4.6" Maiasaura Hadrosaur Dinosaur Rib Bone Fossil Two Medicine FM Montana COA

Location: Two Medicine Formation, Montana (Private Land Origin)

Weight: 4.6 Ounces 

Dimensions: 4.6 Inches Long, 1.6 Inches Wide, 0.8 Inches Thick 

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Cretaceous Age 83-70 Million Years Old.

Name: Maiasaura

Type: Herbivore

Size: 9 meters in length.

Maiasaura is a large hadrosaurid dinosaur from the Upper Cretaceous of North America, dated to approximately 65–70 million years ago. Fossil material from the Two Medicine Formation has provided exceptional data on growth patterns, reproductive behavior, and herd dynamics among ornithischian dinosaurs. The discovery of extensive nesting grounds near Choteau represents one of the most significant contributions to understanding dinosaur reproductive strategies.

Morphologically, Maiasaura possessed a broad edentulous beak for cropping vegetation and complex dental batteries containing hundreds of teeth adapted for efficient mastication of fibrous plants. Cranial anatomy included a small bony crest positioned between the orbits, while limb proportions indicate facultative quadrupedalism, with longer hind limbs supporting bipedal movement when necessary.

Ontogenetic studies suggest rapid growth, with individuals attaining adult size within seven to eight years and reaching lengths մոտ eight meters with an estimated mass of around four metric tons. These features position Maiasaura as an important model for studying herbivorous dinosaur ecology and social behavior during the Late Cretaceous.