The Eocene Green River Formation provides one of the richest records of fossil birds worldwide. As part of a reevaluation of this avifauna, we describe 12 new specimens of the stem roller Primobucco mcgrewi from the well-dated (51.66 ± 0.09 Ma) Fossil Butte Member (FBM) of the Green River Formation of Wyoming. FBM specimens represent most of avian diversity in the Green River Formation and include the oldest well-constrained record of the roller lineage (Coracii). These fossils provide new anatomical data, including the first observations on the palate, and broaden our understanding of the distribution, abundance, and taphonomy of P. mcgrewi. Using museum records and lithological comparisons, 14 of the 15 known P. mcgrewi specimens can now be assigned to specific quarries within Fossil Lake. The species is now known from five distinct localities representing both nearshore and mid-lake environments and accounts for >10% of the 148 FBM avian specimens reviewed in this study. Pectoral elements are disproportionately represented in the FBM P. mcgrewi specimens, and more than half of the sample exhibits broken elements. These new fossils and other key specimens from the Eocene of North America and Europe clarify our understanding of the evolution of the clade Coracii. Extant parts of this lineage (i.e., Coraciidae and Brachypteraciidae) have specialized ecologies and restricted Old World distributions, whereas stem representatives appear more generalized and were a major component of some North American avifaunas.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.