WASHINGTON - A foot-long piece of bone unearthed in Australia is the first evidence that ancestors of the mighty T. rex once lived in the Southern Hemisphere.
The bone comes from a much-smaller animal, but will add to the knowledge of how that type of dinosaur evolved, researchers said.
"The new discovery tells us that 110 million years ago, in the middle of their history, tyrannosaurs were everywhere. So the question is, why did they achieve giant size as apex predators in the north, but dwindle away in the south?" Benson said in an interview via e-mail.
Dinosaurs dominated the land for 170 million years, holding the place in the ecology that mammals do today, he said.
Learning about how species change and diversify, and about past mass extinctions, can help us understand modern threats, he said.
It also helps our understanding of the evolution of modern animals, he said, noting for instance that "Tyrannosaurs are relatively close to birds."- AP