EXHIBIT 04
Brachiosaurus altithorax
Air-filled ribs, towering shoulders, and a fossil record with big gaps.
TWO WAYS TO PICTURE THE PAST
Compare the evidence with the familiar movie image. The illustrations are not to a shared scale.
The artist identifies this as B. altithorax and cites Scott Hartman’s skeletal drawing as its basis. Giraffatitan is a separate African genus. The American holotype lacks the skull, neck, feet and most of the tail, so those regions require comparative reconstruction. The exact neck posture, skin and colors remain interpretations. [5] [1]
Brachiosaurus althi — Levi bernardo. CC BY-SA 3.0. Resized and converted to WebP; complete composition retained.
The sweeping-necked cinema giant, framed to emphasize scale and grandeur. Its high-held neck and rounded silhouette are an artistic interpretation; the incomplete B. altithorax skeleton does not establish this exact outline or posture. [1]
Original artwork · artistic interpretation.
Scientific view: credited paleoart interpreting fossil evidence. Movie-style view: Original artwork. Colors and many soft tissues are uncertain.
MEET THE ANIMAL
Brachiosaurus altithorax was a large plant-eating dinosaur from the Late Jurassic of North America. It belonged to the sauropods, the group that includes many long-necked dinosaurs. Long front limbs contributed to its high shoulders, giving it a different body shape from sauropods with much shorter front legs. Fossils place this American dinosaur in the Late Jurassic. [S1]
The American animal should be distinguished from Giraffatitan, an African dinosaur once placed in the same genus. The original Brachiosaurus skeleton lacks important parts, so a complete body outline depends partly on comparisons with relatives. Published length and weight reconstructions are estimates built around particular remains and assumptions. The original individual had not finished growing, which makes it especially important to avoid treating its estimate as a species-wide adult maximum. [S1]
Even a small detail inside a bone can matter. Openings in ribs show that parts of the respiratory system extended into the skeleton. These air spaces help researchers investigate anatomy that would otherwise be lost. Other aspects of its life remain less clear: the reviewed evidence does not identify its nests, mating displays or herd structure. A towering reconstruction should not hide those gaps in the fossil record. [D3]
PREHISTORIC ANIMAL DOSSIER
The animal, the evidence, and the questions still open.
Brachiosaurus altithorax is the American brachiosaur from the Late Jurassic Morrison Formation. Its incomplete fossils differ from African Giraffatitan, so complete body reconstructions require explicitly stated comparisons.
Profile scope: Species — Brachiosaurus altithorax
Source supported identifies a description documented by the cited source. Inferred marks a reconstruction or functional estimate. Debated marks competing interpretations. Not established means the sources reviewed for this dossier do not support a firm conclusion; it does not mean a behavior never occurred.
A size reference is an estimate, not a population range. Nesting evidence does not by itself establish courtship, mate choice, or lifelong pairing.
Maybe about 25 m (subadult reconstruction)
Taylor's tentative reconstruction concerns the holotype-sized animal. Missing head, neck and tail geometry uses comparisons with Giraffatitan; this is not a directly measured complete skeleton or adult maximum. [D2]
About 28.7 tonnes (2009 model)
Taylor's holotype-based model gives 28,688 kg with assumed density and reconstructed missing parts. The holotype was subadult; this is not a species-wide adult mass. [D1]
Plant eater
Sauropod relationships support herbivory, and the museum includes this species among plant-eating sauropods. Exact plant selection is unreviewed. [D4]
Morrison Formation, North America
The study identifies Late Jurassic fossils from Colorado, Utah and Oklahoma, with some referrals uncertain. Precise microhabitat preference is unreviewed. [D1]
Four-legged terrestrial movement
Limb anatomy and sauropod comparisons support quadrupedal movement. A precise gait or maximum speed is not established here. [D1] [D4]
High shoulders; air spaces in ribs
Long forelimbs contributed to high shoulders. Pneumatic rib openings record respiratory-system extensions into bone. [D1] [D3]
Not established here
Reviewed sources do not identify B. altithorax eggs, clutch size or nest behaviour.
Not established here
Reviewed sources do not establish B. altithorax mating displays or mating posture.
Not established here
Reviewed sources do not establish a B. altithorax herd structure or group size.
Sources and inspection notes for the claims in this profile.
THE STORY IN THE FOSSILS
The type skeleton of Brachiosaurus altithorax was collected in western Colorado in 1900 and named by Elmer Riggs in 1903. It includes vertebrae, ribs, girdle material, a right humerus and a right femur, but lacks a skull and neck. The humerus helped establish its distinctive high-shouldered proportions. [1]
A 2023 study found openings into air spaces in two ribs. This skeletal pneumaticity records extensions of the respiratory system entering bones. Herbivory is inferred from its sauropod identity; the Australian Museum explicitly lists B. altithorax among a group introduced as plant-eating sauropods. [2] [4] [1]
B. altithorax differs from Giraffatitan brancai, an African dinosaur once assigned to Brachiosaurus. A detailed comparison supports separate genera and a longer, deeper trunk in the American animal. Complete-looking reconstructions contain substantial inference because the American fossils leave much of the body unknown. [1]
We have not established a comparable adult total-length estimate for this taxon in this draft. Specimen measurements in the text describe those individuals. A numerical age interval has not been reviewed here. Unknown does not mean zero.
Sources and evidence notes for this exhibit.
KEEP EXPLORING
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A small head, a skyline of plates, and four spikes at the tail.
