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Post by theropod on Jul 30, 2013 1:22:22 GMT 5
Of a theropod at least as big as those of the Cretaceous, something you cannot deny, and which is all this was about; that gigantism is pretty widely spread, and not one time and place (eg. Cenomanian South America) appears particularly special and there are giants of many taxa from many periods, simply depending on when and where that clade was most dominant (eg. you'll probably find the biggest sauropods in the Jurassic, and the biggest Ornithopods or Ceratopsians in the Cretaceous).
The majority of publications considers ichnites in the 40-50cm range as very large or even gigantic theropod traces ("similar in size to a big Allosaurus"). If we can believe da Silva et al., 2012, known, up to 5,5m long triassic theropods could not have made any of the tracks above 30cm. And those included clawmarks.
We are talking about a huge theropod, no question.
How large exactly, that's difficult to say, I agree, but most indicates something in excess of 14m, consequently comparable to big Carcharodontosaurs or Tyrannosaurs in terms of bulk, perhaps bigger. This has to be taken as a rough indication, there is not a lot of precision here. But that doesn't make it wrong.
Note I'm being cautious here. I'm not using the estimate from Moreno et al., 2012 to extrapolate linearly or anything.
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Post by Grey on Jul 30, 2013 17:43:31 GMT 5
Gigantic theropods yes, perhaps comparable to the largest tyrannosaurids and carcharodontosaurids sure. Indicates something in excess of 14 m ? I ask a proper study, not a self-made assumption. You still have this tendency to make your own datas and to strongly believe in them (remember that sentence from Matt Wedel "that we make estimates does not mean we believe in them".. We have already years of studies, uncertainties and discussions regarding the exact size of animals known by hard remains, it is premature to make estimates based on fossilized footprints, proven to be hardly reliable. You can believe in your estimates, but don't obligate others to believe them, nor to make them facts while they are not, that's only your opinion. The history of paleontology regarding size issues should have advised to be more cautious but at the end of the day no one can reproach you to be enthusiastic, that's as well a quality and a failing.
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Post by theropod on Jul 30, 2013 19:37:32 GMT 5
I think it is you making a whole bunch of assumptions and allegations there, not me.
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Post by Grey on Jul 30, 2013 20:10:51 GMT 5
It is not me who assume 14 m theropods, based on footprints, despite the huge unreliability of track marks for predict precise size. Don't be upset because I don't believe your assumptions, you can think anything you want.
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Post by theropod on Jul 30, 2013 20:19:54 GMT 5
It's not me who's upset, but I already know where this would be going if we continued discussing this.
The "huge unreliability", which you didn't back up with evidence btw, didn't and doesn't keep scientists from estimating the sizes of ichnotaxa, and that I estimate an approximate size that is objectively speaking most likely, based on the hard data and scientific works, does not mean I strongly believed (as in, "won't change that opinion when proven wrong" which you are obviously implying), and even less, want to believe. That it makes sense is not my fauls, neither that the data suggest it.
I already demonstrated some of those. You are of course free to come up with ways how my figure is wrong, basing on more than the assertion of it being a "self-made assumption". It was you accusing me of "making facts" or "forcing others to share my opinion" (Where did I do that?), so I think you should at least have a better alternative.
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Post by Grey on Jul 30, 2013 20:39:02 GMT 5
Calm down, this is not because I question the reliability of your 14 m + theropod that you must become anxious.
I simply ask some backup work, not your assumptions.
What annoys me is that I very often look at the discussions between paleontologists on blogs or facebook articles and I've yet to see one taking seriously sizes extrapolaed from footprints. No wonder, most of the fanboyistics datas from trackmarks on the internet comes from Carnivora.
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Post by theropod on Jul 30, 2013 20:54:28 GMT 5
Maybe reading some ichnological literature is a good idea? I posted a lot of data on giant theropod ichnites on page 10 of the giant theropods thread, for that exact purpose, informing people about them and roaming out the myth that they were incredibly worthless for everything concerning those animal's palaeobiology.
Also I think you are misinterpreting the few points made about footprints in the blogs you are referring to. Our prime subject of debate, the trackmaker post on SVPOW, did take footprints seriously. The whole field of ichnology does, also for size estimations as you can read in the countless papers I provided.
