How big was Amphicoelias fragillimus? I mean, really?

February 19, 2010

Lovers of fine sauropods will be well aware that, along with the inadequately described Indian titanosaur Bruhathkayosarus, the other of the truly super-giant sauropods is Amphicoelias fragillimus.  Known only from a single neural arch of a dorsal vertebra, which was figured and briefly described by Cope (1878) and almost immediately either lost or destroyed, it’s the classic “one that got away”, the animal that sauropod aficionados cry into their beer about late at night.

Amphicoelias fragillimus, holotype dorsal vertebral neural arch in posterior view. From Osborn and Mook (1921:fig. 21), which in turn was gently tweaked from Cope (1878:unnumbered and only figure).

I’m not going to write about A. fragillimus in detail here, because Darren’s so recently covered it in detail over at Tetrapod Zoology — read Part 1 and Part 2 right now if you’ve not already done so.  The bottom line is that it was a diplodocoid roughly twice as big as Diplodocus in linear dimension (so about eight times as heavy).  That makes it very very roughly 50 m long and 100 tonnes in mass.

But Mike!, you say, Isn’t it terribly naive to go calculating masses and all from a single figure of part of a single bone?

Why, yes!  Yes, it is!  And that is what this post is about.

As I write, the go-to paper on A. fragillimus is Ken Carpenter’s (2006) re-evaluation, which carefully and tentatively estimated a length of 58 m, and a mass of around 122,400 kg.

As it happens, Matt and a colleague submitted a conference abstract a few days ago, and he ran it past me for comments before finalising.  In passing, he’d written “there is no evidence for sauropods larger than 150 metric tons and it is possible that the largest sauropods did not exceed 100 tons”.  I replied:

I think that is VERY unlikely. [...] the evidence for Amphicoelias fragillimus looks very convincing, Carpenter’s (2006) mass estimate of 122.4 tonnes is conservative, being extrapolated from Greg Paul’s ultra-light 11.5 tonne Diplodocus.

Carpenter’s estimate is based on a reconstruction of the illustrated vertebra, which when complete he calculated would have been 2.7 m tall.  That is 2.2 times the height of the corresponding vertebra in Diplodocus, and the whole animal was considered as it might be if it were like Diplo scaled up by that factor.  Here is his reconstruction of the vertebra, based on Cope’s figure of the smaller but better represented species Amphicoelias altus:

One possible reconstruction of the Alphicoelias fragillimus vertebra, from Carpenter (2006:fig. 1).  Part A is Cope’s original figure annotated with lamina designations; part C is Cope’s illustration of an Amphocoelias altus dorsal; part B is Carpenter’s reconstruction of the former after the latter.

Matt’s answer to me was:

First, Paul’s ultra-light 11.5 tonne Dippy is not far off from my 12 tonne version that you frequently cite, and mine should be lighter because it doesn’t include large air sacs (density of 0.8 instead of a more likely 0.7). If my Dippy had an SG of 0.7, it would have massed only 10.25 tonnes. Second, Carpenter skewed [...] in the direction of large size for Amphicoelias. I don’t necessarily think he’s wrong, but his favoured estimate is at the extreme of what the data will support. Let’s say that Amphicoelias was evenly twice as large as Dippy in linear terms; that could still give it a mass as low as 90 tonnes. And that’s not including the near-certainty that Amphicoelias had a much higher ASP than Diplodocus. If Amphicoelias was to Diplodocus as Sauroposeidon was to Brachiosaurus—pneumatic bones about half as dense—then 1/10 of its volume weighed ½ as much as it would if it were vanilla scaled up Dippy, and we might be able to knock off another 5 tonnes.

There’s lots of good stuff here, and there was more back and forth following, which I won’t trouble you with.  But what I came away with was the idea that maybe the scale factor was wrong.  And the thing to do, I thought, was to make my own sealed-room reconstruction and see how it compared.

So I extracted the A.f. figure from Osborn and Mook, and deleted their dotted reconstruction lines.  Then I went and did something else for a while, so that any memory of where those lines might have been had a chance to fade.  I was careful not look at Carpenter’s reconstruction, so I could be confident mine would be indepedent.  Then I photoshopped the cleaned A. fragillimus figure into a copy the A. altus figure, scaled it to fit the best as I saw it, and measured the results.  Here it is:

My scaling of a complete Amphicoelias fragillimus vertebra: on the left, Cope’s figure of the only known vertebra; on the right, Cope’s figure of an A. altus dorsal vertebra, scaled to match the preserved parts of the former.  Height of the latter scaled according to the measured height of the former.

As you can see, when I measured my scaled-to-the-size-of-A.f. Amphicoelias vertebra, it was “only” 2293 mm tall, compared with 2700 mm in Ken’s reconstruction.  In other words, mine is only 85% as tall, which translates to 0.85^3 = 61% as massive.  So if this reconstruction is right, the big boy is “only” 1.87 times as long as Diplodocus in linear dimension — maybe 49 meters long — and would likely come in well below the 100-tonne threshhold.  Using Matt’s (2005) 12-tonne estimate for Diplodocus, we’d get a mere 78.5 tonnes for Amphicoelias fragillimus.  So maybe Matt called that right.

Amphicoelias altus dorsal vertebra, almost certainly the holotype, in left lateral view, lying on its back.  Photograph by Matt Wedel, from the collections of the AMNH.  I can’t believe — can’t BELIEVE — that I didn’t take ten minutes to look at this vertebra when I was in that basement last February.  What a doofus.

The Punchline

Folks — please remember, the punchline is not “Amphicoelias fragillimus only weighed 78.5 tonnes rather than 122.4 tonnes”.  The punchline is “when you extrapolate the mass of an extinct animal of uncertain affinities from a 132-year-old figure of a partial bone which has not been seen in more than a century, you need to recognise that the error-bars are massive and anything resembling certainty is way misplaced.”

Caveat estimator!

References

  • Carpenter, Kenneth.  2006.  Biggest of the big: A critical re-evalustion of the mega-sauropod Amphicoelias fragillimus Cope, 1878.  pp. 131-137 in J. Foster and S. G. Lucas (eds.), Paleontology and Geology of the Upper Jurassic Morrison Formation.  New Mexico Museum of Natural History and Science Bulletin 36.
  • Cope, Edward Drinker.  1878.  Geology and Palaeontology: a new species of Amphicoelias.  The American Naturalist 12 (8): 563-566.
  • Osborn, Henry Fairfield, and Charles C. Mook.  1921.  Camarasaurus, Amphicoelias and other sauropods of Cope.  Memoirs of the American Museum of Natural History, n.s. 3:247-387, and plates LX-LXXXV.
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127 Responses to “How big was Amphicoelias fragillimus? I mean, really?”

  1. Jay Says:

    Excellent punchline!

  2. Andrea Cau Says:

    I agree with this extrapolation, and with the punchline. Once, I reconstructed the A.f. vertebra in a similar manner, and the animal resulted about 45-50 m long.

  3. Mike Keesey Says:

    “it’s the classic ‘one that got away'”

    Nice!

  4. Nathan Myers Says:

    And here I thought the punchline would be that size or mass estimates should never be reported or repeated without carrying along a figure quantifying the uncertainty of the estimate.

  5. Mike Taylor Says:

    In cases like this one, Nathan, I don’t really see how you could even come up with a meaningful figure to quantify the uncertainty — I surely wouldn’t like to give a 90% confidence interval or anything like that.

  6. Steveoc Says:

    I think when dealing with animals like this it is more useful to provide a range of estimates using as many different animals for comparison. What would happen if you use different diplodocid vertebra as a guide. What would happen if you used different diplodocid body plans as a guide etc.

    Still, I hope your smaller estimate is more correct. Giant dinosaurs are amazing but I think there is a limit to what I can take. I look at images of a 9-10m tall diplodocid and my puny human brain can’t comprehend it; I don’t want it to be real.

  7. Mike Taylor Says:

    Steveoc:

    That is why you fail.

  8. Jaime A. Headden Says:

    I tend to thing the carry away message here is that when taking vertebrae of incomplete preservation and applying them to apparent similar but also disimilar specimens, especially when those speicmens vary greatly in size, one makes so many assumptions that making any extrapolation thereupon unfalsifiable, and unverifiable.

    The seemingly true take-away here is that the material is not only incomplete, it is uncertain what its ASP actually was, it is uncertain what its position in the vertebral column was (especially given that the most similar specimen is incomplete relative to this question), and finally it is difficult without involving engineering constraints applied at higher volumes and scales to similar vertebrae will result in the same morphology when variation in species is used to quantify those same differences.

    It thus seems particular for anyone to make estimates of mass of an incredibly partial and missing vertebral fragment, from Cope, to Paul, to Carpenter, to Taylor or to Wedel.

