My first reaction:
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My second reaction:
As someone earlier in the thread said, there is a platypus like species, Monetrematum Sudamericanus (which now belongs to genus Obdurodon, what, from what can I gather, are simply prehistoric platypuses with teeth), that lived in what is now Argentina. Now, platypuses (or similar creatures) seem to date at least to the age of dinosaurs (South America and Australia were still sort of connected by that age), and they all seemed to live in Gondwana (The continent formed by South America, Africa, Australia and Antartica before they split up and went to make solo albums). There's no evidence they lived in North America at all, and the two Americas became connected about 3 million years ago, and platypuses were long extinct in South America by then. I'm not sure what kind of butterflies could giant Argentine platypuses make on history... But even if South American monotremes survive, unless North America and South America join sooner, there is no natural way* I can think of making platypuses live in North America, and such geological changes may butterfly the Everglades and even humanity itself.
*Unless there was a species of platypus in North America I'm not aware off.
All very true. However, these "platypuses" would probably not look much like OTL platypuses, nor would they necessarily live in similar habitats.