''Calodiscus'' is a genus of Eodiscinid

trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...

in the family

Calodiscidae The Calodiscidae Kobayashi, 1943 'nom. transl.'' Öpik, 1975 ''ex'' Calodiscinae Kobayashi, 1943are a family of trilobites belonging to the order Agnostida that lived during the Lower Cambrian (Botomian and Toyonian). They are small or very smal ...

. It lived during the late Lower Cambrian, with remains found in Canada (Newfoundland & Labrador), the United States (Massachusetts, New York State), Greenland, The United Kingdom (England), Sweden, France, Germany, Italy (Sardinia), Kazakhstan, the Russian Federation and China. The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

by original designation is ''Agnostus lobatus'' Hall, 1847 from the upper part of the lower Cambrian Browns Pond Formation (formerly Schodack Formation) at Troy in the Taconic region of New York State, USA ''Calodiscus korolevi'' Pokrovskaya ''in'' Ergaliev and Pokrovskaya, 1977; ''Calodiscus lakei'' Rasetti, 1952; and ''Calodiscus'' n. sp. A of Geyer, 1988, according to Cederström ''et al''., 1988 Lochman (1956) demonstrated that ''Calodiscus agnostoides'' (Kobayashi, 1943) represents late meraspid instars of ''C. lobatus'' (Cederström ''et al''., 1988, p. 500). Of four named ''Calodiscus'' species from the Lower Cambrian of the Siberian Platform revised by Korovnikov and Bushuev (2024) only two, ''C. resimus'' Repina, 1972 and ''C. schucherti'' (Matthew, 1896) were retained in the genus. ''C. helena'' (Walcott, 1889) and ''C. granulosus'' Jegorova et Shabanov, 1972 (Korovnikov and Bushuev, ''op cit.'') were considered significantly different to assign them a new genus, ''Paracalodiscus'', within the family

Weymouthiidae The Weymouthiidae are an extinct family of eodiscinid agnostid trilobites. They lived during the late Lower Cambrian and earliest Middle Cambrian (Botomian to Delamaran) in the so-called ''Olenellus''- and ''Eokochaspis''-zones in the former ...

Kobayashi, 1943. The generic

homonym In linguistics, homonyms are words which are either; '' homographs''—words that mean different things, but have the same spelling (regardless of pronunciation), or '' homophones''—words that mean different things, but have the same pronunciat ...

''Calodiscus'', as described by L. Rabenhorst in 1853, is a genus of freshwater diatom. However the type species, ''Calodiscus superbus'', has been reclassified as '' Campylodiscus superbus'' (Rabenhorst).VANLANDINGHAM, S.L. (1968). ''Catalogue of the fossil and recent genera and species of diatoms and their synonyms. Bacteriastrum'' through ''Coscinodiscus'' Part 2. pp. 494-1086. Lehre: J. Cramer.

References

Agnostida genera Cambrian trilobites Cambrian trilobites of Europe Eodiscina Cambrian genus extinctions {{Agnostida-stub