Palaeobiology Nemegtomaia

diagram showing remains , body outline of nesting specimen

the nemegtomaia specimen mpc-d 107/15 found associated nest eggs; feet placed in centre of ring of eggs, arms folded across tops of eggs on each side of body, posture similar seen in other fossils of brooding oviraptorids. collected part of nest 90 cm (35 in) wide , 100 cm (30 in) long; skeleton occupies upper 25 cm (10 in) of block, whereas remaining 20 cm (8 in) occupied broken eggs , shells. there no evidence of plant material in nest, there fragments of undetermined bones. nest not preserve complete eggs or embryos, prevents determination of size, shape, number, , arrangement of eggs in nest. probable there 2 layers of eggs below body, , there not appear have been eggs in centre of nest. eggs (seven distinct eggs have been identified) , egg fragments recovered either in lower layer of nest or under skull, neck, , limbs of specimen, , bones either rested directly on eggs or within 5 mm (0.2 in) of surfaces. skeleton directly positioned on top of shows nest not covered sand. though placement of eggs not suggest specific arrangement in nest, other oviraptorid nests show eggs arranged in pairs in 3 levels of concentric circles. eggs of mpc-d 107/15 therefore displaced during burial, or external factors, such strong winds, sandstorms, or predators. supports idea upper layer of eggs not buried, buried eggs have been less transported external factors.

eggs preserved nesting specimen

oviraptorid eggs appear have been 17 cm (6 in) long on average, , complete eggs found mpc-d 107/15 thought have been 5 to 6 cm (2 to 2.3 in) wide , 14 16 cm (5 to 6 in) long when intact. eggs identical have been found in mongolia, , have therefore been assigned oofamily (egg-taxon family) elongatoolithidae. eggshells relatively thin, between 1 and 1.2 mm (0.03 and 0.04 in), , outer surface covered ridges , nodes rise 0.3 mm (0.01 in) above shell. micro-structure of eggshells not studied, calcite has been heavily altered , re-crystallized.

the nesting specimen found in stratigraphic area indicating oviraptorids preferred nesting near streams provided soft, sandy substrate , food in environments otherwise xeric (receiving small amount of moisture). many oviraptorids have been found in brooding positions, indicating may have brooded relatively long periods, similar modern birds such ostrich, emu, , black-breasted buzzard, brood more 40 days limited supply of sustenance. nesting in desert environments can harmful adults stay in nest large parts of day, , eggs , nestlings, due heat stress. choice of nesting area may therefore have been mechanism successful incubation in extreme heat. has been suggested evolution of tail-feathers in oviraptorosaurs adaptation shading , protecting eggs in nests. second finger of ingeniine oviraptorids reduced in size compared robust first finger may explained change in function; may related presence of long wing feathers attached second finger. these wing feathers used protect eggs during nesting. when second finger began functioning feather support, ability grasp reduced, , function taken on first finger, therefore became more robust. third finger reduced in size, too, because positioned behind wing feathers in way not effective grasping.

the brooding behaviour of oviraptorids thought have been similar of birds such ostriches; here, male somali ostrich

various studies have suggested several individuals gather eggs in single nest, , arrange them protected 1 individual, possibly male. in 2010 david j. varricchio , colleagues found relatively large clutch-size of oviraptorids , troodontids similar of modern archosaurs (birds , crocodilians, closest living relatives of dinosaurs) practice polygamous mating , extensive male parental care (as seen in paleognaths such ostriches , emus). reproductive system pre-dates origin of birds , therefore ancestral condition modern birds, biparental care (where both parents participate) being later development. many oviraptorosaurs known have had pygostyles on end of tails, suggests presence of feather-fans; these have been used intraspecific communication such courtship rituals.

diet

lower jaw of holotype specimen, beak on right

the diet of oviraptorids has been interpreted in various ways since time oviraptor wrongly thought have been predator of eggs. has been suggested oviraptorosaurs whole herbivores, supported gastroliths (stomach stones) found in caudipteryx, , wear facets in teeth of incisivosaurus. in 2010 longrich , colleagues found oviraptorid jaws had features similar seen in herbivorous tetrapods (four-limbed animals), of dicynodonts, extinct group of synapsid stem-mammals. oviraptorids , dicynodonts share features such short, deep, , toothless mandibles; elongated dentary symphyses; elongated mandibular fenestrae; , downwards-projecting bar in palate. modern animals jaws resemble of oviraptorids include parrots , tortoises; latter group has tooth-like projections on premaxillae. longrich , colleagues concluded due similarities between oviraptorids , herbivorous animals, bulk of diet have been formed plant matter. oviraptorids found @ high frequencies in formations known from, similar pattern seen in dinosaurs known herbivorous; these animals more abundant carnivorous dinosaurs, more energy available @ lower trophic level in food chain. jaws of oviraptorids may have been specialised processing food, such xerophytic vegetation (adapted environments little water), have grown in environment, not possible demonstrate, little known flora of area @ time. 2013 study lü , colleagues found oviraptorids appear have retained hind limb proportions throughout ontogeny (growth), pattern seen in herbivorous animals. in 2017, gregory f. funston , colleagues suggested parrot-like jaws of oviraptorids may indicate frugivorous diet incorporated nuts , seeds.

diagrams showing hands of specimen mpc-d 107/16

in 1977 barsbold suggested oviraptorids fed on molluscs, longrich , colleagues rejected idea practised shell-crushing altogether, since such animals tend have teeth broad crushing surfaces. instead, shape of dentary bones in lower jaws of oviraptorids suggests had sharp-edged beak used shearing tough food, not cracking hard food items such bivalves or eggs. symphyseal shelf @ front of dentary may have given ability crushing, relatively small area, not main function of jaws. fact oviraptorids have been found in sediments interpreted having been xeric , arid or semi-arid environments argues against them having been specialised eaters of shellfish , eggs, unlikely there have been enough of these items under such conditions support them.

longrich et al. pointed out robust forelimbs , enlargement of single finger in ingeniine oviraptorids similar seen in modern animals eat ants , termites, such anteaters , pangolins, morpholology of ingeniine jaws not support them being insectivorous. researchers found function of ingeniine forelimbs unclear, suggested have been used scratching, tearing, or digging, though not prey capture.

in 2004 lü , colleagues proposed articulation between quadrate , quadratojugal bones in skull of nemegtomaia suggested these bones movable in relation each other, have affected how jaws functioned. in 2015 christophe hendrickx , colleagues found unlikely nemegtomaia , other oviraptords had bird-like kinesis in skulls, due quadrate bone being immobile.