Age, Ontogeny and Dimorphism of Macrocephalites triangularis Spath - The Oldest Macrocephalitid Ammonite From Kutch, India

Macrocephalites triangularis Spath is the oldest macrocephalitid species in Kutch. Judging from the associated taxa and comparison of similar macrocephalitids and other forms between Kutch and other parts of the world, a Late Bathonian age for M. triangularis is reaffirmed. Previous systematic description was based on only two specimens. A fair number of well preserved specimens has enabled us to trace the ontogenetic development and decipher sexual dimorphism. The importance of this species in the evolution of later rnacrocephalitids of Kutch is explored.