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Post by Grey on Jul 2, 2013 23:22:56 GMT 5
Response from Holtz just at now about T. rex preying on adult Alamosaurus :
Me : Dr. Holtz, you consider this as a possibility when talking about one lone T. rex attacking one adult Alamo on occasion, or were you more likely thinking about a possible pack-hunting ? The Alamosaurus specimens with bite marks were more likely scavenged/small individuals ?
Thomas Holtz : It was a big individual. Beyond that we can't say. But keep in mind that the Acro-Sauroposiedon pair (which seems to be a solo attack) is very comparable in relative sizes.
About T. rex and Acrocanthosaurus :
Me : Dr. Holtz, have you a source or a basis indicating that Tyrannosaurus had more powerful muscles necks than Acrocanthosaurus ? It seemed to me that Acrocanthosaurus was particularly robust in this region ?
Thomas Holtz : I'm in an airport right now, but can't hunt them up. Do a scholar.google search on tyrannosaurus cervical muscles. But there is really NOTHING about Acro's skull that is "robust": it is very narrow from side to side, with very little lateral expansion of the nuchal region. Muscles were probably much like Allosaurus: quite good at vertical motion and pulling, lousy at most everything else.
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Post by creature386 on Jul 2, 2013 23:27:00 GMT 5
@brolyeuphyfusion
Well, I believe we should stick to known animals (Epanterias is also believed to be an Allosaurus), I would have no problems with it being a Tyrannosaurus, I only have problems with all those made up figures.
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Post by Deleted on Jul 2, 2013 23:28:10 GMT 5
So then it was probably a critically sick Alamosaurus. He did state that we don't know beyond the big individual part after all, and predators normally go for the weakest members of a herd.
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Post by Deleted on Jul 2, 2013 23:30:15 GMT 5
@brolyeuphyfusion Well, I believe we should stick to known animals (Epanterias is also believed to be an Allosaurus), I would have no problems with it being a Tyrannosaurus, I only have problems with all those made up figures. I have problems with any size figure and species assignment of UCMP 137538, and btw a coracoid is less variable than a toe bone |
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Post by Grey on Jul 2, 2013 23:35:06 GMT 5
Sick or not, the vision of a theropod engaging lonely something several times its size is mind-striking.
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Post by creature386 on Jul 2, 2013 23:55:39 GMT 5
@brolyeuphyfusion Well, I believe we should stick to known animals (Epanterias is also believed to be an Allosaurus), I would have no problems with it being a Tyrannosaurus, I only have problems with all those made up figures. I have problems with any size figure and species assignment of UCMP 137538, and btw a coracoid is less variable than a toe bone Do you have evidence for toe bones being more variable? P.S. The point was if not diagnostic animals should be referred to known specimen or not, as Epanterias is still not diagnostic, I don't believe this really matters. |
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Post by theropod on Jul 3, 2013 0:12:17 GMT 5
Epanterias has a 25cm tall axis and a 33cm long Coracoid. Obviously, a better base for a size estimate than a phalanx. Grey: Here's my response, and don't misinterpret it again: I did the suggested research long before you even posted that. If we take Allosaurus as a base, as suggested (albeit it's making the whole thing too simple imo), we can note the following: It has expanded ventroflexive moment arms, compared to greatly reduced ones in T. rex (paroccipitals and basitubera for m. longissimus capitis superficialis/profundus, iliocostalis and rectus capitis ventralis) and attachment areas, as well as attachments for strong dorsiflexion (a large nuchal crest for transversospinalis capitis, with noted similarity to Tyrannosaurs in this regard[Anton et al., 2003] and a big tendon attachment in Allosaurus, an