The evolutionary trend of platform denticulation in middle triassic acuminate gondolellidae (Conodonta)

Abstract

Acuminate Middle-Late Triassic Gondolellidae are characterized by an ellipsoid platform with a central to posterior amygdaloid basal cavity and an octomembrate apparatus of gondolelloid affinity. Starting with a neospathodiform proteromorph during the Anisian, their anagenetic lineage developed during the Fassanian, Longobardian, and Julian, ending in another neospathodiform proteromorph. As the increase in complexity in the platform denticulation is an important evolutionary trend, three new genera are proposed: Guexispathodus n. gen., Marquezella n. gen., and Kirilella n. gen., which, together with Pseudofurnishius and Mosherella, represent the subfamily Marquezellinae n. subfam.