Spinosaurus bite force

[theropod]

@fragillimus: True, that's pretty strange.

2t was approximated, based on the estimate Sakamoto reportedly made for Baryonyx.

[theropod]

Because an animal with an impressively deep rostrum would not necessarily require a strong resistance to lateral stress, as their killing style would revolve around vertical techniques.

That's what will generally be the case, but it doesn't mean an animal with a deep skull cannot also have a laterally resistant skull.

I did not mean "suffer" literally. I simply meant that cacharodontosaurids were characterized by particularly narrow jaws.

Undoubtedly they are narrow, but that doesn't have to mean they are deep or vice versa.

Again, do not take all of my terminology literally. Biologically, spinosaurus was characterized by a relatively deep rostrum/dentary, thus it is logical to call that "emphasis on depth". It had nothing to do with the actual tests.

Well, then that's no point why their modeling should be in any way inaccurate.

So the reconstruction in Japan is MNHM? Well then there you have it; that specimen has a quite robust rostrum (which is where most of my plights in regards to dental and snout robusticity and morphology come from), which is why I feel it was unwise to use a more gracile specimen in this case.

yes, but it's save to assume it's not completely different in it's mechanical properties, since it's still the same genus and of a very similar shape. I think the increased with in MNSN is allometric.

What I think has been disregarded is a different thing I noted later.

If I am not mistaken, the only pantherine that often crushes prey animals' skulls is the jaguar. I am unsure about tigers doing this.

Or they puncture the spine. Not really that important in this context. As I pointed out to you regarding Allosaurus and Stegosaurus neural arches are not especially robust in most animals and could likely be broken easily.
Cougars too use skull bites(I'm well aware it's no pantherine but I was referring to cats in general), and as far as I know all cats do it on smaller prey items.

Are you referring only to the specimen used or the considerably more heavily-built MNHM specimen?

Spinosaurus in general. Large specimens of Mecistops seem quite comparable.

Well there you have it. Using the entire rostrum of the more robust morph (the Japanese one) would have been more wise. The lateral strength of the entire rostrum would have most likely been reasonably higher due to the more broadened center and rear of it compared to the premaxilla.

This was not a question of which specimen was used (neither are there "morphs", and the rostrum in question is not in Japan but in Italy).
It's a question of the compared regions. Incidentally that was the narrowest and shallowest in Spinosaurus while it wasn't in the crocodilians.

The skulls of allosauroids in general were adapted for vertical killing, as evidenced by their impressive depth, little emphasis on width (although some groups like allosauridae had reasonably wider jaws in relation to depth), and thin dentition (which would have obviously been horrible for gripping). Their jaws were still very lightly-built too (put two and two together: narrow jaws that were very sparse and lightly-built), so impressive lateral resistance is likely not a characteristic of any allosauroids; it is not necessary and it would have been unnecessary to put so much extra and unneeded stress on the skull.

I was not arguing it was, I was merely arguing against the principles you had used to deduce that. It's very well possible a deep-skulled animal like an allosaur could have jaws that were very resistant to lateral bending.
In the specific case of allosaurs, that doesn't appear to be the case, owing to a variety of very specific factors in these animals.

On the other hand, T. rex too has a deep skull, and a skull that's laterally resistant (again, owing to a variety of factors), at least resistant enough to use inertial feeding.

[creature386]

Dec 15, 2013 23:38:50 GMT 5 Godzillasaurus said:

In any case their bites are powerful enough to puncture the skulls or spinal medullae of decent-sized prey animals, that's proof in itself. their bites are strong enough to utilise a precise puncturing bite, which is what I suggest spinosaurus did against mid-sized terrestrial prey.

If I am not mistaken, the only pantherine that often crushes prey animals' skulls is the jaguar. I am unsure about tigers doing this.

I don't know if this counts (no predator/prey situation), but there is some 1912 account, where a tiger killed a lion with a skull bite.

[Godzillasaurus]

That's what will generally be the case, but it doesn't mean an animal with a deep skull cannot also have a laterally resistant skull.

