Giant theropods overview thread

[theropod]

Well yes, the size difference between the Scotty and Sue material is almost negligible. Previous studies actually reported its femur circumference (and length) as smaller than Sue’s. And other studies reported larger measurements for sue, up to 134 cm femur length in Larson 2008. The difference is very small when considering the error inherent in the measurements. But we don’t commonly do that with other animals, so we shouldn’t here.

Persons et al. is the most recent study and the most detailed one, and it lists measurements for several bones, with the average of all measurements being about 2% bigger than Sue’s. So it should be our default that their measurements are correct and that it is about 2% bigger (or perhaps 1% if you prefer to only go by the femur). In volumetric terms, that is quite consistent with what Hutchinson is quoted sayig in the article Switek linked ("at best maybe 5% larger"). That gives us at best 12.5 m btw (though vertebral length measurements would be more telling in that regard, not the 13 m + that keeps circulating.

The study’s strong focus on the size of this specimen is a bit inappropriate¹ considering the size difference is so small both percentage-wise and in absolute terms, but sometimes titles can reflect the need to convince a journal something is worth publishing (as one of the articles put it, "T. rex discovered 28 years ago is roughly the same size as largest previously known one" just doesn’t have the same ring to it). In the text itself, they do correctly put this into perspective and also highlight that this is exceptionately large for T. rex, and that other theropod’s known specimens reach greater size than the typical Tyrannosaurus.

But at least we can be pretty confident around which size it was. It doesn’t really matter whether it was half a ton heavier or lighter, or a few tens of cm longer or shorter.
What we do know is that it’s about this size with a fair degree of certainty. Something we cannot say for specimens that are just a single bone, which doesn’t automatically make the latter smaller, but definitely less reliable, simply because a single element results in a lower signal (impact of body size) to noise (random individual variation) ratio.

¹Though granted the same can also be said for Coria & Calvo’s paper on MUCPv-95, but with so little Giganotosaurus material being described, we can still be very happy about every little bit there is.

[jdangerousdinosaur]

This is from Franoys on the discord
Scotty is larger than Sue in 11 out of 13 measurements, and since the probability is equal to the frequence in equiprobable events, the probability of Scotty being larger is a 84.6% according to the measurements available, while the probability of them being the same size is a 7.7% , and Sue being larger is a 7.7%....unless the bones that dont have comparative measurements in the paper are all larger in Sue, Scotty has a higher probability of being larger. And that would be a case of dishonesty regarding the authors of the paper

And he did this It's a comparison between the measurements of Scotty and Sue according to the last publication docs.google.com/spreadsheets/d/1xbuGjf_PaBcJNKJSu4sEixEqZzEc-wyvfrg1iTnCSno/edit#gid=0

For anyone interested.

[theropod]

These are not equiprobable events though, unless you claim the scapular blade width or the length of a manual phalanx is just as important as the femur length. But yes, it is clearly probable from these bone measurements that Scotty is larger, albeit just slightly.

I added up all measurements, thereby weighing them by bone size. That should be the most sound way to compare such things, at least when the bones you are comparing are have major differences (E.g. a femur and a phalanx). Otherwise, if you have measurements of femur, ilium (btw not significantly correlated with body size in adult T. rex specimens I know measurements of for some reason), scapula and skull that are 10% bigger, but measurements of four phalanges that are 10% smaller, you would have to conclude the specimens were the same size, but the former are constituting a much bigger part of the animal and are hence obviously more important. If there were sufficient dependable data on the respective overall size you’d likely see this reflected in the quality of the correlation for each measurement, but you can already see this a bit of it without that, sue is clearly noticeably bigger than the other specimens (except scotty) in that table (some of which we have decent skeletals of, like stan, CM, AMNH, MOR 555 etc.), yet its phalanges are actually among the shortest.

Scotty is 1-2% bigger than sue or less in most of the larger bone measurements (femur, ilium, dentary, tibia, fibula), the only ones where the differences are considerably more than that are small things, like the phalanges or width measurements. Obviously differences in 1-1.5 m long measurements are a lot more reliable than 10-20 cm ones, as an animal can easily have a 20 % larger hand without being a 20% bigger animal, while the same does not go for a femur or skull.

[dinosauria101]

Anyone have anything on the NMC Spinosaurus humerus? I've seen that it's 17.12 meters scaling from MSNM V 4047 on Deviantart, but that sounds fishy

[jdangerousdinosaur]

I have looked it up before and all that comes up is how its a fanboy Spinosaurus thing so its most probably bull shit but if you are really unsure just bring it up on the discord. This should not be seen as anything to do with VS so it should be okay.

