From the Super Mario Wiki
Toad reading about the Cowazaurus
First appearance Quest for Pizza (1989)

The Cowazaurus is a hybrid of a dinosaur and a cow briefly seen in the The Super Mario Bros. Super Show! episode Quest for Pizza, when Toad was looking at a book with a picture of it. It is shown to have an udder, black spots on its skin, a pinkish hue around the mouth white hooves, bluish fur, and saggy ears. Some of its dinosaur-like traits are its long neck, and tall body in general. The only thing missing is the tail, which both cows and dinosaurs normally have.