Fig. 8. 3D reconstructions of the heads of †Gerontoformica gracilis (on the right) and outgroup taxa (on the left) illustrating character transitions at the root of the total clade Formicidae.The relevant characters and states are marked with cyan outlines for plesiomorphies and magenta outlines for apomorphies; where applicable, physical directions of state changes are marked by arrows of the same colors. Complete illustrations of character states in all investigated taxa can be found in the character list at the end of this contribution. Char. 24: Frontal view on the head of Sceliphron caementarium and †G. gracilis, showing a flat versus bulging frontal region between the toruli. Char. 34: Lateral view of the head of Ampulex sp. and †G. gracilis showing large versus small compound eyes. Char. 57: Sagittal view of the tentorium of Ampulex sp. and †G. gracilis showing a long versus a short dorsal tentorial arm. Char. 73: Outer surface of the labrum of Ampulex sp. and †G. gracilis showing absence versus presence of a transverse line of setae.Char. 79: Frontal view of the scapopedicellar articulation of Ampulex sp. and †G. gracilis showing a basally straight and cylindrical versus a basally curved and flattened pedicel, in addition to an anteriorly deeply notched scapus tip. Char. 83: Lateral view of the mandibular articulation of S. caementarium and †G. gracilis showing a short versus elongated dorsal (secondary) mandibular articulation. Char. 145: Dorsal view of the cephalic digestive tract of †G. gracilis showing presence of the pharyngeal gland (absence in outgroups not shown).

Published as part of Richter, Adrian, Boudinot, Brendon, Yamamoto, Shûhei & Katzke, Julian, 2022, The First Reconstruction of the Head Anatomy of a Cretaceous Insect, †Gerontoformica gracilis (Hymenoptera: Formicidae), and the Early Evolution of, pp. 1-80 in Insect Systematics and Diversity 6 (5) on page 22, DOI: 10.1093/isd/ixac013, http://zenodo.org/record/7301493