EXHIBIT 154
Bactrosaurus johnsoni
Bactrosaurus was a crestless plant-eating hadrosauroid with robust limbs and tooth batteries, represented at several growth stages. [1]
TWO WAYS TO PICTURE THE PAST
Compare the evidence with the familiar movie image. The illustrations are not to a shared scale.
Displayed cranial and jaw bones identified as B. johnsoni in Brussels. The source supplies no specimen number or life stage; separated bones do not show a complete head outline. Fossil colors do not establish living colors or soft tissues. [2]
Bactrosaurus johnsoni.jpg · Ghedoghedo. CC BY-SA 3.0. Proportionally resized Commons preview and converted to WebP; no anatomy edits.
The photograph or figure shows the credited fossil material; displayed mounts and labels can include interpretation.
Original cinematic interpretation. The back contour is modest and the incomplete hands and whole-body posture are reconstructed comparatively. Colors, soft tissues and setting are artistic. Lighting, coloration and scenery are artistic choices. This image does not document a fossil locality or behavior.
Original artwork · artistic interpretation.
Scientific view: source-informed reconstruction, credited paleoart or specimen-based imagery. Movie-style view: Original artistic interpretation. Reconstructions involve uncertainty.
MEET THE ANIMAL
Bactrosaurus was a plant-eating dinosaur from Late Cretaceous China. The museum provides a general length reference of about six metres. It is an educational estimate without a specified individual or growth stage, rather than a verified maximum. Skull fragments and body bones have been found from multiple animals, including younger and older individuals; their age differences need careful interpretation. [D3]
Descriptions document cheek-tooth batteries and incomplete hand bones that could potentially bear weight. The batteries are groups of teeth involved in processing vegetation. Hand anatomy makes forelimb use a testable question, while missing elements limit the reconstruction. Preserved bones do not reproduce the exact steps of a living animal or turn the pose of a mount into an observed walking style. [D1]
Scientific names associated with Bactrosaurus also need careful checking. A study could not substantiate an older assignment of material called Bactrosaurus prynadai to Tanius, another named dinosaur. Such a proposal is not a settled synonym for all Bactrosaurus. Comparisons must identify which specimen and species are being discussed before combining their evidence into one animal's profile. [D5]
PREHISTORIC ANIMAL DOSSIER
The animal, the evidence, and the questions still open.
Juvenile-to-adult comparisons distinguish growth-related changes from diagnostic features; association of isolated bones and precise formation age require caution. [D2]
Profile scope: B. johnsoni from Erenhot: size-associated disarticulated type AMNH 6553, other juvenile/adult bones and new Sino-Belgian material. [D1]
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.
About 6-6.5 m; largest-material reconstruction
Largest AMNH 6365 cranial and AMNH 6553 limb/jaw comparisons define a size-based adult reference. AMNH 6553 contains multiple individuals; this is not one measured animal or a species range. [D2]
About 1.8 t; adult-material model
Benson models mature-labelled AMNH 6553 limb circumferences. The collection contains multiple individuals; these size-associated bones are not securely paired. [D4] [D2]
Plant eater
Museum classification and the described cheek-tooth batteries support herbivory. Exact plants and seasonal preferences are unresolved. [D3] [D1]
Late Cretaceous Iren Dabasu Formation
Erenhot bonebeds in Inner Mongolia preserve Bactrosaurus. Published studies disagree about finer formation age; no narrow numeric interval is adopted. [D2]
Probably mainly four-legged
Skeletal correlates favor predominant quadrupedality in Bactrosaurus, although occasional bipedal stance is not excluded. [D6]
Crestless skull, deep jaws and robust limbs
Adult limb shafts and muscle-attachment flanges are more developed than in juveniles; these differences cannot automatically diagnose separate species. [D2]
Not established here
An ontogenetic series documents juvenile and adult bones, not a securely attributed nest, parental care or reproductive age. [D2]
Not established here
Growth variation establishes neither sex differences nor mating behavior. [D2]
Not established here
Disarticulated bones of different sizes occur together. Their association does not alone distinguish a living herd, transported remains or repeated accumulation. [D1]
Sources and inspection notes for the claims in this profile.
THE STORY IN THE FOSSILS
The new Sino-Belgian collection clarified Bactrosaurus anatomy, including incomplete hand elements that could bear weight. Such fossils make posture a testable skeletal inference while leaving exact hand reconstruction incomplete. [1]
Juvenile and adult skulls and limbs differ in robustness and proportions. The study distinguishes developmental change from diagnostic features. [2]
The dossier identifies the scope of each reference estimate. A mount, an individual fossil and a species-wide adult range are different measurements. Comparison metrics remain unavailable where adult scope has not been established. Unknown does not mean zero.
Sources support the stated claims and scopes. Refer to the evidence notes for uncertainty.
KEEP EXPLORING
Tsintaosaurus spinorhinus
Tsintaosaurus was a plant-eating hadrosaur whose distinctive crest remains a subject of reconstruction and reassessment.
Amurosaurus riabinini
Amurosaurus was a hadrosaur with tooth batteries and skull architecture supporting a hollow crest whose complete shape remains unknown.
Olorotitan arharensis
Olorotitan was a hollow-crested hadrosaur distinguished by a broad helmet-like crest and an unusually long neck.
