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T.rex running/walking/what ever



I came across some interesting articles today (But I don't know if it'd help
the argument for leg posture or not, or if the authors had the room to
mention them in their article).

Alexander, R. McN., and Malony, G. M. O., 1989. Locomotion of African
mammals: In: The Biology of large African mammals in their environment,
Symposia of the Zoological Society of London, v. 61, edited by Jewell, P.
A., and Malony, G. Mo. O., p. 163-180.

Excerpt from the Synopsis...The dynamic similarity hypothesis predicts that
animals of different sizes will tend to move in dynamically similar fashion,
when traveling at speeds that give them equal Froude numbers. Mammals
traveling with equal Froude numbers tend to use the same gait, as the
hypothesis predicts. However, the relationships between relative stride
length and Froude number are different for primates (which take remarkably
long strides), non-cursorial mammals and cursorial mammals...

I take this to mean that quadrapedal animals and bipedal (or some bipedal)
animals have different stride lengths. Is the stride length in T. rex longer
than that of an elephant? I don't know. They also state that Cursorial
non-primates walk and run on relatively straight legs, T. rex (as far as I
know) didn't, does this mean anything?

How do the toes play in the equation? Elephants walk on their tiptoes with a
huge pad of cartilage and 'stuff', dogs run on their toes, along with the
other large mammals. Bird's run/walk on long toes and helps 'spring' (I
think that's the term) the foot as it leaves the ground. Don't the toes play
a big part in the leg motion cycle? T. rex has long toes. Also I believe the
femur did move past the midline (unless the ilia stopped that some how, and
if so I'd like to know what the restriction is, easy Greg, easy :) ). And
wouldn't the most powerful stroke of the leg be when the femur, tibia/fibula
and metatarsals are in a straight line? (like when a human runs?) and would
be a big push off propelling the body forward?

Lanyon, L. E., 1981, Locomotor loading and functional adaptation in limb
bones: In: The Biology of large African mammals in their environment,
Symposia of the Zoological Society of London, v. 61, edited by Jewell, P.
A., and Malony, G. Mo. O., p. 305-329.

I don't know if this has any relevance in the discussion, it just sounds
interesting.

Alexander, R. McN., 1981, The gaits of tetrapods: adaptations for stability
and economy: In: The Biology of large African mammals in their environment,
Symposia of the Zoological Society of London, v. 61, edited by Jewell, P.
A., and Malony, G. Mo. O., p. 269-287.

It's interesting in that he states in the conclusion...The model suggested
the amble as the most economical running gait, but most mammals prefer to
trot...Can't animals do things right? :)

Tracy L. Ford
P. O. Box 1171
Poway Ca  92074