This review deals with recent studies on the lungs of fossil and extant coelacanths with classical techniques (dissections, photonic histology) and modern techniques (SEM, X-ray tomography). This recent knowledge allows to attest the homology between: i) the large bony plates of the calcified organ of extinct coelacanths and the small plates that surround the lung of the extant coelacanth Latimeria; ii) the (supposed functional) lung covered with bony plates of extinct coelacanths and the vestigial (non-functional) lung of the extant coelacanth Latimeria. These results point the fatty organ of Latimeria as probably a mesenteric specialization, questioning its previous attribution to its pulmonary origin.