occipital/parietal crest described as taller in Carcharodontosaurus than in T. rex...). It is obviously less adapted for lateroflexion, with no specific specialisation and comparatively smaller lateral divisions of musculature (attachments for complexus muscle are reported to be smaller and very broad opistothics in T. rex, just like T. rex having weaker ventroflexors!) (Snively & Russel, 2007). That Acrocanthosaurus has greatly hypertrophied neural spines indicates it was even more adapted for dorsiflexion, but a direct comparison with Allosaurus is tricky, since the latter happens to have long but low ones, likely for flexibility, since these are attachments were dorsiflexive muscles originate. A large nuchal crest is present, see this: link1 and this link2. Tyrannosaurs are not exceptional as regards overall neck power. They have a visually more robust neck because their necks are relatively shrot and usually portrayed as more strongly curved than other theropod's, and they are quite wide to fill the space between torso and skull and control a more massive cranium. They are built for different movements, but not overally "better", as rigorous methods (not amateur's drawings)show. All the credible literature (including some of Holtz' own work) suggests their neck strenght was absolutely comparable, with different specializations. The comment we are discussing focuses too much on one direction of movement. It has already been demonstrated a narrow skull does not equal being weak (Rayfield, 2001). Quite the contrary, carnosaur skulls were likely very strong and the deep narrow shape is advantageous for some muscle groups' attachments. Its neck is thicker due to allometry and because its head is heavier. T. rex represents pretty much the opposite of Carnosaurs. That doesn't mean it is more powerful (in terms of actual applicable force), and even less that other theropods were "lousy". If the last isn't a sensationalistic term, I don't know what is. as someone who frequently accuses me of being overenthusiastic, one should expect a more critical view from you. So I do also consider the claim of Allosaurus having whimpy neck musculature as sensationalistic towards Tyrannosaurs. Allosaurs are specialized towards powering different motions, that is why different muscles are well-developed in them. Some (ventroflexion) they are better at, while in others (lateroflexion) tyrannosaurs are. If you consider this biased because it is in disagreement with an enthusiastic opinion from Holtz you got on facebook, that is not my problem. No functional analysis directly comparing them has ever been performed. No scientifically supported claim of one being "lousy" or "tremendously more powerful" has ever been made, and rigorous works have not shown that. BTW, being good at vertical motion and pulling already leaves only lateral motion to be "lousy" at (and by the same arguments, Holz's own, tyrannosaurs are in turn "lousy" at ventroflexion). That this is not what they were adapted for (surprise, surprise, perhaps you should have read a few of my posts on theropod cervical myology!) is completely made up for by much more well-developed ventroflexive musculature and moment arms ( stated by holtz himself to be degenerated in Tyrannosaurs, even tough I think he is too sensationailstic here as well). Their functional power remains comparable. |
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Post by creature386 on Jul 3, 2013 0:23:50 GMT 5
It was not about estimating the size, the debate is about assigning undiagnostic animals to a species.
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Post by theropod on Jul 3, 2013 0:29:40 GMT 5
Well, the only paper that did assign species assigned it to Allosaurus fragilis. I have since then not found reason to doubt that, so I'll stick with it
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Post by Grey on Jul 3, 2013 0:36:54 GMT 5
But who are you for judge if terms such as "lousy" or "tremendeously more powerful" are adequate or not ? That's only because that's about Rex, that's why.
The neck muscles of Rex are more powerful, period. All the time arguing...
