Representatives of the avian taxon Zygodactylidae are among the best known small arboreal birds from the early Palaeogene. Still, however, the anatomy of zygodactylids is not fully understood. It is therefore important that new anatomical elements are observed and studied in detail to further support their position within the modern phylogenetic system of birds. In this study an almost complete specimen of the Zygodactylidae from the Early Eocene of Messel, Germany has been studied. This fossil belongs to the species Primozygodactylus major, and for the first time a Messel bird was investigated with a micro computed tomography (CT) scanner. This is the third known specimen of P. major and is compared with previously described zygodactylids from various fossil localities (Messel, Germany, Green River Formation, Wyoming, USA and Luberon area, Southern France) and extant higher land birds . This study is the first to create a three-dimensional model of the quadrate and the os carpi radiale of the Zygodactylidae. The quadrate shows a resemblance to previously examined specimens of the Zygodactylidae, but also shows unique characters only seen in the Upupiformes (wood hoopes and hoopes). The following are new anatomical characters of Primozygodactylus major observed in PMO 212.659; Quadratum: The capitulum squamosum is situated higher than the capitulum oticum, with a small slope between them, and no vallecular intercondylaris is present, the capitulum oticum has an extensive medial protrusion, the laterocaudal condyle ends with a sharp-edged flange, a shallow depression on the cotyla quadratojugalis, the medial condyle exceeds the lateral condyle ventrally, a large laterocaudale condyle, with a small depression between the lateralocaudal and medial condyle, and is most likely a lateral trochlea on the medial condyle. Os carpi radiale: shows similarities to the other Zygodactylidae, Zygodactylus luberonensis, and to some of the Coraciiformes.