(Chapter 21) Footnote 74:

De ossibus 766.8-13: “Some anatomists call this combination acromion, but others maintain that besides these two conjoined bones there is a third bone, found only in man, which they call catacleis or acromion.” (tr. Singer 1952 p. 773, with the following note: “The discovery that it is a separate ossification is ascribed by Rufus (c. AD 110) . . . to one Eudemus. The two centres by which the acromion ossifies unite with the scapular bone about the age of 16. It is untrue that they are peculiar to man.”). See Rufus Ephesius De corporis humani appellationibus 73.1.