Teeth of tyrannosaurus ancestor dating back 140 mil years found in Hyogo

The fossilized teeth of a carnivorous dinosaur that is believed be an ancestor of the greatest of its kind, tyrannosaurus, were found in Tamba, Hyogo Prefecture, museum officials said Saturday. The dinosaur, whose teeth were exhumed from strata dating back 140 million years ago in the city, is estimated to have been about 5 meters long, said the Museum of Nature and Human Activities, Hyogo.

The size is much larger than other 1- to 3-meter-long dinosaurs found in similarly old stratum at home and abroad, the museum said. Since the era of the strata is tens of millions of years earlier than the age of the over 10-meter-long tyrannosaurus, the creature was in the course of evolution to tyrannosaurus, it added. Haruo Saegusa, a curator at the museum, said, ‘‘If the dinosaur belongs to the same era of the strata, the tyrannosaurus could have started to grow larger much earlier than previously thought.’’

The teeth, about 1.8 centimeters long and 0.6 cm wide, were found by museum staff as they were cleaning a fossil of a herbivorous dinosaur.