Fig. 3. 3D in The First Reconstruction of the Head Anatomy of a Cretaceous Insect, †Gerontoformica gracilis (Hymenoptera: Formicidae), and the Early Evolution of

Fig. 3. 3D reconstructions of the head of †Gerontoformica gracilis specimen CASENT0741232, showing external and internal skeletal elements. (A and D) Dorsal view. (B and E) Ventral view. (C) Lateral view. (Cʹ) Dorsolateral view of the torulus. (F) Sagittal view. (G) Frontal view of the oral foramen of the head capsule. (A–C) Complete head. (D–F) Internal skeleton. (H) Labrum outer surface. (I) Labrum inner surface. Abbreviations: alf, atalar fossa; ant, antennifer; ata, anterior tentorial arm; atp, anterior tentorial pit; bb, bulbus; bbn, bulbus neck; ce, compound eye; cl, clypeus; cli, clypeal inflection; clp, clypeal process; clc, clypeal chaetae; cor, circumocular ridge; dma, dorsal mandibular articulation; dta, dorsal tentorial arm; ess, epistomal sulcus; esr, epistomal ridge; fc, frontal carina; fr, frontal area; hc, cardinal condyle of hypostoma; hygl, lateral hypostomal groove; hygm, medial hypostomal groove; hyp, hypostomal triangular process; hysci, inner hypostomal carina; hyscor, oral hypostomal carina; hyscou, outer hypostomal carina; hyt, hypostomal corner; ll, lateral tentorial lamella; lbre, outer labral surface; lbri, inner labral surface; ltra, transverse row of labral setae; md, mandible; ml, medial tentorial lamella; oc, ocellus; oca, occipital carina; occ, occipital area; ocf, occipital foramen; pgb, postgenal bridge; pgr, postgenal ridge; plb, labial palp; pmx, maxillary palp; poc, postocciput; pta, posterior tentorial arm; sc, scapus; sfg, subforaminal groove; st, stipes; tb, tentorial bridge; tba, tentorial bridge anteriomedian process; to, torulus; toi, inner torular rim; vma, pleurostomal fossa. Symbols: blue line, epistomal sulcus.