What does the fossil family Zygodactylidae reveal about extinct piciform birds?

The fossil family Zygodactylidae was established in 1971 to classify three species of extinct birds discovered in the Miocene deposits of western Europe.1

Because fossil records for the order Piciformes are extremely scarce, the Zygodactylidae family serves as a rare point of reference for understanding the group's history. The existence of such families suggests that modern piciform groups may be specialized remnants of a formerly more diverse assemblage, with the generalized groups that likely contained the common ancestors of today's families now being extinct.1

The name Zygodactylidae relates to the zygodactyl foot structure—an arrangement where two toes are directed forward and two are directed backward—which is a characteristic feature shared by modern woodpeckers and their allies. Beyond this classification, the dearth of fossil evidence means that the evolutionary history of the order must largely be interpreted through inferences based on the morphology of existing families.12