Physiology of dinosaurs and that this was a feature they shared with birds. In 2007 Oliver Wings reviewed references to gastroliths in scientific literature and found considerable confusion, starting with the lack of an agreed and objective definition of "gastrolith". He found that swallowed hard stones or grit can assist digestion in birds that mainly feed on grain but may not be essential—and that birds that eat insects in summer and grain in winter usually get rid of the stones and grit in summer. Gastroliths have often been described as important for sauropod dinosaurs, whose diet of vegetation required very thorough digestion, but
Chased by Dinosaurs Chased by Dinosaurs Chased by Dinosaurs is a five-episode spin-off of the BBC program "Walking with Dinosaurs" which originally aird on BBC One during Christmas 2002 and November 2003. In a departure from the series usual format, these specials feature zoologist Nigel Marven as a time traveller who investigates and encounters dinosaurs in the wild. The specials are known only by their individual titles (with the subtitle 'A Walking With Dinosaurs Special/Trilogy') on-screen; The umbrella title 'Chased by Dinosaurs' was used to market the series in the United States. The production company Impossible Pictures and producer Jasper James would produce