Ammonites as biological stopwatch and biogeographical black box: a case study from the Jurassic-Cretaceous boundary (150 Ma) of Kutch, Gujarat

Some ammonites provide high time resolution and some others record precise palaeolatitudinal position of the sedimentary basins which harboured them. The Late Jurassic fossil record in Kutch was poor until recently. The present discovery of four genera, viz. Micracanthoceras, Spath, 1925; Durangites, Burckhardt, 1912; Corongoceras, Spath, 1925 and Tithopeltoceras, Arkell, 1953 helps in drawing precisely the Jurassic-Cretaceous system boundary in Kutch and in palaeocontinental reconstruction. Besides, faunal migrational pathways across different palaeobiogeographical provinces have been discussed.