Ancestral sequence reconstruction of mammalian FMOs. A, Compressed tree of FMOs from jawed vertebrates. The tree depicts the explosion of FMOs in tetrapods. The five FMO clades are shown and those colored in green have been analyzed in this work. B, Close up of the FMO4 and FMO1 clades. Taxonomic distribution is depicted with silhouettes as follows: ancestral tetrapod (), bony fishes (), mammals (), aves () and testudines (). Reconstructed mammalian ancestors are shown with blue circles. On the right the corresponding graphs of the posterior probability distribution per site are shown.