See query. According to Aristotle and Woody Allen, for two.
Kangaroos.
All the other primates.
Kangaroo rats.
um… I dunno what kinda ostriches they have at your zoo, zoogirl, but all the ones I’ve seen had feathers…
No other primate walks bipedally.
Humans and birds are the only animals that habitually walk bipedally. As mentioned, kangaroos and their relatives, as well as kangaroo rats and a variety of other hopping rodents, are bipeds but hop rather than walk.
Bears, apes, and some lemurs may sometimes walk bipedally for short distances but are not true bipeds.
Well, there’s always Bigfoot. Nobody ever finds any giant hand tracks.
Specifically, humans walk with plantigrade motion (toes and metatarsals in contact with the ground with the center of gravity in static balance). Few other animals walk in plantigrade fashion and those that do are primarily quadruped. (There is the instance of a bear with a damaged forelimb which walks upright but that is an abnormality due to injury.) Birds, kangaroos, and wallabys move by saltation with both legs moving in symmetric motion to produce a hopping motion. The closest any non-primate comes to bipedal motion are penguins which make a stiff waddling motion.
Stranger
Most birds walk rather than hop, especially ground birds such as ratites, galliformes, and others. It’s mainly passerines that hop. Birds are however digitigrade rather than plantigrade.
Thanks for the correction/clarification; I knew that wasn’t quite correct but ran out of edit time and got distracted by something els…Ooohhh, shiny!
Stanger
As far as the OP question, there’s Diogenes’ plucked chicken…
PS It was Plato quoting Socrates about the definition of humans as “featherless bipeds”, not Aristotle.
Define “us”. Because there’s a whole lot of bipedal hominins besides Homo sapiens. Also various (currently non-feathered) dinosaurs from Eoraptor on. Even archosaur proto- crocodilians like Effigia. A
Well, wings are used for flight, a form of locomotion. So we can consider birds to be technically quadruped, and so covered under “four legs good”.
Several varieties of protohumans, going back up to 6 or 7 million years, depending upon which evidence you buy
Of course, they’re not around anymore, so I suppose they don’t count. Possibly there aren’t any more because we killed off the competition.
Quite a few saurischian dinosaurs were bipedal, but it now appears that a lot of them had feathers, which makes them ineligible for your definition. Some may not have had them, depending on the fossil evidence. But they’re not around, either.
bipedal dinosaurs stayed upright by using their long tails as counterbalances. In many cases, like allosaurs, there were extensive cartiligenous structures strengthening the tail to keep it straight and off the ground (unlike those images of dinosaurs we had as kids). In the case of bids, the legs are located under the center of mass of the body, which often extends as far behind the legs as before them.
Human beings, however, keep their upright stance and keep ourselves from falling forward at the waist in large part by using our massively developed gluteal muscles. It’s a unique solution. Those muscles are used in running, too, but in standing they’re still working to hold us up. When we run, leaning forward, they still help keep us upright in the absence of a counterbalancing tail or projecting rear half (as with ostriches, say). It’s not the weight of our butts that keeps us upright, but the force they exert.
Man is unique in this. When Bears or otters or other animals that can adopt an upright pose run, they drop to all fours. When apes run, they “knuckle walk” on all fours. When birds run, their legs are under the center of the horizontal mass of their bodies. When dinosaurs ran, they had that counterbalancing tail. The basiliscus “Jesus Lizard”, which can run so fast it can run on water, has a counterbalancing tail.
Only Man (and Woman) do without the counterbalance. We have The Butt. Arguably our greatest innovation.
Not all apes-- only chimps and gorillas.
Gibbons (and siamangs, if you want to go there) are apes and they don’t knuckle walk. In fact, they are kinda-sorta bipedal when they move on the ground, which they rarely do, preferring to stay arboreal. They often “walk” with their very long arms spread out for balance. I’ll defer to Colibri as to whether or not they are officially considered bipedal when on the ground.
Their normal mode of locomotion is brachiating, and they have no equal in the primate family when it comes to that. Chimps do it amazing well, considering their size, but gibbons are the masters.
Orangs are “great apes” that don’t knuckle walk, either. They do something called “fist walking” which is distinct from knuckle walking.
Thnx. And it was quite a screw up…
Like the tailor said, you rip dese, you mend dese.
Yours,
Icebeg
Cx: screwed up my own joke: “Iceberg”
Huh? The joke only works if you include the insultingly phony Italian accent.
You rip-a dese, you men-a dese. I.e. Euripides and Eumenides.