Calodiscus

Calodiscus is a genus of Eodiscinid trilobite in the family Calodiscidae. It lived during the late Lower Cambrian, with remains found in Canada, the United States, Greenland, The United Kingdom, Sweden, France, Germany, Italy, Kazakhstan, the Russian Federation and China.
The type species by original designation is Agnostus lobatus Hall, 1847 from the upper part of the lower Cambrian Browns Pond Formation at Troy in the Taconic region of New York State, USA .
Lochman demonstrated that Calodiscus agnostoides represents late meraspid instars of C. lobatus.
Of four named Calodiscus species from the Lower Cambrian of the Siberian Platform revised by Korovnikov and Bushuev only two, C. resimus Repina, 1972 and C. schucherti were retained in the genus. C. helena and C. granulosus Jegorova et Shabanov, 1972 were considered significantly different to assign them a new genus, Paracalodiscus, within the family Weymouthiidae Kobayashi, 1943.
The generic homonym Calodiscus, as described by Rabenhorst in 1853, is a genus of freshwater diatom. However the type species, Calodiscus superbus, has been reclassified as Campylodiscus superbus.