A new zygodactylid species indicates the persistence of stem passerines into the early Oligocene in North America.

ABSTRACT:

Background

The lake deposits of the informal Ruby Paper Shale unit, part of the Renova Formation of Montana, have yielded abundant plant fossils that document Late Eocene - Early Oligocene global cooling in western North America. A nearly complete small bird with feather impressions was recovered from this unit in in 1959, but has only been informally mentioned.

Results

Here we describe this fossil and identify it as a new species of Zygodactylus, a stem lineage passerine with a zygodactyl foot. The new taxon shows morphological traits that are convergent on crown Passeriformes, including an elongate hallux, reduced body size, and a comparative shortening of proximal limb elements. The fossil documents the persistence of this lineage into the earliest Oligocene (~ 33 Ma) in

SUBMITTER: Hieronymus TL 

PROVIDER: S-EPMC6321701 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature