21-Foot-Long Tyrannosaur, the Oldest Yet Known, Is Found in Thailand

French and Thai researchers have discovered in Thailand the grandfather of all tyrannosaurs--the oldest example of the vicious, meat-eating dinosaur ever found. The new dinosaur, dubbed Siamotyrannus isanensis, is 20 million years older than the earliest known tyrannosaur and may prove that the species evolved in Asia, the researchers say in the June 20 issue of Nature.

Eric Buffetaut of the University of Paris and colleagues at Thailand’s Geological Survey say the creature was about 21 feet long, about half the size of its better-known descendant Tyrannosaurus rex. Tyrannosaurs may be one of the dinosaur groups that originated in Asia during a period of relative isolation in the early Cretaceous Period, 65 million to 140 million years ago, and later spread to North America, the researchers say.