A confuciusornithiform (Aves, Pygostylia)-like tarsometatarsus from the Early Cretaceous of Siberia and a discussion of the evolution of avian hind limb musculature

ABSTRACTWe describe a new isolated tarsometatarsus from the Early Cretaceous (Barremian-Aptian) Ilek Formation Shestakovo-3 locality in western Siberia. The new specimen represents a new taxon, <i>Evgenavis nobilis</i>, gen. et sp. nov., significantly increasing the Mesozoic avifauna from Russia. The specimen shares morphologies with a number of basal ornithothoracine taxa, but shows most similarity to the basal pygostylian <i>Confuciusornis sanctus</i>, the oldest known beaked bird and most common taxon from the Yixian Formation. <i>Evgenavis</i> may represent the first record of Confuciusornithiformes outside of the Jehol Group and its equivalent deposits. However, this is not supported by cladistic analysis, which weakly resolves the new species and <i>Mystiornis</i> both within the diverse Enantiornithes, indicating that additional material is required to assess the systematic position of <i>Evgenavis nobilis</i> (Aves incertae sedis). The three-dimensional preservation of the specimen allows for a partial reconstruction of the pedal musculature, revealing a primitive stage in the evolution of the neornithine condition.SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at http://www.tandfonline.com/UJVP.