Sotheby's says 67-million-year-old Tyrannosaurus rex fossil, which includes 'exceptionally preserved' skull containing a gaping jaw of powerful teeth, is now the most expensive set of dinosaur bones ever auctioned.

Private buyers are increasingly outbidding museums for fossils. That’s making it difficult—or even impossible—for researchers to improve our understanding of the past.

A Tyrannosaurus rex skeleton from South Dakota, nicknamed Gus, has become the world’s most expensive fossil sold at auction.