Figure 2.

Skull and jaw joint in Psittacosaurus gobiensis (LH PV2). (a) Skull reconstruction in lateral view. (b) Skull reconstruction in dorsal view. (c) Left quadrate condyle in posteroventral view. (d) Posterior end of the right lower jaw in dorsal view. Scale bars, 1 cm in (c), 2 cm in (d). Abbreviations: a, angular; adm, attachment surface for the depressor mandibulae; almf, anterolateral maxillary foramen; apmf, anterior premaxillary foramen; aqco, articular surface for the quadrate condyles; ar, articular; bo, basioccipital; cp, coronoid process; d, dentary; d1, 9, dentary tooth 1 and 9; df, dentary flange; en, external naris; f, frontal; fo, foramen; j, jugal; jh, jugal horn; l, lacrimal; lco, lateral condyle; lf, lacrimal foramen; m, maxilla; m1, 8, maxillary tooth 1 and 8; mco, medial condyle; mfo, maxillary fossa; mp, maxillary protuberance; n, nasal; p, parietal; pap, palpebral; pd, predentary; pl, palatine; pm, premaxilla; pmri, premaxilla-maxilla ridge; po, postorbital; pocr, postorbital crest; pojfo, postorbital-jugal fossa; pojh, postorbital-jugal horn; popr, paroccipital process; prf, prefrontal; prfcr, prefrontal crest; ps, parasphenoid; pt, pterygoid; q, quadrate; qco, quadrate condyle; qh, quadrate head; qj, quadratojugal; qjp, quadratojugal protuberance; r, rostral; rp, retroarticular process; sa, surangular; sc, sagittal crest; sq, squamosal; v, vomer.