Functional Morphology of Animal Feeding Apparata

[dinosauria101]

sam1
Infinity Blade

How's this?

Kronosaurus vs Purussaurus skull from Wikimedia commons

[Infinity Blade]

What does Purussaurus have to do with this?

[dinosauria101]

I just used it as an example of a broad snouted animal.
Regardless I believe the disparity is still shown

[sam1]

Oct 11, 2019 18:03:38 GMT 5 dinosauria101 said:

sam1
Infinity Blade

How's this?

Kronosaurus vs Purussaurus skull from Wikimedia commons

The embedded image is barely visible..too low resolution. 
I notice you keep posting such stuff, how is it possible that you don't notice that?
Maybe it's because I'm on mobile, and things look different on desktop/windows.

[Infinity Blade]

^You have to click on the image to view it at a higher resolution (it will show up on a different window).

[dinosauria101]

Oct 11, 2019 18:11:43 GMT 5 sam1 said:

Oct 11, 2019 18:03:38 GMT 5 dinosauria101 said:

sam1
Infinity Blade

How's this?

Kronosaurus vs Purussaurus skull from Wikimedia commons

The embedded image is barely visible..too low resolution. 
I notice you keep posting such stuff, how is it possible that you don't notice that?
Maybe it's because I'm on mobile, and things look different on desktop/windows.

Like Infinity Blade said, click for higher resolution. That should work for all of my screenshots

[sam1]

Oct 11, 2019 18:14:48 GMT 5 dinosauria101 said:

Oct 11, 2019 18:11:43 GMT 5 sam1 said:

The embedded image is barely visible..too low resolution. 
I notice you keep posting such stuff, how is it possible that you don't notice that?
Maybe it's because I'm on mobile, and things look different on desktop/windows.

Like Infinity Blade said, click for higher resolution. That should work for all of my screenshots

Well, then.. excuse my stupidity. Nice work!

[Verdugo]

Oct 1, 2019 21:59:23 GMT 5 theropod said:

2) Hmm, problem seems to be that while there is a large number of in vivo bite force measurements for Tegus, neither are the figures themselves available as a dataset, nor are accompanying measurements of the animals. This study measured quite a lot of tegu bites:
repositorio.unesp.br/bitstream/handle/11449/21155/WOS000270695800006.pdf

However they focused on behavioural correlates of bite force, not the actual figure or its relation to body or skull size. Very interesting, but a little frustrating if we want to use the data to estimate bite force from skull size or body mass. They also list a correlation of BF with SVL, so they must have measured the latter, but they don’t seem to show it anywhere.

From their plots we can see that the maximum bite force of the male Tegus they measured is around 1000 N, but this doesn’t help a lot without knowing the size of the tegu.

I knew a couple of papers on Lizard/Tegu Bite force stuffs but none of them seems to be presented in a way that could be useful for extrapolation of extinct species. You may want to take a look:
www.semanticscholar.org/paper/Built-to-bite%3A-feeding-kinematics%2C-bite-forces%2C-and-Schaerlaeken-Hol%C3%A1%C5%88ov%C3%A1/d02a3002157e9b6d8ab11269a2d732aa1eb78838
www.researchgate.net/publication/236327445_The_importance_of_accurate_muscle_modelling_for_biomechanical_analyses_A_case_study_with_a_lizard_skull
jeb.biologists.org/content/jexbio/221/23/jeb180240.full.pdf?with-ds=yes

There is actually a dry skull BF of Mosasaur though
www.cambridge.org/core/journals/netherlands-journal-of-geosciences/article/feeding-the-mechanical-mosasaur-what-did-carinodens-eat/09A2B9E159FEAE793695B88BD29C57E1

The BF estimate appears to be underestimated so i'm not sure if it has any use for comparison purpose with other modelled BF studies. They did not even account for pterygoid muscles.

BF and skull performance studies of Mosasaur are rather limited AFAIK. So far, i still have not seen any FEA Mosasaur skull.

[Infinity Blade]

Verdugo

Do you have any thoughts on my last post to you in this thread? I'm genuinely curious.

[theropod]

Verdugo: Well, we can at least get some rough measurements from the figures in the first paper you linked.
Based on the lines of best fit, the average predicted BF for individuals of both taxa at SVL of 400 mm would be about 400 N (the graph says "bite force in mm", but I assume they must have meant to write N).
The scaling trends appear to be different between the two, but they don’t provide the equations. We could measure the slopes, but I’m not sure whether it would tell us much, as I don’t know which of the two would be better.

The head width for that SVL would be 57 and 71 mm for T. merianae and D. guianensis respectively (skull width would have to be slightly lower, so I suppose the results ignoring that and scaling to skull width would be slightly on the low side). However, are there any Prognathodon specimens with preservation allowing the skull width to be measured? All the ones I know are badly crushed, probably not very reliable.
However, the width across the temporal region in P. currii seems to be at least around 60 cm. Since the skull is flattened dorsolaterally, that might be relatively accurate (though also perhaps a bit too low).

Scaling up from the lizards using those figures would give conservative estimates of 29-46 kN at the tip of the jaws. So yes, probably T. rex territory, although I’m not totally clear on whether the figures they reported for the teijus were peak or sustained BFs.

I certainly wouldn’t want to get bitten by one of these guys.

[Verdugo]

Oct 12, 2019 16:39:58 GMT 5 Infinity Blade said:

Do you have any thoughts on my last post to you in this thread? I'm genuinely curious.

You meant this one?

Slight tangent, but the only real gripe I have is the fact that they used a steel skull cast. Like, obviously I have no problem believing a real T. rex could effortlessly crush cow bones, but then they decided to test it against a car (which it also destroyed). They were able to make the Triceratops skull out of resin (I'm not sure how much that mimics the strength of bone), so was it or was it not possible for them to use something that more closely mimics bone for the T. rex skull?

