Dinosaurs were so advanced that their civilization transitioned into biodegradable technologies that's why we only see fossils of their bones.
They were unluckily killed off by their hubris before they were able to colonize space.
Edit: WAIT WAIT WAIT. I'M SORRY, I ONLY READ THE TITLE. I didn't know this was true crime. I'm leaving this post though, I'm standing by my error and accepting the consequences.