Over and over again, the newspaper lead is that the platypus is "weird" or "odd" or worse, they imply that the animal is a chimera — "the egg-laying critter is a genetic potpourri — part bird, part reptile and part lactating mammal". No, no, no, a thousand times no; this is the wrong message. The platypus is not part bird, as birds are an independent and (directly) unrelated lineage; you can say it is part reptile, but that is because it is a member of a great reptilian clade that includes prototherians, marsupials, birds, lizards and snakes, dinosaurs, and us eutherian mammals. We can say with equal justification that we are part reptile, too.

Now look at the cladogram. Birds (archosaurs) and lizards and snakes (lepidosaurs) exhibit meroblastic cleavage. Marsupials and eutherians divide holoblastically. To say that the platypus is part bird because of that is misleading; what we'd say instead is that meroblastic cleavage is likely to be a primitive character