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Limits to dinosaur size?
Topic Started: Jun 12 2012, 12:50 AM (3,887 Views)
SpinoInWonderland
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On the thread "south america: land of giants", someone got a 170-200 tonne Puertasaurus by scaling it from an Argentinosaurus. That would be in the weight range of a blue whale, and beyond the limits of terrestrial creatures.

I don't want that thread to go off-topic, so I'll make this one.

How high is the limit to dinosaur size?

EDIT: I now believe that the limits of terrestrial creatures far exceed the mass of a blue whale
Edited by SpinoInWonderland, Sep 2 2012, 10:36 AM.
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JaM
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I don't think that such a big size is possible. Whenever a new gigantic record size dino is found, it's only a matter of time before it "shrinks". It has already happened with the Argentinosaurus, even without any further fossils found. They got to have been somewhat light in some way, or their legs wouldn't be able to support them for walking. Some of the big dinos didn't have all that big feet, so they would also sink into the ground if it was just a little bit soft! I think, when I look at the various reconstructions, that the big hornless rhinoceros isn't any smaller than any of the big Dinos. The biggest mammoths doesn't seem much smaller than the Giraffatitan at the Humbolt museum. Surely it wasn't the biggest, but honestly, was Argentinosaurus really that much bigger? The length estimate has already shrunk from 40 to ~30 m, which seems like a typical development.

There was an exhibition of an absurdly big Mamenchisaurus a while ago, that one looked just as big as all those other "record" dinos, but what was real, and what was imagined?
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dinocat
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http://www.telegraph.co.uk/science/dinosaurs/9312462/Dinosaurs-much-lighter-than-previously-thought.html

There is a new study that says dinosaurs were a lot lighter than previously thought (ex. Brachiosaurus was 23 tons).
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theropod
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Is there any study concerning the maximum size for terrestrial animals?
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coherentsheaf
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Yes: http://www.miketaylor.org.uk/dino/hokkanen/Size-Hokkanen.html
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JaM
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coherentsheaf
Jun 12 2012, 09:03 PM
Interesting. He doesn't address the dino foot size though, and the stress would probably be on the joints, not on the bone (when moving). The stress would be at least 30 tons on each leg, and the leg would have to be angled, which maybe wouldn't be too much for the bone, but the stress on the joints would be huge. Maybe those big dinos could only move with very small steps? In any case, it's more relevant whether the actual dino's legs as they were could take the pressure, not some calculated hypothetical leg which could.*

Despite his calculations, I still think that a 100 ton dino is out of range, though mostly because the dino bodies aren't too different in size compared with the biggest mammals. Those who are much bigger are usually only known by a few fragments, and they're extrapolated. Only the Humboldt museum Giraffatitan is nearly complete, and even that one is based on several animals, not a single complete specimen. It is one of the few bigger dinos where most of the reconstruction isn't pure fantasy, which is the case with nearly all the biggest dino reconstructions. It will be interesting to see the Futalognkosaurus, I believe that it is more complete, though it still misses a lot, unfortunately also the legs!

The dino footprints should make it possible to calculate almost the exact pressure of the foot on the ground, if the property of the soil is known. It wouldn't even have to be calculated, it could easily be determined by experimentation. I wonder if anyone have done anything like that?

* There must be a limit to how much of the dinos weight which would consist entirely of leg - it would have to be a viable organism in every aspect, not just a set of potentially strong enough walking legs.
Edited by JaM, Jun 12 2012, 09:42 PM.
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coherentsheaf
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JaM
Jun 12 2012, 09:37 PM
coherentsheaf
Jun 12 2012, 09:03 PM
Interesting. He doesn't address the dino foot size though, and the stress would probably be on the joints, not on the bone (when moving). The stress would be at least 30 tons on each leg, and the leg would have to be angled, which maybe wouldn't be too much for the bone, but the stress on the joints would be huge. Maybe those big dinos could only move with very small steps? In any case, it's more relevant whether the actual dino's legs as they were could take the pressure, not some calculated hypothetical leg which could.*

Despite his calculations, I still think that a 100 ton dino is out of range, though mostly because the dino bodies aren't too different in size compared with the biggest mammals. Those who are much bigger are usually only known by a few fragments, and they're extrapolated. Only the Humboldt museum Giraffatitan is nearly complete, and even that one is based on several animals, not a single complete specimen. It is one of the few bigger dinos where most of the reconstruction isn't pure fantasy, which is the case with nearly all the biggest dino reconstructions. It will be interesting to see the Futalognkosaurus, I believe that it is more complete, though it still misses a lot, unfortunately also the legs!

The dino footprints should make it possible to calculate almost the exact pressure of the foot on the ground, if the property of the soil is known. It wouldn't even have to be calculated, it could easily be determined by experimentation. I wonder if anyone have done anything like that?

