There may be some ground for believing that brontosaurs ate... soft foods. If the possibility of gizzard stones is ignored, the brontosaurs' dentition does seem little equipped to deal with meals of tougher plants. But there are no ground whatsoever for believing it of duckbills. The mouth of a duckbill dinosaur contained one of the efficient cranial Cusinarts in land-vertebrate history. Duckbill teeth and jaws were incomparable grinders, designed to cope with foods right inside the duckbill's oral compartment.
The Dinosaur Heresies: A Revolutionary View of Dinosaurs (1986), Longman Scientific & Technical, p. 160-161 - The Dinosaur Heresies (1986)
