New Specimens of Nemegtomaia from Mongolia Figure 4. Feeding traces left by colonies of dermestid beetles in specimen MPC-D 107/15. Articular surfaces have been completely obliterated in the left forearm (A), left leg and pes (B), as well as in the right forearm (C). Circular borings are particularly evident in the left side of the skull (D–F). G, Bone-chip burrow found under the skull of the specimen. H, large traces of reworked sediment under the skeleton. doi:10.1371/journal.pone.0031330.g004 front of the premaxilla and the posterior margin of the paroccipital process are preserved on each side of the skull, and both sides show that the skull was 172 mm long. The dorsal and posterior margins of the orbit are preserved on the right side of the skull, whereas the anterior, ventral and ventroposterior margins of the orbit are preserved on the left side. The skull length is slightly shorter than that of the holotype of Nemegtomaia (179 mm), whereas the diameter of the orbit is approximately the same size (52 mm). Other overlapping measurements of the two specimens are also similar, including jaw length (153 mm in holotype, 152 mm in MPC-D 107/15), and maximum dentary height (49 mm in holotype, 50 in MPC-D 107/15). Equivalent measurements (skull and jaw lengths) in MPC-D 100/42 (Citipati sp.) suggest that this virtually complete individual is also approximately the same size as the two Nemegtomaia specimens. The femur length in MPC-D 100/ 42 is 305 mm and its shaft circumference is 95 mm (which suggests the animal weighed 40 kg using the formulae of [41]), and the length of the skeleton is 1.95 meters. It is therefore likely that MPC-C 107/15 was an individual with a total length of about 2 meters, and that it weighed approximately 40 kg. The edges of the premaxilla, nasal, frontal and parietal clearly show that MPC- D 107/15 was a crested oviraptorid like Citipati, Nemegtomaia and Rinchenia [10,17,39]. The crest is similar to those of both Citipati and Nemegtomaia in that it is relatively low and is centered above the antorbital region, in contrast with the much taller crest of Rinchenia that is centered more posteriorly. Whereas crest development extends posteriorly to thicken and pneumatize the frontals in Citipati [40], this region is thin, flat and not pneumatized in MPC- D 107/15 and the holotype of Nemegtomaia. Like the holotype of Nemegtomaia, the ventral part of the anterior margin of the premaxilla of MPC-D 107/15 is nearly vertical to the main axis (as seen in lateral view) of the suborbital portion of the jugal. This is in contrast with known specimens of Citipati, where the anterior margin of the premaxilla slopes anterodorsally. The jugal process of the postorbital (Fig. 5a) forms the upper two thirds of the posterior border of the orbit in MPC-D 107/15 and most other oviraptorids, but Citipati is unusual in that the jugal process extends to the ventral margin of the orbit. As in Nemegtomaia, the ventral end of the exoccipital of MPC-D 107/15 (Fig. 5B) is level with the suborbital process of the jugal, which is considerably lower than in Citipati. Whereas Citipati is from Djadokhtan-aged strata of Dzamyn Khond and Ukhaa Tolgod, the holotype of Nemegtomaia came from the Nemegt Formation less than 500 m from where MPC-D 107/15 was collected. Similar morphology, similar size, PLoS ONE | www.plosone.org 5 February 2012 | Volume 7 | Issue 2 | e31330