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[Infinity Blade]

Started by thesporerex on Carnivoraforum. Title explains all.


I'll start, how massive was Baurusuchus, and did it really have a build like the below picture?


Image by felipe-elias.

[Vodmeister]

According to the majority of data online, Baurusuchus averaged about 3.5 meters (11.5 feet) in length and weighed about 200 kg (440 lbs) in weight (and that would have been an average adult male specimen). Large ones grew beyond 4 meters (13.1 feet) and 227 kg (500 lbs) in size.

As for its build, quite impressive even for such a large animal;




That is all I can say about the animal. I can't answer more than that.

[Infinity Blade]

I may sound stupid for this, but



Dragons: A Fantasy Made Real attempted to give a scientific explanation as to how their hypothetical dragons are able to breathe fire. But is it actually plausible? Just the idea of fire through a throat......

[mechafire]

Breathing fire would burn its teeth, internal organs, face, prey, destroy forests, mountains, etc., and put itself in severe risk of getting burned.

Considering their build (long legs, etc), they probably run a lot faster than modern lions. How fast do you think the american lion can run?

[Deleted]

What's the line between art and not art?

[creature386]

This is very subjective. To me, it doesn't depend on quality, but on intent. If it has the intent to be art, it is art.

[Infinity Blade]

Might be a dumb question, but if you went back in time to the Mesozoic, could you live off of any of the flora that lived then? Like, any fruits, vegetables, or tubers? There weren't even any angiosperms in the Triassic, Jurassic, and early on in the Cretaceous, so how would you cope with the plant matter then?

[creature386]

Well, you could eat ferns:
en.wikipedia.org/wiki/Fiddlehead_fern
Ginkgo trees could provide you with fruits. According to this source, pine seeds are also edible:
www.survival-manual.com/edible-plants/pine.php
SO, you could probably survive, but it would be hard and not very tasty.

[Infinity Blade]

So, you all are familiar with how medieval*, early modern, and even late modern (what I've read about the cleanliness of Victorian England, especially, was not flattering) Europe (at least in some regions) wasn't exactly the most clean, sanitary place ever? Were there any other places (i.e. not in Europe) in the past where the amount of filth, levels of hygiene, and sanitation was the same as in medieval and early-late modern Europe? Obviously no time and place from the distant past was clean or sanitary by modern standards, but I'm talking places where filth and bad hygiene really stuck out. I tried using one of TV Tropes' pages (focusing on the real life examples, obviously) to help me out, but I'd like to see reliable sources.

Only two (at least potential) places come to mind, namely industrial New York (having watched a documentary on that) and seemingly Heian period Japan in certain regards (that was one source I did find from TV Tropes).

*Perhaps overplayed for the Middle Ages (link), but of course cleanliness, hygiene, and sanitation was still not up to par with today's standards, and some places in medieval Europe (e.g. 14th century London, having watched a documentary on that as well) do seem to have been quite filthy.

[Infinity Blade]

So, I know that when you have no idea how old something is (which was the case before we found the true age of fossils, rocks, etc.), you use multiple different methods that overlap in the time periods in which they are useful; if the results are consistent you have a good idea of the age of the object, but if not the sample is either contaminated or out of the age range of at least some of the dating methods. If you suspect the latter, you use other kinds of dating methods that overlap in time, and then see if you get consistent results. Once you do, you have an idea of how old the sample is.

So how did we figure out what intervals of time a radiometric dating method is useful? Did we just date a whole bunch of stuff, see through "trial and error" (for lack of a better term) what times different methods give consistent results, and then map out what time periods different methods are useful in? Or was it through another way?

[creature386]

When a radioisotope has a very short half-time, it is sometimes not even possible to accurately determine its concentration in older rocks. Similarly, some radioisotopes decay so slowly that you need long timeframes for your instruments to determine meaningful differences. What is worse, there can be background processes that very slightly alter the isotope ratios.

To give you an example, let's look at radiocarbon dating.
As we all know, carbon-14 is produced in the atmosphere, breathed in by plants and eaten by animals. It decays into nitrogen. By measuring the ¹⁴C/¹⁴N ratio in a dead animal, scientists can determine its age, provided it got all of its carbon-14 before its death. And here's the problem:
There are processes in the ground unrelated to those in the atmosphere which can produce more carbon-14 in old deposits. By that, I mean nuclear reactions involving alpha particles and free neutrons (which are produced by the decay of Uranium or Thorium). Here are a few examples:
¹⁷O + n → ¹⁴C + α
¹⁴N + n → ¹⁴C + p
¹³C + n → ¹⁴C
¹¹B + α → ¹⁴C + n
²²⁶Ra → ²¹²Pb + ¹⁴C
Now, the amount of ¹⁴C is negligible. However, if almost all of the atmospheric ¹⁴C has decayed, such ¹⁴C will be all you measure.

So, yeah, the exact application ranges are probably measured by trial and error, however, this theoretical understanding helps us realize that the inconsistencies are not jut results of the scientist's incompetence.

[dinosauria101]

How many Megistotherium to beat an Ankylosaurus?

[Infinity Blade]

Two months ago I had started my own WordPress blog and today I've finally gotten around to posting about something. I was wondering if you could help me find any errors or help me improve it so I don't make myself look like an idiot (even though probably no one's going to read it).

Here's the blog post as it is right now (saved but not posted):

No, the large ground finch does not have a bite "pound for pound" 320 times more powerful than that of T. rex

Or at least, not the way I understand it. Recently a paper came out by Manabu Sakamoto et al. regarding the rapid evolution of bite force in animals, as well as relative bite force. An interesting paper with interesting findings, no doubt.

