Palaeoecology Nemegtomaia

maps, diagrams, , photos showing relation between baruungoyot , nemegt formations

nemegtomaia known nemegt , baruungoyot formations, date upper campanian–lower maastrichtian ages of late cretaceous period, 70 million years ago. though taxon known nemegt locality, unidentified oviraptorid remains form other localities may belong it. nemegt massif has numerous canyons or gorges, 45 metres (148 ft) deep, have of best exposures of these formations. rock facies of nemegt formation thought represent humid, fluvial (associated rivers , streams) environment, whereas of baruungoyot formation thought represent arid or semi-arid environment, aeolian (affected wind) beds. these 2 formations diverse fossils historically thought represent sequential time periods different environments, in 2009 david a. eberth , colleagues found there partial overlap across transition between them. 2 formations interfinger across stratigraphic interval 25 m (82 ft) thick, suggests fluvial , aeolian environments coexisted when area sedimented.

the environment of nemegt formation has been compared okavango delta of present-day botswana. habitats in , around nemegt rivers provided home wide array of organisms. aquatic animals include molluscs, fish, turtles, , crocodylomorph shamosuchus. fossils of mammals such multituberculates have been found, , birds such gurilynia, judinornis, , teviornis known. herbivorous dinosaurs of nemegt formation include ankylosaurids such tarchia, pachycephalosaurian prenocephale, hadrosaurids such saurolophus , barsboldia, , sauropods such nemegtosaurus, , opisthocoelicaudia. other theropods include tyrannosauroids such tarbosaurus, alioramus, , bagaraatan, troodontids such borogovia, tochisaurus, , saurornithoides, therizinosaurs such therizinosaurus, , ornithomimosaurians such deinocheirus, anserimimus, , gallimimus.

other oviraptorosaur genera known nemegt formation include basal avimimus, oviraptorids rinchenia, nomingia, , ajancingenia, , caenagnathid elmisaurus. in addition, conchoraptor known baruungoyot formation. in spite of high number of oviraptorid taxa in these formations (the nemegt has highest known diversity of them anywhere), none of them closely related. nemegt formation unique in having both oviraptorid , caenagnathid oviraptorosaurs, , in 1993 phillip j. currie , colleagues suggested diversity due 2 groups preferring different environments in area. in 2016 takanobu tsuihiji , colleagues suggested oviraptorids may have preferred drier environments, while caenagnathids preferred fluvial environments, based on type of formations have been found in. funston , colleagues suggested oviraptorids found in both xeric , mesic environments (but more abundant in former), whereas other oviraptotosaur groups avoided xeric environments, , coexistence of families can explained niche partitioning in diet. environment of nemegt formation may have acted oasis , thereby attracted oviraptorids.

taphonomy

feeding traces skin beetles in nesting specimen

the nesting specimen mpc-d 107/15 has provided information taphonomic processes (changes during decay , fossilisation) in baruungoyot formation. specimen preserved in facies thought have been deposited through sandstorm or dune-shift. not seem have been transported after death, body appears have shifted right, indicating sediment in deposited came towards left side. neck curved left, left hand folded backwards, , legs folded crouching position. vertebral column, neck, , hips deteriorated during burial, , of damage skeleton thought have been caused activity of invertebrates.

borings in bones, burrows, , reworked sediments (perhaps caused construction of pupal chambers) in specimen indicate scavenged upon colonies of skin beetles (dermestidae) , perhaps other scavenging insects. there many feeding traces in joints of skeleton, , surfaces bones articulated have been obliterated. there tunnels in nest under neck , skull, , no egg remains have been found in parts such traces. modern skin beetles feed on muscle tissue not on moist materials, , activity prevented rapid burial. therefore thought specimen mpc-d 107/15 partially buried @ first, upper part being exposed enough colony of skin beetles develop. damage skeleton (especially in vertebral column) may have been caused scavenging of small mammals.