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Apatosaurus, an extinct genus of sauropod dinosaurs, lived around 152 to 151 million years ago. For more than a century, Brontosaurus has been wrongly considered as a junior synonym for Apatosaurus However, a detailed study published in 2015 suggested that Apatosaurus and Brontosaurus were distinct from each other.


Scientific classification

Kingdom Animalia
Phylum Chordata
Clade Dinosauria
Order Saurischia
Suborder Sauropodomorpha
Family Diplodocidae
Subfamily Apatosaurinae
Genus Apatosaurus
Species Apatosaurus ajax (type species)

Apatosaurus louisae

Quick Fact Sheet

Name Meaning Deceptive reptile
Pronunciation a-PAT-o-SAWR-us
Geological Time Period Tithonian age, Late Jurassic era
Size Length – 69 to 80 ft

Height – 10 to 15 ft

Neck length 25 to 40 ft
Tail length 40 to 50 ft
Weight 16.4 metric tons (18.1 short tons)
Range/Location North America
Diet Herbivore
Habitat Semiarid environment
Closest relative Supersaurus
Top speed 20 to 30 km per hour
Locomotion Quadrupedal

Physical Description

Apatosaurus was a heavily built animal with a long neck and a long tail. Their forelimbs were shorter than their hindlimbs. They possessed a small brain structure compared to their overall body structure. They had squared snout, chisel-like teeth, deeply bifurcated neck vertebrae, a hollow backbone and column-like legs. Their nostrils were placed on the top of their head. Their cervical vertebrae were more robust and stouter than other diplodocids. They had long ribs, and less elongated and more heavily constructed cervical vertebrae. It had a single claw on each foreleg and three on each hindleg.

Behavior and Adaptation

Apatosaurus shared their habitat with other dinosaurs like Stegosaurus, Camarasaurus, Allosaurus and Diplodocus. Even though many sauropods lived in herds, yet it is believed that Apatosaurus were solitary and terrestrial. They could not move fast because of their heavy built. They could cover around 20 – 40 km area per day. Some theories suggest that they were non-selective browser, probably feeding on ferns, cycadeoids and algae. It is believed that they used their neck for intraspecific combats; and used their tail as a whip to produce loud sounds. There are several hypotheses regarding the use of its single claw on the forelimb, such as defense, or grasping objects, or feeding. They had a long lifespan.


The genus name Apatosaurus comes from Greek words “apatēlos” meaning ‘deceptive’ (“apatē” meaning ‘deception’) and “sauros” meaning ‘lizard.’ Marsh, then a Professor of Paleontology at Yale University, gave the name because of its chevron bones that were not similar to those of other dinosaur genus, but identical to with mosasaur chevrons.

Discovery and species

In 1877, Othniel Charles Marsh, then a Professor of Paleontology at Yale University, described the type species Apatosaurus ajax, from an incomplete juvenile skeleton. The holotype was unearthed on the foothills of the Rocky Mountains. The remains were shown as distinct from Atlantosaurus. Marsh, after two years, revealed the discovery of a new sample that was larger and more complete. All specimens considered as belonging to the Apatosaurus were found from the Morrison Formation. The specimen, which is now on display at the American Museum of Natural History, was unearthed in the Morrison Formation in 1898 by Walter Granger. The very first skull sample was found in 1909 during an expedition led by Earl Douglass. But no mention of Apatosaurus skull was found till the 1970s when David Berman and John Stanton McIntosh redescribed the skulls of Apatosaurus and Diplodocus. It 2005, several A. ajax specimens (date from late Kimmeridgian to early Tithonian ages) were found. Species Apatosaurus louisae was described in 1916 by Holland. This species was first known from a sample discovered in Utah.

Interesting Facts

  • A trackway of a juvenile Apatosaurus has made some researchers believe that they were capable of bipedal locomotion.
  • Some research suggested that their neck was less flexible than it is actually presumed.
  • A microscopic study of Brontosaurus and Apatosaurus bones, in 1999, suggested that the animals grew rapidly when they were young, and they reached near-adult sizes in 10 – 15 years.
  • Scientists believe that sauropod dinosaurs laid eggs while walking. It is even thought that they did not look after their eggs.
  • A full-grown Apatosaurs did not have any enemies, but babies and younger ones were easy prey to predators like Ceratosaurus and Allosaurus.

Published on September 30th 2015 by under Reptiles.
Article was last reviewed on 16th September 2019.

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