AGE, ONTOGENY AND DIMORPHISM OF MACROCEPHALITES TRIANGULARIS SPATH - THE OLDEST MACROCEPHALITID AMMONITE FROM KUTCH, INDIA

Macrocephalites triangularis Spath is the oldest macrocephalitid speci es in Kutch. Judging from the associated taxa and comparison of simila r macrocephalitids and other forms between Kutch and other parts of th e world, a Late Bathonian age for M. triangularis is reaffirmed. Previ ous systematic description was based on only two specimens. A fair num ber of well preserved specimens has enabled us to trace the ontogeneti c development and decipher sexual dimorphism. The importance of this s pecies in the evolution of later macrocephalitids of Kutch is explored .