New Specimens of Nemegtomaia from Mongolia Figure 2. Location map showing the position of the measured section discussed in the text. A, Northern Sayr, where specimen MPC-D 107/15 was collected. B, lithostratigraphic logs showing the relative stratigraphic occurrence of the interfingering Baruungoyot and Nemegt formations. C, In-situ and partially reworked caliche glaebules and concretions, Baruungoyot Formation. D, tubular burrow fills interpreted as nonmarine invertebrate feeding traces, Baruungoyot Formation. E, cross-bedded deposits in the basal deposits of the Nemegt Formation. F, photograph showing the interfingering contact between the Baruungoyot and Nemegt formations in the Northern Sayr (litho-log c). MPC-D 107/15 was collected just below the Nemegt tongue deposits. doi:10.1371/journal.pone.0031330.g002 support previous studies suggesting that aeolian and fluvial environments coexisted at the beginning of Nemegt sedimentation [33]. E 101u04.7069) (Figure 1). It includes a complete right hand, the left hand with partial ulna and radius, a few ribs, both femora, and a partial ilium. Methods Specimen MPC-D 107/15 was collected from the red sandstones of the Baruungoyot Formation in the Northern Sayr of the Nemegt locality (N 43u30.3539, E 101u03.3839) (Figure 2). In order to preserve the spatial relationships of the bones and eggs, the specimen was collected in a single block delimited by the last occurrence of preserved eggs. The lower side of the block is only partially prepared to expose mostly egg fragments, whereas the upper surface has the articulated partial skeleton of an oviraptorid dinosaur overlying the nest (Figure 3). It includes the skull, both scapulae, the left arm and hand, right humerus, pubes, ischia, femora, tibiae, fibulae, and the distal portions of both feet. Much of the skeleton was subjected to intense scavenging by small predators and dermestid coleopterans during an early stage of burial (Figure 4). The second specimen (MPC-D 107/16) was collected from the uppermost layers of the Baruungoyot Formation in the eastern portion of the Nemegt locality from the Red Walls (N 43u30.3279, Results Description of MPC-D 107/15 The oviraptorid affinities [10] of MPC-D 107/15 are unquestionable with its relatively short snout, and its deep, edentulous, beaklike lower jaws (Figure 5). Similarly, there are many characters in the postcranial skeleton as well as in the eggs that clearly show it is an oviraptorid (Figure 3). Much of MPC-D 107/15 was damaged by post-mortem, pre-burial insect activity, crushing during burial, and most recently by erosion; it is nevertheless rich in morphological and phylogenetic information. Similar to other nests of brooding oviraptorids [4,8,37,38], the animal had its feet in the center of what was probably a ring of eggs, and the arms were folded across the tops of the eggs on either side of the body. Although the individual bones have been damaged by borings and other scavenging, their shapes and lengths can be reconstructed because of the fact that the bones were held immobile in the sediments while they were being eaten by insects, and because their margins are often preserved. The Figure 3. Nest and preserved elements of Nemegtomaia barsboldi (MPC-D 107/15). A, dorsal view; B, left lateral view; C, right lateral view; D, posterior view. lf, left femur; lfi, left fibula; lh, left humerus; lm, left manus; lp, left pes; lpu, left pubis; lr, left radius; ls, left scapula; lt, left tibia; lu, left ulna; rf, right femur; rfi, right fibula; rh, right humerus; rp, right pes; rpu, right pubis; rs, right scapula; rt, right tibia; sk, skull. Scale bar 10 cm. Reconstruction by Marco Auditore. doi:10.1371/journal.pone.0031330.g003 PLoS ONE | www.plosone.org 4 February 2012 | Volume 7 | Issue 2 | e31330