Of course not, but in general spinosaurus was simply far better adapted for withstanding lateral stress.

Undoubtedly they are narrow, but that doesn't have to mean they are deep or vice versa.

My point was though that vertical resistance is simply not a problem for carcharodontosaurids, as their specialization lies within such a killing style. Whereas they were simply not designed for gripping and/or resisting lateral stress.

Well, then that's no point why their modeling should be in any way inaccurate.

I never said that it was inaccurate, just that I feel using the more robust skull reconstruction would be wiser in that case.

Or they puncture the spine. Not really that important in this context. As I pointed out to you regarding Allosaurus and Stegosaurus neural arches are not especially robust in most animals and could likely be broken easily.
Cougars too use skull bites(I'm well aware it's no pantherine but I was referring to cats in general), and as far as I know all cats do it on smaller prey items.

I just had a few issues regarding the skull-bite technique in felids, as most sources seem to point to them killing with lethal tracheal bites (as in suffocation and the deep penetration of the trachea). Smaller animals could easily be killed with the skull bite, but larger animals would undoubtedly be killed using a different strategy.

This was not a question of which specimen was used (neither are there "morphs", and the rostrum in question is not in Japan but in Italy).

Gotcha

It's a question of the compared regions. Incidentally that was the narrowest and shallowest in Spinosaurus while it wasn't in the crocodilians.

If they used the entirety of the rostrum as opposed to just the premaxilla, like you said, the spinosaurus would have most likely scored much higher on the lateral resistance tests and most certainly would have scored higher than mecistops for similar reasons that I have already stated.
.

On the other hand, T. rex too has a deep skull, and a skull that's laterally resistant (again, owing to a variety of factors), at least resistant enough to use inertial feeding.

Well that is entirely dependent on it not only possessing a deep skull, but a very wide and robust skull as well (the same thing goes for most tyrannosaurids, although albertosaurines had slightly more gracile skulls than tyrannosaurines). Whereas allosaurs, with much more lightly-built skulls and dentition, would have relied primarily on their reasonable rostrum depth for vertical resistance as opposed to robust rostrums.

I don't know if this counts (no predator/prey situation), but there is some 1912 account, where a tiger killed a lion with a skull bite.

Was it the actual skull itself that was damaged or the anteriormost region of the neck?

[theropod]

My point was though that vertical resistance is simply not a problem for carcharodontosaurids, as their specialization lies within such a killing style. Whereas they were simply not designed for gripping and/or resisting lateral stress.

which does not have any inplications for the case of Spinosaurus.

I never said that it was inaccurate, just that I feel using the more robust skull reconstruction would be wiser in that case.

Then I misunderstood you. what exactly did you mean with this:

The reason why it did worse on the resistance tests (to lateral stress) was because there was much more emphasis on their rostrums being deep.

I just had a few issues regarding the skull-bite technique in felids, as most sources seem to point to them killing with lethal tracheal bites (as in suffocation and the deep penetration of the trachea). Smaller animals could easily be killed with the skull bite, but larger animals would undoubtedly be killed using a different strategy.

Tracheal bites tend to be common especially in lions, and especially in large prey (ie. several times the size of a single lion).
From what I read tigers use this technique less frequently.
But I'm no cat expert.

If they used the entirety of the rostrum as opposed to just the premaxilla, like you said, the spinosaurus would have most likely scored higher on the lateral resistance tests.

And the vertical ones as well. It can be expected that we'd see a sudden drop in the strenght at the point of the disatema, and the region posterior to it will certainly be stronger.
In other words, I'd expect Spinosaurus' rostrum to be more comparable to that of Mecistops in it's overall strenght than to that of Gavialis.

Well that is entirely dependent on it not only possessing a deep skull, but a very wide and robust skull as well (the same thing goes for most tyrannosaurids, although albertosaurines had slightly more gracile skulls than tyrannosaurines). Whereas allosaurs, with much more lightly-built skulls and dentition, would have relied primarily on their reasonable rostrum depth for vertical resistance as opposed to robust rostrums.

