clei·​thrum | \ -rəm \
plural cleithra\ -​rə \

Definition of cleithrum

: a bone external to and beside the clavicle in the pectoral arch of some fishes, stegocephalians, and primitive reptiles

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History and Etymology for cleithrum

borrowed from German, Latinization of Greek kleíthron, klêithron “bar fastening a door”

Note: Term introduced by the German biologist Karl/Carl Gegenbaur (1826-1903) in “Clavicula und Cleithrum,” Morphologisches Jahrbuch, 23. Band, 1. Heft (September 10, 1895), p. 10 (“Ich nenne daher den bei den Fischen bisher als Clavicula geltenden Knochen Cleithrum, und belasse die Clavicula den pentadactylen Wirbelthiere in ihrem alterworbenen Namensrecht.” - “Hence I give the name cleithrum to the bone that up to now has been regarded among fishes as the clavicule, and leave ‘clavicle’ with its long-acquired nomenclatural rights to the pentadactyl vertebrates.”) Gegenbaur explains the name in a footnote by giving the Greek form kleîthron [sic] and the translation “Schloss, Riegel” (“lock, bolt”).

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“Cleithrum.” Dictionary, Merriam-Webster, Accessed 6 Mar. 2021.

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