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RE: Walking Rex Paper



<<This remark is just so precious..... "For extant animals, our results matched 
reality: alligators cannot run bipedally, whereas chickens are adept runners. 
Our dissected Alligator only had about 3.6% mbody per leg as extensor muscles, 
but we estimated that it would need about 7.7% mbody per leg to run quickly on 
its hind limbs." Is it just me? I mean, it could be just me, but.... those 
sentences are so pointless on so many, many levels, that I fail to see why they 
were even written for this paper.>> 

I guess you've never heard of providing a baseline to make sure your methods 
are accurate?  The point of this statement is to show that the methods used to 
come to conclusions about locomotion are accurate, because they match empirical 
data.

<<Example: "Although our T estimates are somewhat high (10â21% mbody per 
leg), a more columnar limb orientation could easily have reduced T enough to 
enable fast running (5% mbody)."  So, the flexed knees of all the fast 
terrestrial animals, with their flexible ankles and all, is wrong.>>

Hmmm, again you are missinterpreting this statement.  The point being made is 
to show how variation in the limb orientation changes results.  However, as you 
point out, flexible ankles are the way things work, so they are showing that 
their own estimates, while high, are realistic.

<<Or, since the paper didn't take into account spring-loaded tendons, the 
completely different musculature setup, and that wonderful shock absorbing, 
joint lubricating stuff called cartilage, but only paid attention to hip height 
and muscle mass comparable to a croc's and a chicken's, the calculations and 
conclusions are just wrong.>>

Umm, perhaps you didnt read John Hutchinson's post on list.  He has studied all 
of this, and addressed it!  Part of the problem with papers in Nature and 
Science is the length restrictions, so while it may be addressed in the study, 
it may not be explicitly stated in the paper.

<<"We isometrically scaled-up our chicken model to 6,000 kg to simulate a 
Tyrannosaurus-sized chicken. Our model shows that a gigantic chicken, using the 
same limb orientation as an extant galliform........ Features such as the more 
posterior position of the trunk centre of mass of Tyrannosaurus explain why we 
obtained lower estimates of T for Tyrannosaurus (43% mbody per leg) than for 
the 6,000 kg chicken"..... Uh huh....... What about,... oh I don't know...... 
The completely different locomotary apparatus that tyrannosaurs have??? You 
think that could have been one of your other features???????>>

Perhaps you should read this again.  They are using it as an analogue, not 
homologue.  Not only this, they state right in the quote that the difference in 
locomotor pattern explains the different values!

<<This sucker is a barrel of laughs. Given that I'm a no-body on this list, and 
have only just started posting on it, I'm leary about pissing off too many 
people as of right now. I've watched for years and have seen what happens to 
those that are black listed.>>

I dont know if anyone will black-list you, but you might piss people off by 
posting on a paper before you read it carefully.  I've attended several talks 
by John on this subject, and he has gone to great pains to reduce error in 
methods and calculations.  This is a very well done study, and I dont think you 
are giving it enough credit.  Yes, there is a possibility that in the future it 
will be proven wrong, but that is the march of science.  Right now, it is the 
most accurate biomechanical study of large theropods.

<<If the situation was different, I would have posted this on the list for one 
and all to read and then beat me.>>

Judging by this comment, I don't think he wanted the post on list, Tracy.

Tracy said:
<<I suppose for me to get listened to Iâll have to get a PhD.>>

No, just read the paper carefully before you comment on it.  Afterall, aren't 
you the one who advocates looking at actual specimens and reading stuff 
carefully, not just acting on internet hearsay?

Regards,
Randall Irmis