I was always taught live birth was also one of the requirements. Are there any other exceptions besides platypus?
Comment on egg time
JasonDJ@lemmy.zip 3 days ago
Do you secrete milk from mammary glands?
Bc that’s like legit the only requirement. We set the bar low. Not like those avians.
prole@lemmy.blahaj.zone 2 days ago
mika_mika@lemmy.world 2 days ago
Echidna also lay eggs.
prole@lemmy.blahaj.zone 2 days ago
That’s right!
They also have really weird penises if I recall
WhiskyTangoFoxtrot@lemmy.world 2 days ago
Well, you have to be descended from a particular branch of the evolutionary tree that has the ability to secrete milk from mammary glands. If, say, a mollusc independently evolved milk production that wouldn’t make it a mammal.
JasonDJ@lemmy.zip 2 days ago
They wouldn’t independently evolve mammary glands, because only mammals have mammary glands, and they are not mammals, but mollusca.
I’d say that’s a bit of a chicken/egg situation, but I don’t think we need to bring in more classes.