alt=|thumb|534x534px|Cleithrum and Scapula#In other animals|scapula from a [[wrasse. The larger bone is the cleithrum.]] The cleithrum (: cleithra) is a membrane bone which first appears as part of the skeleton in primitive bony fish, where it runs vertically along the scapula. Its name is derived from Greek κλειθρον = "key (lock)", by analogy with "clavicle" from Latin clavicula = "little key".
alt=|thumb|534x534px|Cleithrum and Scapula#In other animals|scapula from a [[wrasse. The larger bone is the cleithrum.]] The cleithrum (: cleithra) is a membrane bone which first appears as part of the skeleton in primitive bony fish, where it runs vertically along the scapula. Its name is derived from Greek κλειθρον = "key (lock)", by analogy with "clavicle" from Latin clavicula = "little key".
In modern fishes, the cleithrum is a large bone that extends upwards from the base of the pectoral fin and anchors to the cranium above the gills, forming the posterior edge of the gill chamber. The bone has scientific use as a means to determine the age of fishes.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).