Allosaurus

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A reference overview

Allosaurus ( AL-o-SAWR-us) is a genus of theropod dinosaur that lived 155 to 143 million years ago during the late Jurassic period (latest Oxfordian to latest Tithonian ages). The first fossil remains that could definitively be ascribed to this genus were described in 1877 by Othniel C. Marsh. The name "Allosaurus" means "different lizard", alluding to its lightweight vertebrae, which Marsh believed were unique.

Overview excerpt from Wikipedia contributors · Allosaurus, under CC BY-SA 4.0. Excerpt may be shortened. Overview retrieved 2026-10-09.

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The evidence behind this discovery

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This overview is attributed to Wikipedia contributors and was retrieved on 2026-10-09. Retrieval is not independent scientific review.

Reference media

The picture has a linked creator and license. Extinct-animal images may show a fossil, specimen or reconstruction; a reconstruction is not a photograph of the living animal.

Scope and uncertainty

Map points represent selected regions, not complete ranges or live sightings. References and identifications can change. A linked source is not an expert certification.

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Allosaurus

A reference overview

The evidence behind this discovery

Where will this discovery take you?

Tyrannosaurus rex ↗

How do fossils become evidence? ↗

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