Dinosaurs under the big sky

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TC: TC2005.2.1, TC2005.2.2

Contents: two brown resin jaw section pieces

These two replica sections from the left jaw can be used to show how a hadrosaur (Maiasaura, specifically) chewed. The red arrows on the casts point to the inside of the mouth. The green diagonal line indicates how to line up the upper and lower jaw sections. To orient the jaw correctly, the green line should then face away from you (they will then be oriented as if you were the dinosaur). The teeth meet at an approximately 45-degree angle that tapers to a flat grinding surface.
Upper—This is a replica of a slice out of a Maiasaura upper left jaw. This section shows a portion of the upper tooth row including tooth detail on the outer surface and the wear pattern (chewing surface) on the inside. On the outer surface the teeth can be seen protruding from a bony covering. The main jawbone is smoother than the teeth and bone covering the teeth.
Lower—The lower jaw section shows a good example of the diamond shaped pattern formed by hadrosaur teeth. The pattern is visible on the inside (red arrow points to inside) of the jaw. Below the tooth battery a thin bony covering is visible with lines from the ridges along the sides of the teeth evident. On the outer surface of the replica a very well formed chewing surface is evident.

  • Hand visitors both sections and ask them to demonstrate how they think the dinosaur chewed. What kind of food did the hadrosaurs eat? Do your teeth work the same way? What kinds of food would be difficult to eat with teeth like this?

  • Compare the hadrosaur occlusion with the ceratopsian occlusion. How is the occlusion similar/different? How are the teeth batteries similar/different?

  • Have visitors try to recognize individual teeth in the lower jaw section. How did the teeth fit together?

  • Have visitors take a close look at hadrosaur skulls in the exhibit. Which way do the jaws face? Which is the top/bottom/outside/inside?

Hadrosaur Vertebra

TC: n/a
Contents: one real dark brown/black vertebra fossil

This real fossil is a vertebra from just before or just after the pelvis of a young hadrosaur (duck-billed dinosaur), likely from a Maiasaura. It was found in the Two Medicine Formation (from the late Cretaceous period about 76-77 million years ago) at Egg Mountain near Choteau, Montana. This vertebra and the other real fossil vertebra are not from the same dinosaur. The hole in the fossil is the canal through which the spinal cord ran. The neural spine (long spine) is where the muscles attached. Ribs were attached to the transverse processes (protrusions sticking out) on the sides of the vertebra. This is the original bone material; dark color due to presence of manganese in the matrix (rock) in which it was buried.

Hadrosaur Centrum

TC: n/a

Contents: one real dark brown/black vertebra fossil

The other real fossil “vertebra” is actually just the centrum (round part) of a vertebra. It comes from a young hadrosaur. We can tell this because it is small, but also because the rest of the vertebra (neural arch) is not fused to the centrum yet. This is from the tail of the dinosaur. It was found in the Two Medicine Formation (from the late Cretaceous) at Egg Mountain, near Choteau, Montana. It is about 76-77 million years old. This is NOT from the same individual as the other real fossil vertebra in the cart materials. This is the original bone material; dark color due to presence of manganese in the matrix (rock) in which it was buried.

Hadrosaur skin impression

TC: n/a

Contents: Two round white sections of preserved dinosaur skin impression

Skin tissue does not preserve in fossils because it rots away. However, impressions from the skin can be preserved under the right conditions. In the case of X.rex, the tail was buried in fine-grained sediments under calm enough conditions that excellent skin preservation can be seen. Along the back of the tail, under the tail and near the foot bumpy sections are visible indicating the skin texture. The skin impression replica was taken from a different hadrosaur specimen from the Royal Tyrell Museum. When cast, the bumpy texture creates a positive reproduction allowing visitors to “feel” what hadrosaur skin texture would have felt like.

  • Hand the replica to visitors and ask them what they think it is. Encourage them to make descriptive observations. What do you think this is? What do you notice about it?

  • Encourage visitors to think about the skin of dinosaurs. Is there any way to know what color the skin would have been? How do we know what the skin of Torosaurus was like (large model in the Hall of Horns and Teeth)? Why is it different from this skin sample?

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