Cololites or pre-coprolites represent gut contents fossilized in situ. Pre-coprolites are very useful in determining the producers diet. Fossilized gut contents found in the stomachs of plesiosaurids and pliosaurids indicate that these ancient marine reptiles had a diet of cephalopods and smaller marine reptiles.

   These cololites can also provide information about feeding mechanisms and the environment the producer lived in. Pre-coprolites of a Late Cretaceous Hadrosaur, found in western Canada show a diet of tough conifer twigs, seeds and needles. These gut contents, however did not contain gastroliths, therefore suggesting a different kind of feeding mechanism. A feeding mechanism that breaks down tougher conifer needles and such, rather than a mechanism that uses stomach stones to help crush softer vegetation.