I think the encyclopedia was a grocerystore Funk & Wagnalls, which I realize is not one of our more respected reference works, but this one is just too preposterous to ignore. In distinguishing between apes and monkeys, it said that most monkeys have tails, while apes have either no tails or “very short ones”. The same article said that apes and monkeys formed the superfamily Cercopithecoidea, which I doubt that any zoologist would accept.
But where does this idea of tailed apes come from? Gibbons don’t usually figure prominently in discussions of apes that are aimed at laymen, so I’m thinking maybe there are species of gibbons that have caudal stumps. Are there? Or is this just another example of F&W sloppiness?
The only way in which it would be true is if they were using the word “ape” in the non-technical sense to mean “tailless higher primate.” Some Old World Monkeys are tailless or nearly so, and are popularly referred to as apes, as in the Barbary Ape and Celebes Ape (both kinds of macaques). In the technical sense “ape” today only applies to the gibbons and great apes (all of which are tailless).
When I say ‘sloppy’, the most egregious stunt that I remember was an error in an equation in the Calculus article…if you go around thinking that some apes have “very short tails” you might be subject to some gentle ridicule and correction, but with a math problem, there are going to be people who sit for hours and try to work the theorem out and get the same answer as in the book, and they won’t be able to!
I’ve seen artists’ reconstructions of some extinct (possible) apes that had tails. It probably comes down to what it means to be an ape. I recall seeing such a picture of Aegyptopithecus, with a tail, but the caption said “…in life the animal was an ape…”.
My impression from the article’s statement, was that extinct apes were not being referred to.
Aegyptopithecus predated the split between the Old World Monkeys and the true apes, and so it wasn’t an ape in the restricted sense of the world. It probably had a tail, since many of its descendents did.
AFAIK few of the earliest true ape fossils are complete enough so it would be possible to tell if they had tails or not. Some of the earliest forms may well have. Presence or absence of a tail isn’t a definingg trait of the ape clade; AFAIK it’s defined on other skeletal characteristics.