first dinosaur to play hamlet

"Alas, Poor Yorick!" The actor playing Hamlet is a Leaellynasaura: it lived in regions that got cold enough for snow, so it had a coat of downy feathers over much of its body. The theropods that ate it (forelimb in upper right) were similarly equipped for the cold. The costume is the one that Sarah Bernhardt wore when she played Hamlet in 1899.

It apparently makes no difference whether you say that dinosaurs were primitive birds, or that birds are modern dinosaurs. Today all birds are classified in Dinosauria, a subset of Reptilia.