If you don’t control a Dinosaur as Tilonalli’s Knight attacks, its ability won’t trigger at all. If you don’t control a Dinosaur as the ability of Tilonalli’s Knight resolves, that ability has no effect.

Once the ability of Tilonalli’s Knight resolves while you control one or more Dinosaurs, Tilonalli’s Knight gets +1/+1 for the rest of the turn even if you no longer control a Dinosaur later in the turn.