The relationships within the 'higher land birds' and putatively related taxa are analysed in a study using 89 morphological characters and DNA sequences of three nuclear, protein-coding genes, c-myc, RAG-1, and myoglobin intron II. Separate analyses of the different data sets and a 'total evidence' analysis in which the data sets of the morphological and molecular analyses were combined are compared. All three analyses support the hitherto disputed sister group relationship between Pici (Ramphastidae, Indicatoridae and Picidae) and Galbulae (Galbulidae and Bucconidae). Previously unrecognized osteological synapomorphies of this clade are presented. All analyses further resulted in monophyly of the taxon [Aegothelidae + (Apodidae/Hemiprocnidae + Trochilidae)]. Analysis of the morphological data and of the combined data set also supported monophyly of the taxon [Strigiformes + (Falconidae + Accipitridae)]. The morphological data further support monophyly of the taxon (Upupidae + Bucerotidae). Other placements in the three analyses received either no or only weak bootstrap support.

A passerine avifauna from the late Oligocene (c. 26–25 mya) of Germany was characterized by a high diversity of conspicuously small birds ranging in size from the smallest known Oscines to moderately small forms. The avifauna comprised both Oscines and Suboscines. Other passerine fragments showed such an unexpected mosaic of characters that it was impossible to assign them with certainty to any subordinate clade within the Passeriformes. The isolated remains of oscine passerines are the earliest evidence of this taxon in the Northern Hemisphere. Coexistence of oscine and suboscine passerines during the late Oligocene is also documented for the first time in the Northern Hemisphere. These finds reduce a major gap in the passerine fossil record and allow new insights into the composition and natural history of ancient avifaunas.

The cladistic analysis of 69 morphological and behavioural characters supports the recent DNA sequence–based hypothesis that Hemicircus forms the sister group of all the remaining true woodpeckers (Picinae), but also indicates a sister‐group relationship between Dendropicini and Malarpicini, which challenges the results of previous analyses. The present phylogeny further allows a more detailed reconstruction of the stepwise evolution of adaptations for drilling, tapping and climbing up head first on vertical surfaces. The last common ancestor of woodpeckers (Picidae) was neither capable of excavating nest cavities by drilling with its beak nor of climbing up tree trunks. First adaptations for drilling such as reinforced rhamphotheca, frontal overhang and proc. dorsalis pterygoidei evolved in the ancestral lineage of piculets (Picumninae) and true woodpeckers (Picinae s.l.). Further adaptations for drilling and tapping are an enlarged condylus lateralis of the quadrate and fused cotylae mediales and laterales of the lower jaw, but these characters evolved in the ancestral lineage of Picinae s. str. and are primarily lacking in Hemicircus. The inner rectrix pairs became stiffened, and the lamina pygostyli was enlarged in the ancestral lineage of true woodpeckers (Hemicircus + Picinae s. str.). These features can be regarded as first adaptations for climbing up head first and were retained by Hemicircus. In the ancestral lineage of Picinae s. str., however, the tail feathers became further transformed into a specialized support tail, the discus pygostyli became greatly enlarged, and the ectropodactyl toe arrangement evolved. The last mentioned characters might have been the prerequisites for the enormous increase in body size in different lineages of Picinae s. str., namely Megapicini such as Campephilus and Malarpicini such as Dryocopus and Mulleripicus.

We report on the oldest European songbird (Passeriformes), from the early Oligocene (30-34 million years ago) of Frauenweiler in Germany. The specimen represents the earliest associated remains of an early Tertiary passerine described so far. It ties the first appearance of Passeriformes in Europe to a minimum age of 30 million years. Passeriform birds are absent in Eocene deposits that yielded abundant remains of small land birds and apparently dispersed into Europe around the Eocene/Oligocene boundary (about 34 million years ago), not at the Oligocene/Miocene boundary (about 24 mya) as hitherto thought. This possibly relates the appearance of songbirds in Europe to a well-known major faunistic break at the Eocene/Oligocene boundary, called the " grande coupure". The Frauenweiler songbird most notably differs from extant Passeriformes in having a larger processus procoracoideus on the coracoid and appears to be outside Eupasseres, the taxon which includes Oscines (all modern European and most Old World songbirds) and Suboscines (most South and Central American songbirds). It shows that there were earlier dispersal events of non-oscine songbirds into Europe before the arrival of Oscines from the Australian continental plate towards the late Oligocene.