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RE: New Nature paper on Tyrannosaur Locomotion



 

 

-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of MariusRomanus@aol.com
Sent: Wednesday, February 27, 2002 9:20 PM
To: dinosaur@usc.edu
Subject: Re: New Nature paper on Tyrannosaur Locomotion

 

Ok..... This is really interesting.... BUT... we are doing the math based on the wrong assumptions again. Here, we are saying that theropods ran like birds and mammals. They ran like neither. They ran like theropods. Why is this fact usually shoved under the carpet and the couch moved over it? Never mind that we are talking about a combination of crocodilian hips coupled with an avian lower leg that no longer exists in modern animals, but you have a huge ilium that gives great leverage. You have the crocodilian pull of the tail.... The get up and go bit..... This pulls it off its mark and gets it going. The caudofemoralis... it's huge in tyrannosaurs. It's tiny in birds. Bird locomotion is thus all in the knees. And mammals? Mammals have both the knee as well as the lumbar. The âarch-range of motion' of the femur is increased by the lumbar region as it acts as a sort of spring. The shoulder region in mammals also acts as their spring. This âarch-range of motion' is rare in bird femurs most of the time in the first place, and never seen aided by a moving lumbar region because their dorsal vertabrae are fused. We all know this. In birds, their spring is in the cnemial tendons. Only when the pectoral region grows larger to help power the flight muscles do we see the increased lower limbs in birds and this is most likely because of weight. With all the weight forwards the body in birds, they needed to move the gut back to displace some weight. This spreading of both the distal symphysis of the ischia and pubis, as well as flare in the ilium in a lateral manner of birds, put the femur at a disadvantage mechanically. So, the only way birds could make up for this was to select for moving the motion of the femur that was once a prime mover of the rear limb to the knee. They did this by elongating the tibia as well as the metatarsal elements. In this way it helped also to balance the animal as well by being able to keep its feet further forward when standing... I'm going offf on a tangent....... Someone smack me...

So anyway, non-avian theropods use the entire leg...... They use their femur to make up for the difference. Their caudofemoralis. Leg length.... Foot prints.... Everything shows this. Yes, the study definitely showed that they walked fast.... Tyrannosaurs were speed walkers... Works for me... BUT... they still could also take off from the ground as well... They still had a "ballistic phase". It's all the knee cartilage and tendon spring.  In birds, its the cnemial tendons. In theropods, you have the cnemial tendons and lots of cartilage as well. And by the way, crocodilians are slow??? I guess the footage of "galloping" crocodiles must be more of that Lucasfilm movie magic....
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This is what Iâve been trying to say and am glad to see someone who knows math state this. We are on the same wave length on this.

 

I use to work at a factory in the warehouse and the product we worked with also worked closely with technicians, and with working so closely with them showed me that anything works on paper, but when it comes to real lifeâ

 

Bird legs donât move like theropods and Iâm with you wishing theyâd finally realize this.

Tracy L. Ford

P. O. Box 1171

Poway Ca 92074