Robusticity depends on botht he depth and the width. If a structure has a high dorsoventral moment of area but a rather low mediolateral one, one compensates for the other in terms of overall robusticity.
Hence, Allosauroids also relied on robust crania, even tough they are different in shape and the direction they are strongest in.

[coherentsheaf]

Dec 16, 2013 1:52:09 GMT 5 theropod said:

Robusticity depends on botht he depth and the width. If a structure has a high dorsoventral moment of area but a rather low mediolateral one, one compensates for the other in terms of overall robusticity.

Correct formulation would be: Height not only increases the dorsoventral second moment of area, but also the mediolateral one, though it does so to a lesser extent.

[creature386]

Dec 16, 2013 1:12:50 GMT 5 Godzillasaurus said:

I don't know if this counts (no predator/prey situation), but there is some 1912 account, where a tiger killed a lion with a skull bite.

Was it the actual skull itself that was damaged or the anteriormost region of the neck?

It was a bite in the jaw. And sorry, I got something wrong, the lion wasn't killed. You can read this for further information:
animalsversesanimals.yuku.com/topic/4326/Fight-between-tiger-and-lion-1912-Tiger-bites-lions-skull#.Uq4nOShfJXI

[Godzillasaurus]

Then I misunderstood you. what exactly did you mean with this:

I said that when I thought that spinosaurus did so horribly on those tests because it apparently had a rostrum that was deeper than it was wide. But then you told me that it likely did worse because the specimen used was more gracile and they only used the diastema region of the rostrum as opposed to the entire rostrum. It is vey confusing, so I am not really sure how the biomechanics work in this case. We at least know that the most generalized spinosaurus rostrums were far more robust than those of both mecistops and tomistoma and were more than likely much more resistant.

And the vertical ones as well. It can be expected that we'd see a sudden drop in the strenght at the point of the disatema, and the region posterior to it will certainly be stronger.

The vertical results would still be affected when using the entire rostrum, but it would really not make much of a difference in the realm of relation to mecistops, as it already had an inherently deeper rostrum anyway (although I forgot how baryonyx and the American alligator did in vertical resistance tests). But still, this is part of the reason why I do not believe that using only the premaxilla was a good idea, due to its overall robusticity in relation to the regions of the rostrum posterior to it (this is also the reason why I argued against the potency of using the diastema area for both the dentary and rostrum when biting the neck or back of a large animal; the jaws in this case would be easily damaged regardless of tooth size and build in that area).

In other words, I'd expect Spinosaurus' rostrum to be more comparable to that of Mecistops in it's overall strenght than to that of Gavialis.

The Indian gharial would be a horrible analogy anyway for spinosaurus, as the snout differences between it and the theropod are to a much higher degree than the differences between mecistops (or tomistoma) and spinosaurus (I pointed these out earlier).

Robusticity depends on botht he depth and the width.

That depends entirely on how you define "robusticity". We know for one that allosauroids were not characterized by particularly heavily-built skulls (and were actually quite gracile) and that spinosaurus, despite lacking a relatively (compared to most other groups of large, macro predatory theropods) wide and/or deep snout, actually possessed a quite heavily-constructed and dense rostrum (the same thing goes for its dentary). Spinosaurus was clearly characterized by a more robust rostrum than carcharodontosaurus and related genera.

[Godzillasaurus]

actually, no, they appear longer, have a stronger curvature and also seem wider and to have straighter carinae. Not totally Tyrannosaurus-like, but not that Allosaurus-like either. I think assuming the latter two to have the same biting mode isn't wise.

Oh yea, and when I was talking about megalosaurus tooth shape, I was talking about thickness, not length or curvature. Just FYI. It still retained a similar structure in that regard to the teeth of allosaurus and related genera. Its dentition actually appears to have been perfectly-designed for ripping and slicing; the curvature would actually have been very useful in hooking flesh so that a forceful backward pull would create massive tissue and muscular damage. Again, megalosaurus dentition would have been poorly adapted as impalers (such as when an allosaurid would use its rostrum in the hatchet-bite), but would have been very specialized at ripping. Not that this matters or anything to this actual topic.

