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Re: Eustreptospondylus Q's



To the list,

  Hoping that anybody's not sick of this thread, I'm posting this for
Janet (below) and should have done so a day ago. Sorry.

  Anyway, she originally sent this to me, and with her permission I
duplicate this here. I would invite comments on her statements, as I
believe they are quite constructive and represent some subjects which
have _bot_ been beaten to death. One question may have relevance in
the Muscle Fiber threads.

----------------------------------
  Original Message:

<1.   I've never quite understood how it is known that dinosaurs built
apparently like kangaroos did not hop like kangaroos.>

  Kangaroo hindlimb bones are built much differently than in any
dinosaurs, such as in the metatarsals being very appressed to each
other, and muscle attachment sites are _very_ different in the two
groups. Comparing the muscular reconstructions of Paul (1988, 1989),
Russell (1972), and Norman (1983; reprint, 1998), there is a
sufficient difference between the two that a true "hop", where the
hindliegs move in tandem to propell the animal up and forward, would
not be feasible in most dinosaurs. However, myology is not my strong
suit, and I've only been getting into this since early 1998 to answer
some questions on theropod reconstructions and jaw kinetism and
strength.

<2.   Isn't comparing cheetahs & antelope in reference to sprinting &
distance running truly like comparing apples & oranges? More relevant
might be Russian Wolfhounds & track greyounds, or quarter horses &
thoroughbreds.>

  Apples and oranges ... comparing a prosauropod (*Thecodontosaurus*)
to an ornithschian (*Heterodontosaurus*) amounts to the same; there
are comparable analogies here, though, as both are fairly primitive
dinosaurs (Late Triassic to Early Jurassic, I beleive). Now, your
allusion to track and hunting animals is very interesting, but I find
the similarity quite comparable: what differences in the bones do
wolfhounds and greyhounds have from each other? This, like the
previous question I sent to the List on osteological characters
hinting at muscle fiber type, might go a way towards helping all of us
(amateurs like me and pros like Horner, Paul, and Bakker where the
behavior and capacities of the living animal are more of a focus)

<3.   Is there any extant model besides that cute frilled lizard from
Austrailia (& that's only a defense mechanism apparently) that  moves
bipedally
comparable to the animations of T. rex  (other than birds, of course).>

  The basilisk, or Jesus lizard, which casn achieve about 17 miles an
hour over water. Another defense mechanism, I believe, but I think it
was offered in the lit. that there were observable times the animal
ran just to get to the other side.

<4.   Are any of the ratites distance runners??  sprinters???>

  Ostriches. Rheas can run for a long time, and no one has ever
doubted the speed of the kiwi.

<5.   Back to #2. The skeletal anatomy of sighthounds & regular dogs
is incredibly distinctive relevant to their running ability,  but I'm
not aware of any dinosaurs that have similar skeletal structure &
balance to compare? At least  among the carnivores. All the herbivores
I can picture look either like dikers or rhinos, or very distinctive
(stegs, sauros, hadros).>

  See answer for #2.

  "Dikers", or "duikers"?

<7.    The problems associated with anesthetizing sighthounds as
opposed to regular dogs is what got me interested in the incredible
anatomical, dynamic, physiological, & metabolic differences between
distance runners & sprinters - both distinct from non-cursorial.
Unfortunately that was long after college so my ability to learn about
these distinctions is pretty limited.>

  Bah. Immerse yourself the in the lit. and the study will bring back
old memories. Here's another thing that touches on the subject of
anaerobic verses non-anaerobic muscle, and associated differences in
white and dark muscle. I am not knowledgeable to answer this
sufficiently, not without a whole lot of misunderstandings involved.

<8.   Another thought:  birds both walk & hop, but I can't remember
ever seeing a 'roo or a rabbit use their rear legs in a
"one-at-a-time" movement.>

  I've seen crows walk in alternating steps. And also, this goes back
to questions of whether squirrels could alternate their hindlimbs when
crossing narrow ledges or branches, instead of hopping, and I have so
observed them taking "normal" steps, but slowly. They turn to hopping
when they pick up speed. Meaning, scansorial animals do not require
locked hindlimbs to climb. And for those who didn't see "National
Geographic Explorer" Sunday, neither do Golden Lion Tamarins, fully
and functionally arboreal.

  <Janet>

==
Jaime A. Headden

Qilong, the website, at:
http://members.tripod.com/~Qilong/qilong.html
---
All comments and criticisms are welcome!

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