  9. Matt Wedel Says:

    I tend to thing the carry away message here is that when taking vertebrae of incomplete preservation and applying them to apparent similar but also disimilar specimens, especially when those speicmens vary greatly in size, one makes so many assumptions that making any extrapolation thereupon unfalsifiable, and unverifiable.

    And this meaningfully extends the punchline Mike provided how?

    it is uncertain what its ASP actually was

    Yes, of course, but it’s not idle speculation to assume that its ASP was somewhat higher than that of Diplodocus. Cope, who had seen and worked on material from several Morrison sauropods, still gave the Big A the specific name of fragillimus (“most fragile”) because the bone was so delicate. That suggests that it was remarkably lightly built even for a sauropod, and Cope’s description confirms that.

    It thus seems particular for anyone to make estimates of mass of an incredibly partial and missing vertebral fragment, from Cope, to Paul, to Carpenter, to Taylor or to Wedel.

    Is it possible you meant to say “peculiar” instead of “particular”?

    Also, if I read you right–and please tell me if I’m wrong–you’re saying that the field of Amphicoelias mass estimation is so littered with uncertainty as to be a complete waste of time. But people are going to continue to be curious about these things and if someone asks, “How heavy might Amphicoelias have been?”, responding with, “There is no falsifiable or verifiable way to tell” is both unsatisfying, and incorrect. I can’t see how it does any harm to go ahead and make the estimates, especially if you are clear about what your assumptions were and about the massive uncertainty of the result–as pretty much all of the authors you mentioned have done.

    It’s incorrect because the mass of Amphicoelias is poorly constrained, not completely unconstrained. We can be pretty certain that it didn’t mass 40 tons or 300 tons. Could it have massed 80 tons, or 120 tons? Certainly, given different starting assumptions. For my part, I find the process of exploring how changing those assumptions changes the final answer to be illuminating in its own right.

    Finally, mass estimates for Amphicoelias are _not_ untestable, at least in principle. They are subject to the same test as almost every other paleontological hypothesis, which is confirmation or contradiction by further discoveries. If someone finds a complete articulated skeleton of Amphicoelias, then the range of possible sizes will shrink. If a further millennium of Morrison collecting turns up no animals larger than the BYU Supersaurus, that won’t prove that Cope’s illustration was inaccurate, but it will suggest that either the illo was incorrectly scaled or A. fragillimus was some kind of freak one-off and not an important player in Morrison paleoecology.

    I admit that hypothesis testing by the “wait and see” method may not be very satisfying either, but many times it’s all we’ve got.

  10. William Miller Says:

    Are there decent mass estimates for Amphicoelias altus? How pneumatic was it?

  11. Mike Taylor Says:

    No, to the best of my knowledge no-one has ever attempted a rigorous reconstruction or mass estimate for A. altus. It tends to get treated as “sort of like Diplodocus”.

  12. Mike B. Says:

    I know this may not be the right place, but I wanted to ask you about the “ultrasauros” scapulocoracoid, if it really belonged to B. altithorax, how much bigger than the type specimen it would be? I have read Paul’s paper and he says that it was about the same size as the HMN XV2 specimen of G. brancai.
    Using your last paper as a basis, that the subadult type specimen of B. altithorax was 25 m. long (having a 23% longer torso and a 25% longer tail than the 22.16 m. G. brancai holotype) and 28.7 tonnes of weight, wouldn’t that make the BYU 9462 a 28 m. long, 41 tonnes specimen?

  13. William Miller Says:

    OK, thanks. Several months back I was trying to find info on it, and couldn’t find much.

    That would be an useful baseline, it seems – if A. altus was unusually pneumatic, or unusually low-pneumaticity, that might be relevant. (Of course, Cope probably intended when choosing the name to imply that fragillimus was more lightly built than altus…)

    Even a 78.5-metric-ton animal is still colossal, especially for a diplodocid – that’s Argentinosaurus-sized! (It would still be by a long shot the biggest diplodocid, right? Supersaurus and Diplodocus hallorum didn’t get even close to that mass, big as they were….)

  14. Mike Taylor Says:

    But, William, there is no very convincing reason to think that A. fragillimus is actually congeneric with A. altus anyway. Yes, that’s how Cope referred it; but those guys made all sorts of crazy referrals. So we were really are whistling in, if not exactly the dark, then at least crepuscular conditions.

    And, yes, however you reconstruct the vertebra, A. f. is still by far the biggest known diplodocoid, way bigger than Supersaurus or “Seismosaurus”.


  15. “No, to the best of my knowledge no-one has ever attempted a rigorous reconstruction or mass estimate for A. altus. It tends to get treated as “sort of like Diplodocus”.”

    Looking up A. fragillimus in Foster’s ‘Jurassic West’, he suggests the two are probably synonymous and that Diplodocus will need to go the way of Brontosaurus (not likely, if any sauropod genus would get an ICZN petition passed this would be it). Still, has A. altus ever been rigorously compared to other diplodocids?

  16. Heinrich Mallison Says:

    Let me just add that scaling is rearely proportional:

    Therrien F. and Henderson D.M. 2007. My theropod is bigger than yours… or not: Estimating body size from skull length in theropods. Journal of Vertebrate Paleontology 27:108-115

    :)
    H

  17. Andreas Johansson Says:

    Let me just add that scaling is rearely proportional

    I was thinking the same. In particular, Diplodocus being pretty skinny to start with, would simple doubling of the linear dimensions leave the limbs tough enough to carry it around with a sensible safety margin?

  18. Bruce Schumacher Says:

    For sake of completeness, per Carpenter (2006)

    Math here, volume (hence mass) changes in proportion to the third power of the linear dimension (Schmidt-Nielsen, 1984)

    So, D. carnegii = 26.25m and 11,500 kg (Paul, 1994)

    Thus, Amphicoelias = 58m and 122,400kg

    I’m fine so far, but:

    Seismosaurus and Supersaurus = ave 33m and 38,800 kg? (according to my math, 33/26.25 = 1.26; 1.26 third power = 1.98; 1.98 * 11,500 kg = 22800 kg)

  19. Jamie Stearns Says:

    @ Mike B.:

    Actually, it was probably smaller than the holotype. To quote Taylor (2009):

    “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 addition, the same paper mentions that the Dry Mesa specimen lacks the deflected glenoid seen in Brachiosaurus, so they’re probably not from the same taxon.

  20. Mike B. Says:

    I don’t remember that part, well, at least we know that the holotype is a subadult so it can be bigger.

  21. IanC Says:

    Does anyone know what happened to the ‘coming soon – new info on Amphicoelias that will amaze and astound you!’? On one of Darrens posts there were rumours of SVP abstracts, papers etc to be revealed to the world… A while back now…

  22. Mike Taylor Says:

    No, the Coming Soon Amazing News thing never did materialise. I seem to remember that Jerry Harris was somehow involved, so you might try hassling him about it. I could be wrong. Very disappointing, anyway.

  23. William Miller Says:

    I was looking at the Cope paper “On the Vertebrata of the Dakota Epoch of Colorado”, and in that he named a species called “Amphicoelias latus”. I had never heard of this before: do the specimens still exist, and if so are they still thought to go in the genus Amphicoelias?

  24. Mike Taylor Says:

    A. latus was synonymised with the type species A. altus by Osborn and Mook (1921).


  25. [...] specific number. As usual, the two-part take home message is that (1) mass estimates of sauropods are inherently imprecise, so all we can do is make our assumptions as clear as possible, and (2) even the biggest sauropods [...]

  26. Peter Adlam Says:

    Changing the subject are you interested in other dinosaur clades apart from sauropods? I myself am also interested in Hadrosaurs and was recently stunned by the news that shantungosaurus and lambeosaurus laticaudus have been ousted as the biggest ornithiscian dinosaurs by Zhuchengosaurus.The Zhuchengosaurus is 9.1m tall, 16.6m long and estimated at over 20 tons in weight, don’t you think this is colossal for a non-sauropod dinosaur? I think its staggering that it stands 9m tall ( 3/4 of girafftitan) when it doesn’t have a long neck.

  27. Mike Taylor Says:

    Peter, yes, we’re interested in massive ornithischians, too. They’re not as cool as sauropods, obviously, but they are the coolest bipeds. That said … 9.1 m in height for a hadrosaur? I don’t think so! I’d like to see the paper that described Zhuchengosaurus but I don’t have it, so I don’t know what actual bones, if any, have been measured — or whether the quoted dimensions are those of a 99% fictional “mount”.

  28. LeeB Says:

    Hi Peter,

    there is a paper in chinese with an english abstract at http://www.abclunwen.com/lunwen-free-487859/
    which states that Zhuchengosaurus is a junior synonym of Shantungosaurus.

