Spinosaurus bite force

[Godzillasaurus]

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

Of course not

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.

I was talking about rostrum in general, not just the premaxillary teeth. They appear to have been perfect for penetrating deeply and creating broad puncture wounds, as evidenced by their long shape and being laterally compressed (and serrated) at the same time:



As far as I am aware, not much has been studied on ceratosaurus (and related genera) dentition. So much of their function is hypothetical for now.

But we should really get back on topic

[coherentsheaf]

Dec 17, 2013 0:31:28 GMT 5 theropod said:

Y
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?

In a stiff body yes. But real materials have some elasticity to them and will deform before breaking. The exact amount it deforms is dependent n the material. That is why we need so mch effort in modelling these structures.

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?

Exact interactions are ften complicated. Materials deform and so on. Would have to ko more about the exact circumstances.

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?

The interactions you need are complicated. The second moment of area tself needs calculus in more than one variable to be formulated, which is beyond school levels in Austria. I am afraid there is no easy way of learning this. I am not the best person to ask for easy introductions though, as I have trainimg in math and therefore can access most of the stuff pretty easily and do not need to look for formulations that are light on high level abstractions. In any case I would advice you to take close attention in school in the next 1-2 years. (You are in 7th grade now?) You will learn calculus (or "Differential und Integralrechnung" in german). This is the most important tool in understandng most of modern physics and math. In particular learn to solve "Extremwertaufgaben" and to calculate areas. Once you have mastered these concepts, take some introductory physics lecture at university (You do nt have to inscribe in the courses, but to learn the stuf it is obligatory that you solve the exercises). With this training you will come a long way. Understanding most of the research in animal mechanics should be doable after this.

As a general note I would strongly suggest not beating yourself up over math and physics you do not understand yet. The fact of the matter often is: What one fool can do, anoter can follow. While it is hard, all of these things can be learned if you keep at it.

[creature386]

coherentsheaf,
Do these formula belong to what you were talking about (if yes, I guess that's something for me to download)?
www.brinkmann-du.de/mathe/gostpdf/p7_formelsammlung.pdf
Because this is the formula collection of a website(section) talking about the calculus. I have already learned some of them at school and I guess theropod will know most of them too (as he is older than I am).

[coherentsheaf]

Dec 17, 2013 20:24:29 GMT 5 creature386 said:

coherentsheaf,
Do these formula belong to what you were talking about (if yes, I guess that's something for me to download)?
www.brinkmann-du.de/mathe/gostpdf/p7_formelsammlung.pdf
Because this is the formula collection of a website(section) talking about the calculus. I have already learned some of them at school and I guess theropod will know most of them too (as he is older than I am).

These are pretty basic. You might need a lot more.

[creature386]

Thank you for the response! I downloaded the one above for school and this one for further studying:
tutorial.math.lamar.edu/pdf/Calculus_Cheat_Sheet_All.pdf

[coherentsheaf]

Sry I just realized my phoe did ot display the stuff properly. The formulas o the second page of the german document are the ones you need to learn at school - preferably to an extent that you know them by heart and can apply them in many situations. If you can do that yu have come a long way.

[theropod]

Thanks, that´s already quite helpful (both of you). Funny enough, we started calculus at school about three hours ago!
I recall you already told me I should pay attention in calculus lessons some time ago (I´mll take care to do so!).

So the yield strenght and its relation to the second moment of area is dependant on the material? And the more elastic it is, the less important I gets for it´s yield strenght (eg. rubber band vs concrete)?
How does this apply to the case of (living cortical) bone?

I presume that generally is advqantageous for a bone´s strenght to be deepest in the direction it´s loaded in, be it only because if it is not (as in your example of a 1mm thin skull) it will be more prone to partial failure (eg. fracture of just the oral margin of the skull even if as a whole it´s not that weak). Did I get this right?

PS: Yes, I´m in 7th grade. It´s not necessary to give me the German terms tough.

[theropod]

Dec 17, 2013 3:51:39 GMT 5 Godzillasaurus said:

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

Of course not

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.

