Author:
Bardhan S.,Datta K.,Jana S. K.,Pramanik D.
Abstract
Kheraiceras Spath, 1924, is known mainly from macroconchs. Matching of dimorphic pairs at species level is difficult due to the rarity of microconchs and consequent difficulty in establishing contemporaneity. The present study reveals dimorphism within Kheraiceras cosmopolitum (Parona and Bonarelli, 1895) from the lower part of the Callovian Chari Formation, Kutch, India, where microconch closely resembles macroconch except for the size, being about three times smaller and having an aperture characterized by terminal construction. The evolution of Kheralceras from Bullatimorphites Buckman is based on macroconchs only. The discovery of coeval microconch specimens and study of known microconchs within the lineage indicate “parallel” evolution in macro- and microconchs and improves the understanding of evolutionary trends that involve complex heterochronic processes.
Publisher
Cambridge University Press (CUP)
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