Jurassic Carnivore Theropods

Allosaurus fragilis

Allosaurus fragilis

Pronunciation: [AL-oh-SORE-us FRAJ-ih-lis] Meaning: “Different lizard, fragile”

The most common and lethal apex predator of the Late Jurassic Morrison Formation, hunting with gaping jaws, slashing bites, and robust three-clawed forelimbs.

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Mounted fossil skeleton of the apex Jurassic theropod Allosaurus fragilis (specimen CMC VP 7180) at the Cincinnati Museum Center.
Verified Museum Specimen
CMC VP 7180 mount • Cincinnati Museum Center, Cincinnati, Ohio
Photo: Fritzmann2002 (CC BY-SA 4.0) (CC BY-SA 4.0) • Specimen Record ↗

Specimen Field Matrix

Empirical morphological and stratigraphical records
Geologic Period Jurassic
Temporal Range Late Jurassic, 155–145 Ma
Dietary Guild Carnivore
Taxonomic Clade Theropods
Total Length 8.5 m (27.9 ft)
Standing Height 3 m (9.8 ft)
Body Mass Estimate 2,000 kg (2 t / 4,409 lbs)
Locomotion Bipedal
Fossil Localities Western United States (Morrison Formation), Portugal
Stratigraphic Formations Morrison Formation, Lourinhã Formation
Field Dispatch & Natural History

Paleontological Overview

The most common and lethal apex predator of the Late Jurassic Morrison Formation, hunting with gaping jaws, slashing bites, and robust three-clawed forelimbs.

Allosaurus fragilis was described from fossil material recovered in the Morrison Formation, Lourinhã Formation.

Biomechanical Proportions

Human Scale Comparison

Proportional anatomical comparison between an average adult human (1.8 m / 5.9 ft) and Allosaurus fragilis (8.5 m / 27.9 ft length, 3 m / 9.8 ft standing height).

Ground Level (0.0 m) 1.8 m (5.9 ft) Length: 8.5 m (27.9 ft) 3 m height
Adult Human: 1.8 m (5.9 ft)
Allosaurus fragilis: 8.5 m (27.9 ft) length • 3 m (9.8 ft) standing height
Paleogeography & Stratigraphy

Where & When It Lived

Geographic Range & Habitat

North America
Fossil Deposit Localities:
Western United States (Morrison Formation), Portugal
Geological Formations:
Morrison Formation, Lourinhã Formation

Fossil specimens of this species have been recovered from terrestrial floodplains, ancient river channels, and coastal sandstone facies deposited during continental rifting and tectonic reconfigurations.

Geologic Epoch & Chronology

Jurassic Period Late Jurassic, 155–145 Ma

Radiometric dating of volcanic ash layers (bentonite horizons) places this taxon between 155 and 145 million years before the present.

Visual Archives

Specimen & Life Restoration Gallery

Verified Museum Specimen CMC VP 7180 mount
Biomechanical Profile Cincinnati Museum Center, Cincinnati, Ohio
Scientific Bibliography

Peer-Reviewed References & Institutional Literature

Monographs and peer-reviewed taxonomic papers for this record are compiled from international paleontological journals and museum collections.

Scientific data peer-reviewed and verified on March 25, 2026 • Dinosaurs Facts Paleontological Registry
Mesozoic Kinship

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