"Lambeosaurus" lived during the later Cretaceous period, about 76 to 75 million years ago (mya). Fossils of it have been found in Alberta (Canada), Montana (USA), and Baja California (Mexico), but only the two Canadian species have been described in detail. Apparently, the Mexican species, "Lambeosaurus laticaudus", grew to be about 50 feet long (15 m), weighing 5.6 tons. It is the longest-known ornithischian dinosaur. The other species were smaller.