    And if you really want to blow your mind have a look at http://english.peopledaily.com.cn/90001/90782/6790629.html
    This is a picture of a hadrosaur skeleton, presumably Shantungosaurus from the Zhucheng area which recently produced Sinoceratops.
    It is stated to be 21m long and 10m high.
    THere is an english article and other pictures on the same website.
    There have been similar pictures online elsewhere in the last year showing different views of at least two skeletons.
    I wouldn’t like to guess what this creature weighed.

    LeeB.


  29. The 10m height of that mount is due to it’s old-fashioned, upright bipedal stance. In reality, these things were probably primarily quadrupeds and couldn’t have adopted such a pose without breaking the tail.

  30. LeeB Says:

    Yes but even if it was only occasionally bipedal, with the spinal column held horizontally, that is still a lot of weight to carry on two legs.
    Perhaps the juveniles were more bipedal than the fully grown adults.
    I also wonder how long the skull shown in one of the other pictures was, if the overall length is 21m it must be quite large.
    And with that length and a relatively short neck and by sauropod standards a short tail they must mass about the same as a medium sized sauropod.
    Quite some beast.

    LeeB.

  31. LeeB Says:

    There is more on this beast here including pictures of a more than six foot long femur and an impressively large skull:

    http://dinosaursabbatical.blogspot.com/2010/12/walking-in-footsteps-of-giants.html

    LeeB.

  32. Peter Adlam Says:

    21m for a ornithopod is quite staggering, it must weigh as much as an Apatosaurus or more and its hind legs bigger than that of most sauropods, I’d like to see a theropod tackle one of those.Do the biggest hadrosaurs all come from china? Where does lambeosaurus laticaudus come from? it is my favourite hadrosaur because of the unique shape of its head.

  33. Peter Adlam Says:

    So are you saying shantungosaurus has already won its crown back as the biggest ornithscian?

  34. Mike Taylor Says:

    Before I start swallowing speculative numbers like 21 m for an ornithopod, I want to see hard measurements of specific bones — something we can cross-scale from, based on better-known species. I am not saying that 21 m is impossible, and personally I would love it to be true, but I want some evidence before I start hanging out the bunting.

  35. LeeB Says:

    How does a 1.8m plus femur compare to that of a large Edmontosaurus?
    And also to that of the original smaller specimens of
    Shantungosaurus.
    There must be some figures out there somewhere.

    LeeB.

  36. Mike Taylor Says:

    Where does the 1.8 m figure come from?

  37. LeeB Says:

    From the blogspot link above which has a picture of a femur described as more than six feet.

    LeeB.


  38. Ok, let’s assume you’re right, Mike, and the dorsal vertebrae of Amphicoelias was ‘only’ 2.29 meters tall. If I’m not mistaken, Hatcher (1901) listed the 9th dorsal vertebrae of the CMNH 84 specimen of Diplodocus carnegii as 94.6 cm tall and the 10th dorsal vertebrae as 96.6 cm tall.
    Osborn and Mook (1921) suggest that the dorsal vertebra in A. fragillimus was the 9th or 10th. Then this means that if A. fargillimus was roughly proportional to D. carnegii it was 229/96.6=2.37 times as large in linear dimensions which means it was 13.31 times as voluminous (and thus that many times heavier). This means if D. carnegii was 25 meters long, then A. fragillimus was about 59.25 meters long. And if D. carnegii massed 11.4 tonnes as Greg Paul suggests, then A. fragillimus was 13.31*11.4=151.73 tonnes!

    I’m not sure where Carpenter got his mass and length estimates–since he says he basically says he just scaled it up isometrically. A 2.7 meter tall vertebra is 2.79 (270 cm/96.6 cm=2.79)times as tall as the D10 in D. carnegii which means a length of 69.75 meters if D. carnegii was 25 meters long or 73.23 meters if it was 26.25 meters like Carpenter assumes. A resulting mass estimate should then be 247.38 tonnes (2.79^3=21.7; 21.7*11.4 tonnes=247.38 tonnes)!

    And this is assuming it was the 10th dorsal! What if it was the 9th? Scaling the vertebrae, we get 270/94.6=2.85; 2.85^3=23.14; 23.14*11.4 tonnes=263.79 tonnes! Even assuming your reduced height estimate we get 229/94.6=2.42; 2.42^3=14.17; 14.17*11.4 tonnes=161.5 tonnes!

    I’m not sure how Carpenter got such low mass estimates and length estimates, but going off of them is bound to produce massive errors, assuming I haven’t missed something. So no matter what, as far as I can tell Amphicoelias massed way over 100 tonnes, probably over 150 tonnes even with the reduced height estimates.

    For what its worth, I tried scaling the preserved portion in A. fragillimus with the similar portion in A. altus in GIMP and I get an estimated height of 2.7 meters also for A. fragillimus.

  39. LeeB Says:

    Peter Adlam,

    Shantungosaurus does appear to be the largest Hadrosaur and the recent specimens seem to be larger than the original ones.

    Lambeosaurus laticaudus is from Baja California state in Mexico.
    As far as I know there is no known material showing the shape of its crest; and recent hadrosaur phylogenies suggest it probably doesn’t belong in the genus Lambeosaurus.

    More material of it needs to be excavated to determine what it really looked like; with all the recent work on dinosaurs occurring in Mexico this may actually occur; as numerous specimens of hadrosaurs often occur where they are preserved.

    The piece linked above fron the blog suggests that the large Shantungosaurus skeleton may be scanned, this would determine its size accurately and any resulting paper may give us its accurate measurements.

    Hopefully not too far in the future.

    After all if people are sitting on a huge quarry containing numerous specimens of the largest Hadrosaur ever found you would think they would publish something.
    And the ceratopsian from the same site was published on recently.

    We will just have to wait I guess.

    LeeB.

  40. William Miller Says:

    ‘Lambeosaurus’ laticaudus is also most probably not as big as is often suggested (Wikipedia says 23 tonnes!); this estimate goes back to a 1972 paper (before the species was actually named), and it’s based on scaling-up an estimate which is probably itself too big (from Colbert, the same guy with the 80 ton HM SII). This scaling-up was based on LACM 26757, the largest humerus (which incidentally was not actually referred to “Lambeosaurus” laticaudus in the 1981 paper naming the species).

    This is a species that really needs more study: the last serious work done on it seems to be the description, nearly 30 years ago, which is very obsolete (describing the species as probably aquatic…) — as LeeB said, it has been mentioned in some recent analyses, but only very briefly.

  41. Peter Adlam Says:

    I read somewhere that a paleantologist posted an estimated length for Amphiceolias Fragillimus at between 4.3m-4.6m, is this a joke? Since if the creature did exist most people believe it was a scaled up Diplodocus so a 4.6m femur equates to a ridiculously oversized Diploducus. Diplodocus Carnegi has a 1.5m femur and a length of 26m, a 4.3m femur produces a length of 74m and a 4.6m femur produces a staggering 79.5m length. Now imagining this to be true could a creature this size ever exist, hypothetically?

  42. Peter Adlam Says:

    A 4.3m -4.6m femur length obviously, i missed that bit out at the beginning of the previous post.

  43. Mike Taylor Says:

    Here’s what Carpenter (2006) wrote about the possible femur length of A. fragillimus:

    In order to put A. fragillimus into perspective, Cope (1878b) speculates on the size of the femur. He notes that the femora of A. altus and Camarasaurus supremus were about twice as tall as their tallest dorsals, and he conjectured that the femur of A. fragillimus was over 12 feet (3.6 m) tall. In Diplodocus, the ratio of femur to D10 ranges from 1.6 (CM 84) to 1.7 (USNM 10865). Assuming a similar range in A. fragillimus, the femur was 4.3-4.6 m tall (Paul [1994] estimated a femur length of 3.1-4.0 m).of neck-end of sacrum) of 9.25 m, and a tail length of 32 m. The forelimb is 5.75 m and hind limb 7.5 m.

    So 4.6 m does not look completely out of the question. It’s at the top end of the credible range, but not ridiculous.

  44. Peter Adlam Says:

    a 4.6m femur does not fit into 7.5m hind limb, that leaves 2.9m for the tibia, fibula and the foot. A 4.6m femur would fit roughly into a 9m hind limb. So maybe 4.6m is the extreme but i hope it is true, can you imagine a sauropod with a 4.6m femur that is just gigantic. I think the Argentinosaurus has the biggest femur of any credible dinosaur and how big is that? I don’t think there are many sauropods with over a 2m femur or am i wrong?

  45. Mike Taylor Says:

    Peter, there a sort of unofficial threshhold that a femur over 2 m in length is considered “big”. The longest femur of Giraffatitan, at least so far as is mentioned by Janensch (1961) is that of specimen XV 1, which is 214 cm in length. I can’t offhand think of a femur that is much bigger than that (can anyone remind me of one), although partial femora referred to Argentinosaurus have been reconstructed as longer. So, yes, a 4.6 m femur would be well over twice as long as the longest one known. It takes a lot of believing in.