[spartan]

Dec 14, 2019 19:28:16 GMT 5 dinosauria101 said:

The time has finally come! At long last!

There are many types of fanboys I take serious issue with, but some of the worst hands down have got to be Tyrannosaurus fanboys, both “awesomebro” and scientific. They often claim enough C-R-A-P to make my toilet jealous.

Let us begin with the wide and wonderful world of animal vs animal, where these fanatics tend to be most prevalent. To start, we shall examine scientific fanatics of Tyrannosaurus; those who write big long fancy posts and twist the meaning of words in order to make their hogwash look believable. They pass off rather large Tyrannosaurus (CM 9380, BHI 3033/Stan) as average

We know a lot about Rex, and as far as I am aware the average specimen seems to be around Stan's size (37-39 feet depending on your methods). Assuming the CM 930 or BHI 3033 (7500ish kg) represent the average T. rex and MUCPv-Ch1 represents an average Giganotosaurus (6800ish kg), even if the southern giant is longer overall, it would take a true giant like MUCPv-95's liberal estimate to outweigh the Tyrannosaur.

Often focus on Sue and Sue sized specimens to match with more or less everything (this is a very common size comparison they post_,

Suggesting an average size of 7.5t for the adult T. rex is certainly not "crap" or "hogwash". It's by no means certain, but it's reasonable.  See this post:


theworldofanimals.proboards.com/post/25584

The average Tyrannosaurus femur is something like 121 cm long, suggesting a mass of ~6,600 kg. However, this excludes several quite large and a couple of very small specimens - I have postulated in the past that including these in the sample could suggest an average individual actually had a femur around 127 cm long (~7,600 kg), but that is a rough estimate at best.

And Spinodontosaurus surely isn't some fanatic.

[dinosauria101]

No, he is not.
However, taking into consideration ALL known adult specimens from USNM 6183 to FMNH PR 2081, the Theropod Database gives 119 cm average femur length, which would give an animal 6-7 tonnes, probably on the lower end of it: www.theropoddatabase.com/Tyrannosauroidea.html#Tyrannosaurusrex

6.6 tonnes average isn't unreasonable or off the table but it always helps to include more specimens.

[creature386]

Moved a small discussion on Tyrannosaurus size here in accordance with my "minimize debates" policy for the fanboy/hater thread.

The "minimize debates" policy is in fact one of the reasons why I wish members could also minimize personal opinions/original research. Dinosauria's claims on Tyrannosaurus' average size are unfortunately an example of this.

[dinosauria101]

Perhaps I can put disclaimers to debate me elsewhere if I give masses for an animal or something like that?

[creature386]

There are other reasons for the "minimize original research" rule. The main one is to avoid labeling someone a "fanboy" or a "hater" for disagreeing with your personal hypotheses.

[dinosauria101]

It's not my own. AFAIK, Theropod, Broly, and Mortimer all got it.

[creature386]

Stop searching for loopholes again.

Do you think there is reasonable disagreement regarding this average? If yes, people who disagree with it are not automatically fanboys.

[dinosauria101]

That’s not a loophole, is it? It’s literally where I got the estimate from; it was not my own research and was done by other people, and I’m just using it as reference. Wouldn’t my own work (and therefore a 'loophole' in this context) be something like scaling up a GDI of a Trike to get a new mass estimate others haven’t arrived at yet?

As for the second part, yes and no. It doesn’t necessarily MAKE them fanboys, but it does fall under what most fanboys do, which is exaggerating an animal.

[creature386]

It is a loophole in the sense that you take things too literally.

2. Keep original research to a minimum. Ideally, you should refute people that disagree with the scientific consensus, not with your personal pet theories. To ask yourself if you are presenting original research or not, ask yourself if you are making a controversial claim. If yes, ask if you can find a source for it. If yes, add it to your reference section. If not, either get rid of it or be prepared to argue at length for it. In general, controversial statements must either be sourced or defended in sufficient detail so that people can understand your train of thought.

These estimates are not published and certainly represent no consensus whatsoever.

Even so, you can present original or unpublished research provided your argumentation is strong enough and if the reasoning can be clearly understood (in this case, it would mean showing the math). This wasn't the case.

Maybe you should have focused on their averages being unreasonably high rather than on them disagreeing with your preferred average. You could have still mentioned your preferred average, but I would have done it more in passing if you were not willing to argue for it.

[dinosauria101]

So then, when I get the chance to update my post I should say the averages they use are unreasonably high and then show why this is?