* There must be a limit to how much of the dinos weight which would consist entirely of leg - it would have to be a viable organism in every aspect, not just a set of potentially strong enough walking legs.
I agree with you that the evidence for even 75 tonnes plus land animals is pretty bad, to say the least. The best I know of is Mazetta et al: http://www.miketaylor.org.uk/tmp/papers/Mazzetta-et-al_04_SA-dino-body-size.pdf

Here is the relevant part from the discussion section:

"Impressive as this undeniably is, Brachiosaurus is,
however, clearly not the largest dinosaur known.
This title currently befalls to Argentinosaurus.
It probably did not, however, reach the figure of
100 tonnes, proposed as the more conservative upper
mass limit for a land tetrapod by Hokkanen (1986),
unless some specimens were much larger than the
holotype. Unfortunately, this cannot be checked until
new findings are produced. Other dinosaurs are
known, however, that may have approached
Argentinosaurus in body mass. “Ultrasauros” (Jensen,
1985) was said to be of extraordinarily colossal
dimensions, often credited with a body mass of 100
tonnes or more (e.g. Ostrom, 1978; Benton, 1988;
Gillette, 1994). In reality, the scapulocoracoid (250 cm
long, not 270 cm as stated in Jensen, 1985) of
“Ultrasauros” cannot be shown to be different from
those of the genus Brachiosaurus (Curtice and Curtice,
1996), and it could well belong to the type species
B. altithorax. It is from a specimen larger than the
holotype FMNH 25107, but not by more than around
10 or so tonnes (Paul, 1988; Curtice and Curtice,
1996). It probably had a mass of 45–50 tonnes.
Additionally, equally large remains of B. brancai have
been known, but clearly not discussed, for nearly a
century. The scapula on HMN SII is nearly as large
(193 cm, scapulocoracoid 238 cm), and an even larger
scapula (203.5 cm) is on exhibition at the Museum
fu¨ r Naturkunde, Berlin (Christiansen, Personal
observation). This is as large as that of “Ultrasauros”.
The reported dorsal vertebra of “Ultrasauros” is
not even brachiosaurian but from a diplodocid
(Curtice and Curtice, 1996). The type specimen of
“Ultrasauros” was not the scapulocoracoid but that
large diplodocid dorsal vertebra, now referred to
Supersaurus (Britt and Curtice, 1997).
Supersaurus (Jensen, 1985) is a huge diplodocid, and
at an estimated body mass of around 50 tonnes it is the
largest diplodocid for which there are substantial
remains (Paul, 1988, 1997). Seismosaurus halli
(Gillette, 1987, 1991) is not as large, and claims of a
body length of 50m (Gillette, 1994) are based on
dimensions other than vertebral lengths. Paul (1997)
estimated that this animal would have had a body
mass of around 30 tonnes, at an overall length of
32–35m. The only other sauropods which could have
been subequal in size to Argentinosaurus are known
from only very fragmentary remains. Sauroposeidon
proteles is a gigantic brachiosaurid (Wedel et al., 2000a)
that appears to have been substantially larger than
B. brancai HMN SII. However, it would probably not
have had a greater body mass than Argentinosaurus,
andWedel et al. (2000b) suggestedthat it probably had
a mass of 50–60 tonnes, subequal to A. giganteus.
The incomplete vertebra of the diplodocid
Amphicoelias fragillimus (Cope, 1878) apparently
was of colossal dimensions, indicating an animal
potentially larger than even Argentinosaurus
(Appenzeller, 1994; Paul, 1994, 1997). However,
this vertebra has been lost for more than a
century, making its true size and phylogenetic
affinities uncertain.
Recently, Smith et al. (2001) described the partial
skeleton of Paralititan stromeri, an extremely large
titanosaurian sauropod from the Late Cretaceous of
the Bahariya Oasis, Egypt. However, and according
to these authors, this new species is probably not as
large as Argentinosaurus but represents one of the
biggest terrestrial vertebrates yet discovered.
Finally, one of the included species in this analysis
(A. giganteus) is also one of the largest dinosaurs ever
discovered. The huge bones of the holotype have
long been regarded as remains of one of the largest of
all sauropods known. Paul (1988) estimated its body
mass at 40–50 tonnes, but our results indicate that
this value is too low. Janensch (1938) noted that its
femora were the largest long bones from any known
sauropod, and with the exception of the only known
complete femur of Argentinosaurus, this still holds
true today. However, its femoral length is 235 cm, not
231 cm as given by most previous authors. Van Valen
(1969) estimated that A. giganteus had a body mass of
around 80 tonnes, based mainly on comparisons
with Colbert’s (1962) inflated mass of 78 tonnes for
Brachiosaurus. As explained earlier, our body mass
estimation for A. giganteus yielded a figure of about
69 tonnes, which is intermediate to those pointed out
for previous authors."


As for Puertasaurus: The high estimates seem to stem fro a completely overexaggerated reconstruction done on the Paleoking blog. The single vertebra we have is from an animal abut as large as Argentinosaurus.

Since the fossils of Amphicoelias fragilimus and Bruhathkayosaurus seem to be lost ... there is no need to speculate about them.

