A new passeriform (Aves: Passeriformes) from the early Oligocene of Poland sheds light on the beginnings of Suboscines

The paper describes a complete specimen of a passerine bird from the early Oligocene of Poland, preserved as imprints of bones and feathers on two slabs. Crosnoornis nargizia gen. et sp. nov. is just the fifth passerine species described from the Paleogene worldwide and the fourth complete. The features preserved in the distal elements of the wing exclude Acanthisittidae and Oscines and indicate that this bird can be included in Suboscines, making it the second complete representative of this group in the Paleogene. A strong, straight beak indicates that this bird could feed on a variety of foods, including hard seeds, fruit and invertebrates, and, therefore, occupied a different foraging niche than the Oligocene passerines described so far. The wing proportions, a very short tail and relatively long legs indicate that this bird spent most of its time in the forest, close to the ground in dense shrubs or dense tree crowns.