SUPERORDER PHOSPHATOTHORACICA GALE, 2019

Diagnosis: Thoracicans with phosphatic shell plates; the number of shell plates formed is between four (paired scuta and terga) and six (rostrum and carina added). The primary mineralogy of living taxa was discussed by Reid et al. (2012), and the plates are composed of a hydrogen phosphate-like calcium phosphate biomineral.

Comment: The extant forms possess only four plates (paired scuta and terga).