Jurassic Herbivore Sauropods

Brachiosaurus altithorax

Brachiosaurus altithorax

Pronunciation: [BRACK-ee-oh-SORE-us AL-tih-THOR-ax] Meaning: “Arm lizard with high chest”

A colossal macronarian sauropod with disproportionately long forelimbs and an elevated neck built for high-canopy conifer browsing during the Late Jurassic.

Compare Specimen View Key Metrics ↓
Outdoor cast skeleton mount of Brachiosaurus altithorax (specimen FMNH P 25107) at the Field Museum of Natural History, Chicago.
Verified Museum Specimen
FMNH P 25107 mount • Field Museum of Natural History, Chicago, Illinois
Photo: Matt Wedel (CC BY 3.0) (CC BY 3.0) • Specimen Record ↗

Specimen Field Matrix

Empirical morphological and stratigraphical records
Geologic Period Jurassic
Temporal Range Late Jurassic, 154–150 Ma
Dietary Guild Herbivore
Taxonomic Clade Sauropods
Total Length 26 m (85.3 ft)
Standing Height 12 m (39.4 ft)
Body Mass Estimate 35,000 kg (35 t / 77,162 lbs)
Locomotion Quadrupedal
Fossil Localities Colorado, Utah, Wyoming (Morrison Formation)
Stratigraphic Formations Morrison Formation
Field Dispatch & Natural History

Paleontological Overview

A colossal macronarian sauropod with disproportionately long forelimbs and an elevated neck built for high-canopy conifer browsing during the Late Jurassic.

Brachiosaurus altithorax was described from fossil material recovered in the Morrison Formation.

Biomechanical Proportions

Human Scale Comparison

Proportional anatomical comparison between an average adult human (1.8 m / 5.9 ft) and Brachiosaurus altithorax (26 m / 85.3 ft length, 12 m / 39.4 ft standing height).

Ground Level (0.0 m) 1.8 m (5.9 ft) Length: 26 m (85.3 ft) 12 m height
Adult Human: 1.8 m (5.9 ft)
Brachiosaurus altithorax: 26 m (85.3 ft) length • 12 m (39.4 ft) standing height
Paleogeography & Stratigraphy

Where & When It Lived

Geographic Range & Habitat

North America
Fossil Deposit Localities:
Colorado, Utah, Wyoming (Morrison Formation)
Geological Formations:
Morrison 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, 154–150 Ma

Radiometric dating of volcanic ash layers (bentonite horizons) places this taxon between 154 and 150 million years before the present.

Visual Archives

Specimen & Life Restoration Gallery

Verified Museum Specimen FMNH P 25107 mount
Biomechanical Profile Field Museum of Natural History, Chicago, Illinois
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

Related Dinosaurs & Contemporaries

Field Dispatches

Related Paleontology Articles

12 min read

Diplodocus: How Long Was This Whip-Tailed Giant?

Among all the colossal dinosaurs unearthed from the Late Jurassic rock strata of western North America, Diplodocus has long captivated the human imagination as the quintessential long-necked titan. With an ultra-elongated neck counterbalanced by an extraordinarily slender, tapering tail composed of up to 80 vertebrae, Diplodocus achieved lengths that few land animals have ever approached. […]

Read Dispatch →
12 min read

Brachiosaurus: The Giant That Reached the Treetops

Among the titanic sauropods that strode across the prehistoric world, Brachiosaurus stands out as an architectural marvel of evolutionary biomechanics. While most long-necked dinosaurs—such as Diplodocus and Apatosaurus—held their vertebral columns nearly horizontal to graze across vast expanses of low-lying ferns, Brachiosaurus altithorax evolved an extraordinary upward posture. With front limbs significantly longer than its […]

Read Dispatch →