f A. Mesozoic time scale

We present an integrated geomagetic polarity and geologic time scale for the Triassic, Jurassic and Cretaceous, with age estimates and uncertainty limits for 30 stage boundaries. The Mesozoic time scale uses a suite of 340 radiometric dates that meet calibration standards. Stratigraphically critical data underpinning this large framework involve the observed, first order ties between (1) radiometric dates, biozones and stage boundaries, and (2) between biozones and magnetic reversals on the seafloor and in sediments.