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Jinfengopteryx
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What about the Predator/Prey relationship? Doesn't a big and succesfull macropredator mean an oround of 20 times heavier prey?(Than wouldn't Giga have had a Dino what reached up to 200t weight?)
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coherentsheaf
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You mean like Megalodon having prey items weighing 1000 tonnes? :D
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JaM
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Jinfengopteryx
Jun 12 2012, 10:18 PM
What about the Predator/Prey relationship? Doesn't a big and succesfull macropredator mean an oround of 20 times heavier prey?(Than wouldn't Giga have had a Dino what reached up to 200t weight?)
No. Usually prey is actually smaller than the predator. I can't really think of any case where the prey is 20 x the predator, unless the predator is a social animal. Even in that case it's probably still very uncommon prey, and not a kind of prey which is necessary for the predators survival in general. I would expect that at a certain size, the prey would have to be smaller than the predator, since it would be able to harm the predator just by walking into it. Mass grows cubed and surface grows squared, so at some point even a powerfully built predator would be vulnerable and fragile. This is also one of the reasons why I think that the Spinosaurus probably ate relatively small prey items, if it really was as big as people say here - especially if it was really tall and heavy!

Take the white shark for example - it mostly eats fish, smaller dolphins and seals. It may eat elephant seals in some cases, but they're certainly not the usual prey item, the vast majority of prey items are far smaller than the shark itself.

The big cats do eat animals bigger than themselves - but not always. Their prey is usually not 20 x their size, more like the same size and up to four times. Their biggest prey items are exceptions - this applies to all predators. Extremely large prey is not the mainstay of their diet, and as such is not required as prey species at all.
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JaM
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coherentsheaf
Jun 12 2012, 10:05 PM
I agree with you that the evidence for even 75 tonnes plus land animals is pretty bad, to say the least. The best I know of is Mazetta et al: http://www.miketaylor.org.uk/tmp/papers/Mazzetta-et-al_04_SA-dino-body-size.pdf

Since the fossils of Amphicoelias fragilimus and Bruhathkayosaurus seem to be lost ... there is no need to speculate about them.

Amphicoelias fragilimus seems more like a myth than a reality. It would be cool if it was real, but that can only be known if another specimen is found. I would like to be wrong about my assertion about weights.

Anyway, thanks for the link. I think the most interesting fossil right now is the Futalognkosaurus, if it really is as complete as they say. It seems like it had a very long neck, and if the Argentinosaurus was built in a similar way, then maybe the smaller estimates (I believe around 28 m) may be too conservative after all. I wonder how tall they really were, to the top of the back?

Something about dino size and Futalognkosaurus, written by Matt Wedel.
http://svpow.com/2008/01/16/how-big-was-futalognkosaurus/

When I mentioned that the biggest mammals seemed in the same size range, I was thinking of the Giraffatitan in Berlin. However, there are of course bigger specimens known, but they're not complete skeletons. I guess in the case of absolute certainty of the identity, it could mean that the Giraffatitan should be scaled a bit up, considering that the mounted specimen represents a juvenile. So it was probably a good deal bigger than any land mammal - but there's just no complete skeleton of such a big specimen. The biggest mammals aren't as "pneumatic" in their skeleton, but the width of the dino was bigger - though I've read that the width of Giraffatitan depends on how it's recontructed, and presumably it held its feet close to the centerline when walking, which could mean a taller, more narrow animal, but with a deep body vertically. According to this: http://svpow.com/2009/03/16/brachiosaurus-both-bigger-and-smaller-than-you-think-incomplete/ the biggest found was 12-13% bigger, I suppose it would have been more than 6 metres at the back over the shoulder, and as the article says, up to 40% heavier.


Edit: I usually use metric tons or tonnes. It actually makes a bit of a difference. I do remember when I originally read about the Fenykovi elephant, it said around 10.7 tonnes, which is slightly less than 12 short tons. But after reading about the inflated sizes of extinct mammals, and considering that some dino sizes are underestimated, perhaps the biggest dino is heavier than I imagine after all - it may be so that the Giraffatitan is especially lightly built. So even Giraffatitan, in its full grown state, was probably much bigger than any land mammal. Maybe around 35 tonnes or more.
Edited by JaM, Jun 19 2012, 12:28 AM.
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Fragillimus335
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The limits for terrestrial animals is probably in the range of 500-1000 tons. There is actually a decent amount of evidence for sauropods exceeding 200 tons.
Broome titanosaur tracks
Amphicoelias
Plagne didlodocid tracks
Parabrontopodus prints
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theropod
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^nice to see some people think there were sauropods larger than a blue whale weightwise.

I think it would be possible to figure out how heavy a terrestrial animal can get. for that we only need to know how much muscle mass is needed to hold a smaller sauropods weight, then we can calculate how much more muscle a larger Sauropod would need proportionally, and then we have to see when the muscles can´t fit the animals skeleton any more.
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Superpredator
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500-1000t!  :o
Edited by Superpredator, Sep 3 2012, 04:38 PM.
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SpinoInWonderland
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I think it's about 400-450 tonnes...
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