A Fluvioviridavis-like bird from the Middle Eocene of Messel, Germany

A new avian taxon is described from the Middle Eocene of Messel in Germany. This bird closely resembles the Lower Eocene North American Fluvioviridavis platyrhamphus Mayr and Daniels, 2001. Eurofluvioviridavis robustipes n. gen. et sp. and F platyrhamphus are classified in the new taxon Fluvioviridavidae. These birds exhibit a bauplan that is unknown among modern birds in combining a flycatcher-like beak with greatly abbreviated leas. Eurofluvioviridavis is distinguished from Fluvioviridavis by its much stronger toes, indicating that the new Messel species occupied a different ecological niche from its North American relative and that the Fluvioviridavidae were an ecologically diversified group in the Eocene. Despite their morphological distinctness, however, the phylogenetic affinities of the Fluvioviridavidae are still uncertain. Their phylogenetic affinities are evaluated in a cladistic analysis of 96 morphological characters, but the resulting position basal to a cluster of several modern higher level taxa is only weakly supported.