But then news outlets reported this. And we all know how they can sometimes (of course, not necessarily always) be when reporting scientific papers, especially when they pertain to paleontology (I'm sure they misconstrue the message of papers in other fields too, I've simply seen more examples with paleontological papers given my interests).

Note the quote below from Mother Nature News Network:

"That's the news from an analysis published in the Royal Society journal Proceedings B that looked at bite forces across evolution. The tiny Galapagos large ground finch, which weighs just over 1 ounce (33 grams) has a bite force of 70 Newtons, an impressive showing for such a lightweight animal. The T. rex, by comparison, weighed around 8 tons and had a bite force of 57,000 Newtons, which is merely average for a creature of that size. This makes the finch's bite 320 times more powerful, pound-for-pound, than the T. rex's."

I'm not exactly sure how they had come up with this "320 times more powerful" figure. Did they assume bite force scales linearly with body size (it doesn't)? Even using elementary cross multiplication where the figure for bite force would scale the same as with body mass (you know, 0.033 kg/70 Newtons=7,257.48 kg/x Newtons, where you would solve for x with 70*7,257.48 and divide this result by 0.033) I get a result suggesting the finch would bite anywhere between ~270 to ~298 times harder, not quite 320 times harder.

This is beside the point, however, as bite force doesn't scale the same way as does body mass. As per the square cube law, bite force (or any other muscular force produced by any other part of any animal, for that matter), in a sense, "lags behind" body mass as an animal gets bigger. Because of this, smaller animals will always seem "pound for pound" more powerful than larger animals.

To get a good idea of how hard one animal will bite compared to another on a proportional basis, we need something a bit more complicated than what I have above. We need data on the animals' total body mass and bite force. From their supplementary information in the form of an Excel spreadsheet, the only data they have for the bite force of Geospiza magnirostris is from Herrel et al. (2005), which measured bite force with in vivo methods (i.e. on living animals). According to it, a finch that weighs 0.03277 kilograms will have a maximum bite force (labeled F_Bite2 in Sakamoto et al.'s spreadsheet) of 70.77 Newtons. Sakamoto et al. have multiple pieces of data for bite force in Tyrannosaurus rex, but let's stick with the one that they calculated in their own study. One of the two specimens they examined for their own study was BHI 3033 ("Stan"), which they had as weighing 8,385 kg (Hutchinson et al. 2011). Using the dry skull method, the authors estimated this specimen to have had a maximum bite force of 45,379.51362 Newtons. The authors' body mass figure for the other specimen, AMNH 5027, was equal to that of Stan, but its maximum bite force was (interestingly) even higher, at 48,505.14364 Newtons.

How would we find out how proportionately hard the finch bites compared to the tyrannosaur? We scale it up to the same size as the tyrannosaur (...yeah...we're going to make ourselves an >8 tonne finch). And then consider cube roots and squaring of bite force to correct for the bias towards smaller animals in bite force. See the below formula:

((cube root of (8,385 kilograms/0.03277 kilograms)^2)*70.77 Newtons

From this we calculate that the bite force of an 8,385 kg large ground finch (equivalent in size to their body mass estimate of Stan) would be 285,233.3347 Newtons. This would make its bite anywhere between ~5.9 to ~6.3 times harder than that of an equivalent sized T. rex assuming the latter bites as hard as estimated. That's still a huge difference for sure, but nowhere near the 320x figure spread through the media.

Moral of the story: you can't always believe the sensationalist "facts" news articles will spew when reporting on scientific findings. As if we didn't all already know that.

More specifically, I'm interested in providing a better explanation for why bite force does not scale so simply with body mass (I don't want to simply say "square cube law"), and why we would use the "true" formula I have above. Of course, any other edits are welcome.

I do want to make note of two things: one, I actually think their body mass for Stan is too high and I know I'm comparing a dry skull estimate for the tyrannosaurid with an in vivo measurement for the finch. But for the sake of argument, I didn't even bother mentioning these (and Sakamoto et al. might have a good explanation for using their own dry skull estimates as legitimate absolute bite force figures for the animals they studied).

[theropod]

If I’m understanding you correctly and what you want is explain why there is such a thing as the square-cube-law in the first place, I think I’d use a simple rope-analogy.

Just like the tensile strength of a rope is proportional to its cross-sectional area, not its overall volume (the rope doesn’t become any weaker just because its shorter, that much should be obvious to anybody), the tension of a muscle is proportional to its cross-sectional area, not its mass. The cross-section determines the number of muscle fibres, and force is proportional to the number of recruited muscle fibres (that is just like more people pulling on something will obviously pull with more force).

Also based on the exact figures cited I’m getting a factor of 301
(8 000 000/33*70.77)/57 000=300.98

[creature386]

The rope analogy is quite good. If you want to go more in-depth on the physics behind it, you could mention that it is technically not force, but pressure that decides if an object is deformed or not. Remember the definition of force is acceleration times mass while pressure is force per area. The force of a bullet is not that high, as it is so light, but the force is spread over a very low area.
A bite does not just produce force but also pressure to its muscles. The thinner the muscles are, the more pressure they take and muscles can only take so much pressure before they break.

If you want to derive your equation, I have a simple task for you:
en.wikipedia.org/wiki/Square_cube_law#Description

Look at the equations Wikipedia cites. Replace "volume" with "mass" and "area" with "force". Then solve both equations after l₁/l₂ and equate them.

If you're aiming for a more casual "blog post" tone, you could introduce the issue by saying "To those unfamiliar with the 'square-cube law', have you ever wondered why elephants are so much beefier than ants? Or why being really big with a longer stride does not make you the fastest? Or why kaijus only exist in movies? All these questions can be answered through simple physics and mathematics."