Yeah, dinosaurs were not all contemporary to one another. They emerged about 230 million years ago and most were extinct by 66 million years ago. That's over 150 million years in which to see many species rise, fall, diverge, etc.
For comparison, the first homo
genus appeared less than 3 million years ago, and we've identified at least 12 species in that genus which predate modern humans. There are likely numerous species of dinosaurs--perhaps many tens of thousands--we'll never even know about because no fossils survived.