Gastroliths (aka stomach stones, from the Greek "gastro", meaning stomach and "lithos", meaning stone) are stones which are swallowed and either held in the muscular gizzard (aka gastric mill) or passed through the digestive system along with food by animals that lack grinding teeth.
Rubbing against each other these stones act like surrogate grinding teeth, pulverising tough foods, thus aiding digestion. However, not all gizzard stones were used for this purpose. Some water-dwelling critters swallow stones for ballast.
Rubbing against each other these stones act like surrogate grinding teeth, pulverising tough foods, thus aiding digestion. However, not all gizzard stones were used for this purpose. Some water-dwelling critters swallow stones for ballast.
References
• P. J. Currie & K. Padian (1997) "Encyclopedia of Dinosaurs".
(Page 220 "Gastroliths").
• Wings, Oliver (2007) "A review of gastrolith function with implications for fossil vertebrates and a revised classification". Acta Palaeontologica Polonica 52(1):1-16.
• Michael Ryan and Brenda Chinnery-Allgeier (2010) "New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian". Page 333 "Gastroliths".
