The story
Named for Hieronim Florian Radziwill Konstanty, Count Branicki, a Polish nobleman. The species is not a mouse, but is in the order Rodentia. The genus name Dinomys comes from Ancient Greek δεινός (deinós, “terrible”) + μῦς (mûs, “mouse”).
Etymology from Wiktionary, CC BY-SA 4.0.