now, because I don't want to tread on the toes of Darren's Part 2.

The biggest sauropod?

Well aside from Amphicoelias fragillimus (of which new remains have so far not materialized) and Bruhathkayosaurus (which flat out frustrates me due to no decent published photos or diagrams)... I'd say there's one real giant among giants:

PUERTASAURUS. IMO it's the biggest dinosaur we have good, well-described, and currently extant evidence for. So for now, it's the DE FACTO biggest in a sense...

Further down the scale, you have six other huge titanosaurs all in roughly the same size and weight range...

Thanks for comments. With regard to Mike's comments about my confusing mis-use of the 'Ultrasauros' scap-coracoid BYU 9462, I had screwed up by putting the image of Graeme and BYU 9462 next to the wrong bit of text. Have now corrected this, and have added the pic of the lady... hopefully all is now clear.

Does Taylor (2009) support referral of BYU 9462 to Brachiosaurus altithorax? Indeed he does: despite the caveats used in the text on p. 788, the specimen is specifically referred to Brachiosaurus altithorax on p. 798, though it is noted that 'Not all referrals are certain'. Most readers will, like me, conclude from this that you ARE supporting referral of BYU 9462 to Brachiosaurus altithorax, even though you can't be 100% sure about it. In fact the 'cannot be confidentally referred' statement on p. 788 seems somewhat contradictory to the inclusion of the specimen in the list of referred specimens on p. 798.

for those of us (such as myself) who missed this the first time around, thank you for re-posting it.

I read the article thrice - partly to be sure I was understanding which is bigger than which, and partly to know whether the lovely lady leaning on a (arm?) bone was meant for this page. (or if internet coding was pulling a fast one on us all - it's been known to do that, after all).

thank you for sharing this. and poor Cope.

By Anthony Docimo (not verified) on 29 Dec 2009 #permalink

It's not so much a new method as it is the reasoning that since sauropods had large airsacs in their bodies, they may have weight as little as half of what we thought originally. Also, when the skeletons of elephants, hippos, rhinos, and other big mammals were weighed using the method for estimating the masses of dinosaurs, the masses were WAY off--sometimes by up to 75%.

By gray Stanback (not verified) on 29 Dec 2009 #permalink

(arm?) bone

Shoulder blade.

Incidentally, in all those photos the ladies tend to be off scale. Too small, that is.

By David MarjanoviÄ (not verified) on 30 Dec 2009 #permalink

What happened with these theoretical estimations how much a land animal could weigh?

It seemed obvious to me that the referral list on p798 of Taylor (2009) was merely a summary of the much more detailed discussions on previous pages, and should be interpreted in that light. Evidently I was wrong -- I did not make it obvious. Well, now you know: that was my intent. In case it's still not clear, let me say right out that I do not think there is compelling reason to think that BYU 9462 belongs to B. altithorax.

gray Stanback, check out Matt Wedel's fine 2005 book chapter on the effect of air-sacs on (among other things) lightening sauropods. You can get it for free at -- in a nutshell, the mass reduction was likely around 8-10% (p220). Figures a little higher than that could be supported, but 50% is ludicrous.

"and Bruhathkayosaurus [sic] (which flat out frustrates me due to no decent published photos or diagrams)..."

B. frustrates me too, especially since the published description asigned it to Theropoda and nobody seems to know why it was ever moved to the Sauropoda. I hope it wasn't just because "it seems way too big to be a theropod"; that's completely unscientific.

By Michael O. Erickson (not verified) on 31 Dec 2009 #permalink

The spelling Bruhathkayosaurus is correct.

that's completely unscientific

No, it's based on fairly obvious ecological considerations... but of course it needs to be tested, and that still hasn't happened.

By David MarjanoviÄ (not verified) on 01 Jan 2010 #permalink

I think isn t in the second photo?

By piese auto (not verified) on 03 Jan 2010 #permalink

in all those photos the ladies tend to be off scale. Too small, that is.

Surely that's a matter of personal preference?

By John Scanlon FCD (not verified) on 03 Jan 2010 #permalink

"The spelling Bruhathkayosaurus is correct."

I actually put the "[sic]" there because the name wasn't italicized... I wanted people to know that that was becasuse that's how the original message was written, not something of my doing. I'm just a stickler for the proper italicization of scientific names.

"No, it's based on fairly obvious ecological considerations... but of course it needs to be tested, and that still hasn't happened."

Well, the lack of testing is mainly what I was referring to - but I still think that from a scientific standpoint, "it's too big" ain't all that compelling. Makes good common sense, yeah, but it's not really that scientific.

By Michael O. Erickson (not verified) on 03 Jan 2010 #permalink

It's an argument from parsimony. "Compelling" and "scientific" isn't the same thing. :-)

By David MarjanoviÄ (not verified) on 04 Jan 2010 #permalink

I also wonder about that Mamanchisaurus that Lee B. mentions. If that really is 35 m, and if it's actually based an a reasonable amount of bones, shouldn't that be the longest?(Ignoring Amphicoelias fragillimus ) Allegedly it's based on a find from 2001, but I couldn't find anything relevant info about it?
If it's the same species as the the other, more complete finds, it should be much easier to reconstruct, at last dimensionally, compared to the other giant sauropods, (perhaps)? The neck must be really long, perhaps 16 metres or so?