Want to know what your dinosaurs are up to? You can see what your dinosaurs need by turning on paddock icons from the Gameplay menu in your Settings. An icon will appear about your dinosaur's habitat at certain points, which will tell you if they're hungry, ready to evolve, or ready to fuse into hybrids!
Feed: If you have a dinosaur which has not reached its maximum level to evolve, a blue up arrow will appear above the paddock, indicating that you should feed your dinosaur
Evolve: If your habitat contains two dinosaurs at the same maximum level of evolution (example: two dinos at level 10 or two at level 20) a green molecule icon will appear, indicating that your dinosaurs are ready to evolve to the next stage.
Fusion: If your habitat contains a level 40 dinosaur which is ready to fuse with another dinosaur to become a hybrid, a purple DNA icon will appear above the habitat. Note: the icon won't appear until both dinosaurs of the hybrid are ready to fuse.