RECORD OF TITHOPELTOCERAS ARKELL (AMMONOIDEA) FROM THE LATE TITHONIAN OF KUTCH, INDIA: ITS STRATIGRAPHIC AND PALEOBIOGEOGRAPHIC SIGNIFICANCE

Jurassic-Cretaceous sedimentation in Kutch took place on an epicontinental platform which experienced many transgressive-regressive phases and became progressively shallow (Biswas, 1991). As a result, marine fossils, like ammonites and other stenohaline groups, are not ubiquitous and uniformly distributed throughout the succession. From the Late Jurassic the Kutch basin witnessed major sea-level fluctuations and during the Tithonian the effects of transgressive-regressive couplets were more frequently registered. The record of ammonites in many areas, especially in the Indo–Madagascar Faunal Province, including Kutch (personal observation), are mainly associated with the transgressive events (Riccardi, 1991 and references therein). In Kutch, the spatiotemporal distribution of the ammonite-bearing beds is discrete in nature and these are not always regionally persistent. Many previous works based on the study of museum collections (e.g., Spath, 1927–1933) were plagued with stratigraphic imprecision and inadequate knowledge of the ammonite-rich localities, and generally lacked accurate lithologic description of any section. This led to poor resolution of the regional biostratigraphy based on Tithonian ammonites.