Well, if i am honest, i don't think i really know any better than you regarding this. But since you insisted...

---

Like, obviously I have no problem believing a real T. rex could effortlessly crush cow bones, but then they decided to test it against a car (which it also destroyed)

I don't think it's entirely unrealistic for a T-rex to damage a car like that. For example, mild steel has a compressive strength of <200MPa

If the steel is C15, with the material at 900°C 144 MPa, while at 1200°C 65 MPa.
At ambient temperature between (160 to 200) MPa. It depends according to the deformation grade applied

while enamel has a compressive strength of close to 400 MPa:

The compressive strength of enamel (384 MPa) and dentin (297 MPa) and the fracture strength of a natural tooth (molar = 305 MPa; premolar = 248 MPa) offer excellent mechanical standards to select the optimal strength for posterior composite resins.

Obviously i do not clearly know about the material of the car they used in the show but i don't think it should be stronger than mild steel. The car in the show does not look exactly modern but in modern cars, their materials are made to be damaged quite easily (in order to absorb car crash kinetic force). So yes, i think T-re may have the mechanical requirements for such task. However, that does not mean it will not damage its teeth and mouth in many ways it it ever does so.

---

They were able to make the Triceratops skull out of resin (I'm not sure how much that mimics the strength of bone), so was it or was it not possible for them to use something that more closely mimics bone for the T. rex skull?

Yeah i don't know just how appropriate it is to use resin to replicate bones. However, composite resin has been suggested to be good replacement materials for human teeth (Willems 1993):

Based on these standard criteria, it can be concluded that in the 21st century the ultrafine compact-filled composite resins may be the materials of choice for restoring posterior cavities.

Obviously, this also depends on the type of resins they used in the show. I have read quite a few paper on FEA modelling and they usually consider it is difficult to accurately replicate bone properties in FEA. For example, in Slater 2010:

Ideally, we would have assigned complex material properties to our models to account for regional variation in the distribution of cortical and cancellous bone, and the orthotropic material behavior of bone. Because the use of homogenous material properties in FEMs has been shown to produce surface strains that fall within the range of values of obtained from in vivo strain gauge studies [45] and material properties are currently not available for polar or brown bear cranial bone, we made the simplifying assumption here to assign homogeneous isotropic material properties based on values for domestic dog cortical bone, following [46], [47] (E = 13.7 GPA, ν = 0.3). Our study is not validated and thus absolute values of results should be treated with caution. However, as the aim of our study is comparative and both skulls were modeled in identical ways, we should still be able to draw broad conclusions regarding comparative performance of the skulls of the two species from the results obtained

This study only researched on modern Bears and even so, data on cranial material properties, cortical/cancellous bone distributions are not available. Thus, i suppose it must be very difficult, if not nigh-impossible to perfectly replicate a skull of an extinct animal down to every details (like material properties)

The thing is, they intended to crash the skull of the Triceratops anyway, so it does not matter if it breaks. On the other hand, they intended to put the T-rex skull through quite a lot abuses and they also wanted to add some JP novelty to it (with the car chomping part) so it would be suck if the skull breaks in the process and they have to build a new one.

[Verdugo]

Tylosaurine morphological adaptations for ramming Lingham-Soliar 1992. The animal described here is Hainosaurus bernadi but i think it has been reassigned to be Tylosaurus bernadi.

Of prime consideration must
be the fact that the impact on the skull during ramming
would clearly have been enormous. The key structure I
therefore looked at in tylosaurs and hainosaurs was the
bone leading from the rostrum and premaxilla, the
internarial bar, which is generally very slender and delicate in mosasaurs and sutured to a narrow anterior
extension of the frontals between the external nares. In
striking contrast, in the Tylosaurinae, it is unique in two
ways: it is exceedingly robust and broad and arises from
a wide rectangular base. Of further significance is the
deeply interdigitated nature of the suture well within the
frontal, that provides a large interfacial sheer area, thus
allowing the transfer of increased stress (Fig.l2B).
Hence there is greater resistance to forces such as bending, shearing and breaking. The significance of the
highly modified internarial bar in tylosaurs and hainosaurs is of fundamental importance for absorption of
the initial shock waves to the head during ramming. A
delicate bar sutured between the external nares, as in virtually all other mosasaurs, would simply have fractured
or dislocated. Furthermore, location of the mosasaur
brain in a robust bony case that formed a sliding joint
with the skull roof at the posteriormost part of the
exceedingly long skull was probably sufficient to cushion the brain from any severe shock. Further support
for this hypothesis lies in the unique condition of a double locking suture between the premaxilla and maxilla in
Hainosaurus (Fig. 12A) that presumably provided stability of the rostrum by a lock and key arrangement with
the maxilla. This was enhanced by the large ventral projections from the premaxilla that acted as a strut between the maxilla and premaxilla.

Robust internarial bar (bones connecting frontal and premax) and interlocking premax-max structures of T.bernadi are well suited to resist stress and are distinct from other Mosasaur, even the robust skulled ones like Mosasaurus or Prognathodon do not have these adaptations.

[dinosauria101]

Does anyone have any data on how wide jaguars can open their mouths relative to size? Would be very useful for the Jaguar vs Orinoco Crocodile thread

[creature386]

Less than 65°, that's all I could find:

The maximum possible gape in conical-toothed felids is about 65° for Panthera leo

Click me, I am a ridiculously long PDF link!
Considering how you are not comparing it to a close relative, but to a crocodile, it's at least something.

[dinosauria101]

^Thanks creature!
I may be able to determine something based on that and GuateGojira's size charts.