Robert T. Bakker is a prominent American paleontologist whose revolutionary theories reshaped modern understanding of dinosaurs. He was a leading figure in the 'dinosaur renaissance' of the late 20th century, famously arguing that dinosaurs were warm-blooded, active, and intelligent creatures, rather than cold-blooded and sluggish reptiles. His influential book, The Dinosaur Heresies, brought these ideas to a wide public audience and challenged long-standing scientific orthodoxy. Bakker also served as an advisor for the film Jurassic Park and is known for his distinctive appearance, often seen wearing a cowboy hat.