Apparently, arsenic in different forms (important in terms of measuring toxicity and pathways of entry into humans) was used as late as the second half of the 20th century ("was used on birds at the Smithsonian until the early 1970s"), although the impression is that 19th and early 20th century is the more likely time ...

The earliest known use of the adjective taxidermized is in the 1890s. OED's only evidence for taxidermized is from 1890, in the writing of W. B. Leffingwell. taxidermized is formed within English, by derivation. Etymons: taxidermize v.

Taxidermy is a way of preparing, stuffing and/or mounting an animal for display or study. It usually involves arranging an animal's real skin over a fake body to make the animal look alive! It is a way of preserving the body so that scientists or Museum visitors can see what the animal was like when it was alive.