A friend told me about this once. I think he later allowed me to listen to his audiotape copy of it. Maybe. But this was in the late 1980s -- call it "thirty years ago" -- and my memory is far from clear. I have no idea of the name of the comedian who had performed this. (Someone male, and speaking fluent English, is all I can swear to.)
Here's the basic idea: This humorous piece is a comic monologue, some minutes long, in which the narrator is playing the part of an announcer at a race track. Except that the contestants aren't horses or greyhounds or even wyverns; they are entire species (or families or kingdoms of related species, or whatever) who are one another's rivals in trying really hard to evolve into humans. "Crossing the finish line," in this context, will mean turning into people, but the announcer describes it as if everything is happening in a matter of minutes, rather than eons, in some sort of cross-country "race." The announcer describes which groups get off to a good, strong start in the first minute or two, and who already is lagging behind and thus should be considered a very long shot.
One example which my friend described to me was: "Even at this early stage, the vertebrates are really showing their backbone!"
Likewise, some humorous spin is placed on the stroke of bad luck which suddenly knocks the dinosaurs out of the running.
I think the comedy routine wraps up with the announcer saying something along these lines: "And that's the end of the Great . . . Human . . . Race!"
I'd like to listen to it again. Does anyone know who recorded this?