Barosaurus fossil map
Where fossils of Barosaurus have been found, shown on the Earth as it looked about 145 million years ago and on today’s map.
Dots are fossil collections recorded in the Paleobiology Database. The “then” view moves today’s fossil sites back to their positions 145 million years ago (the time slice nearest the median age of the fossils) using the Merdith et al. (2021) plate model; positions are approximate. Open on the timeline map →

| Group | Sauropods & prosauropods |
|---|---|
| Lived | 157.9–143.1 million years ago |
| Periods | Jurassic |
| Family | Diplodocidae |
| Named by | Marsh 1890 |
| Fossil records | 19 occurrences at 17 locations (PBDB) |
| Found in | United States, Zimbabwe |
| Rock formations | Morrison, Kadzi |
About Barosaurus
Barosaurus ( BARR-oh-SOR-əs) ("heavy lizard") is a genus of large sauropod dinosaur that lived in present-day North America during the Late Jurassic period. It was described by American paleontologist Othniel Charles Marsh in 1890. The genus contains a single valid species, B. lentus, though the African species B. africanus has since been assigned to Tornieria. B. lentus' holotype (name-bearing) specimen initially consisted of four caudal (tail) vertebrae that were found in 1889 in South Dakota by Ms. Isabella R. Ellerman. However, later excavations found vertebrae, limb bones, and other postcranial remains from the same individual. Several other specimens have been collected outcrops of the Morrison Formation in Utah and Montana, though fossils potentially from the genus have been reported from Colorado, Wyoming, and Oklahoma as well. Barosaurus is known from the Kimmeridgian stage of the Late Jurassic period, which dates to around 152 to 150 million years ago.
Text in “About” is quoted from the Wikipedia article Barosaurus (revision 1380215547), licensed under CC BY-SA 4.0; introduction excerpted verbatim, formatting removed. Ages, family, authority and fossil records: Paleobiology Database, accessed 22 October 2026. Ages are those of the rock layers the fossils were found in. Wikidata: Q309390.