A group of paleontologists discovered a skull fossil in a sedimentary layer. Initially, they believed the skull belonged to a young mastodon, a now-extinct relative of modern elephants, due to the size of the teeth which appeared to be juvenile. However, mastodons are known for their large tusks, and the skull's structure would not accommodate the tusks of an adult mastodon. Based on this, the paleontologists concluded that the skull fossil indicates a different species closely related to the mastodon.

Which of the following, if true, would best provide evidence showing that the conclusion above is possibly flawed?