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Apatosaurus

Apatosaurus herdApatosaurus was a huge sauropod that lived in North America during the Late Jurassic period. It was one of the largest land animals ever to have lived. Its fossils were discovered in the Morrison Formation, an area of sedimentary rocks in the western United States and a rich source of Late Jurassic dinosaur fossils. As with Diplodocus and Barosaurus, fellow members of the diplodocid family, its head was small in proportion to its body size, but Apatosaurus was more heavily built than its relatives. It had long ribs compared to Diplodocus, giving it an unusually deep chest. It had pillar-like legs, with the hind legs slightly longer than its front ones. It held its long, slender tail above the ground as it walked. There was a single claw on each front foot and three on each hind foot. The front claws may have been used for grasping tree trunks when rearing up to feed on leaves high in the trees.



Apatosaurus and other dinosaurs that lived alongside them in Late Jurassic North America
A large herd of Apatosaurus lumber through a Jurassic forest, stripping enormous amounts of leaves from the trees as they go.

Neck

Apatosaurus’s neck was shorter and thicker than that of Diplodocus. The neck bones contained air sacs: they were partly hollow. This kept its neck relatively light for its size. Some palaeontologists think Apatosaurus held its head horizontally most of the time. It would not have been able to raise its neck to eat from the tops of trees, browsing on low branches or ground plants instead. Other experts say its neck was flexible enough to be held up high, forming a swan-like S-shape.
Apatosaurus skeleton

Feeding

n 2008, footprints of a juvenile Apatosaurus were discovered in the Morrison Formation rocks. They indicated that juveniles might have been able to run on their hind legs—although this is disputed by some palaeontologists.

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