I was talking about rostrum in general, not just the premaxillary teeth. They appear to have been perfect for penetrating deeply and creating broad puncture wounds, as evidenced by their long shape and being laterally compressed (and serrated) at the same time:



As far as I am aware, not much has been studied on ceratosaurus (and related genera) dentition. So much of their function is hypothetical for now.

But we should really get back on topic

I like to view them as sabre-toothed cat analogues. Instead of particular reliance on head-depressive and ripping motion I think Ceratosaurus would have used the lenght and particularly good penetration and slicing capabilities of those long lateral teeth (plus a pretty monstrous skull in terms of size).
What I meant was that the premaxillary teeth always tend to be pretty robust in theropods, so a whole dentition shouldn´t be judged by them (I made that mistake myself once).

[coherentsheaf]

Dec 18, 2013 16:48:45 GMT 5 theropod said:

Thanks, that´s already quite helpful (both of you). Funny enough, we started calculus at school about three hours ago!
I recall you already told me I should pay attention in calculus lessons some time ago (I´mll take care to do so!).

So the yield strenght and its relation to the second moment of area is dependant on the material? And the more elastic it is, the less important I gets for it´s yield strenght (eg. rubber band vs concrete)?
How does this apply to the case of (living cortical) bone?

I presume that generally is advqantageous for a bone´s strenght to be deepest in the direction it´s loaded in, be it only because if it is not (as in your example of a 1mm thin skull) it will be more prone to partial failure (eg. fracture of just the oral margin of the skull even if as a whole it´s not that weak). Did I get this right?

PS: Yes, I´m in 7th grade. It´s not necessary to give me the German terms tough.

You are welcome!
The second moment is always importat as it always will give you the stress at a given point in a beam,regardless of material. The material however determines wheter it will break under this stress, or deform.

Being deep in the direction of the applied force will decrease the stress you experience overall. You can achieve this with very little material: A hollow tube is far more resistant to bending than a solid one (not to buckling though, or local failure of material).

[Godzillasaurus]

Dec 18, 2013 16:48:45 GMT 5 theropod said:

Thanks, that´s already quite helpful (both of you). Funny enough, we started calculus at school about three hours ago!
I recall you already told me I should pay attention in calculus lessons some time ago (I´mll take care to do so!).

So the yield strenght and its relation to the second moment of area is dependant on the material? And the more elastic it is, the less important I gets for it´s yield strenght (eg. rubber band vs concrete)?
How does this apply to the case of (living cortical) bone?

I presume that generally is advqantageous for a bone´s strenght to be deepest in the direction it´s loaded in, be it only because if it is not (as in your example of a 1mm thin skull) it will be more prone to partial failure (eg. fracture of just the oral margin of the skull even if as a whole it´s not that weak). Did I get this right?

PS: Yes, I´m in 7th grade. It´s not necessary to give me the German terms tough.

You're in seventh grade!?!?!? I thought you were like 18!?

Or is there some different grading system in Austria (that's where you live, right?) than where I live?

I like to view them as sabre-toothed cat analogues. Instead of particular reliance on head-depressive and ripping motion I think Ceratosaurus would have used the lenght and particularly good penetration and slicing capabilities of those long lateral teeth (plus a pretty monstrous skull in terms of size).

Yea, that's what I like to think of them as. And even though its skull was quite long in proportion to body size, it still wasn't necessarily the most robust of all theropods either, as part of the reason why it would have been deadly with vertical killing techniques is because its skull was relatively deep (just like allosaurus and related genera) and its dentition would have been perfect for doing so. But that is irrelevant here. We should talk about it elsewhere before we spam the thread.

Now I think that it might be a good time to go back on topic. It kind of ruins threads when this sort of thing happens

[theropod]

Seventh grade of high school + middle school (that's how we usually count them), I'm 17. Overall, that's the 11th grade when including the whole time at school, which will luckily be over in not even two years (but not before I've learned calculus ).

I think we pretty much reached an agreement on the topic, didn't we? We were just repeating a few details but I got the feeling we both were aware of and thought the same.

