The correct answer to this open question is the following.
The duck-billed dinosaur tooth fossil led scientists to believe that plants also existed in Antarctica because this dinosaur was herbivore according to scientists and scholars. If that was the case, then, this dinosaur had to eat different plants in order to survive.
Scientists also have another name for this dinosaur: Hadrosaur. Scientists led by an Argentina team have explored and found dinosaurs fossils on Vega Island, in the East side of Antarctica. The tooth of this animal was found in a place form the Cretaceous period, approximately 65 million years ago.