Fossil finds are exciting moments that sometimes introduce the world to an ancient mammal or dinosaur that existed millions of years ago. But a longstanding problem in paleontology is that fossils are often incomplete, and subtle differences between certain species, along with major changes that can occur as an animal grows, complicate species identification. A paper published this month in Paleobiology lays the groundwork for a new approach to correctly identifying ancient animal fossils, with significant implications for vertebrate paleontology.