RE: Built Like a Race Horse, Slow as an Elephant?

[John Hutchinson <jrhutch@rvc.ac.uk>]

Much of this has been covered earlier on the list or elsewhere/in
publications, without much new lately, so my quick response is:

1. Yes, African elephants probably move at the same top speed of ~15mph.
This is published recently by my team in J Exper Biol (pdf available at my
pubs page:
http://www.rvc.ac.uk/AboutUs/Staff/jhutchinson/Publications.cfm  )

2. To me as an anatomist (and someone who knows a bit about racehorses
firsthand), a tyrannosaur is built like a racehorse about as much as it's
built like an elephant. These sorts of comparisons don't help much, in my
opinion.  The locomotor mechanics are fairly far removed from the anatomy.

3. It has been shown that elastic similarity does not apply to tyrannosaurs;
that was a misconception. See papers by Gatesy, Carrano, and Christiansen.
Like most dinosaurs, the interspecific scaling is around geometric
similarity, on average, with a slight but not very impressive positive
allometry at larger sizes. Finally, elastic similarity is a pretty dead
theory for locomotor design; the mechanical grounds it was based upon are
falsified by real data for moving animals (e.g. see papers by Alexander
discussing this stuff).  What does exist is geometric similarity (or less
than that, in some taxa) and various degrees of positive allometry, up to
static stress similarity scaling (in a select few species such as
ceratomorphs). Not much surprising or interesting left to say there;
skeletal scaling has been done to death, for the most part.

4. Yes, my work suggests a top speed 15-25mph for big tyrannosaurs. We're
trying to narrow it down but it's challenging considering the many unknowns;
with any method (even good footprints) there is huge potential error so
distinguishing 15 from 25mph is Really Hard.

5. Emu top speeds aren't really documented (same for ostriches); a lot of
guessing though, as usual for animal speeds. Probably somewhere in the
20-35mph range.  People I work with, as well as myself, are trying to add
hard data for this sort of stuff, to end speculations.

Cheers
John

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John R. Hutchinson
Structure & Motion Lab
Royal Veterinary College, Univ. London
Hawkshead Lane, Herts AL9 7TA, UK
phone  (+44) (0)1707-666-313
fax    (+44) (0)1707-666-371 or 652-090
mobile (+44) (0)7843-629-162
web    http://www.rvc.ac.uk/sml  and
http://www.rvc.ac.uk/Staff/jhutchinson/index.cfm
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