Data to Richter et al. 2022 "The first reconstruction of the head anatomy of a Cretaceous insect, †Gerontoformica gracilis (Hymenoptera, Formicidae), and the early evolution of ants" in Insect Systematics and Diversity. The dataset contains PDFs of ACCTRAN and DELTRAN parsimony reconstructions of character evolution, image and data files of an anlysis of mandibular muscle fiber lengths, a ORS Dragonfly file containing the segmentation of head structures of †Gerontoformica gracilis, the focal study object of the article, and 4µCT scans of wasps used as outgroups in the study. Details of these µCT scans can be found in the methods section of the related article. The scans are provided in 2D TIF files and represent datasets cropped to just the head and transformed to align the main head axes with the viewing planes, and resampled with a bin 2x2x2 in ImageJ for easier data handling, as they were used in the article. The scan files also include scan parameter log files; importantly, due to binning, the given camera pixel size has to be multiplied by 2. The datasets cover Parischnogaster sp. (de Saussure, 1852) (Hymenoptera, Vespidae), Methocha sp.(Hymenoptera, Thynnidae), Ampulex sp. (Fabricius, 1781) (Hymenoptera, Ampulicidae), and Sceliphron caementarium (Drury, 1773) (Hymenoptera, Sphecidae). All taxa were stained in a 2% iodine solution in ethanol for a week prior to scanning. They were transferred to a sealed off pipette tip of appropriate size filled with ethanol and mounted on a metal sample holder. They were scanned at a SkyScan 2211 (Bruker, Billerica, USA) at the Max Planck Institute for the Science of Human History in Jena, equipped with a high resolution (4000 × 2600 pixel) X-ray sensitive CCD camera in the nanofocus mode. Scanning parameters for the extant taxa are summarized in Table 2 of the related article.