    Zach (and others) on the status of Seismosaurus. It’s true that this genus was synonymised with Diplodocus by both Lucas et al. (2006) and Lovelace et al. (2008). But these two papers didn’t reach the same conclusion as each other: in the former, it remained its own species, Diplodocus halllorum, and in the latter, it was considered conspecific with D. longus — a conclusion that Lucas et al. considered possible, but not capable of being properly established given the weak state of Dipodocus species-level taxonomy. Given that I heard somewhere (sorry, don’t remember where) that Gillette is preparing or at least considering a rebuttal, I don’t think that we can consider this case closed yet — there’s no established scientific consensus. Most likely there will be in a few more years, and most likely Seismosaurus will indeed be considered either a species of Diplodocus or an individual of an already known species of that genus. But it’s a bit premature to bury it permanently.

    References

    Janensch, Werner. 1961. Die Gliedmaszen und Gliedmaszengurtel der Sauropoden der Tendaguru-Schichten. Palaeontographica, suppl. 7 (1), teil 3, lief. 4: 177-235.
    Lovelace, David M. Scott A. Hartman and William R. Wahl. 2008. Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny. Arquivos do Museu Nacional, Rio de Janeiro, 65 (4):
    527-544.
    Lucas, S.G., Spielmann, J.A., Rinehart, L.F., Heckert, A.B., Herne, M.C., Hunt, A.P., Foster, J.R., and Sullivan, R.M. 2006, “Taxonomic status of Seismosaurus Hallorum, a Late Jurassic sauropod dinosaur from New Mexico”: New Mexico Museum of Natural History and Science Bulletin, vol.36, pp.149-162. (PDF)

  46. Matt Wedel Says:

    According to Mazzetta et al. (2004), Bonaparte (1996) published a measurement of 250cm for a complete femur of Argentinosaurus. I don’t have Bonaparte (1996), so I can’t check whether this is an actual measurement or an estimate or what. Mazzetta et al. (2004) make a pretty good case that the incomplete Argentinosaurus femur they figure was a bit over 2.5 meters long when complete.

    Also worth remembering is that in the post Mike found that A. fragillimus could plausibly have been only 1.85x the size of Diplodocus in linear terms, and in one of the comments Zach Armstrong found it could plausibly have been as much as 2.85x as big. So we’re working with a HUGE amount of uncertainty here.

    Bonaparte, J.F. 1996b. Dinosaurios de Ame´rica del Sur. Museo Argentino de Ciencias Naturales, Buenos Aires.

    Mazzetta, G.V., Christiansen, P., and Farina, R.A. 2004. Giants and bizarres: body size of some southern South American Cretaceous dinosaurs. Historical Biology 2004:1-13.

  47. Peter Adlam Says:

    1.85 times the length of a 26m D.carnegi is 49m and 2.85 times equals 75m so a 4.6m femur does fit in with the upper estimate. However i fear that there wont be any substansial discoveries of A.Fragillimus in my lifetime anyway, it is such a long shot that even a 49m specimen (lowest estimate) could have more than 10% of it’s skeleton preserved.

  48. Domer Says:

    Great article. It has long been looking for sketches of the dinosaur.

  49. Dean Says:

    Not to mention dozens of feet of cartilage taking up space throughout a 230 foot body
    !

  50. Seismosaurus Says:

    Well Seismosaurus was about 120-150 feet long but Amphicoelias was 190-200 feet long. Argetinasaurus wasnt the biggest dino. it was Aphicoelias.And I believe that seismosaurus was the second biggest dino and argetinasaurus wasnt the biggest

  51. Mike Taylor Says:

    Seismosaurus” has been reassessed by a couple of different groups now: both of them concluded that it is merely a biggish specimen of Diplodocus, and also that it was nowhere near as big as initially estimates — perhaps in the region of 35 m long, about 115 feet. As you have seen in this very post, all size estimates of Amphicoelias fragillimus are very, very tentative, but 200 feet is at and beyond the outer limit of what can really be supported. It’s possible but my no means certain that it was “bigger” (i.e. heavier) than Argentinosaurus, but “Seismosaurus” certainly was not.

    Check the SV-POW! archives for more on all these beasts.

  52. Dean Says:

    Ahhhhh!!!!! Everyone please Read Zach’s comment, Amphicoelias was way over 200 feet!!! Dippys vert was only .95 meters tall!!!


  53. I’m not sure a 200 ft long A. fragillimus is completely unsupported. Even using Mike’s reduced size estimate for the A. fragillimus dorsal you still get, by isometric scaling from extrapolating from Diplodocus a length of at least 59.25 meters for A. fragillimus, which is about 194 ft. As I made clear in my comment here it’s definitely possible that A. fragillimus was around 70 meters (or about 230 ft) long if we assume isometric scaling.

    The trouble with that is that I can’t think of any large animal that is a close isometrically to a significantly smaller animal. An even bigger trouble is that we are basically missing a whole dimension of information on A. fragillimus. What if it had a super anteroposteriorly short centrum like some other sauropods? Our length estimate could be way off.

    For instance, let’s say Futalognkosaurus was 26 meters long. The description says its anterior dorsal are 100 cm wide across the transverse processes. In Puertasaurus the width of its anterior dorsal (probably the 2nd) is 168 cm. So, it we assumed perfect isometric scaling that logically we would assume it was 68% longer too, right? Wrong. If we did so we would give a length estimate of over 43 meters long. However, if you look at the illustrations in the description of Puertasaurus is it quite clear that the dorsal centrum is very short anteroposteriorly and the illustration suggest it is between 30 to 32 cm long (excluding the anterior condyle). The description of Futalognkosaurus suggest a 2nd dorsal centrum length of about 28 or 29 cm long. This suggests that at least in the dorsal column, Puertasaurus was maybe only 10 or 11% longer thatn Futalognkosaurus suggesting a length of less than 29 meters long, 14 meters shorter than suggested by comparing the widths of the dorsal vertebrae.

    If something similar was the case with A. fragillimus, it could easily be only 2/3 of the longest length estimate I gave, which would be 2/3 of 73 meters or “only” about 48 meters (~157 ft) long. It’s just too fragmentary to be sure.

  54. Mike Taylor Says:

    Zach — I have nothing to add to your comment beyond noting my agreement on all points. Good stuff.


  55. Thanks, Mike. By the way, I was just looking at Lull’s (1919) redescription of Barosaurus, and he listed some vertebral measurements for Diplodocus carnegii , which he says he obtained from ” Mr. O. A. Peterson of the Carnegie Museum, Pittsburgh, who supplied measurements from the type of Diplodocus carnegiei [sic], the mounted skeleton of which is there displayed.”

    I assume this is the specimen described by Hatcher (1901). Something caught my eye, however, that is relevant to the discussion of the size of A. fragillimus: several of the measurements are different from Hatcher (1901). In particular, the total height of the tenth (X) dorsal is listed as 1070 mm tall and the ninth (IX) dorsal is listed as 1028 mm tall in Lull (1919), whereas the same vertebrae are listed as 966 mm and 946 mm respectively. So what’s the deal? Have more recent new measurements been taken? This potentially affects any size estimates of Amphicoelias. (The other odd thing I noticed is that, scaling from the plates in Hatcher using GIMP, the 10th dorsal has to be taller than 966 mm when comparing it to the 9th dorsal…)

  56. Mike Taylor Says:

    Excellent catch, Zach — most intriguing. I don’t know what the correct measurements are, nor why there is a discrepancy between those of Hatcher (1901) and Lull (1919). This just goes to show — once more — how little we really know about even the very best known sauropods (which the Carnegie Diplodocus surely is).

    Someone in Europe — I want to say Munich but I’m not sure — there is a cast of that specimen that for one reason and another was never mounted. That means that the elements are stored somewhere, presumably in a way that would make them relatively easy to measure. Someone ought to get over there and find out how big those dorsals really are.

  57. seismosaurus Says:

    actually they say that seismosaurus was truly bigger than argentinasaurus , argentinasaurus was only thicker and heavier.

  58. Mike Taylor Says:

    Well. “Bigger” usually means “heavier” rather than “longer”, at least among scientists. Would you describe a bootlace worm as bigger than a blue whale?

    But in any case, it’s far from clear which was longer between Argentinosaurus and “Seismosaurus” (now recognised as a species of Diplodocus, or perhaps just a large individual of the type species Diplodocus longus. The length of the latter was greatly overestimated in the initial description, and is now usually given as around 35 m — about the same as for Argentinosaurus. But Argentinosaurus is known from such incomplete remains (e.g. no vertebrae at all from the neck or tail) that all length estimates are purely speculative anyway.