The same thing goes for animals like ceratosaurus; it did not have the same proportionate tooth length as the dentition of allosaurus (and was actually quite enlarged in the rostrum), but they were still highly adept at causing massive blood-loss and ripping damage, specifically in areas like the spinal cord.

[theropod]

Lateral Ceratosaurus teeth seem to be much narrower than those of Megalosauroids.

I said that when I thought that spinosaurus did so horribly on those tests because it apparently had a rostrum that was deeper than it was wide. But then you told me that it likely did worse because the specimen used was more gracile and they only used the diastema region of the rostrum as opposed to the entire rostrum. It is vey confusing, so I am not really sure how the biomechanics work in this case. We at least know that the most generalized spinosaurus rostrums were far more robust than those of both mecistops and tomistoma.

well, great depoth does in no way negatively impact lateral resistance, even tough it doesn't increase it near as much as greater width would-that was all I was saying.

The vertical results would still be affected when using the entire rostrum, but it would really not make much of a difference in the realm of relation to mecistops, as it already had an inherently deeper rostrum anyway (although I forgot how baryonyx and the American alligator did in vertical resistance tests). But still, this is part of the reason why I do not believe that using only the premaxilla was a good idea, due to its overall robusticity in relation to the regions of the rostrum posterior to it (this is also the reason why I argued against the potency of using the diastema area for both the dentary and rostrum when biting the neck or back of a large animal; the jaws in this case would be easily damaged regardless of tooth size and build in that area).

That's also why I never proposed it would use this region to transmit it's bite force.

The Indian gharial would be a horrible analogy anyway for spinosaurus, as the snout differences between it and the theropod are to a much higher degree than the differences between mecistops (or tomistoma) and spinosaurus (I pointed these out earlier).

You don't need to tell me that, I just posted why this was probably the case.
Again, had the analysis found them to be comparable on the basis of the complete rostrum, that would have been compelling evidence for them being close analogies, but since that's not the case, I'd preferr more robust albeit still slender-snouted crocodilians (ergo not a gharial, but not an alligator or nile croc either).
The point here is to find the best analogy, not to find a perfect analogy. Crocodilians, despite some geometric resemblance, will never be a perfect extant analogy anyway; Spinosaurus is much too complicated as an animal to be just "modeled" as a giant bipedal croc.

That depends entirely on how you define "robusticity". We know for one that allosauroids were not characterized by particularly heavily-built skulls (and were actually quite gracile) and that spinosaurus, despite lacking a relatively (compared to most other groups of large, macro predatory theropods) wide and/or deep snout, actually possessed a quite heavily-built and dense rostrum (the same thing goes for its dentary).

with robusticity I referred to the overall strenght of the skull, regardless of how it is achieved.
of course you can use varying definitions in this regard (eg. a skull that's deep, wide and short, or a skull that's relatively apneumatic...), but I think that's the one that makes most sense since it's what counts for the function.

coherentsheaf: What I meant to say is that if a structure is very resistant to bending in one direction, but not that much in another (due to being relatively deep in one dimension but not in the other), it will still be an overally robust structure, even tough it is primarily in one direction.

[coherentsheaf]

Dec 16, 2013 22:57:28 GMT 5 theropod said:

coherentsheaf: What I meant to say is that if a structure is very resistant to bending in one direction, but not that much in another (due to being relatively deep in one dimension but not in the other), it will still be an overally robust structure, even tough it is primarily in one direction.

Really depends on how thin it is in one direction. If an Allosaurus had a head only 1mm wide, it would not be very mediolaerally resistan, unless it was enormously tall (even then, it would break just locally, even if the resistance to bending is high). In general the formula for the second moment f area of a rectangle is b*h^3/12 where h is the side parallel to the direction of bending, and b the perpendicular side. Assuming for a moment that the skull of allosaurus is rectangular in crosssection, then increasing the b will make the second moment grow only very slowly compared to increasing the h. Should the h be very low, you would to increase the b by an extraordinary amount to be "robust".

