Apatosaurus
A large, long-necked sauropod from the Late Jurassic.
Apatosaurus is a genus of herbivorous sauropod dinosaur that lived in North America during the Late Jurassic period. It is known for its long neck, whip-like tail, and robust build, and has been a subject of taxonomic debate, particularly regarding its distinction from Brontosaurus.
- field
- Paleontology
- known_for
- Large size, robust cervical vertebrae, and historical confusion with Brontosaurus
- average_length
- 21–23 m (69–75 ft)
- average_mass
- 16.4–22.4 t (16.1–22.0 long tons; 18.1–24.7 short tons)
Lore & Background
Fossils have been found in the Morrison Formation of Colorado, Oklahoma, New Mexico, Wyoming, and Utah.
Reader's Guide
Apatosaurus is a member of the diplodocid family, distinguished from Diplodocus by its more robust cervical vertebrae and leg bones. It had a single claw on each forelimb and three on each hindlimb. Its vertebrae were lightened by air sacs, and its tail may have been used as a whip or sensory organ. Apatosaurus lived alongside Allosaurus, Camarasaurus, Diplodocus, and Stegosaurus. Its size estimates vary, with some specimens suggesting lengths up to 30 m and masses up to 33 t, though upper estimates have been revised downward.
Did You Know?
- Apatosaurus means 'deceptive lizard'.
- Apatosaurus had air sacs that made its vertebrae internally full of holes to lighten the skeleton.
Frequently Asked Questions
What is Apatosaurus?
Apatosaurus is a genus of large, herbivorous sauropod dinosaur characterized by its elongated neck, thick body, and slender whip-like tail. It roamed North America during the Late Jurassic period, roughly 150 million years ago.
How big was Apatosaurus?
Adults typically measured between 21 and 23 metres (about 69–75 feet) in length and weighed somewhere in the range of 16 to 22 tonnes. That made it one of the heaviest land animals of its era, though slightly smaller than some of its close relatives.
What's the difference between Apatosaurus and Brontosaurus?
For over a century, Brontosaurus was treated as a separate genus, but most modern paleontologists now consider it a junior synonym of Apatosaurus, meaning the two names refer to the same animal. The distinction hinged on subtle differences in cervical vertebrae that many researchers no longer regard as sufficient to warrant separate classification.
What did Apatosaurus eat and how did it feed?
As a strict herbivore, it likely cropped low-growing conifers, cycads, and ferns using its broad, blunt teeth. Its long neck allowed it to browse across a wide vertical range without constantly repositioning its massive body.
Why is Apatosaurus important in paleontology?
It was one of the first large dinosaurs ever described in detail, and the Apatosaurus–Brontosaurus naming dispute became a landmark case in how taxonomic priority and synonymy are handled. Its robust build and well-preserved specimens also made it a key reference point for understanding sauropod anatomy and growth patterns.
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