  59. seismosaurus Says:

    In some wikipedias they say that seismosaurus was 50 meters and argentinasaurus so i believe that seismo was the second to the biggest dinosaur and it was alot stronger than argentinosaurus.

  60. seismosaurus Says:

    Wait i forgot to write that argentinosaurus was 36 meters

  61. Mike Taylor Says:

    “In some wikipedias they say that seismosaurus was 50 meters.”

    Not if they are following the primary scientific literature that is written by and for qualified scientists, who have access to and the ability to understand, the actual fossils. Gillette’s original (1991) length estimate for Seismosaurus was based on the misidentification of anterior caudal vertebrae as mid-caudals, and was not supported by the size of other preserved elements. No active palaeontologist believes that estimate, which has been revised dramatically downwards by both Lucas et al. (2006) and Lovelace et al. (2007).

    Sorry, but it’s true.

  62. seismosaurus Says:

    Well that’s ok at least you had help me more about the seismosaurus thx for replying in what is right.

  63. seismosaurus Says:

    So mike what is the second biggest sauropod ?

  64. Matt Wedel Says:

    seismosaurus: Probably the biggest sauropod of all time was Amphicoelias fragillimus, and the second biggest was probably Bruhathkayosaurus matleyi. I qualify these with ‘probably’ because (a) both were represented by remains best described as ‘hideously incomplete’, (b) these remains were only known to the vast majority of scientists by drawings and measurements in published papers, and (c) the original material of both taxa has now been lost. See this post for more details.


  65. Woah, wait, the B. matleyi holotype has been *lost*?

  66. Matt Wedel Says:

    Yep, washed away in a flood, apparently. Mike knows more about it than I do.

    So we’re in the uniquely crappy situation that both of the world’s (potentially) largest sauropods have suffered the second extinction, and are no longer represented by physical remains (at least, that anyone can locate).

  67. seismosaurus Says:

    So if that was the second biggest was,seismosaurus any of the biggest souropod :mike ?
    some even say seismo was the longest dino in terms of size.

  68. Mike Taylor Says:

    Sorry, seismosaurus, but your namesake animal Diplodocus hallorum is almost certainly not even in the top ten. (I suppose some day we should do a post listing a credible countdown, but I am sure you can find that kind of thing elsewhere.)

    And, yes, the Bruhathkayosaurus material is gone, astonishingly. We really should blog about that some time.


  69. Based on published sources, “Seismosaurus” hallorum is #6 in terms of length and #10 in terms of size/weight:

    http://en.wikipedia.org/wiki/Dinosaur_size#Longest_sauropods

    However this site only lists published estimates, and some very large sauropods that are certainly in the top 10 do not have any.

  70. seismosaurus Says:

    You know what mike i think we can blog about the dinos sometime. :)


  71. [...] moment, the article “How big was Amphicoelias fragillimus? I mean, really?” lives at http://svpow.wordpress.com/2010/02/19/how-big-was-amphicoelias-fragillimus-i-mean-really/ BUT if that web-page ever goes away, it’ll be because we’ve moved SV-POW! [...]


  72. [...] is with SV-POW! itself, where we’ve often had excellent, busy, informative comment-threads (example 1, example 2, example 3) that have resulted in us learning a lot from our commenters.  So why is it [...]


  73. [...] 201). So D10 from this individual was probably between 1.7 and 2 meters tall–not quite in Amphicoelias territory but getting closer than I’ll bet most people [...]


  74. [...] most would feel some obligation to cite it in order to give credit. You might not want to cite this SV-POW! post as authority for a length of 49 m for Amphicoelias fragillimus; but you would hardly use the sacrum [...]

  75. Super saber Says:

    Amphicoelias is’t biggest sauropod.There are 2 larger.1 is alecosaurus.Second is anlesiesaurus.Alecosaurus is bigger than anlesiesaurus.

  76. Mike Taylor Says:

    I have never heard of either Alecosaurus or Anlesiesaurus, and I don’t see meaningful hits for either on Google. Do you have details?


  77. [...] at Wikipedia or about.com. Also, you can read some critiques of Carpenter’s mass estimate at SVPOW or [...]

  78. Fragillimus335 Says:

    [NB: The person posting here as 'Fragillimus335' and 'Brolyeuphyfusion' is a troll who has appropriated those names, and at least some of these arguments, from other people on other sites. We don't want to disrupt the flow of the thread by deleting these comments, just be aware that this is not the 'Fragillimus335' and 'Brolyeuphyfusion' you're looking for. --Matt]

    In his paper Carpenter says he simply scaled up Diplodocus c.’s vertebra to 2.7 meters. The only problem is that he used the dimensions from Seismosaurus for diplodocus’s vert, but said the length of Diplodocus was only 26.25 meters. This small mistake of recording diplodocus’s vert as 1.22 meters instead of .946 meters has lead to the widespread belief that Amphicoelias was 60 meters long and 120 tons in weight. In reality using carpenter’s method with the correct numbers we get, 2.7/.946=2.864. 2.854×26.25 meters=75 meters long. Also 2.856^3=23.2. 23.2×12 tons=278 tons.

    A quote from Zach Armstrong on the subject. (note, he uses a 11.5 ton Diplodocus)

    I’m not sure where Carpenter got his mass and length estimates–since he says he basically says he just scaled it up isometrically. A 2.7 meter tall vertebra is 2.79 (270 cm/96.6 cm=2.79)times as tall as the D10 in D. carnegii which means a length of 69.75 meters if D. carnegii was 25 meters long or 73.23 meters if it was 26.25 meters like Carpenter assumes. A resulting mass estimate should then be 247.38 tonnes (2.79^3=21.7; 21.7*11.4 tonnes=247.38 tonnes)!

    And this is assuming it was the 10th dorsal! What if it was the 9th? Scaling the vertebrae, we get 270/94.6=2.85; 2.85^3=23.14; 23.14*11.4
    tonnes=263.79 tonnes!

    Adding intravetebral cartilage, which accounts for ~10% of the body lengths of most birds and reptiles, increases the dimensions even more.

    These estimates are backed by scientific methods, and are the best way we have of guessing Amphicoelias’s dimensions.

    Spread the word!

    Measurement for Diplodocus’s vert is from: Osborn, H.F., and Mook, C. C. (1921). “Camarasaurus, Amphicoelias and other sauropods of Cope.”

  79. Matt Wedel Says:

    Fragillimus335, the point is not whether Carpenter’s reconstruction of the vertebra is right or wrong; the point is that it is one estimate. Mike’s independent reconstruction got a dorsal height of only 2.3 meters. Please also see Zach’s comments about reconstructing three-dimensional animals from a single dimension of a single vertebra, here.

    These estimates are backed by scientific methods, and are the best way we have of guessing Amphicoelias’s dimensions.

    No–these estimates are backed by some extremely dodgy assumptions about isometric scaling, which virtually never applies to large animals, at at best they allow us to quantify our uncertainty and ground our speculation. Please do not mistake them for the “right answer”.

  80. Fragillimus335 Says:

    [NB: The person posting here as 'Fragillimus335' and 'Brolyeuphyfusion' is a troll who has appropriated those names, and at least some of these arguments, from other people on other sites. We don't want to disrupt the flow of the thread by deleting these comments, just be aware that this is not the 'Fragillimus335' and 'Brolyeuphyfusion' you're looking for. --Matt]

    Dude it’s actually a simple mistake, just read the paper. And the guys at SV-POW have talked about the problem in the comments for the post about Amphicoelias. Paleontologists are not immune from mistakes, and guys behind laptops are not incapable of correcting them.

    The sizes are not fully improbable! They are the most accurate estimate we have, are you paying attention? Every professional that has worked on Amphicoelias has agreed it’s basically a scaled up diplodocus, so Amphicoelias was most likely ~2.85 times as long as a 26.25 meter diplodocus.

  81. Mike Taylor Says:

    I’m sorry that things aren’t as simple as you’d like them to be, or as you think they are. The original conclusion of this piece stands: “when you extrapolate the mass of an extinct animal of uncertain affinities from a 132-year-old figure of a partial bone which has not been seen in more than a century, you need to recognise that the error-bars are massive and anything resembling certainty is way misplaced”.

  82. Fragillimus335 Says:

    [NB: The person posting here as 'Fragillimus335' and 'Brolyeuphyfusion' is a troll who has appropriated those names, and at least some of these arguments, from other people on other sites. We don't want to disrupt the flow of the thread by deleting these comments, just be aware that this is not the 'Fragillimus335' and 'Brolyeuphyfusion' you're looking for. --Matt]

    Sadly, I am not able to chat with a professional Paleontologist. But the fact is, I don’t need to, the problem is as simple as a typo, just fix it and move on. Please read the paper yourself, and come to your conclusion. Here’s my new scale, with an 85 meter Amphicoelias.

