Hi Platyanon, anon who went to the London Zoological Museum here, there was a victorian era replica made from brass wire, plaster and horsehair of a late eocene playpus/monotreme. He was kept in a glass cabinet with bones from the australian late eocene, he was probably retired for three reasons: the model was water damaged in the 60s, and growing mold. The model was anachronistic in terms of monotreme taxonomy, as the artist made a representation of the ancient animal from recovered vertebrae and a pelvic bone. Modern plaoetology is running against the grain of his phenotype of this ancient animal, the artist just developed his creation along the lines of the platypuses of his day.
Finally: Me. Yes I had a part to play in this. The lovely lady who runs this section of the museum annex tried to take the plaster platy out for me, after I sent her a email asking if I could take a picture of it, unfortunately Jimmy partially fell apart when he was touched. For the record I never asked that Jimmy be removed, that was the Professor being lovely, after I explained I just like platypuses and wanted to take a picture of Jimmy with my wife to post on the internet. (she really is one of the nicest people I have ever dealt with).
Even though Jimmy is old and falling apart, he is valuable as a piece of art, he had to be sent to an art restorer immediately.
Anyway, you see why I didn't explain this from my convoluted mess of a comment. I am a botanist like my wife so wikipedia will give you a better explanation of the monotreme the mass of a labrador dog. Professor Rice of the London Natural History Museum is an absolute legend