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Old 09-19-2010, 04:15 AM   #1103686  /  #1
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Default Tyrannosaurus arms

This is just an idle speculation but maybe one of the more authoritative contributors round here could comment. One of the unusual features of Tyrannosaurus Rex is its relatively diminutive arms which indicate that as a full-sized adult it would have relied on the combined of forces of its massive head, powerful bite and big pointy teeth to do the damage. However these attributes would have been proportionately less effective as a juvenile or hatchling. Nevertheless in the BBC Walking With Dinosaurs program the young were depicted as in proportion to the adult with tiny, essentially non-functional upper limbs.

What I wonder is whether is is more likely that when hatched, the arms might have been more in proportion to the rest of its body, like a raptor or dromaeosaur, but just not have grown as fast as the rest of its body & especially its head?

It seems to me that a bright paleontology PhD student could run some calcs & show that there'd be a cost-benefit transitional size when arms become less useful and sheer size kicks in. And if there's tyrannosaur fossils of different sizes available, you could test the hypothesis that the larger the animal, the smaller its arms would be in relative terms. It might even show up some smaller carnivorous dinosaur fossils as juvenile tyrannosaurs instead of a different species.

Has anyone ever researched this angle?
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Old 09-19-2010, 04:24 AM   #1103693  /  #2
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There are some good ontogenetic sequences described for Tyrannosaurus. Juveniles and subadults were morphologically and ecologically very different from the large adults.

For example:

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Old 09-19-2010, 04:30 AM   #1103699  /  #3
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So my speculation's not far off the mark? Cool...
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Old 09-19-2010, 04:34 AM   #1103701  /  #4
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More or less. There's a huge literature out there on the subject. TBH, the BBC just dropped the soap on that one.
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Old 09-19-2010, 04:36 AM   #1103703  /  #5
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you could at least have softened the blow a bit in telling me my idea was shallow and unoriginal








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Old 09-19-2010, 04:38 AM   #1103706  /  #6
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Nah, it means you're thinking in the right direction. The only problem is that anything that can be done on T. rex has been done on T. rex. Probably multiple times, too.
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Old 09-19-2010, 04:39 AM   #1103707  /  #7
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that was better [mopes off]
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Old 09-19-2010, 08:52 AM   #1103856  /  #8
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Quote:
Originally Posted by rmacfarl View Post
This is just an idle speculation but maybe one of the more authoritative contributors round here could comment. One of the unusual features of Tyrannosaurus Rex is its relatively diminutive arms which indicate that as a full-sized adult it would have relied on the combined of forces of its massive head, powerful bite and big pointy teeth to do the damage. However these attributes would have been proportionately less effective as a juvenile or hatchling. Nevertheless in the BBC Walking With Dinosaurs program the young were depicted as in proportion to the adult with tiny, essentially non-functional upper limbs.

What I wonder is whether is is more likely that when hatched, the arms might have been more in proportion to the rest of its body, like a raptor or dromaeosaur, but just not have grown as fast as the rest of its body & especially its head?

It seems to me that a bright paleontology PhD student could run some calcs & show that there'd be a cost-benefit transitional size when arms become less useful and sheer size kicks in. And if there's tyrannosaur fossils of different sizes available, you could test the hypothesis that the larger the animal, the smaller its arms would be in relative terms. It might even show up some smaller carnivorous dinosaur fossils as juvenile tyrannosaurs instead of a different species.

Has anyone ever researched this angle?
Size does affect allometry. However, if the arms played no significant part in the fitness of the animal, [as a juvenile or adult] then we would expect no selection pressure to keep the arms "big". Maybe big arms reduced fitness. ?
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Old 09-19-2010, 01:24 PM   #1103953  /  #9
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Those tiny arms are fascinating.
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Old 09-19-2010, 01:28 PM   #1103958  /  #10
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And its notable that they may have evolved more than once, depending on where Raptorex goes in the phylogeny. Certainly the basal ones like Eotyrannus didn't have them.
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Old 09-19-2010, 01:33 PM   #1103964  /  #11
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has anyone ever discussed whether the tiny t-rex arms helped in the construction of the ark?
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Old 09-19-2010, 01:34 PM   #1103965  /  #12
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Maybe they were the result of an industrial accident?
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Old 09-19-2010, 04:02 PM   #1104062  /  #13
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Thalidomide like compound in their drinking water?
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Old 09-19-2010, 04:19 PM   #1104075  /  #14
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I think I may be related to T-Rex.
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Old 09-19-2010, 05:58 PM   #1104199  /  #15
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Quote:
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Those tiny arms are fascinating.
I agree with you, Socrates. All we are ever told is that the short arms would be useless but then we're supposed to believe evolution is true?

