Ancestral estate was 'strictly tied to the family.
In other respects the palaeotheres resemble the ancestral horses.
The discovery as fossil, in South America, of primitive or ancestral forms of marsupials has given it much support.
For regarding the monstrous form as necessarily primitive or ancestral, nor even as a stage in the ontogeny of the organ.
Keeping this in mind, we may fairly conclude that the flamingo with B X Y points to an ancestral condition A B X Y, which is still represented by Platalea and Ibis, whilst the other storks proper have taken a different line, leading to A X Y.