  83. Mike Taylor Says:

    You are able to talk to a professional palaeontologist. There are half a dozen of us right here. The problem is, you don’t seem to be able to listen.

  84. Fragillimus335 Says:

    [NB: The person posting here as 'Fragillimus335' and 'Brolyeuphyfusion' is a troll who has appropriated those names, and at least some of these arguments, from other people on other sites. We don't want to disrupt the flow of the thread by deleting these comments, just be aware that this is not the 'Fragillimus335' and 'Brolyeuphyfusion' you're looking for. --Matt]

    First, we must fill in missing info and estimate the length of Amphicoelias altus.

    If we were to scale up using Diplodocus, we would get:
    ~28.5 meters based on femur length, and,
    ~25.4 meters based on LTV height.

    If we were to scale up based on Barosaurus, we would get:
    33.04 meters based on femur length, and,
    ~27.36 meters based on LTV height.

    Amphicoelias fragillimus vertebra has been estimate to be 2.7 meters tall. Also, Greg Paul estimated it to be 2.4-2.6 meters tall.

    To be as unbiased as possible, all three measurements will be used. That vertebra has been thought to be the last to second to last trunk vertebra.

    We will assume it to be the last trunk vertebra for now.

    Since the last trunk vertebra height of A. altus is 1.075 meters, A. fragillimus would have dimensions ~2.512 times that of A. altus based on a 2.7-meter LTV height, ~2.42 times based on 2.6-meter LTV height, and ~2.23 times based on 2.4-meter LTV height.

    So we have come to estimate the size of Amphicoelias fragillimus:

    First, the Diplodocus-based estimates:

    Based on the ~28.5-meter length for A. altus, which was based on femur length and scaled from Diplodocus, we get:
    71.592 meters based on a LTV height of 2.7 meters for A. fragillimus,
    68.97 meters based on a LTV height of 2.6 meters, and,
    63.555 meters based on a LTV height of 2.4 meters.

    Based on the ~25.4-meter length for A. altus, which was based on last trunk vertebra height and scaled from Diplodocus, we get:
    63.8048 meters based on a LTV height of 2.7 meters for A. fragillimus,
    61.468 meters based on a LTV height of 2.6 meters, and,
    56.642 meters based on a LTV height of 2.4 meters.

    Now, for the Barosaurus-based estimates:

    Based on the 33.04-meter length for A. altus, which was based on femur length and scaled from Barosaurus, we get:
    82.99648 meters based on a LTV height of 2.7 meters for A. fragillimus,
    79.9568 meters based on a LTV height of 2.6 meters, and,
    73.6792 meters based on a LTV height of 2.4 meters.

    Based on the ~27.36-meter length for A. altus, which was based on last trunk vertebra height and scaled from Barosaurus, we get:
    68.72832 meters based on a LTV height of 2.7 meters for A. fragillimus,
    66.2112 meters based on a LTV height of 2.6 meters, and,
    61.0128 meters based on a LTV height of 2.4 meters.

    Now, the real issue is which vertebra height is most likely, for that, we must see the quote by Zach:

    http://svpow.com/2010/02/19/how-big-was-amphicoelias-fragillimus-i-mean-really/#comment-10857

    It is the last paragraph.

    So it seems that the 2.7-meter figure for the LTV height, and thus the higher estimates, are more likely.

    The mass will be estimated later.

  85. Mike Taylor Says:

    PLEASE tell me that your seven-significant-figures vertebra-size estimates are intended as a joke.

  86. Fragillimus335 Says:

    [NB: The person posting here as 'Fragillimus335' and 'Brolyeuphyfusion' is a troll who has appropriated those names, and at least some of these arguments, from other people on other sites. We don't want to disrupt the flow of the thread by deleting these comments, just be aware that this is not the 'Fragillimus335' and 'Brolyeuphyfusion' you're looking for. --Matt]

    Thanks, and as Amphicoelias a. goes, its femur was measured at 1.77 meters, and supposedly had a total length of ~30 meters. According to Greg Paul. Running the numbers for Amphicoelias again, I seem to be getting numbers clustering in the 75-85 meter range. This is with an isometrically longer neck, but no additional intervertabral cartilage. Weights of 350 tons seem fully possible.

    I don’t think Haplo is a good proxy for Amphicoelias.

    I think size may be more indicative of form than phylogenetic relationships. An animal Amphicoelias’s size would likely have evolved closer to the form that maximizes feeding envelope and weight reduction. This indicates a Supersaurus/Barosaurus type morphology, rather than a Haplocanthosaurus/Dicerasaurus type.


  87. hm, half-arsed speculation, isometric scaling at will, and the inability to understand a text you read. Interesting. But not for serious palaeontologists.

    I’m with Mike here: at best this game gives us an indication of how big our uncertainty is.

  88. JayNair Says:

    ‘Dude’, why wouldn’t Haplo body proportions be a good proxy?
    If Amphicoelias occupied a “basal” position in diplodocoid phylogeny, then assuming proportions similar to taxa occupying neighboring branches, like Haplo, makes sense. This would be grounded in something beyond just pure speculation at least.

  89. Brolyeuphyfusion Says:

    [NB: The person posting here as 'Fragillimus335' and 'Brolyeuphyfusion' is a troll who has appropriated those names, and at least some of these arguments, from other people on other sites. We don't want to disrupt the flow of the thread by deleting these comments, just be aware that this is not the 'Fragillimus335' and 'Brolyeuphyfusion' you're looking for. --Matt]

    This is why we need an Amphicoelias altus skeletal…it’s not just like a Diplodocus otherwise they would have been synonymized already…

  90. Brolyeuphyfusion Says:

    [NB: The person posting here as 'Fragillimus335' and 'Brolyeuphyfusion' is a troll who has appropriated those names, and at least some of these arguments, from other people on other sites. We don't want to disrupt the flow of the thread by deleting these comments, just be aware that this is not the 'Fragillimus335' and 'Brolyeuphyfusion' you're looking for. --Matt]

    Actually I am just being open-minded towards the possibility of sauropods being larger than the blue whale.

    The fact that you called them “bullshits” instead of speculations proves that you’re a bit close-minded.

    They are based off of simple scaling.

    The upper limit for terrestrial animals is suggested to lie between 105 and 106 kilograms, or between 100 and 1000 tonnes…

    http://www.miketaylor.org.uk/dino/hokkanen/Size-Hokkanen.html

  91. Mike Taylor Says:

    “They are based off of simple scaling.”

    That is why you fail.

  92. Brolyeuphyfusion Says:

    [NB: The person posting here as 'Fragillimus335' and 'Brolyeuphyfusion' is a troll who has appropriated those names, and at least some of these arguments, from other people on other sites. We don't want to disrupt the flow of the thread by deleting these comments, just be aware that this is not the 'Fragillimus335' and 'Brolyeuphyfusion' you're looking for. --Matt]

    This has nothing to do with this topic…

    The possibility is still open though, as the discovered fossil record is puny compared to those that are undiscovered.

    Not really, it’s because if it had Brachytrachelopan’s wimpy neck, it’s feeding area would not be enough to sustain a massive body…

    If Amphicoelias fragillimus was a gigantic ~30-meter Brachytrachelopan, then it would have a mass of approximately 185.19-370.37 tonnes*…a wimpy Brachytrachelopan-type neck isn’t going to sustain it…

    *I scaled from a 9-meter, 5-10 tonne Brachytrachelopan, from this: http://scienceray.com/biology/brachytrachelopan-the-short-necked-sauropod/

    That would make a 30-meter Brachytrachelopan about ~111 tonnes, but Brachytrachelopan isn’t really that much related to Amphicoelias, so that still does not speak of it’s size.

    That would make Amphicoelias fragillimus about ~81.14 meters long with a mass of ~364.72 tonnes…

    But I was looking for femur lengths for basal diplodocoideans, not flagellicaudatans, so I can make estimates to satisfy both sided.

  93. Matt Wedel Says:

    Here is why you’re having such heavy sledding here:

    1. You’re using simple scaling, and ignoring the near-certainty of allometry. For example, maybe in bigger sauropods the dorsal vertebrae are larger, proportional to body size, than in smaller sauropods. That would fit with what we know about sauropod vertebrae in general (i.e., they are larger in diameter, relative to body size, than the vertebrae of most non-sauropods), and with what we know about pneumaticity (i.e., it allows the animal to get more bone “outside” the air space–see for example this figure from the paper we published today). So although it’s untested, in that no one has gone and looked at how dorsal vertebra size scales across sauropods, either ontogenetically or phylogenetically, the likelihood that Amphicoelias was just a simple scale-up of something Diplodocus or even A. altus is pretty darned low. After all, Europasaurus is not just a perfect miniature of Giraffatitan or Brachiosaurus–precisely because of the problem of relative growth, which D’Arcy Thompson was writing about 96 years ago.

