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RE: Knuckle-walking Platypus (was Re: pterosaur femora sprawl)



Thanks Dann, that's surprising. I don't recall seeing any knuckle-walking
tracks illustrated in Barbara Triggs' book
(http://www.amazon.com/Tracks-Scats-Other-Traces-Australian/dp/0195536436).
There also don't seem to be any remarks on the treadmill surface used in the
Fish et al. study, so it would be interesting to find out what substrate
properties influence whether the claws are tucked or extended on land (it
might be something of a challenge to work with a treadmill coated in moist
clay).

-----Original Message-----
From: Dann Pigdon [mailto:dannj@alphalink.com.au] 
Sent: 06 June, 2008 4:01 PM
To: dinosaur@usc.edu
Subject: Knuckle-walking Platypus (was Re: pterosaur femora sprawl)

Dann Pigdon writes: 

> Platypus are 'knuckle-walkers'...

See "ENERGETICS OF TERRESTRIAL LOCOMOTION OF THE PLATYPUS
ORNITHORHYNCHUS ANATINUS": 

http://jeb.biologists.org/cgi/reprint/204/4/797.pdf 

Page 797:
The platypus forages in water, and its life cycle is tied to
burrows constructed in the banks of streams. However, the
animals are frequently seen moving overland and are known
to climb steep slopes in moving between lakes (Grant, 1989).
Cineradiographic analysis of the animal during walking shows
substantial long-axis rotation of the humerus, thus twisting the
antebrachium over the positioned manus. This pattern is
repeated in the two other genera of monotremes, the echidnas
(Pridmore, 1985). However, as first pointed out by Burrell
(Burrell, 1927), the major difference between the three is that
the platypus is a 'knuckle walker' with the manus distally
flexed on contact with the substratum... 


___________________________________________________________________ 

Dann Pigdon
GIS / Archaeologist              http://geo_cities.com/dannsdinosaurs
Melbourne, Australia             http://heretichides.soffiles.com
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