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Barosaurus, Late JurassicMorrison Formation, Utah · named 1890
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Barosaurus

BAIR-oh-SORE-us

"heavy lizard"

Lived
155 to 143 million years ago, Late Jurassic
Diet
Herbivore
Length
about 24 m (79 ft)
Group
Sauropods, Diplodocidae
Found in
United States
Named by
Marsh 1890

Size comparison

To scale

Where its fossils were found

The evidence

Today

15 finds

150 million years ago

Map: C. R. Scotese, PALEOMAP

Also reported from Zimbabwe.

Habitat

It lived on river floodplains in the Morrison Formation. Ferns and conifers probably grew across the landscape, which also supported Stegosaurus, Apatosaurus and Camarasaurus.

Field notes

About Barosaurus

What it was like

Barosaurus was a giant, long-necked plant eater, with a neck longer in proportion to its body than most of its relatives, balanced by a shorter tail. It grew to about 24 meters (79 feet) long, one of the longest animals of its time, and likely swept its head along the ground and through low branches to feed on huge amounts of plant material each day.

Its world

Barosaurus lived in what is now the western United States, with possible remains also reported from Zimbabwe, during the Late Jurassic into the Early Cretaceous, between about 155 and 143 million years ago. Its bones, fifteen finds in all, come mostly from the Morrison Formation across Utah, Wyoming, Colorado, and South Dakota.

It shared this landscape with fellow sauropods Diplodocus, Apatosaurus, and Brachiosaurus, the armored Stegosaurus, and predators such as Allosaurus and Ceratosaurus.

How it was found

Marsh named Barosaurus in 1890. It belongs to Diplodocidae, the family of long-tailed sauropods that also includes Diplodocus, Apatosaurus, and the enormous Supersaurus. With fifteen finds, Barosaurus is reasonably well known, though its close resemblance to Diplodocus has made some remains difficult to tell apart.

Field gallery

More views of Barosaurus

Scenes reconstructed from the available fossil evidence.

Barosaurus in its habitat, photo 1

1 of 7

Lived alongside

Found in the same rock formations

A rock formation can hold fossils laid down millions of years apart, so not every animal here met Barosaurus.

The evidence

The science behind Barosaurus

Which parts of the picture come from its own bones, and which come from its relatives.

From its own fossils

  • Adult skeletons preserve stretched-out neck vertebrae, back and tail bones, and the limbs of a huge plant eater.
  • Its neck vertebrae are longer and wider than those of Diplodocus.
  • Hollow spaces in a young animal's back vertebrae suggest an air-sac system like that of birds.

Borrowed from relatives

  • The small, narrow head is restored from close relatives such as Diplodocus.
  • Scaly skin and the covering over its feet follow other sauropods.

Still unknown

  • Its skin color and markings.
  • How high it usually held its neck while feeding.
  • Whether adults cared for their young.

Often drawn wrong

  • Its tail should be held clear of the ground, rather than dragged through the mud.
  • Its front feet formed upright supports, rather than spreading out like a lizard's toes.

Discovery timeline

  1. 1890Named itMarsh
  2. 2015Family treeTschopp, Mateus & Benson
  3. 2016Growing upMelstrom et al.
  4. 2016How it fedTaylor & Wedel
  5. 2022PostureTaylor

Key papers

The research behind what we know of Barosaurus

Close relatives

Other members of Diplodocidae

Sources: Wikidata