Super cute game! I loved the "conga line" of dino's.
Having the player get used to new dino's and the game at the start felt very good, but then my 3rd dino just spawned while a rock was already halfway across the screen. I wasn't quick enough to hit the right key and I lost right away. If you could always keep a few seconds of grace period when a new dino hits, I think that would help a lot with the new player experience.
Overall really well made. Good job!