Final answer:
Some dinosaurs swallowed stones, called gastroliths, to aid in digestion, similarly to how modern birds and crocodilians do to assist in grinding up their food. This process was essential because these animals did not possess teeth suitable for chewing and needed to break down food for nutrient absorption.
Step-by-step explanation:
Some dinosaurs swallowed stones to aid in digestion. These stones are known as gastroliths and they perform a similar function to the gizzard stones in birds. Dinosaurs, like birds, did not have teeth adapted for grinding food. Instead, the swallowed stones would reside in the stomach, where they helped to grind and break down tough food materials, making it easier for nutrients to be absorbed during the digestive process.
Similarly, birds also ingest stones, which then reside in their gizzard. The gizzard is a specialized, muscular part of the stomach that uses these swallowed stones to grind up food. Birds have a high metabolic rate and a digestive system that is adapted for efficiency, necessitating such methods to quickly break down food without the aid of teeth.
Crocodilians, creatures that are evolutionarily related to the dinosaurs, also use gastroliths for digestion. The two-chambered stomach of crocodilians, the first of which is highly muscular, benefits from the presence of these stones to aid in the digestion of their prey. The adaptations seen in crocodilians provide insight into how dinosaurs likely utilized gastroliths in a similar manner.