So, when is a minotaur a form of centaur? Or more specifically, the Minotaur, the one from the labyrinth at Minos on Crete. Think about that for a second or two.
According to Harald Haarmann, in his book Das Rätsel der Donauzivilisation (The Puzzle of the Danube Civilization), the Minotaur is the most famous centaur (p. 68). Consider that statement for a bit. The picture on p. 69 of the book is of a pottery vessel in the shape of a centaur – except it is a human head on an animal body, as best you can tell from the photo. I can see a few folks scratching their heads saying, “Ah, hang about, that’s not at all like the centaurs from Fantasia or my books of Greek mythology.”
Apparently, either in German or in the specific usage of linguists and some students of ancient Greek culture and mythology, any human-animal combo is a centaur. Thus the most famous specific instance of this is the Minotaur of Crete. For English speakers, the Minotaur is a Minotaur, and a centaur is a half-human half-horse. English uses either the specific name for the combination (Minotaur) or “chimera” as a generic term for critter+critter=new critter-ish.
Just another fascinating quirk of language that caught my fancy.