A new species of dinosaur that was probably a princely ancestor of T. rex, the king of the dinosaurs, has been identified from fossils excavated in Mongolia.

Altogether, the pieces reveal a slender tyrannosaur that roamed Cretaceous Mongolia about 86 million years ago and was about 13 feet long—or about the size of juvenile T. rex that would stalk North America 20 million years later.

Those bones belong to a new species, now named Khankhuuluu mongoliensis, or “Prince of Dragons.” This slim, fast-moving predator didn’t rule the landscape like its infamous descendant, Tyrannosaurus rex. But it may have set the evolutionary stage for the tyrant lizard kings that would come millions of years later.