The Collaborative International Dictionary of English v.0.48:

Lophosteon \Lo*phos"te*on\, n.; pl. L. Lophostea, E.
   Lophosteons. [NL., from Gr. lo`fos a crest + ? a bone.]
   (Anat.)
   The central keel-bearing part of the sternum in birds.
   [1913 Webster]