Tyrannosaurus rex versus Spinosaurus aegyptiacus

[Runic]

Jun 5, 2013 1:29:00 GMT 5 theropod said:

Of course some smaller prey items can be more formidable in exchange, that was not what I meant. I meant like most predators the main component in T. rex' diet were probably specimens smaller than itself, not record-sized 9t ceratopsians or the very largest hadrosaurs.

Once again it's not the size. Example which would you think T.rex would attack first. A sub-adult triceratops or a hadrosaur smaller than it? The rex would attack the hadrosaur because even a sub adult trike has more dangerous ways of injuring a rex than the hadro. It is not really the size but the time and effort it would take to kill the animal. I'm sure if elephants were just walking mounds of meat and defenseless a lion would kill them before they tried attacking a say a group of hyenas or a crocodile.

[theropod]

I was talking about Triceratops specimens. Which is more dangerous a 5t trike or a 9t trike?

Size is still an important factor, it is responsible for how dangerous and durable something is. A large sauropod for example would have an easy time killing a lone theropod, due to sheer mass and strenght. It is of course not the only factor, but just as important as the others.

[elosha11]

On a different biological point, how useful would either of these animal's forelimbs be in a conflict? Obviously T-rex's are very short and likely not be of use. However, I do note that some researchers used scanning imagery on fossil remains to estimate that the bicep functioning muscles for T-rex were able to lift over 400 pounds. With that kind of strength, if it could somehow get close enough to a Spinosaurus to engage its claws in gripping or pulling motions, they might be able to do some level of local damage and aid T-rex in placing a more deadly bite.

Obviously, we can assume Spinosaurus' much longer forelimbs and large claws would have been more of an advantage in a fight. Is there enough fossil remains to make an estimate of their strength and range of motion? I would assume Spino could also manipulate its forelimbs in a broader range of motion than a T-rex.

Also, what type of comparisons can be made about the relative strength of their leg muscles? I've always understood that T-rex had heavily built legs. Although Spinosaurus had to have powerful legs to hold such immense weight, I've assumed its legs may be relatively less robust than those of T-rex. If T-rex's legs were more powerful that might give it an edge in driving back/knocking over Spinosaurus, which could effectively end the fight. Of course, that discounts the probable weight advantage of Spinosaurus which may cancel out any disparity in leg power.

[Fragillimus335]

Jun 5, 2013 19:52:37 GMT 5 elosha11 said:

On a different biological point, how useful would either of these animal's forelimbs be in a conflict? Obviously T-rex's are very short and likely not be of use. However, I do note that some researchers used scanning imagery on fossil remains to estimate that the bicep functioning muscles for T-rex were able to lift over 400 pounds. With that kind of strength, if it could somehow get close enough to a Spinosaurus to engage its claws in gripping or pulling motions, they might be able to do some level of local damage and aid T-rex in placing a more deadly bite.

Obviously, we can assume Spinosaurus' much longer forelimbs and large claws would have been more of an advantage in a fight. Is there enough fossil remains to make an estimate of their strength and range of motion? I would assume Spino could also manipulate its forelimbs in a broader range of motion than a T-rex.

Also, what type of comparisons can be made about the relative strength of their leg muscles? I've always understood that T-rex had heavily built legs. Although Spinosaurus had to have powerful legs to hold such immense weight, I've assumed its legs may be relatively less robust than those of T-rex. If T-rex's legs were more powerful that might give it an edge in driving back/knocking over Spinosaurus, which could effectively end the fight. Of course, that discounts the probable weight advantage of Spinosaurus which may cancel out any disparity in leg power.

There have been giant humeri found that likely came from a largish Spinosaurus, the estimated complete length scaling from Baryonyx is 80 cm, and 90 cm when scaled up to MSNM V4047. As you can see in the comparison, the arms would have been massively strong compared to rex, and due to carrying at least 4-5 extra tons, the legs would be stronger too.

[elosha11]

Thanks fragillimus. That's a great comparison and really demonstrates that spinosaurus probably had another unique strength over tyrannosaurus. Those powerful arms and claws could to significant damage to t-rex's face or body although of course t-rex could attempt to bite them off if within range. But if spinosaurus managed to grab t-rex with its arms, it could possibly maneuver into better position for a bite. With it's size and limb advantage, I think spinosaurus' advantages negate t-rex more powerful bite. But either animal could win especially if t-rex got in a good bite. I still think t-rex may have also been the more aggressive more experienced fighter based on its lifestyle and prey choices.

[theropod]

I doubt T. rex could really come close enough to use its forelimbs in a fight. After all its head extends several metres in front of them, and there is a limit to how far the massive neck could be pulled back. To me it always appeared most likely their purpose was to aid in rearing up, which would explain the tremendous strenght.


It is an entirely different think with some other large theropods, especially allosaurs and megalosauroids. These taxa alltogether have longer, (even) more robust arms, and longer, more well-developed radii, ulnae and manus, with very powerful claws. There are some very impressive shots of the arms of Suchomimus in an Archosaur Musings-post, try googling it if you have time.


