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-----Original
Message----- 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... 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 CaÂ
92074 |