A platypus is classed as a mammal because it has fur and feeds its offspring milk, yet it lays eggs, which is uncommon for mammals but not for other vertebrates. Which of the following pieces of evidence would be most helpful in strengthening the case for continuing to classify it with the mammals?

Question

anonymous · Answer

a. DNA evidence showing it was more closely related to mammals than to other vertebrates.
b. Evidence that some platypuses have evolved to bear live young under certain circumstances.
c. Evidence that all vertebrates share a common ancestor.
d. Fossil evidence of platypuses living alongside other ancient mammals.

blues · Answer

And which do you think it is?

anonymous · Answer

i think c

blues · Answer

I think C means that the platypus is a vertebrate, but it doesn't say anything about what the question asks: how do platypuses relate to a certain class of vertebrates, the mammals.

I think it's A. A is the only option which gives any info at all about how platypuses relate to other mammals (not just other vertebrates).

anonymous · Answer

ok what about d though

blues · Answer

Fossil evidence that the platypus lived at the same time as other mammals doesn't say much about the relationship between them. Plenty of organisms which weren't mammals - weren't even animals, for that matter - lived at the same time as early mammals...

anonymous · Answer

ok so a it is thanks, i understand.