and that they were at least 25 million years older than any similar dinosaur type previously

and they are at least 25 million years older than those of any similar dinosaur type that previously was

and the fossils are at least 25 million years older than any similar dinosaur types that previously were

fossils that are at least 25 million years older than those of any similar dinosaur type previously

fossils at least 25 million years older than similar dinosaur types previously