Urolite is a term compound of two Greek words, uro- meaning "urine" and lithos meaning "stone" and was first used to differentiate the fossil of a nonliquid urinary secretions, produced by some groups of reptiles, in relation to coprolites. The first evidence of occurrence of liquid waste elimination attributed to a dinosaur was presented to the public in 2002, but no scientific paper had been reported a fossil evidence of liquid waste of tetrapods elimination to assume that dinosaurs urinated.
In 2004, a paper of the paleontologist Marcelo Adorna Fernandes brought a studied of trace fossils that had been preserved in three aeolian flagstones.[1] These trace fossils show a pattern that could be formed by an abundant falling stream of fluid and that is different from the structures described before in other occurrences in the paleontological records. The aspect of these urolites is very similar to the deformation caused in the soil by elimination of liquid wastes of modern ostriches, and certain groups of dinosaurs could have a similar urinary physiology. These urolites are the first evidences of the liquid waste attributed to dinosaurs.