A taxonomic and phylogenetic study of Kutchithyris – A Jurassic terebratulide from Kutch, India

Abstract Kutchithyris , the dominant terebratulide genus of the Jurassic sequence of Kutch, India made its first appearance in the Middle Bathonian continuing till the Oxfordian–Kimmeridgian boundary. The genus has been sporadically reported from the Upper Bathonian of Pamir, England and New Zealand and the Callovian of Madagascar and Israel, but its oldest and most diverse record is from Kutch. Kutchithyris systematics have been in a state of flux with most earlier works resorting to subjective splitting or lumping. The genus consists of 12 species; the present study deals with the taxonomy of nine species including one new species, Kutchithyris mitra . This revisionary work is undertaken on the basis of a large number of specimens that have been collected with precise stratigraphic data as well the type materials collected by earlier workers. A parsimony analysis of the genus indicate that the evolution was governed by heterochrony particularly paedomorphosis.