I am not trying to extrapolate astronomic figures, I'd be fine with no figure at all, but many people need something more specific to believe in the reality of it. If I wanted, that would be no problem. In fact my assumption is a pretty conservative one considering the data (that you can look up if you want).
I've done a lot of backup work, so maybe you could drop your provocations and have an actual look at it, a look at the facts and suggestions in the field you want to dismiss as pretty much worthless.
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Post by Grey on Jul 30, 2013 21:20:09 GMT 5
I don't provok you, I question you.
I've read your links, now I ask your methodology and basis for predict this, possibly with a professionnal opinion as back up.
Why I can't found Holtz, Hartman, Cau or Currie talking of the existence of 14 m + theropods with seriousness ? Perhaps because this is not serious.
I'm always surprised how much you become agressive when I question your assumptions.
Now you believe anything you want, I don't care.
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Fragillimus335
Member
Sauropod fanatic, and dinosaur specialist
Posts: 573
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Post by Fragillimus335 on Jul 30, 2013 21:44:23 GMT 5
It is not me who assume 14 m theropods, based on footprints, despite the huge unreliability of track marks for predict precise size. Don't be upset because I don't believe your assumptions, you can think anything you want. Although the tracks do seem to indicated a large theropod, I think Grey is right on this one. Estimating body size from Sauropod tracks is iffy enough, but due to the morphology of Theropod tracks, I think we should be saying things like, "Possibly greater than 12m" not 14m+. |
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Post by theropod on Jul 30, 2013 22:43:46 GMT 5
The morphology of theropod ichnites is mostly much more detailed and distinct than with sauropods (the latter often roughly circular or oval shapes, the former markedly tri- or tetradactyl impressions). Deformations will be much easier to spot, are apparently less common and lenght measurements are more precise due to the marked shape.
What you can see from those prints is without a doubt a huge animal, comparative foot and associated body sizes (I think Hh formulas are probably less reliable due to allometric changes of proportion at varying sizes) make it quite clear.
I'm not and I wasn't fabricating some astronomic baseless number with speculative assumptions, I'm using what is suggested by virtually all the literature. Footprints actually ought to give a pretty good (better than some body fossils perhaps?), albeit inprecise general idea of body size.
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stomatopod
Junior Member
Gluttonous Auchenipterid
Posts: 182
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Post by stomatopod on Jul 30, 2013 23:22:24 GMT 5
Yes, some of those footprints surely come from pretty large animals, but giving a precise figure is nigh impossible, especiall when you do not have the imprint in front of you.
There are multiple factors that are unknown, like the amount of soft tissue. Then there are things like variations between different species, and even intraspecific variation (which can be tremendously high).
Sometimes we have to say that we do not know the entire truth.
(BTW, the large imprint from Marocco actually was a little distorted due to the movement of the foot while making the imprint. Roughly translated by me from the paper: "The imprint of digit IV is under the rock, the one of digit III is rounded and the one of digit III is complicated (read: abnormal), seemingly as the result of movement during the formation of the footprint."
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Post by theropod on Jul 31, 2013 0:43:00 GMT 5
I'm not giving a precise figure, but a rough one.
At least as big (in overall size=weight, that should have a pretty good correlation with foot size) as the biggest (non-spinosaurian) cretaceous theropods, or "14m+" which would most likely correspond to that. Very likely at least 8t, more likely 9.
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Post by Grey on Jul 31, 2013 1:21:11 GMT 5
The biggest tyrannosaurids and carcharodontosaurids are not 14 m +.
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Post by theropod on Jul 31, 2013 1:36:28 GMT 5
I am talking about size, not lenght. An Allosaurid of approximately 14m in lenght is about the same size as a slightly to somewhat (depends on individual built) shorter carcharodontosaur or tyrannosaur. And I already clarified that in my last post. Those are most plausibly Allosaurids we are talking about, or at least animals with morphology analogous to them.
And if you don't provoke me, what for are these permanent hints of me becoming "anxious" or "upset" for? If you just question me, with which I'm prefectly fine and which is to be encouraged, please do so in a factual tone.
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Post by Grey on Jul 31, 2013 1:47:13 GMT 5
Well, unless I'm totally dumb, 14 m + corresponds to length. The last time I've checked, there's no carcharodontosaurids or tyrannosaurids that large (which does not mean it never happened but we have no evidence).
For sure, these footprints likely belong to giants allosaurids, especially carcharodontosaurids.
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