Online news editor David Grimm shares stories on 66-million-year-old Tyrannosaurus rex tracks, a signature of human consciousness, and a second try at domesticating cats. Mathieu Ossendrijver joins host Sarah Crespi to discuss newly translated Babylonian tablets that extend the roots of calculus all the way back to between 350 B.C.E. to 50 B.C.E. Read the related research in Science.