    None of that means that the simple scaling-up is wrong. It means that it’s untrustworthy, for a host of biological reasons that we are familiar with but you are either ignorant of or are choosing to ignore.

    2. You’re only looking at the max possible size. If you don’t also look at the minimum possible size, you’re doing what we call “counting the hits and ignoring the misses”. In other words, you’re not doing science, you’re just arbitrarily picking the most exciting number and going with it. Don’t be surprised if practicing scientists first try to point this out gently, but then treat you like a child when you choose to ignore them.

    3. You’re being a jerk. You’re acting like all of this is stuff that we’ve never considered before, like we’re a bunch of hidebound, blinkered ivory tower doofuses who are just out to rain on your parade. When in fact we have very good reasons for being skeptical of the numbers you’re throwing around, because you keep insisting on mixing bad biology (point 1) with bad math (point 2).

  94. Brolyeuphyfusion Says:

    [NB: The person posting here as 'Fragillimus335' and 'Brolyeuphyfusion' is a troll who has appropriated those names, and at least some of these arguments, from other people on other sites. We don't want to disrupt the flow of the thread by deleting these comments, just be aware that this is not the 'Fragillimus335' and 'Brolyeuphyfusion' you're looking for. --Matt]

    Popular articles oftentimes use sensationalistic “facts”…

    If even a sauropod specialist like Zach can’t convince you, I don’t know who can…

    Which is funny because you would be more convinced by that than the words of an expert

    And I’m pretty sure that most if not all of the guys at SV-POW are experts, Zach included…

  95. Mike Taylor Says:

    Uh, I rather think Zach would consider Matt a sauropod specialist.

  96. Matt Wedel Says:

    If even a sauropod specialist like Zach can’t convince you, I don’t know who can…

    Which is funny because you would be more convinced by that than the words of an expert

    Um, what the heck are you talking about?

    Zach posted the thing about the measurements being off.

    We agreed with him. Not because he’s an expert, but because he has facts on his side.

    Now you come along acting as if the maximum possible estimate for the size of Amphicoelias is a proven fact. It’s not. It’s ONE estimate, based on unverified and probably incorrect assumptions about isometric scaling in big animals. Since you seem to be having a hard time grasping this, I am–against my better judgement–going to try to explain it one more time:

    We neither agree nor disagree with estimates. Indeed, as long as there aren’t any math errors, it’s impossible to agree or disagree with them. Yes, if you make certain controlling assumptions, and you put in those numbers, you get such and such result. That’s how math works.

    BUT–and this is the crucial bit–you seem to be mistaking estimates for facts, whereas we hold them at arm’s length, because they’re just estimates. We use them, but we never fall into the trap of believing them.

    And actually it’s even worse than usual in this case, because the original fossil has vanished out of human knowledge. So the results of the estimates are “not even wrong”–they can’t be checked against any external reality. That’s bad for fans of giant sauropods, ourselves included. But it’s especially bad for you, because it means all there is to critique in these estimates are the background assumptions and the methods, and yours suck: you ignore allometry, and you only go with the biggest numbers. As I said before, that’s a lean-to made out of bad biology and bad math. Don’t be surprised that we’re not treating it like a mansion.


  97. Oh, dear (or as Liz Lemon would say, “Blurgh!”). It seems I am being misinterpreted/misquoted. Since I am being referenced, I think a brief rebuttal to Brolyeuphyfusion and Fragillimus335 is in order.

    First off, I am not an expert. At best, I am an amateur and at worst, someone with no paleontological qualifications whatsoever and so should not be cited as an authority. Even if I was an expert, experts aren’t always right. So the argument from authority fails (it is a logical fallacy).

    Second, I think I made it clear in my comments that have been referenced that the size estimates I gave are uncertain. To quote myself:

    The trouble with that is that I can’t think of any large animal that is a close isometrically to a significantly smaller animal. An even bigger trouble is that we are basically missing a whole dimension of information on A. fragillimus. What if it had a super anteroposteriorly short centrum like some other sauropods? Our length estimate could be way off.

    I then refer to the dimensions of Puertasaurus and Futalognkosaurus for empirical support to show that isometric scaling from a lone vertebra is likely to be misleading.

    Third, the numbers and calculations offered by Brolyeuphyfusion and Fragillimus335 are almost certainly wrong. It is unlikely that the 2.7 meter figure Carpenter gave is correct. It’s possible, but not very plausible. I agree with Mike and Matt’s suggestion that the A. fragillimus dorsal was shorter, although my own current reconstruction sits at a tad over 2.4 meters. Also, upon scaling the 10th(?)A. altus dorsal or any other diplodocid dorsal to the same height as the A. fragillimus dorsal it becomes immediately apparent that the dorsal of A. fragillimus is not a simple scaled-up version of another diplodocid.

    Fourth, even if it happens that someone finds a complete A. fragillimus skeleton, and it matches one of the predicted dimensions listed here, one should not assume that their method was correct! Statistically speaking, a sample size of 1 is not enough evidence to imply such an estimation method is scientifically useful.

    Finally, another layer of uncertainty comes in the mass of well-known diplodocids. Diplodocus, for instance, has had it’s mass estimated several times. Most mass estimates are between 10 and 15 tonnes. This may not seem like a lot, but this is actually a difference of 50%!

    Both Mike and Matt make accurate and astute observations about why the comments of Brolyeuphyfusion and Fragillimus335 are in error, and I can say I wholeheartedly agree with them (Mike and Matt, that is).

    One further note: In case I have not been sufficiently clear, my mass estimates for A. fragillimus are informed speculation, and are likely to wrong should another specimen be found.

    That is all.

  98. Matt Wedel Says:

    Thanks, Zach. That was all very well said. One point of clarification: Brolyeuphyfusion and Fragillimus335 are the same person. Speaking of, Bro/Frag, using multiple puppets smacks of trolling, so please pick one handle and stick with it.


  99. [...] this speculation is shot through with uncertainty. As we’ve discussed before, at length, all estimates of Amphicoelias fragillimus length and mass are wildly speculative; and [...]

  100. Gabe Says:

    Hello paleontologists,

    I’m perfectly agreed about you regarding the case of A. fragillimus.

    Beside this highly problematic almost non-existing taxon, what sauropod can be reliably stated as the largest known to date ?
    Traditionnally Argentinosaurus is the first figured but how about Puertasaurus and others ?

    Thank you

  101. Mike Taylor Says:

    I think Argentiosaurus is probably the strongest contender, though Puertasaurus, Futalognkosaurus and others might prove bigger when they’re properly described. It may be about time for a review paper.


  102. Thanks for the clarification, Matt. I thought they might be the same person but wasn’t sure.

    @Gabe and Mike: I think either Argentinosaurus or Alamosaurus is likely the biggest sauropod taxon for which we have solid evidence (see my Alamosaurus skeletal here: http://palaeozoologist.deviantart.com/art/Alamosaurus-skeletal-344422788), depending on how one restores the missing elements.

    Puertasaurus and Futalognksaurus are both large, but both have dorsal vertebrae that are smaller overall than Argentinosaurus. It’s true the sole dorsal vertebra of Puertasaurus is wider than any other sauropod (including Argentinosaurus), but it is also shorter in both height and functional centrum length compared to Argentinosaurus. I might also add that the width comparisons are probably not fair since several authors have suggested that the “1st” dorsal of Argentinosaurus (the widest one preserved) is probably a mid-dorsal instead (see: Salgado & Powell 2010). Since the dorsal vertebrae get significantly wider (total span of the diapophyses) in the anterior-most dorsals in Opisthocoelicaudia and Alamosaurus, it seems that the anterior dorsals of Argentinosaurus might be as wide or wider than that of Puertasaurus.

    Ref —

    Leonardo Salgado, Jaime E. Powell. Reassessment of the vertebral laminae in some South American titanosaurian sauropods. Journal of Vertebrate Paleontology. Vol. 30, Iss. 6, 2010

  103. Gabe Says:

    Thanks gentlemen for this,

    On the internet, we see many speculations of enthusiasts about 200, 300, 400 tons sauropods.

    Do you think that it is reasonnable to think such gigapods could have even existed ? The numerous constraints wouldn’t be too much ? Or do you think there are reastically a limit range that the sauropods may have reached well below this ?

  104. Mike Taylor Says:

    I’ve never seen even speculation of 300-tonne or 400-tonne sauropods, and I wouldn’t take such ideas seriously at this point if I did because there’s never been hint of any evidence of remains of such animals.

