Purussaurus brasiliensis vs. Tyrannosaurus rex

[dinosauria101]

Sept 23, 2019 21:25:16 GMT 5 all said:

When I said that 9.6 short tons and over 15 short tons  weight measurement I meant about Tyrannosaurus rex.  I forgot to put word tyrannosaurus at that place. When I said comparison between measurement of 10.5 and 15 meters I was talking about Deinosuchus. Sorry I probably made myself unclear. 

The largest confirmed T rex specimens are at 8 tons approximately.
And even then, a T rex over 9 tons is not possible. That's beyond the biped weight limit.
So this is 6 ton croc vs 5-8 ton dinosaur

[Infinity Blade]

And even then, a T rex over 9 tons is not possible. That's beyond the biped weight limit.

Citation please?

Actually, no need to answer that. I've posted evidence suggesting that bipedal basal sauropodomorphs have achieved body masses of 10-15 tonnes before. In fact, I posted this in response to a question you've asked about the body mass of bipeds supposedly being no more than 9t.

theworldofanimals.proboards.com/post/41317

Edit: for the record, no, I definitely don't think Tyrannosaurus, at the very least known specimens thereof, was hitting multi-ton body masses.

[dinosauria101]

Sept 23, 2019 21:48:35 GMT 5 Infinity Blade said:

And even then, a T rex over 9 tons is not possible. That's beyond the biped weight limit.

Citation please?

Actually, no need to answer that. I've posted evidence suggesting that bipedal basal sauropodomorphs have achieved body masses of 10-15 tonnes before. In fact, I posted this in response to a question you've asked about the body mass of bipeds supposedly being no more than 9t.

theworldofanimals.proboards.com/post/41317

That was directed at me? Oh.
I did not make the connection between it and my question.

Well, a few things:
1: I did find a study that I posted on Discord, but it's blocked where I am so I will post it when I get the chance. Maybe it was referring only to theropods
2: Another thing: wouldn't T rex have to be somewhat graviportal to achieve weights like that? There's a big difference in the build of T rex and Lehumadafi, and it may be the decisive factor regarding weight
3: For all : What is the source for that? Even disregarding the above 2 points, as I said earlier, the largest confirmed T rex fossils are 8 tons 

[Infinity Blade]

nother thing: wouldn't T rex have to be somewhat graviportal to achieve weights like that? There's a big difference in the build of T rex and Lehumadafi, and it may be the decisive factor regarding weight

First of all, it's Ledumahadi. Second of all, I explicitly said that that's not the name of the giant bipedal basal sauropodomorph, and that it and Ledumahadi are often, but should not be, confused with each other. Third, a biped might very well have to become more graviportal to achieve such sizes. But you said "biped", not explicitly any particular bipedal species.

[dinosauria101]

Sept 23, 2019 22:04:01 GMT 5 Infinity Blade said:

nother thing: wouldn't T rex have to be somewhat graviportal to achieve weights like that? There's a big difference in the build of T rex and Lehumadafi, and it may be the decisive factor regarding weight

First of all, it's Ledumahadi. Second of all, I explicitly said that that's not the name of the giant bipedal basal sauropodomorph, and that it and Ledumahadi are often, but should not be, confused with each other. Third, a biped might very well have to become more graviportal to achieve such sizes. But you said "biped", not explicitly any particular bipedal species.

Spelling error, sorry.

As for 'biped', I meant theropods, maybe should've specified. And just for general reference to anyone who's confused, graviportal animals share a very similar morphology in the body cavity area. Some examples are the woolly/Columbian mammoth and Apatosaurus:
<img src="" alt="" style="max-width:100%;"><img src="" alt="" style="max-width:100%;">
<img src="" alt="" style="max-width:100%;">
As can be seen, they share a similar build in that area - relatively solid bones and robustly constructed. T rex lacks this build.

[Infinity Blade]

I'll wait for this study that estimates biped body mass to be 9t at most to be posted. Not that I wouldn't be skeptical of its methods and corollary results, given what I've posted.

[dinosauria101]

As I said, may have just been referring to theropods. But not sure.

[Infinity Blade]

That doesn’t matter to me.

[jdangerousdinosaur]

To say no Tyrannosaurus can mass 9 tons is a bizarre thing to say both Sue and Scotty have been estimated to mass over 9 tons with the latest estimates and Trix is probably pretty close to that size to I'd love to see this biped weight limit study never heard of it.

[Grey]

Sept 23, 2019 21:48:35 GMT 5 Infinity Blade said:

And even then, a T rex over 9 tons is not possible. That's beyond the biped weight limit.

Citation please?

Actually, no need to answer that. I've posted evidence suggesting that bipedal basal sauropodomorphs have achieved body masses of 10-15 tonnes before. In fact, I posted this in response to a question you've asked about the body mass of bipeds supposedly being no more than 9t.

theworldofanimals.proboards.com/post/41317

Edit: for the record, no, I definitely don't think Tyrannosaurus, at the very least known specimens thereof, was hitting multi-ton body masses.

Now there is a difference between the ecology of Tyrannosaurus and those biped primitive sauropodomorphs, one is a giant endothermic hypercarnivore.

Pretty sure T. rex and maybe other theropods have reached or exceeded 10 tonnes on occasion but I think the 10 tonnes mark is a good mark to limit the upper range of terrestrial carnivorous taxa.

I'm rather surprised though that no crocodilian, not even the gigantic ones, seems to really outsize or even really rival T. rex in body mass despite they live in an aquatic environment.


But perhaps this is linked to the metabolism, the endothermic bipedal Tyrannosaurus vs the ectothermic riparian giant crocodilians.

An ectothermic body and the geological constraints on their habitat maybe prevented them to grow as massive as the largest pliosaurs ?

