[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]


> Date:          Mon, 29 Sep 1997 23:15:40 -0400 (EDT)
> Reply-to:      GSP1954@aol.com
> From:          GSP1954@aol.com
> To:            dinosaur@usc.edu

> I am afraid that the arguments being expressed by Michael and others are
> examples of a problem with the Internet, opinions are expressed as though
> they have scientific content when they may not.

Greg, your comments are taking on a personal quality of attacking 
others.  I resent it and hope you are sensitive enough of a person to 
stop it.  There is no need for disagreement like this to lead to 
email fisticuffs and insults.
> As far as I know Michael has presented no actual data confirming his claim to
> have seen an elephant move as fast as the fastest Olympic sprinters (which do
> ~22.5 mph in the 100 m). 

No, I just gave sources that state elephant charge or flee about 25 
mph, which is faster than world sprinters.  25 is faster than 23+. 

>No film, no measured course, nada. Until he does so
> he is just arm waving. Nor has Kingdon presented such data, or has anyone
> else. The 25 mph speeds often cited in the literature are prime examples of
> repeated nondata, there is no primary well documented source. Those who have
> worked on animal locomotion such as Garland and Alexander have always
> expressed skepticism at such speeds.  

Kingdon is perhaps the most respected mammalogist in East Africa.  
Perhaps you should argue with him as I am quoting him as well as 
other sources.  Now I have seen perpetuation of myth, so I am willing 
to be open about this and relook at the facts from all angles.  I 
only wish you would. 
> Rhinos certainly are much faster than elephants, but that does not mean that
> elephants are fast. I have timed rhinos in video galloping for some distance
> at less than 20 mph, they probably cannot charge must faster than 25 to
> *maybe* 30 mph. For that matter, Alexander et al (1977, J. Zoology 183:291)
> in a large study of speed in African ungulates in the field could not get
> them to go faster than 30 mph when chasing them with a land rover. The notion
> that fast walking elephants can move at anywhere near the speed of galloping
> rhinos and other ungulates - much less as fast as sprinting Olympians - is
> nonsense.

I think that you are missing the fact that elephants have more 
than one gait.  Did you look at the video at the ref site I 
furnished.  I can see the forward acceleration of the limbs 
very well.  
> The scientific burden of proof IS upon those who wish to show that elephants
> can walk as fast as galloping ungulates and the fastest atheletes. 

No, I feel no burden of proof since there is data to back up what I 
said.  I think it would be gentlemanly of us to look at this 
together, rather than get upset over how fast an elephant walk or 
ambles.  It is important, but not enough to fight about.

> The elephant I timed was not, as Betty suggested, slow. It won the elephant
> race!

And provided us with food for thought, debate and a chance to ring 
the bull if we can figure it out.

> Elephants do not, as Jonathon suggested, pace like giraffes, camels or
> trained horses. A pace is the functional equivalent of a trot, and includes a
> suspended phase. The elephantine amble is a slightly modified and sped up
> walk that includes no suspended phase, because at least one foot always
> contacts the ground.

A pace is not a trot. And if the acceleration of the elephants limbs 
are twice what the frequency of a pendulum swing is, and stride 
length is the same, then the animal will go about twice as fast as a 
fast walk.
> Michael displays a disturbing lack of knowledge when he denies that the cost
> of walking and running a given distance is the same in a given animal.

Greg, I'm finding it difficult to be nice considering your 
continuous attacks about my lack of knowledge.  I will quote you 
verbatim from page 707 of Animal Physiology:  The relation between 
velocity and the cost of locomotion is complex.  As velocity of 
running increases in quadripedal mammals, for example, the metabolic 
cost of traveling a given distance initially decreases.  This is 
because nonlocomotory expenses account for a progressively smaller 
fraction of the total energy expended.  However, as velocity 
continues to increase, animals that swim, fly, or run all begin to 
experience an increase in the cost of locomotion as they generate 
near maximal locomotiory velocities.  Figure 16-45 illustrates this 
phenomenon in cephalopods for which a typical U-shaped curve 
describes the cost of locomotion at various locomotory velocities.

O2 consumption per unit distance per weight is linear for mammals, 
with larger animals using less than smaller.

For running animals drag is a major problem for small animals.  NOT 
so for flyer.

> spurious is his claim that the cost of locomotion follows an exponential
> curve, and that drag hinders speed in small animals. Schmidt-Nielsen (1984,
> Scaling: Why is Animal Size so Important? Cambridge Univ P) stated that
> "energy expenditure increases linearly with running speed", and Fig. 14 shows
> lots of nice straight lines for a variety of animals, none of the dips and
> swoops Micheal describes.

I suspect that you do not understand that while the rate of O2 
consumption in excess of the basal metabolic rate increases linearly 
with the velocity, this differs from the cost of locomotion vs 
velocity which is U-shaped.  I can fax you the pages if you like or 
explain it to you by phone, but this has gone too far for further 
email comment for me.

>  S-N further stated that "the cost of
> running......is independent of the speed at which an animal runs". As I
> noted, there are only minor deviations from this rule. People tend to walk at
> 3 mph because it is *just* a little more energy efficient than faster or
> slower speeds.  
> The linear speed/energy cost relationship has been known for three decades.
> I've known about it since the 70s, its old news. It is therefore exasperating
> when someone makes spurious misstatements about well established facts of
> animal locomotion. Considering Michael's weak knowledge base on animal
> locomotion, I suggest others treat his claims that he has shown how elephants
> can walk at 25 mph with skepticism. For example, he asserts that elephants
> "lift their hips" in order to "accelerate" their limbs twice as fast as a
> pendulem would allow. Of course, this does nothing for the forelimbs, which
> carrry most of the mass in elephants. Nor is it clear that Michael has
> actually documented his claim of exceptionally fast leg action in elephants.
> Present the video at a scientific forum. 

I don't have anything constructive to say further.

> Turning to speed of sauropods, it is highly improbable they were any faster
> or slower than elephants, and could do about 12 mph. Sauropods were as short
> backed as elephants relative to the length of their limbs, and very probably
> could amble.  
> GSPaul