New Specimens of Nemegtomaia from Mongolia Figure 5. Skull of Nemegtomaia barsboldi (MPC-D 107/15). A, preserved elements of the right side; B, preserved elements of the left side; C, reversed elements of the left side superimposed to those of the right side (where elements of both sided overlap, the grey is darker); D, reconstruction of the skull. an, angular; d, dentary; ec, ectopterygoid; eo, exoccipital; f, frontal; j, jugal; l, lacrimal; m, maxilla; n, nasal; p, parietal; pm, premaxilla; po, postorbital; q, quadrate; qj, quadratojugal; sa, surangular; sq, squamosal; sr, sclerotic ring. Scale bar 10 cm. Illustration by Marco Auditore. doi:10.1371/journal.pone.0031330.g005 geographic proximity, and the interfingering nature of the Baruungoyot and Nemegt formations make it most parsimonious to identify MPC-D 107/15 as Nemegtomaia. Like all oviraptorids, the skull of MPC-D 107/15 is relatively short compared with other parts of the body (Figure 5). It is, for example, almost half the estimated length of the femur, whereas in other theropods the skull can be more than 90% the length of the femur. Oviraptorid skulls are short overall because of a significant reduction in the length of the antorbital region [10]. The eyes of oviraptorids look large because of the relatively small sizes of most species, but also because of their short skulls. If orbit length is plotted against femur length (logarithmically transforming the measurements) for 76 theropods (Currie, unpublished data), the resulting regression is defined by y = 0.6517x+0.0931 where y represents orbit length, x is femur length and 0.6517 is the allometric coefficient. The allometric coefficient shows that orbit length (roughly equivalent to the size of the eyeball) shows strong negative allometry with size increase. Adding the data for nine oviraptorosaurs where both these dimensions are known clearly demonstrates that the orbit length of each oviraptorid individual is not significantly different from what is expected in any theropod. The orbit of MPC-D 107/15 is 55 mm high, which suggests that the length was 50 mm (compared with 55 mm in the holotype). The anterior margins of the premaxillae are well preserved, and show that the external nares would have been relatively small and positioned high as in the holotype. The lateral temporal opening was clearly large and quadrangular (Figure 5). The antorbital length of MPC-D 107/15 is 78 mm, which is almost ten percent longer than in the holotype. A difference of this scale can be easily accounted for as individual variation or taphonomic distortion, and is not significant. The anterior (premaxillary) and dorsal (nasal) margins of the skull show that MPC-D 107/15 had a prominent crest like many other oviraptorids, including the holotype of Nemegtomaia (MPC-D PLoS ONE | www.plosone.org 6 February 2012 | Volume 7 | Issue 2 | e31330