[Godzillasaurus]

I think we pretty much reached an agreement on the topic, didn't we? We were just repeating a few details but I got the feeling we both were aware of and thought the same.

Yes, we did.

Seventh grade of high school + middle school (that's how we usually count them), I'm 17. Overall, that's the 11th grade when including the whole time at school, which will luckily be over in not even two years (but not before I've learned calculus ).

That's a relief; I thought I have been talking to a 12 year old this whole time!

Just a question about the resistance studies, but when you said that they only utilized the diastema and/or most foremost region of the rostrum, did you mean to say that they only exerted force on one specific area on all of the animal's rostrums (In this case, the thin region just posterior of the cleft in spinosaurus and baryonyx)? If they would have tested the resistance of the (roughly) centermost parts of each animals' rostrums in addition, it would lead to much more accurate results. This is true in that whenever spinosaurus clamped down on another dinosaur, that area would be the most resistant in its case and it would have only done minimal damage if only the premaxilla was used (not to mention that area being horribly adapted for killing large animals and having a higher breaking point). Not only is it illogical to believe that spinosaurus would have killed large terrestrial animals using only the frontalmost portion of its snout (by gripping), but not putting the posterior areas into consideration is unwise in this case. We should not make any hasty conclusions yet about the strength of spinosaurus jaws; they were clearly not as weak as the paper is making them out to be. Man, bias in zoology is more common than I have previously expected.

[theropod]

They did not excert force, but calculated a mathematical measure related to the structure´s resistance. In this case, they just compared the anteriormost 18.5% of the skull, which in the case of the Spinosaurus rostrum equaled basically just the premaxilla, mostly the diastema (you can see it in figure 5 of then study).

Since this is the anteriormost and most gracile region in Spinosaurus´ skull, that´s an obvious problem for comparing overall resistance or bite force, since in the instant of a bite intended to be damaging that would hardly be the part of the jaws that would be used.

They did it because (at least going by the restoration they used) the preserved part of the Baryonyx rostrum was only that large and, of course they wanted to test analogous regions.
However for getting relevant comparative data for Spinosaurus´ skull strenght, it would have been a better idea to include another dataset using the entirety of the preserved remains.

[Godzillasaurus]

They did not excert force, but calculated a mathematical measure related to the structure´s resistance. In this case, they just compared the anteriormost 18.5% of the skull, which in the case of the Spinosaurus rostrum equaled basically just the premaxilla, mostly the diastema (you can see it in figure 5 of then study).

What I meant to say was that they only studied that portion.

Since this is the anteriormost and most gracile region in Spinosaurus´ skull, that´s an obvious problem for comparing overall resistance or bite force, since in the instant of a bite intended to be damaging that would hardly be the part of the jaws that would be used.

Definitely

They did it because (at least going by the restoration they used) the preserved part of the Baryonyx rostrum was only that large and, of course they wanted to test analogous regions.

However for getting relevant comparative data for Spinosaurus´ skull strenght, it would have been a better idea to include another dataset using the entirety of the preserved remains.

Well then I can see why they only studied that portion of the snout. But good God, they shouldn't come to such hasty conclusions like that, as we already know that the region posterior to that appears to have been much more robust and generalized (compared to both the crocodile and gharial AND the diastema region), and would have probably scored more than, if not much closer to the crocodile and gharial rostra (this area, based on its anatomy, appears to have actually been very adept at doing so in spinosaurus). I actually made a thread devoted to this subject on Animalia Enthusiasts. You should check it out.

[theropod]

I don't think they came to particularly hasty conclusions. With scientific papers, it's always necessary to set the data you take from them into context to what they refer to. That's just normal and can be expected from someone who reads and uses their data. Of course this part could have been elaborated, and perhaps included in the study, but it's not their fault we had overlooked it previously.

btw here's the figure in question:
 
www.plosone.org/article/info:doi/10.1371/journal.pone.0065295

You can see the red line marking the anteriormost 18.5% goes right through the symphysis in the Spinosaurus, and that the region anterior to is is both considerably shallower and narrower. Thus it's quite clear The rostrum as a whole was more resistant.