Re: The 3rd metacarpal of *T. rex*

[dinoboygraphics@aol.com]

Ha ha, looks like classic meta-quoting: I don't "strongly" support any 
particular behavioral interpretation of T. rex limbs, I was discussing 
what was likely (and unlikely) possible from a biomechanical point of 
view, e.g. the ability to carry something seemed more plausible than 
using the hands during predation (although obviously others have 
different interpretations).  Also, my "could" was shifted to a "would" 
in a larger discussion of selective forces driving the reduction and 
loss of vestigial features, making me sound fantasticaly prescient in a 
non-testable manor ("In another 10 million years they _would_ have 
lost...").

Sigh...iIt's ok, the original article was going to mirror others on the 
web that claimed that T. rex had 3 _fingers_, so at least we escaped 
years of allosaur-handed tyrannosaurs reconstructions.


Scott Hartman
Science Director
Wyoming Dinosaur Center
110 Carter Ranch Rd.
Thermopolis, WY 82443
(800) 455-3466 ext. 230
Cell: (307) 921-8333

www.skeletaldrawing.com


-----Original Message-----
From: David Marjanovic <david.marjanovic@gmx.at>
To: DML <dinosaur@usc.edu>
Sent: Fri, 26 Oct 2007 5:17 am
Subject: The 3rd metacarpal of *T. rex*


----- Original Message -----Â
From: "Mark Temple" <glitterboy2098@yahoo.com>Â
To: <DinosaurMailingList-KilledThreads@yahoogroups.com>Â
Sent: Friday, October 26, 2007 2:03 AMÂ
Subject: [DinosaurMailingList-KilledThreads] well, this changes thingsÂ
Â
http://dsc.discovery.com/news/2007/10/17/tyrannosaurus-dinosaur.html?category=dinosaurs&guid=20071017093030Â;
Â
T. Rex's Missing 3rd Finger FoundÂ
Â
[No, not the finger. Just the metacarpal, which apparently didn't end 
in a joint.]Â
Â
Three-Fingered Beast Oct. 17, 2007 - It's bad enough to misplace aÂ
finger, much less have it lost for 65 million years. But afterÂ
decades of searching, paleontologists at Montana's Hell Creek haveÂ
found the missing third finger of one of Tyrannosaurus rex'sÂ
undersized "hands."Â
Â
The finger suggests that T. rex had a powerful wrist and its handsÂ
were probably able to hold onto chunks of flesh while the monster'sÂ
gnarly jaws did all the killing.Â
Â
The newfound bone is a right metacarpal, equivalent to one of theÂ
long bones in the palm of a human hand, explains T. rex investigatorÂ
Elizibeth [sic?] Quinlan of Fort Peck Paleontology, Inc., in Fort Peck,Â
Montana. She plans to present the discovery on Oct. 28 at the annualÂ
meeting of the Geological Society of America in Denver.Â
Â
"It's unquestionably the metacarpal," Quinlan told Discovery News. NoÂ
previous T. rex remains have ever been found with a third metacarpal,Â
despite the fact that the other bones suggested its presence. "ThereÂ
is a notch in the side of the second metacarpal that was just beggingÂ
to have something fit into it."Â
Â
The revised anatomy of the hand suggests there was a very strongÂ
tendon that attached to second metacarpal, giving the hand a prettyÂ
decent grip, she said. Still, the puny limbs were almost certainlyÂ
not used by T. rex to grapple with prey or kill.Â
Â
"We were thinking that T. rex did use its upper appendages not soÂ
much in hunting but in feeding," said Quinlan. That means ripping offÂ
pieces of flesh from corpses and clutching the stuff to keep it fromÂ
other hungry predators. "We don't think their table manners were veryÂ
good."Â
Â
"I would strongly support (the hand) being used for carrying a pieceÂ
of meat away," said paleontologist Scott Hartman, science director ofÂ
the Wyoming Dinosaur Center in Thermopolis. "There is a reasonÂ
[to think?] that carrying meat away would be useful."Â
Â
One reason is that the T. rex head is already so large and heavy thatÂ
adding the weight of a large slab of meat between its teeth wouldÂ
make it unable to tip back and stand up, Hartman said. Holding meatÂ
with the arms, which are lower, avoids that overloaded teeter-totterÂ
effect.Â
Â
Another possibility is that the hands were parenting tools. TheyÂ
would have made it possible for a T. rex to carry yummy slabs of dinoÂ
flesh to its carnivorous babies, Hartman said.Â
Â
That said, the new finger bone is not going to cause much change toÂ
reconstructions of T. rex, says Hartman. Throughout the evolution ofÂ
meat-eating dinosaurs there was a trend towards fewer fingers, withÂ
the earliest having five fingers and the T. rex having two. ThisÂ
newfound nubbin of a third finger was already on its way out,Â
and did not stick out much, he said.Â
Â
"In another 10 million years they would have lost (the third finger)Â
completely," said Hartman. Unfortunately for them, however, the ageÂ
of dinosaurs ended before that could happen.Â
Â
[I doubt the trend thing.] Â


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