[creature386]

The discussion was about the bipedal weight limit, not the terrestrial carnivore size limit (although the latter probably does indeed lie near the 10 t mark, unless we discover a new record-sized land carnivore). As you correctly noted, quadrupeds don't outsize the largest theropods either.

[theropod]

Sept 24, 2019 0:13:47 GMT 5 Grey said:

Now there is a difference between the ecology of Tyrannosaurus and those biped primitive sauropodomorphs, one is a giant endothermic hypercarnivore.

The other is a giant endothermic herbivore…
The loss of biomass through the trophic chain means that apex predators are usually smaller than the largest herbivores in their environment, but T. rex environment (or most ecosystems of the latter half of the mesozoic) was apparently able to support larger herbivores (at least in the south, namely Alamosaurus) than the Lower Elliot Formation could, so which one is in the more favourable spot to grow larger ecologically is not clear.

Pretty sure T. rex and maybe other theropods have reached or exceeded 10 tonnes on occasion but I think the 10 tonnes mark is a good mark to limit the upper range of terrestrial carnivorous taxa.

I doubt guessing is of any use in this regard.

I'm rather surprised though that no crocodilian, not even the gigantic ones, seems to really outsize or even really rival T. rex in body mass despite they live in an aquatic environment.

Crocodilians are only semi-aquatic, as long as they still have to move on land, being able to do so remains a constraint. And they are obviously a lot less suited to terrestrial weight-bearing than dinosaurs.

But perhaps this is linked to the metabolism, the endothermic bipedal Tyrannosaurus vs the ectothermic riparian giant crocodilians.

Endothermy is possibly the main factor here. An ectothermic reptile cannot sustain sufficient growth rates to reach such size quickly, and with that, much of the evolutionary advantage of large body size is lost, as most individuals get killed before attaining it. However that doesn’t necessarily mean the crocodilian bauplan itself cannot support larger sizes, it merely would be very unusual for an individual to survive long enough to reach them. We should remember that we have far fewer individuals of P. brasiliensis than of T. rex. At least the larger ones of those are probably within T. rex weight range, but on average, they seem to be smaller, perhaps because they grew more slowly.

An ectothermic body and the geological constraints on their habitat maybe prevented them to grow as massive as the largest pliosaurs ?

I don’t know what you mean by "geological constraints", but clearly an important factor is that pliosaurs were fully aquatic, and did not have to move on land.

[Infinity Blade]

Now there is a difference between the ecology of Tyrannosaurus and those biped primitive sauropodomorphs, one is a giant endothermic hypercarnivore.

Pretty sure T. rex and maybe other theropods have reached or exceeded 10 tonnes on occasion but I think the 10 tonnes mark is a good mark to limit the upper range of terrestrial carnivorous taxa.

Again, irrelevant. dinosauria101 was strictly talking about the biomechanical body mass limits of a bipedal animal, and I accordingly addressed just that. If we were talking about the realistic size limit of carnivorous theropods (particularly terrestrial, endothermic, obligatory carnivorous taxa), then it wouldn't have even crossed my mind to bring up the giant sauropodomorph I mentioned (because it would be irrelevant).

Apart from theropod's point, I also said I don't think Tyrannosaurus, at least known specimens thereof, hit multi-ton body masses.

[Verdugo]

Sept 23, 2019 21:33:30 GMT 5 dinosauria101 said:

The largest confirmed T rex specimens are at 8 tons approximately.
And even then, a T rex over 9 tons is not possible. That's beyond the biped weight limit.
So this is 6 ton croc vs 5-8 ton dinosaur

Where did you get the idea that T-rex is capped at 8 tonnes? Can you provide your citations for that claim? The last time i checked, modern mass estimates for large adult T-rex are in 8+ tonnes range. For instance, the modern mass estimates of Sue are: 8.3 t (GDI by Larramendi); 8.4 t (GDI Hartman, Hartman has updated his skeletal in 2019 so i'm not sure if the mass will still be valid); 8.8 t (GDI Franoys); 9.5 t (Volumetric Hutchinson et al). Estimates for Scotty: 8.7 t (GDI Randondinos); 8.9 t (regression Persons et al)

IIRC, Sampson and Trix also appear to be quite complete and similar in size to the two above. Though i haven't double checked them so don't quote me on that.

Also, where did the 5 tonnes figure for adult T-rex even come from? The last time i heard the 5 t estimates for adult T-rex was in Walking with Dinosaurs... Modern estimates, even for younger, smaller adult T-rex (such as Stan) are in the ~7 tonnes range so suggesting 5 t for adult T-rex is kinda bizarre

I'm not saying that what you're suggesting is unreasonable. However, it's not a matter of my opinion or yours. If you have citations for your figures, please post here.

[dinosauria101]

Sept 24, 2019 0:13:39 GMT 5 jdangerousdinosaur said:

To say no Tyrannosaurus can mass 9 tons is a bizarre thing to say both Sue and Scotty have been estimated to mass over 9 tons with the latest estimates and Trix is probably pretty close to that size to I'd love to see this biped weight limit study never heard of it.

9 tons? What would be the source for that? From what I can tell Hartman and Franoys favor a weight around 8 tons
And this blog makes a valid point about Scotty's size; it might not be quite as big as one would think.
(About the study, however, I am locked out of my email AND discord, for some reason, but it does exist!) creature386, if possible, would you be able to get it (on troop panthera, if you can, just search for biped as the keyword)? Thanks in advance

All that said, I agree on 2 points made here
-Even if that study is invalid, I doubt a T rex would get over 8-9 tons, at least not usually, for the reasons already stated and adding that a land carnivore over 9 tons is going to have a very hard time getting enough to eat
-T rex still very much wins on land. It has everything it needs