We've known about dancing mice for a long time. In the 19th century, Japanese Waltzing Mice were imported to Europe, to the delight of European mouse fanciers. The mice didn't really dance, but spun around nearly continuously due to an inner ear defect. It wasn't in 3/4 time, but it was a novelty and breeders continued to propagate the strain.
Japanese Waltzing Mice were important participants in nascent genetic studies of mice in the beginning of the 20th century.
Singing mice are new. Well, they've probably been singing all along, but we just haven't heard them. Male mice sing in the presence of female mice, but at a pitch too high for the human ear to hear.
Care to have a listen? Here's a little ditty. Here's something a little more operatic.