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Diplodocidae

Brontosaurus excelsus BRON-toh-SOR-us

"Thunder lizard"

Brontosaurus silhouette
You 1.8 m (5.9 ft) tall
Brontosaurus 22 m (72 ft) long
as long as 13 people standing fingertip to fingertip
silhouette · JFstudios (CC0) via PhyloPic
Length
22 m (72 ft) — About 22 m long, ~17 tonnes — once considered the same as Apatosaurus, now its own genus again.
Period
Late Jurassic (156–146 Mya)
Place
North America · Western United States
Food
Herbivore — Low and mid-height plants — similar diet to Apatosaurus.
Clade
Diplodocidae Dinosauria Saurischia Sauropodomorpha Sauropoda Whip-tailed sauropods: Diplodocus, Apatosaurus, Brontosaurus.

The archetypal long-necked "thunder lizard," once dismissed as a duplicate, now its own genus again.

Brontosaurus is back. For a century it was lumped into Apatosaurus and considered an invalid name, but a 2015 study by Tschopp and colleagues looked at hundreds of bone details and found that Brontosaurus is different enough to count as its own genus again. The species we grew up calling Brontosaurus excelsus is once again Brontosaurus excelsus.

More about Brontosaurus

Discovery

Named by Othniel Charles Marsh · 1879 · Como Bluff, Wyoming, in the Morrison Formation

William Harlow Reed collected a large, fairly complete skeleton (missing its skull) from Morrison Formation rocks at Como Bluff. Marsh announced it in 1879 and named it a new genus and species, Brontosaurus excelsus.

The name means "thunder lizard," from the Greek for "thunder" and "lizard." The type species name excelsus comes from the Latin for "noble" or "high."

Portrait of Othniel Charles Marsh
Othniel Charles Marsh An American paleontologist and Yale professor who named Brontosaurus during the Bone Wars, his rushed fossil-collecting rivalry with Edward Drinker Cope.
Is Brontosaurus a real, separate dinosaur or just Apatosaurus?
For decades it was considered a taxonomic synonym of Apatosaurus. A 2015 study by Tschopp and colleagues argued it was distinct, but because the two sit together in the subfamily Apatosaurinae, the boundary between them remains a live taxonomic question.
What did its head actually look like?
The first skeleton lacked a skull, so its true head was long uncertain. In 1975 McIntosh and Berman concluded that Apatosaurus and Brontosaurus probably had a Diplodocus-like skull, and a 1998 apatosaurine skull referred to Brontosaurus excelsus is still undescribed.

What we know

  • Originally named in 1879 by O.C. Marsh, then lumped into Apatosaurus in 1903.
  • Revived as a valid genus in 2015 after a detailed bone-by-bone study.
  • Slightly more lightly built than Apatosaurus, with a longer, lower neck.
  • Lived in the Morrison Formation alongside Allosaurus and Stegosaurus.

What we guess

  • Whether all 'Brontosaurus' specimens really belong to one genus or are more diverse.
  • How it differed in behavior or diet from Apatosaurus given how similar they look.
  • Whether the 2015 split will hold up as more specimens are studied.