Fossils show that one pterosaur, the "Pterodaustro" found in Argentina, had comb-like strainers in its mouth. The pterosaur probably ate by filling its lower jaw with water and pushing the water out of its mouth through the strainers. The strainers could catch any plankton or other small creatures that were in the water, and when the water was gone, the animal could eat what was left. Other species had long, compressed lower jaws, which suggest they were skimmers at the top of the water.