Platypus and the Acidna - A New Class of Animals

The presence of a cloaca raised lots of questions about platypus reproduction. According to scientific nderstanding at the time, only mammals did that. Some experts took the same approach as etienne jaffroy saint hilaire had done and proposed an entirely new genus for these animals. This led to a lot of dispute among naturalists who tried to defend their reputations in the face of seemingly contradictory work. And if all this was impossible then it meant they simply could not produce milk - which is what we're talking about here.