Barosaurus (/ˌbæroʊˈsɔːrəs/ BARR-o-SAWR-əs) was a giant, long-tailed, long-necked, plant-eating dinosaur closely related to the more familiar Diplodocus. Remains have been found in the Morrison Formation from the Upper Jurassic Period of Utah and South Dakota. It is present in stratigraphic zones 2–5.[1] The composite term Barosaurus comes from the Greek words barys (βαρυς) meaning "heavy" and sauros (σαυρος) meaning "lizard"; thus "heavy lizard".