yeah, evolution makes perfect creatures but somehow t. rex has useless arms
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Old 09-19-2010, 06:12 PM   #1104223  /  #16
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guess what bart? you think you owned evolution but there's about twenty science guys here who are ready to shut you down and explain how the t-rex's tiny arms actually have many plausible evolutionary explanations.

and believe me when i say they are going to go into exhaustive detail
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Old 09-19-2010, 06:43 PM   #1104266  /  #17
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It doesnít matter how beautiful your theory is. It doesnít matter how smart you are. If it doesnít agree with experiment, itís wrong.
-Richard Feynman, Nobel laureate in Physics, 1965
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Old 09-19-2010, 06:44 PM   #1104269  /  #18
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On a serious note, it has been found in science that most of these creatures suffered from Gout.
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Old 09-19-2010, 06:46 PM   #1104275  /  #19
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Quote:
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Those tiny arms are fascinating.
Maybe you could start a thread called, "Socrates on T-Rex's tiny arms," and then gas on about it for 450 pages or so.
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Old 09-19-2010, 08:32 PM   #1104375  /  #20
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Quote:
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Those tiny arms are fascinating.
Maybe you could start a thread called, "Socrates on T-Rex's tiny arms," and then gas on about it for 450 pages or so.
... without ever getting to the point.
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Old 09-20-2010, 01:44 AM   #1104699  /  #21
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Quote:
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Those tiny arms are fascinating.
I agree with you, Socrates. All we are ever told is that the short arms would be useless but then we're supposed to believe evolution is true?

yeah, evolution makes perfect creatures but somehow t. rex has useless arms
No evolution does not make perfect creatures, and you know it. No evolutionary biologist has ever claimed such a thing. Fitness is about the differential survival off offspring between individuals in a population. Evolution [generally] does not give a flying fuck about post-reproductive survival. The male Antechinus [an Australian marsupial] literally fucks itself to death. The very high testosterone levels depress it's immune system [like many steroids]. Antechinus's "design" is only as good enough as it needs to be. For this animal, it seems to pay it to put all it's resources into reproduction, and that leaves little else for body maintenance and repair. Other organisms facing different ecological challenges, can be iteroparous rather than senelparous.
People wear glasses, get back problems, suffer hernias and prolapses-the list goes on. No organism is perfect, although evolution can sometimes produce fine designs considering the constraints under which Natural selection etc. work. At other times, evolutionary "solutions" can be clunky, idiotic, and barely work.
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Old 09-20-2010, 03:02 AM   #1104743  /  #22
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Quote:
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guess what bart? you think you owned evolution but there's about twenty science guys here who are ready to shut you down and explain how the t-rex's tiny arms actually have many plausible evolutionary explanations.

and believe me when i say they are going to go into exhaustive detail
Yeah!
Like me!
I'm going to explain how T. Rex evolved from ancestors with longer arms. The longer-armed branch of the family died out, because they were given to self-abuse, spilling their seed in non-reproductive ways.
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Old 09-20-2010, 03:07 AM   #1104749  /  #23
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you want bart to use his productively????
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Old 09-20-2010, 03:08 AM   #1104751  /  #24
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Quote:
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Quote:
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guess what bart? you think you owned evolution but there's about twenty science guys here who are ready to shut you down and explain how the t-rex's tiny arms actually have many plausible evolutionary explanations.

and believe me when i say they are going to go into exhaustive detail
Yeah!
Like me!
I'm going to explain how T. Rex evolved from ancestors with longer arms. The longer-armed branch of the family died out, because they were given to self-abuse, spilling their seed in non-reproductive ways.
I thought the short armed ones went extinct because they could no longer pick their noses, and died from horrible sinus infections.
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Old 09-21-2010, 05:15 AM   #1106205  /  #25
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