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Post by creature386 on Jul 3, 2013 0:38:49 GMT 5
Well, the only paper that did assign species assigned it to Allosaurus fragilis. I have since then not found reason to doubt that, so I'll stick with it The same argumentation can be used for UCMP 137538. The only paper dealing with it assigned it to Tyrannosaurus. |
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Post by theropod on Jul 3, 2013 0:58:34 GMT 5
Well, the only paper that did assign species assigned it to Allosaurus fragilis. I have since then not found reason to doubt that, so I'll stick with it The same argumentation can be used for UCMP 137538. The only paper dealing with it assigned it to Tyrannosaurus. I agree with the assignment to T.rex, since in any case it it the most likely contender. Grey: someone who has intemsely studied the literature, someone who is actually thinking a lot about functional morphology of theropod necks. You apparently haven't or you would agree with me. You cannot say that without evidence, even less like a fact and/or in such a sensationalistic way, there's no objective and scientific basis for it. If you know one, post it! And stop claiming I was the unobjective guy around when you are the one who cannot cope with scientific arguments by producing arguments and instead resorts to insulting allegations! |
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Post by Grey on Jul 3, 2013 1:06:47 GMT 5
If something is much more powerful than another, a word such as "tremendeous" is not oversensationnal. You just don't like it because it makes T. rex more spectacular. That's really silly, and I mean silly, to focuse on such thing only because the opinion of a respected authority does not please you. Using something as "allosaurs had tremendeously more powerful arms than tyrannosaurs" wouldn't disturb you, for sure. Frankly, that becomes a total mess to discuss with you. Even Broly has not expressed some biased criticism on that matter. As for the litterature part :  |
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Post by theropod on Jul 3, 2013 2:23:56 GMT 5
If something is much more powerful than another, a word such as "tremendeous" is not oversensationnal. You just don't like it because it makes T. rex more spectacular. That's really silly, and I mean silly, to focuse on such thing only because the opinion of a respected authority does not please you. Using something as "allosaurs had tremendeously more powerful arms than tyrannosaurs" wouldn't disturb you, for sure. Frankly, that becomes a total mess to discuss with you. Even Broly has not expressed some biased criticism on that matter. As for the litterature part : Again, there he is, omniscient as always, accusing me of bias because he has no better argument at hand... On the arms part, that's not only simply beyond obvious (arm size, attachment size, robusticity), it is noted in the literature, explicitely. Eg in the respective chapters in The Dinosauria (ironically co-authored and authored by Holtz himself) you will be able to read that tyrannosaur arms are not only much less robust and have atrophied attachment sites, but also more heavily constrained movement and are generally much smaller. Hell, even the brachial plexus is atrophied in the neural canal of tyrannosaurids (Griffin, 1995)! A desastrous analogy for sure, you alledged me of believing in scientifically evidenced stuff and not doing so with sensationalist claims. Well, I'll be happy to confirm you in your opinion on that part! I fear for you it is not comparable on this subject. I know this would please you, but at some sort of parity you cannot just make the claim of Tyrannosaurus having the more powerful neck, neither can you use sensationalistic terms for it without any evidence, which you failed to provide and Holtz did not publish in the countless papers I've read of him. Some muscle groups are more extensive in Allosaurs, some in Tyrannosaurs, and neither is generally stronger. Live with it! (period) The IF is the important part, since there is absolutely no evidence for that tremendous overgeneralization holding true. I don't know the exact reason for that hilarious image, but it is obviously intended to be insulting, your usual tactic of replacing doing actual research on subjects and viewing them objectively. I don't know what you want to imply about the literature, but apparently you haven't read it, nor what I explained to you, otherwise you would not be so quick in taking things you seem to like as facts. If we took every non-factual statement as a fact as soon as it was by a scientist, you'd have to believe the Giganotosaurus holotype was "the largest Theropod skeleton currently described" (Holtz, 2004), despite the presence of excellent data on sue and knowledge of at least one other skeleton at least as big (holotype of Spinosaurus aegyptiacus, Stromer, 1931). Just stop it, OK? For me, apparently unlike you, it is of no importance whether I like the facts. And you don't even know what I would like or not like, you just believe so in your biased hatred for everything I write, so stop behaving as if you did and then claiming it was a mess to discuss with ME! Study the literature yourself and find me evidence for your bold claims. All I'm finding evidence for is absolutely comparable functional neck power of similar-sized carnosaurs and tyrannosaurs. And any appliance of the term "lousy" is completely misplaced. |
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Post by Grey on Jul 3, 2013 3:05:17 GMT 5
Really, I don't know how someone can lack of any objectivity.
I Mean it is OBVIOUS, by the words of a great paleontologist himself, that Tyrannosaurus had much more powerful muscles in the neck than Acrocanthosaurus and the paleo-geek is arguing otherwise !
Let me explain you, most of the time : specialized paleontologists > theropod
I give up, he can believe whatever the crap he wants in his little world...Absolutely incredible.
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