Re: Kangaroos Ricochet, Don't They?

[Betty Cunningham <bettyc@flyinggoat.com>]

I'm not sure I'd call them 'hoppers' but the ground locomotion of some
of the lemurs is rather 'hoppy'.  (I think some of the gibbons will do
something similar as well-damn that brachiating)

>From footage I've seen they tend to swing the arms up (out of the way
most likely, but possibly to add momeentum to the leap), then LEAP in
the direction they're aiming at. It's especially odd as the footage I've
seen usually had the animal's body oriented bipedally in one direction
(let's say facing south) and then having the head face west and
travelling west.  A repeated sideways leap.  One instance had the animal
actual reverse body facing in mid air (to face north with face west).

Very peculiar locomotion and I'm not sure what to call it.  And no, I'm
not suggesting a dinosaur would find itself in such straits as having to
resort to it.

-Betty Cunningham

"Jaime A. Headden" wrote:
 However, the idea of a hopper follows the
> following concept: every known hopper uses all four
> limbs to locate itself, including rabbits, agoutis,
> maras (heh, heh, had to throw it in), etc. Kangaroos
> and wallabies (macropodids) as well as kangaroo mice
> and jerboas, locate themselves differently, though,
> and do not use the forelimbs at all in their
> distinctive _modus locatus_, which Muybridge applied
> the term "ricochet" to, also using the tail as a
> propulsive element; they use the forelimbs only when
> "walking."
> 
>   Given the relative shortness of the forelimbs
> relative to the hind and the ridiculously long distal
> limb elements in the latter (including the pes) the
> likelyhood of independant fore to hind limb motion is
> great to me. Hopping rodents do tend to have long
> enough forelimbs, nowhere near the ratio of kangaroos.
> Now, I'm going to have to draw up a log of ratios to
> figure out the proper ratio, but strictly speaking,
> the spine of *Marasuchus* would have to be bent out of
> joint to acheive a functional quadrupedal locomotion
> -- thus ricochetting seems to me to be the more likely
> of the various forms of fast motion in lagosuchids
> (theoretically).


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