Did you know that tusks are enormous teeth? Many animals have them, but the biggest ones belong to elephants and their relatives, including mastodons. Mastodons are now extinct, but paleontologists can use fossil tusks to study the lives of these ancient giants. For our study, we analyzed the right tusk of a male mastodon found in 1998.
We also analyzed two chemical elements preserved in the tusks: oxygen and strontium. Using different forms of these elements (called isotopes), we tracked the season when a particular layer of tusk was grown, as well as where he grew it. We learned that he traveled long distances to mate with females. He also had fights with other mastodons and even died during his final battle!
Why did scientists analyze the chemical elements oxygen and strontium in the mastodon's tusk?
The word isotopes appears in the chunk above. The text mentions 'different forms of these elements (called isotopes).' Isotopes are different versions of the same element with slightly different weights. Why would different isotopes tell scientists different things about where the tusk grew?
Scientists can learn about an animal's whole life by studying one tusk. What is one thing in your life that could tell a story about you-like your height marks on a door, or a journal?
Tusks grow throughout an animal's life, adding layers like tree rings. By studying these layers, scientists can reconstruct a mastodon's entire life history. Each layer preserves a chemical signature of the environment at that time. If the mastodon traveled to a new location, the strontium isotopes in the tusk would change to match the new area's geology. If the mastodon experienced stress, such as a fight or a mating season, the oxygen isotopes might reveal changes in behavior or diet.
This particular male mastodon was not a homebody. He traveled long distances to find mates, which tells us that mastodons had complex social lives. The tusk also showed evidence of injuries and healing, indicating that he had violent encounters with other males. He eventually died in one of these battles. By studying one tusk, scientists reconstructed his migration, mating behavior, and even the cause of his death.
What does the fact that the mastodon traveled long distances to mate tell us about mastodon behavior?
Why are tusks compared to tree rings in the text?
If you could study one object from your life to tell your whole story, what would you choose and why?