I am out of the country for a meeting and so infrequently checking mail, but thought it might be of interest to note that various animals could be considered tripodal in some fashion. Apart from the obvious category of aberrant forms such as injured quadrupeds or partially separated twins, there are at least three general types. Many parrots use the beak as a third limb for climbing in trees. Conversely, some pinnipeds (especially true seals) have very limited independent motion of the hind limbs, so that they function as one. Finally, a wide range of organisms, such as kangaroos, ground sloths, tripod fish, and therazinasaurs, use the tail as a third source of support, along with two hind limbs or elongate fins, while they are stationary.
Dr. David Campbell
"Old Seashells"
46860 Hilton Dr #1113
Lexington Park MD 20653 USA
bivalve@mail.davidson.alumlink.com
"That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks"-P.G. Wodehouse, Romance at Droigate Spa
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