Most people imagine dinosaurs as slow, stupid reptiles. The reality is far stranger and more awesome.
The word 'dinosaur' conjures 100-ton sauropods, but most dinosaurs were smaller than a human. Compsognathus was the size of a chicken. Many small theropods were built for speed and agility, not bulk. Size does not equal dominance.
This is not metaphorical. Modern birds are direct descendants of theropod dinosaurs — the same lineage that produced T. rex and Velociraptor. Your chicken is a living dinosaur. This is why paleontologists classify birds as avian dinosaurs.
Contrary to the 'follows scent' movie trope, T. rex had massive auditory lobes and could hear at frequencies most predators could not. It hunted by sound as much as sight. Its sense of smell was decent but not exceptional.
The movie Velociraptors were based on Deinonychus, which was much larger. Real Velociraptors were about the size of a large turkey — deadly in a pack to small prey, but not the apex predators Hollywood invented. Jurassic Park lied to you.
Many theropods were covered in feathers — not for flight in all cases, but for insulation, display, and camouflage. This includes T. rex relatives. The 'scaly monster' image is partially wrong. Feathered dinosaurs looked more like giant chickens than reptiles.
The asteroid impact 66 million years ago killed most non-avian dinosaurs, but some species survived for thousands of years afterward in isolated pockets before climate change and ecological collapse finished them. It was a process, not a light switch.
Dinosaurs were egg-layers. Some evidence suggests they built nests and cared for young, similar to modern birds. They were not just dropping eggs and abandoning them.
Pro tip: The Cretaceous period (when T. rex lived) is closer in time to us (66 million years ago) than it is to the Triassic (when dinosaurs first evolved, 230 million years ago). Stegosaurus and T. rex were separated by 80+ million years of evolution. The age of dinosaurs lasted longer than most people realize.