Zygodactylus ochlurus sp. nov. (1 Viewer)

Tobin L. Hieronymus, David A. Waugh1 & Julia A. Clarke, 2019

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

BMC Evolutionary Biology201919:3

Abstract: https://bmcevolbiol.biomedcentral.com/articles/10.1186/s12862-018-1319-6

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 North America. It is the latest occurring North American species of a group that persists in Europe until the Miocene.

Conclusions: Eocene-Oligocene global cooling is known to have significantly remodeled both Palearctic and Nearctic mammal faunas but its impact on related avifaunas has remained poorly understood. The geographic and temporal range expansion provided by the new taxon together with avian other taxa with limited fossil records suggests a similar pattern of retraction in North America followed by Europe.

Keywords: Passeriformes, Paleogene, Paleobiogeography, Zygodactylidae

The new species described is Zygodactylus ochlurus sp. nov.

Free pdf: https://bmcevolbiol.biomedcentral.com/track/pdf/10.1186/s12862-018-1319-6

Enjoy,

Fred

Systematic paleontology

Aves Linneaus 1758
Parapasseres Mayr 2015
Zygodactylidae Brodkorb 1971
Zygodactylus Ballmann 1969
Zygodactylus ochlurus sp. nov.

Holotype
YPM VPPU 17053, partially articulated skeleton preserved on main slab and counterpart, including two smaller flakes detached from the counterpart Feather impressions surround the skeleton. Most elements are preserved as mouldic impressions and fragments of bone.

Etymology
From ὀχληρός (ochlhros), Classical Greek for troublesome, in reference to “Trouble,” an orphaned magpie chick that Becker hand-reared in the Fossil Basin camp during his 1959 field season.

Type locality and horizon
Becker locality #2 in Fossil Basin, Upper Ruby Valley, Madison County. Plant fossils from this locality are assigned to the Ruby Basin Flora, lithostratigraphically positioned at the boundary between the Climbing Arrow and Dunbar Creek Members of the Renova Formation. The Dunbar Creek Member is locally capped by the Williams Creek basalt, K-Ar dated to 32.2 ± 0.4 Ma [23], providing a hard upper bound for the age range. Paleoclimate studies place the Ruby Flora in the earliest Oligocene, ca. 33 Ma.

Fred

Fred Ruhe said:

Etymology
From ὀχληρός (ochlhros), Classical Greek for troublesome, in reference to “Trouble,” an orphaned magpie chick that Becker hand-reared in the Fossil Basin camp during his 1959 field season.

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I was wondering what it might mean...
If from ὀχληρός, then it should in principle have been ochlerus, as the normal transliteration of this word is ochlêros.
("ochlurus" in a bird context actually rather suggests a neological "ὀχλουρός", potentially formed from ὄχλος (mob or trouble) + οὐρά (tail) + -ος (adjectival ending) -- whatever this word might mean in practice.)

e-only, no ZooBank registration... :/