What would a Platypus be if it wasn't a mammal

Hi,

I was just wondering, & I know this is a weird question, but what if platypus's didn't have mammary glands? What would it be classified as? Because it certainly could be mammal since mammals have mammary glands (otherwise it isn't a mammal).

Please help me clear this up! =)

Thanks in advance! ~ Blue

(Please no rude answers, this is a serious question)

Even though all living mammals have mammary glands, it is not the defining character of Mammalia. Morganuccodon is considered one of the earliest mammals, but since soft body parts such as mammary glands are usually not preserved, it is impossible to say if the earliest mammals had mammary glands or not. Further, there is strong evidence that Morganuccodon had hair, since it had the Harderian apparatus, the oily secretions of which is used to groom mammalian fur.

Mammary glands are thought to be modified sweat glands. Even though Morganuccodon had hair, there is no assurance that it even had sweat glands. That also means it may not have mammary glands. To conclude, even if the platypus does not have mammary glands, it is still considered a mammal because it has hair, mammalian jaw joint, mammalian middle ear (3 ossicles), respiratory turbinates, and endothermy.

The question doesn't really make sense from a biological standpoint- like saying, "what would a snake be without scales?"

The Platypus fits into the phylogenic tree of life based on the combination of its traits (mammary glands, single jaw bone, inner ear bones, number of skull fenestrae, etc, etc.). Removing one of these traits doesn't move the platypus to a different branch, it just makes no sense.

Well, there's good reason to believe that platypuses and their relatives the echidnas are not mammals. True mammals are all descended from the therapsid mammal-like reptiles of the Permian Period. The platypus and the echidnas are descended from the therocephalians. But what to call them? I don't know.