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Re: Definitions of running (was RE: RE: Complaining)



The categories you suggest seem useful in a qualitative sense, and could make 
for good bins in many behavioral studies.  That said, the reason Hutchison and 
others use a run vs walk distinction alone is that these are the most 
defensible gaits from physical first principles.  The energy storage is 
fundamentally different in those gaits - it is not fundamentally different just 
because an aerial phase occurs.  So, while it may be simplistic from a 
kinematic standpoint, a two-gait system is our best model for quadrupedal, 
non-richochetal motion among vertebrates in a biomechanical sense.

The distinctions you propose would be particularly useful from the standpoint 
of creating animations or other visualizations where the specific "look" of the 
gait is critical, regardless of the underlying physics.  Given the source 
concerns for the thread, I suspect this is exactly your point.

--Mike H.


On Apr 30, 2013, at 6:46 PM, GSP1954@aol.com wrote:

> "We do find evidence that elephants run in a sense,"
> 
>            said first author John Hutchinson, a Stanford
> 
>            postdoctoral research fellow in the Department of
> 
>            Mechanical Engineering. "It's an intermediate
> 
>            sort of gait, but it looks like what we
> 
>            biomechanically would call running. They don't leave
> 
>            the ground, which is the classical definition, but
> 
>            they do seem to bounce, which is the biomechanical
> 
>            definition." 
> 
> The problem with saying that elephants can run is that elephants cannot 
> really run the way most mammals can. Saying animals can either just walk or 
> can 
> run is to simplistic, there are as above notes transitional forms like 
> elephants that have barely some running attributes, but are much slower than 
> most mammals and cannot even trot like hippos much less gallop like rhinos 
> (not 
> a simple size thing, an adult horse the same mass as a juvenile elephant is 
> almost three times faster, its the flexed limbs and perhaps mass dedicated 
> to locomotion that makes the difference).  
> 
> The way it should work is this. 
> 
> If an animal cannot achieve "a bounce" nor a suspended phase then it cannot 
> run and is only walking (fits salamanders I think, turtles, maybe the 
> biggest sauropods since even just walking their long strides could have 
> gotten 
> them to the elephant max of 15 mph). 
> 
> If it can achieve a bounce in a least one set of limbs but cannot bounce 
> enough to get all feet off the ground at the same time then it is semirunning 
> or ambling (elephants, unitatheres, most sauropods, derived stegosaurs). 
> 
> If it can achieve enough bounce to get all feet off the ground then it is 
> achieving a full or true run (bipedal run, hopping, trot, pace, canter, 
> gallop) (most limbed reptiles, most all dinosaurs including giant theropods, 
> giant ornithopods, giant ceratopsid, big ankylosaurs [albeit barely], many 
> birds, most mammals including hippos [they can really haul all that fat 
> around on 
> those dinky limbs, no point in trying to outrun one], brontotheres, 
> indricotheres).   
> 
> GSPaul
> 
> </HTML>