Evolutionary rates of Jurassic ammonites in relation to sea-level fluctuations

An analysis is presented of the diversity and faunal turnover of Jurassic a mmonites related to transgressive /regressive events. The data set containe d 400 genera and 1548 species belonging to 67 ammonite zones covering the e ntire Jurassic System. These data were used in the construction of faunal t urnover curves and ammonite diversities, that correlate with sea-level fluc tuation curves. Twenty-four events of ammonite faunal turnover are analyzed throughout the Jurassic. The most important took place at the Sinemurian-C arixian boundary, latest Carixian-Middle Domerian, Domerian-Toarcian bounda ry, latest Middle Toarcian-Late Toarcian, Toarcian-Aalenian boundary, lates t Aalenian-earliest Bajocian, latest Early Bajocian-earliest Late Bojocian, Early Bathonian-Middle Bathonian boundary, latest Middle Bathonian-earlies t Late Bathonian, latest Bathonian-Early Callovian, earliest Early Oxfordia n-Middle Oxfordian, earliest Late Oxfordian-latest Oxfordian, latest Early Kimmeridgian, Late Kimmeridgian, middle Early Tithonian and Early Tithonian -Late Tithonian boundary. More than 75 percent of these turnovers correlate with regressive-transgressive cycles in the Exxon, and /or Hallam's sea-le vel curves. Inmost cases the extinction events coincide with regressive int ervals, whereas origination and radiation events are related to transgressi ve cycles. The turnovers frequently coincide with major or minor discontinu ities in the Subbetic basin (Betic Cordillera).