Fossils found in 1970s are most recent ancestor of tyrannosaurs, scientists say

Researchers identify new species named Khankhuuluu mongoliensis from skeletons unearthed in Mongolia

Tyrannosaurs might evoke images of serrated teeth, massive bodies and powerful tails, but their most recent ancestor yet discovered was a slender, fleet-footed beast of rather more modest size.

Experts say the new species - identified from two partial skeletons - helps fill a gap in the fossil record between the small, early ancestors of tyrannosaurs and the huge predators that evolved later.