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Baby Dinosaurs by Nicole and Ellen

We're dino-crazy! And we're also lucky, because we live in Montana, an excellent place to study dinosaur fossils. We went to Egg Mountain, an important dig site, to go fossil hunting! Molly, an educator from the Museum of the Rockies, came with us. The Museum of the Rockies has the largest collection of dinosaur fossils from the United States! At Egg Mountain we spied an interesting dinosaur leg bone, which has been found previously by the museum's paleontologists. Our question: Was this dino young or old when it died?

What did we do?
Egg Mountain gets its name because lots of dinosaur nests have been found here. This is also the spot where Dr. Jack Horner, a world-famous paleontologist at the Museum of the Rockies, discovered a new species of the duck-billed dino called the Maiasaura. When searching for fossils, Molly told us to look for dark objects. We found traces of dinosaur nests and pieces of dinosaur eggs. That's what Egg Mountain is famous for! We also saw a big box that paleontologists built to protect some big fossils that they are still removing from the rock. The bones are from a Maiasaura. We measure the leg bone and headed back to the museum to try and figure out how old this dino was when it died.

What did we find out?
The museum staff let us look at some plaster casts of Maiasaura and other dinosaur bones. The Maiasaura leg bone cast we saw was much smaller than the one we saw in the field. To help sort things out, we viewed an interesting display that shows the femur bones of dinosaurs at different ages. The museum staff even gave us special permission to measure these bones. Then we graphed our data. This data helped us estimate that the dinosaur we found at Egg Mountain was almost an adult when it died-but how old is an adult? Paleontologist use growth rings to figure out a dinosaur's growth-sort of like counting tree rings. They think most Maiasaura lived about 30 years. Since ours was almost an adult when it died, we decided it was about 20 years old when it died on Egg Mountain.

What can you do?
  • Visit a museum with dinosaur skeletons. Ask for permission to make measurements of the skeleton bones. Pick something like a leg bone (femur) or a skull. Compare the length of the leg or skull to the overall length of the dinosaur. Is there a relationship between the size of dino skulls and overall dino length?
  • Practice reconstructing a skeleton. The next time your family eats a whole turkey or chicken, ask to collect the bones, clean them off, and start laying them out on a sheet of paper or poster board. Do your best to identify leg, wing, rib, neck, and other bones.
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