9. Smallest Dinosaur Fossil: Hypacrosaurus Altispinus

Photograph from American Museum of Natural History courtesy of Suzi Siegel

Housed at the American Museum of Natural History, this tiny dinosaur is only twenty inches long, three inches wide and eight inches tall. This tiny dino was only a year old and would have grown up to twenty five feet long. Dr. Mark Norell, the curator and division chair of paleontology at the museum, notes that “finding young dinosaur bones used to be extremely rare” and are more difficult to preserve because their bones are very delicate. However, more have been found recently in North and Central America.