Mosquitoes, mites and other little biting insects could have wiped out the dinosaurs, according to new research.
Many people think that a meteor struck the Earth, causing changes that meant the beasts could no longer survive.
But some experts now think that insects carried disease from dino to dino - and that's what killed them off.
The dinosaurs died out about 65 million years ago. The latest theory about what killed them is outlined in a book by scientists George and Roberta Poinar.
What killed off the dinos?
They say that insects could have made it harder for dinos to survive by changing the type of plants that existed on Earth.
Bees and other insects which like pollen encouraged more flowery plants to grow, leading to there being fewer plants that the dinos were used to feeding on.
Another theory about what killed the dinos is that massive volcano eruptions in India led to a change in climate that they couldn't cope with.
It's thought that insects first started buzzing around our planet around 300 million years ago.