Skull of Nigersaurus taqueti and head posture in sauropodomorphs. (Originally uploaded by User:Filip em under a file name that is inappropriate in English language.)

(A)-Lateral view of skull (MNN GAD512). (B)-Anterodorsal view of cranium. (C)-Anterior view of lower jaws. (D)-Premaxillary and dentary tooth series (blue) reconstructed from µCT scans. (E)-Skull reconstruction in anterolateral and dorsal view cut at mid length between muzzle and occipital units (cross-section in red) with the adductor mandibulae muscle shown between the quadrate and surangular. (F)-Endocast in dorsal view showing the cerebrum and olfactory bulbs. (G)-Endocast (above) and transparent skulls with endocasts in place (below) based on µCT scans of the basal sauropodomorph Massospondylus carinatus (BP 1/4779), the basal neosauropod Camarasaurus lentus (CM 11338), the diplodocid Diplodocus longus (CM 11161), and the prototype skull of the rebbachisaurid Nigersaurus taqueti. Endocasts and skulls are oriented with the lateral semicircular canal held horizontal; the angle measurement indicates degrees from the horizontal for a line from the jaw joint to the tip of the upper teeth. Endocasts show brain space and dural sinuses (blue), nerve openings (yellow), inner ear (pink), and internal carotid artery (red). Phylogenetic diagram at bottom shows the relationships of these four sauropodomorphs, with increasing ventral deflection of the snout toward the condition seen in Nigersaurus. Scale bar equals 2 cm in F. Abbreviations: 1–5, fenestrae 1–5; a, angular; amm, adductor mandibulae muscle; antfe, antorbital fenestra; ar, articular; ce, cerebrum; cp, coronoid process; d, dentary; d1, 34, dentary tooth 1, 34; ds, dural sinus; emf, external mandibular fenestra; en, external nares; f, frontal; fo, foramen; j, jugal; m, maxilla; nf, narial fossa; olb, olfactory bulb; olt, olfactory tract; pm, premaxilla; po, postorbital; popr, paroccipital process; q, quadrate; qj, quadratojugal; sa, surangular, saf, surangular foramen; sq, squamosal; vc, vascular canal.