    By contrast, there are, or at least were, remains of two sauropods — Amphicoelias fragillimus and Bruhathkayosaurus of course — which one could imagine massing that much without too much of stretch. Of course since both specimens have been lost or destroyed, it isn’t possible to say much about them, or even to be 100% certain that they ever existed and were as described. But I think we can be say 90% certain. And since it’s vanishingly unlikely that the one specimen ever found of each of these was the biggest they got, my gut feeling is that there very possibly were sauropods that massed 200 tonnes in life.

    Yep, that’s blue-whale size.

    Wow.

  105. Dean Says:

    Woah, woah, woah…I need to clear the air here. This is Dean Hester posting here, my username on a different forum is Fragillimus335. Someone is quote-mining me from said forum and posting them here as attacks on you guys. I have the utmost respect for your opinions, and am fully aware of the speculation involved in these estimations.

  106. Matt Wedel Says:

    Hi Dean, thanks for the clarification. We’ll be keeping an extra close eye on any comments emanating from that IP and email address. It would be a cinch for me to go back and flag the fake “Fragillimus335″ posts as ‘Not Dean Hester!’ or something similar, if you’d like. Let me know.

    Bro/Frag, this is your last warning.

    To everyone who is just spectating: the reason we are so permissive in allowing stupid, abusive comments is that such comments reflect much worse on the commenter than on the commented, and if morons want to fashion their own nooses, we are usually happy to play out the rope. But pretending to be someone else is sufficiently far into the Troll Zone that we’ll shut it down.

  107. Matt Wedel Says:

    Oh, and as long as I’m here, Jay Nair asked a totally legit question a while back that we never followed up on:

    ‘Dude’, why wouldn’t Haplo body proportions be a good proxy?
    If Amphicoelias occupied a “basal” position in diplodocoid phylogeny, then assuming proportions similar to taxa occupying neighboring branches, like Haplo, makes sense. This would be grounded in something beyond just pure speculation at least.

    1. The supposedly basal position of Amphicoelias is based on new material mentioned in the Wilson and Smith abstract from a few years back. So that’s no use on this problem for three reasons: the analysis is not published, the specimens have never been published, and there’s no very good reason for thinking that they belong to the same taxon as A. fragillimus anyway.

    2. Whatever A. fragillimus was, it had a tall, narrow neural spine, and Haplocanthosaurus had short, wide neural spines–see the last image in this post.

    3. All of the known giant diplodocoids–Supersaurus, Diplodocus hallorum, the giant Oklahoma Apatosaurus–are derived apatosaurines or diplodocines. That makes me wonder if maybe basal diplodocoids just didn’t get that big. Now, things like Mamenchisaurus sinocanadorum and Turiasaurus show that non-neosauropod eusauropods could get huge, too, so I don’t think that basal diplodocoids lacked the physiological adaptations to get big. But all the non-diplodocid diplodocoids that we know of so far were fairly small for sauropods (i.e., sub-mounted-Apatosaurus-sized), so based on what we know right now, the size of A. fragillimus is more consistent with a derived position within Diplodocidae.

    4. Cope gave A. fragillimus its species name for the extremely delicate construction of the vertebra, which implies a fairly high ASP, which again is more consistent with a derived diplodocid than a basal diplodocoid. I admit this isn’t totally clear, since at least some rebbachisaurids had very lightly constructed vertebrae, and therefore the optimization of “high ASP” at the base of Diplodocoidea is probably ambiguous (also depending on the position of Haplo, Amazonsaurus, etc.). But still, the only diplodocoids that we know had a combination of high ASPs and giant size were derived apatosaurines and diplodocines, and that makes me think that A. fragillimus belongs somewhere “up there” and not down at the base of Diplodocoidea.

    That’s my thinking, anyway. Feel free to pick it apart!

  108. Dean Says:

    Thanks a bunch Matt! Can’t have slander floating around unchecked! No need to waste your time marking the other posts, I just wanted to clear my name with you guys! :)

    As Amphicoelias goes, I tend to favor the 70m+ camp, but accept that anything 50m and up is possible. I see Amphicoelias as a Barosaurus-morph, seeing that neck length is somewhat allometric, and simply that the 100 ton+ size category favors stretched out sauropods!

  109. Andrea Cau Says:

    As a confirmation that Fragillimus335/brolyeuphyfusion is a troll, he had repeated some of the comments written here but in my Theropoda blog, a few days before. Note that some are the same identical comments repeated whole: http://theropoda.blogspot.it/2012/01/amphicoelias-fragillimus-e-un.html#comment-form

  110. Dean Says:

    I wonder who that scumbag is… >:( Although I do have an inkling…


  111. [...] occurred to me: this should be a cautionary tale for anyone who gets all wound up about the possible max size of Amphicoelias fragillimus. As with A. fragillimus, for the Recapture Creek critter we have part of one bone, and at least for [...]

  112. Sauropodomorph Says:

    I would like to say that I’ve been framed here. The troll copied my posts from a forum and pasted them here. I wasn’t aware of that slanderer posting here until now.

    I never posted a comment here until now, since I cannot let myself be slandered. “brolyeuphyfusion” is my name in a forum, and I would never post those comments in a site like this. I would have never posted here if it weren’t for that slandering troll.

    Why would I even post on Cau’s blog? I can’t read Italian. At all. I don’t actually know much languages other than English.

    I don’t copy my posts on other forums to reply to arguments.

    As for Amphicoelias, I am skeptical of the figures here, and I did calculate higher estimates, around 70-80 meters and 200-270 tonnes, based on isometric calculations, not even taking into account the positive allometry of the neck which would have increased the length figures. I don’t take them as facts though, only possibilities.

    I agreed somewhat with Zach’s calculations(I thought that he was an expert before, but now due to Zach’s post, I know better)but I wouldn’t try to force them on you. You have your reasons for your conservative estimates. I am not the kind to force opinions unto others.

    Matt, can you please delete the posts made by that troll?

  113. Mike Taylor Says:

    Thanks for that, Real Brolyeuphyfusion.

    I prefer not to delete comments, as it mucks up the history and leaves subsequent comments without referent. But now that your own comment is here, it will make it clear to anyone who turns up what happened.

  114. Matt Wedel Says:

    Okay, all of the troll’s comments are now identified as such, and any further comments from the troll’s IP are blocked. Hope you had fun, coward!

    Thanks to everyone who helped us clear this up.


  115. [...] So, as before, caveat estimator when working from scaled illustrations of single partial bones of possibly immense sauropods. [...]

  116. nick Says:

    What are the substantial reasons to propose Amphicoelias fragillimus as possibly 70 m and 200 tons like I’ve read here an there ? Are there real reasons to hink this animal rivaled or exceeded the blue whale in mass ? Plus, a land animal ?

  117. Ted Says:

    Hello,

    Is there real and serious reasons to thin that A. fragillimus could have reached 200 tons in body mass and thus rivalling/exceeding the Blue whale ?

  118. Mike Taylor Says:

    I think we covered all that in some detail in the post. 200 tonnes is not beyond the realms of possibility, but not well supported by the extremely equivocal evidence we currently have.

  119. Ted Says:

    Is 200 tons based on the assumption that larger individuals may have existed, or do you seriously assume that the owner of the lost vertebra could have weighed that big ?

    Rigorously I mean, in scientific thoughts and litterature, what is the most likely range of possible weights for Amphicoelias ?

    Through the discussion I read things like 78-122 tons (Matt Wedel), 100-150 tons+ (Zach Armstrong) and even higher figures up to 240-260 tons.

    In all of this, I don’t get the best range of likelihood !

    Thanks

  120. Mike Taylor Says:

    Ted, I think you’re missing the key point of this post, which is (and I quote):

    Folks — please remember, the punchline is not “Amphicoelias fragillimus only weighed 78.5 tonnes rather than 122.4 tonnes”. The punchline is “when you extrapolate the mass of an extinct animal of uncertain affinities from a 132-year-old figure of a partial bone which has not been seen in more than a century, you need to recognise that the error-bars are massive and anything resembling certainty is way misplaced.”

    Caveat estimator!

    So the “best range of likelihood” is something like 70-150 tonnes, but anything from 50 to 200 or more is credible.

    There is simply no more certainty to be had.

  121. Mike Taylor Says:

    Maybe, maybe not. The page you link to is certainly very far from being authoritative.


  122. […] third top sauropod is Amphicoelias fragillimus, which is more surprising as we’ve not written that much about it. I guess it just reflects a lot of interest in that beast. Boring old Diplodocus is the fourth and […]


  123. […] hip, and tail elements, and those fossils disappeared (much like the near-mythical dinosaur giant Amphicoelias, estimated to be 190 feet long from a long-lost piece of […]


  124. […] sauropod known from fossils that still exist (i.e., not including semi-apocraphyal gigapods like Amphicoelias fragillimus and Bruhathkayosaurus). The current based-on-existing-fossils record-holder is […]


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