Figure 3 in Dromaeosaurid crania demonstrate the progressive loss of facial pneumaticity in coelurosaurian dinosaurs

Figure 3. Craniofacial pneumaticity of Tsaagan. Skull (cast of IGM 100/1015) in (A, C) lateral and (B, D) medial views. Abbreviations: aofen, antorbital fenestra; aof, antorbital fossa; pneu fen, additional maxillary pneumatic fenestra; mf, maxillary fenestra; mx, maxilla; pmf, promaxillary fenestra; pmx, premaxilla. In (B), green is the additional maxillary pneumatic fenestra, blue is the maxillary fenestra, and yellow is the promaxillary fenestra.