Contents: two identical white resin Allosaurushand claw casts
Allosaurus was probably the major predator during the Late Jurassic in Montana (about 150 million years ago). Many visitors mistake Allosaurus for T. rex. They are both theropod dinosaurs but Allosaurus is smaller and lived earlier. Allosaurus also had other differences if you look closely. Allosaurus had three claws per hand—we think T.rex only had two. The Allosaurus claw replicas in the teaching materials are casts of hand claws from “Big Al” (the Allosaurus on display in the Hall of Giants).
These two ribs likely belonged to a small, potentially young, ceratopsian (horned dinosaur).The Triceratops ribs are included here as an example of dinosaur pathology (injury). One rib (the straight one) represents a healthy rib. The other shows signs of injury. On the injured rib there is evidence of injury prior to death (the large lumpy area). The lump shows where the bone grew around the injury to repair the rib. It is likely a sign that the bone became infected as it healed incorrectly. There is another cleaner crack on this rib which most likely represents a post death break (during fossilization). We know this because there is no evidence of bone repair. Histological (microscopic analysis of thin slices of bone) studies of areas of bone growth also show us evidence that bone repair occurred while the animal was still alive. “Big Al”—the Allosaurus in the Hall of Giants shows many pathologies (fossilized evidence of injury and infection in its bones).