What year was 140 million years ago from now?

Presumably it was 140,007,988 B.C., but such precision is deceptive. Years beyond about 7,000 years ago are just estimates.

Funny story, though: A guard in a museum was asked how old a certain dinosaur was, and the guard said, "65 million and sixteen years." Asked how he knew the age so exactly, the guard said, "It came here sixteen years ago and it was 65 million years old then."