Unlike mammals, dinosaurs didn’t hover over their young—juveniles quickly fended for themselves and filled entirely different ecological roles than their parents. That radical life-stage shift may mean dinosaur ecosystems were more diverse and dynamic than scientists ever imagined. Credit: Shutterstock Imagine a baby Brachiosaurus no bigger than a golden retriever searching for plants alongside its siblings while trying to avoid predators eager for an easy meal. Far away, its parents, towering