The range of motion doesn't appear to be particularly great in most large theropods, however through the lenght alone these long-armed species would have an absolutely much greater reach, and judging by robusticity, attachment-size, the already very strong arms of tyrannosaurs and the basic trade-off between power and flexibility a tremendous strenght. Rearing up a bit and flexing the neck would suffice to bring an opponent into reach. It is also possible spinosaurs had a greater range of motion. I haven't read the paper in question, since it is paywalled, and don't know the methods used and how reliable they are tough, so I wouldn't jump to conclusions et.
But these animal's well developed forelimbs seem to clearly indicate a use in predation or fighting, that's for sure.

[Grey]

But are there some works or indications of the size of the muscles in these arms (of non-tyrannosaurids large theropods) and their degree of motion potency.

Tyrannosaurus arms seem to be themselves particularly robust for their size, a small size which does not allow them to do great things in a conflict but to argue that others theropods had themselves also arms as powerful and robust, only larger and armed with big claws, with the same proportion of muscles in T. rex seems to be a bit hazardous, even if I agree that in absolute terms these clawed arms were certainly devastating.

I report a quote from Matt Wedel who, about claws potency in theropods, seems to consider those in Saurophaganax to be the most impressive :

In short, the thumb claw of Saurophaganax is the most impressive instrument of dinosaurian destruction IÂ’ve yet laid eyes on.


svpow.com/2013/04/19/friday-phalanges-megaraptor-vs-saurophaganax/


Well, I think he excludes Spinosaurus because he did not seen, like anybody, arms in it yet. But I'm skeptical about these claims of hugely powerful arms simply because the tiny arms of T. rex are particularly muscled. Is there really any paper about this ?

[theropod]

That blog post by Matt Wedel was partially ironic and making fun of "carnivora-fanboys", and that line was meant as a joke, even tough he certainly considers it formidable (how couldn't he?). He didn't study other arms of theropods, that simply isnÂ’t his field of research.
Sure, if Saurophaganax was an upscaled Allosaurus it would have had very impressive arms, and we already know the claw and a pretty big humerus (tough I really have no clue whatsize the specimen the ungual belonged to, OMNH 780, was, and the humerus is problematic). Not comparable to Spinosaurus tough. Funny thing is, it seems by far the most common fossil to find of Saurophaganax are unguals!


However I am not aware of any reasons to presume other theropods should have proportionally weaker or less movable arms than Tyrannosaurs, and assuming that would be beyond biased (everything actually suggests the majority of carnosaurs and megalosauroids had much more powerful forelimbs).
They are even more robust and show larger attachments, you can see it here:



And consequently they were probably stronger at the same lenght, not weaker.

The deltopectoral crests are described as reduced in all tyrannosaurs except Eotyrannus. The motion is described as constrained as compared to other theropods, the manus is atrophied and has only two functional digits, and the bones are obviously far more slender (albeit still robust). Even the brachial plexus in the neural canal is stated to be atrophied (Griffin, 1995).

You can see this set of facts summarised in The Dinosauria and supported by every publication mentioning theropod arms, eg the following:

Madsen,1976 said:

the forearms, although reduced, are
strong in contrast to their relatively small counterparts
in Tyrannosaurus.

What applies to Allosaurus in this regard does so even more with Spinosaurus.

Everything points out to Tyrannosaurid arms retaining only some specialized function, likely, as indicated by every single scientist in this world and every bit of their osteology, not for predatory tasks.

[grizzly]

One theory of the usage of T-rex arms was for the male to hold onto the female when "doing the wild thing".

[gigadino96]

Spinosaurus, because it was much bigger, too for Tyrannosaurus.

[Fragillimus335]

Well based on Hartman's scaling, Tyrannosaurus turns out to be pretty heavy, ~8 metric tons. If his Spinosaurus comes out at 11-12 tons. That would give Spino a ~50% weight advantage.

[theropod]

Keep in mind Spinosaurus is semiaquatic and probably much denser, which Hartman doesn't include in his estimates.

[Fragillimus335]

Jul 20, 2013 14:19:00 GMT 5 theropod said:

Keep in mind Spinosaurus is semiaquatic and probably much denser, which Hartman doesn't include in his estimates.

Yeah, but I think he make all his theropods a tad too dense, so I think of he keeps it at .915 for Spinosaurus it would be fine.

[Grey]

I'm skeptical toward these assumptions of the great impact of the density on theropod's mass. Without further data I won't comment anything.

Keeping in mind Hartman's comparison and awaiting his post about Spinosaurus total body mass, I would expect the larger Spinosaurus specimen to be overall the most powerful theropod known. However, I honestly cannot reject the possibility for T. rex to inflict a well placed bone-pulverizing bite on the neck of Spinosaurus, which would put an end to the confrontation. Spinosaurus would have to keep its neck out of reach of T. rex jaws.

[theropod]

Jul 20, 2013 22:01:46 GMT 5 Fragillimus335 said:

Jul 20, 2013 14:19:00 GMT 5 theropod said:

Keep in mind Spinosaurus is semiaquatic and probably much denser, which Hartman doesn't include in his estimates.

Yeah, but I think he make all his theropods a tad too dense, so I think of he keeps it at .915 for Spinosaurus it would be fine.

Probably yes. But T. rex likely should have lower specific gravity by comparison, at least if you go by volumetric studies on different Carnosaurs and Tyrannosaurs and the great amount of pneumatisation and hollow bones in T. rex.

And idea of the density of large, extant crocodilians (and ignoring gastrolithes, since what we need is the kind of weight/density actually relevant to how much muscle mass an animal has)?