[theropod]

Yeah, but it isn't only 1mm wide. I was talking about the actual skull of Allosaurus.

One thing about beam theory I'm struggling to comprehend: Obviously, the second moment of area affects resistance to bending (ie. the thicker parallel to the force the less it bends for a given force that's applied), but does it affect the maximum force it can resist before failing in the same way?
As a bowyer I know a structure is more rigid in the direction it's deeper in, but it also seems to take much less extreme bending to make it fail (usually in tension). I don't really get clarity about that from what read on the subject.
Is is the cross-sectional area that counts for the yield strenght, but with a different degree of strain that will be caused and that is needed for yielding, depending on the shape?

As usual, it's "physics/maths+me=catastrophe", which is most unfortunate because I'm actually interested in it and it would be important for me to know about such stuff.

Is there some work that explains this stuff both conprehensive and in an understandable way?

[Godzillasaurus]

Lateral Ceratosaurus teeth seem to be much narrower than those of Megalosauroids.

But that still does not entirely denote the fact that they would have still been very useful in cutting and ripping (as evidenced by their thin shape and presence of serrations). The maxillary dentition seems very well adapted for causing deep (penetrating) spinal wounds more than anything, however.

well, great depoth does in no way negatively impact lateral resistance, even tough it doesn't increase it near as much as greater width would-that was all I was saying.

Of course not. My point was simply that allosauroid rostrums would have been poor at resisting lateral forces as evidenced by both their laterally-compressed dentition and gracile build. They were clearly not designed for killing prey with side-to-side movements. If anything, spinosaurus would be a good deal more resistant in this case due to its more robust snout and dentition. Not only that, but its diet of large powerful fish requires a stronger lateral snout to a much greater extent than carhcarodontosaurus, as it was fundamentally designed to grip as opposed to kill quickly.

Thus, having a slightly wider snout does not mean greater lateral resistance.

That's also why I never proposed it would use this region to transmit it's bite force.

Well of course it would not use this area to exert a massive bite. That region is obviously located posterior to that (where they would have a much lesser chance of breaking).

You don't need to tell me that, I just posted why this was probably the case.

Sorry

Again, had the analysis found them to be comparable on the basis of the complete rostrum, that would have been compelling evidence for them being close analogies, but since that's not the case, I'd preferr more robust albeit still slender-snouted crocodilians (ergo not a gharial, but not an alligator or nile croc either).

The point here is to find the best analogy, not to find a perfect analogy. Crocodilians, despite some geometric resemblance, will never be a perfect extant analogy anyway; Spinosaurus is much too complicated as an animal to be just "modeled" as a giant bipedal croc.

I agree

[theropod]

But that still does not entirely denote the fact that they would have still been very useful in cutting and ripping (as evidenced by their thin shape and presence of serrations). The rostral dentition seems very well adapted for causing deep (penetrating) spinal wounds more than anything, however.

Tyrannosaurine teeth are serrated too, even baryonychine teeth are. That alone doesn't mean they are primarily slicing tools.

You're right regarding the premaxillary teeth, but Ceratosaurus is not the only example for this. In fact, it seems to be the norm for theropod premaxillary teeth to have a completely different cross-section than the lateral teeth. You should check this out on an Allosaurus skull the next time you see one in a museum.

My point was simply that allosauroid rostrums would have been poor at resisting lateral forces as evidenced by both their laterally-compressed dentition and gracile build. They were clearly not designed for killing prey with side-to-side movements.

Certainly not.

[creature386]

Dec 17, 2013 2:17:40 GMT 5 theropod said:

But that still does not entirely denote the fact that they would have still been very useful in cutting and ripping (as evidenced by their thin shape and presence of serrations). The rostral dentition seems very well adapted for causing deep (penetrating) spinal wounds more than anything, however.

Tyrannosaurine teeth are serrated too, even baryonychine teeth are. That alone doesn't mean they are primarily slicing tools.

Godzillasaurus doesn't deny this, judging from his last sentence. He just said they could have done some cutting/ripping work.