NEW YORK, United States (AFP) — One of the world's most complete Tyrannosaurus rex skeletons, nicknamed "Gus," was showcased Wednesday at Sotheby's auction house in New York ahead of its sale later this month. Valued at between $20 million to $30 million -- the highest price estimate ever for a dinosaur -- the giant fossil was discovered on a cattle ranch in South Dakota in 2021. "Gus" lived during the Maastrichtian period, some 72 to 66 million years ago, which was characterised by a warm climate, high sea levels and vast floodable coastal plains.