Cryptoborsonia
Crassitoniella is a genus of minute gastropod molluscs belonging to the superfamily Conoidea, currently unassigned to a family. The genus is a fossil taxon, known to occur between the late Oligocene and the Miocene, and has been found in fossil beds in Victoria, Australia.
Description
In the original description, Powell described the genus as below:
Taxonomy
The genus was first described by A. W. B. Powell in 1944, naming two species, C. pleurotomella and C. rugobela. Powell noted that the genus was problematic to place within extant families, noting some similarities to Cryptoconus, Pleurotomella, Cordieria and Rugobela, and feeling that the twist-like ridge on the two species' pillars made the genus have most in common with Borsonniiae. Holotypes of the two known species are held by the Auckland War Memorial Museum. The genus was placed in the order Neogastropoda by Jack Sepkoski in posthumous work published in 2002, and placed in the superfamily Conoidea but excluded from the family Turridae by Yu I Kantor et al. in 2024.
Distribution
Cryptoborsonia fossils have been found in the Port Phillip Basin, with C. rugobela found in the Jan Juc Formation of the late Oligocene, and C. pleurotomella found in the Muddy Creek Formation of the Otway Basin in Victoria, and the Gellibrand Formation of the Port Phillip Basin, dating to the middle Miocene.
Species within the genus Crassitoniella include: