Nemegt Formation
| Nemegt Formation Stratigraphic range: Late Cretaceous, 70Ma |
|
|---|---|
| Type | Geological formation |
| Location | |
| Region | Asia |
The Nemegt Formation (or Nemegtskaya Svita) is a geological formation dating from the Late Cretaceous sedimentary from the Gobi Desert of Mongolia. It overlies and sometimes forms folds with the Barun Goyot Formation.[citation needed] It consists of river channel sediments and contains fossils of fish, turtles, crocodilians, birds and a diverse fauna of dinosaurs. The climate associated with it was wetter than when preceding formations were deposited; there seems to have existed at least some degree of forest cover.
The absolute age of the Nemegt Formation is unknown but it is thought to be early Maastrichtian to possibly late Campanian in age, very roughly 70 million years old.[1]
Flora and fauna of the Nemegt Formation
Coelurosaurs
Oviraptorosaurs
| Oviraptorosaurs reported from the Nemegt Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic Position | Material | Notes | Images |
|
Avimimus portentosus |
Avimimids. | |||||
|
Indeterminate |
Avimimids. | |||||
|
Elmisaurus rarus |
"[Three] pedes [and a] manus."[2] |
A caenagnathid. | ||||
|
C. gracilis |
|
|
"Partial skeleton wwith skull, [four] partial skulls, [and] numerous skull and postcranial fragments."[2] |
|||
|
"Ingenia" |
"Ingenia" yanshini |
|
|
"Partial skeleton with skull [and five] partial postcrania."[2] |
An oviraptorid, also found in the Barun Goyot Formation. | |
|
Nemegtomaia barsboldi |
An oviraptorid. | |||||
|
N. gobiensis |
"Partial postcranium."[3] |
|||||
|
Rinchenia mongoliensis |
"Skull and fragmentary postcranium."[3] |
An oviraptorid. |
||||
Paravians
| Paravians reported from the Nemegt Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic Position | Material | Notes | Images |
|
Adasaurus mongoliensis[4] |
"Partial skull and fragmentary postcrania."[5] |
|||||
|
Borogovia gracilicrus |
"Partial hindlimbs."[6] |
A troodontid. | ||||
|
Gurilynia nessovi |
"Shoulder girdle and forelimb elements."[7] |
An enantiornithine. | ||||
|
Judinornis nogontsavensis |
"Vertebra."[8] |
A hesperornithine. | ||||
|
S. junior |
Reclassified as Zanabazar junior |
|||||
|
Teviornis gobiensis |
An anseriform related to modern ducks and geese. | |||||
|
Tochisaurus nemegtensis |
A metatarsus.[6] |
A troodontid. | ||||
|
Zanabazar junior[4] |
"Skull with fragmentary postcranial skeleton."[6] |
A troodontid. |
||||
Other coelurosaurs
| Misc Coelurosaurs reported from the Nemegt Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic Position | Material | Notes | Images |
|
Alioramus remotus[4] |
A tyrannosaur, actually present in the Beds of Nogoon Tsav. Nemegt fossils reclassified as A. altai. |
|||||
|
Alioramus altai |
A tyrannosaur. |
|||||
|
Anserimimus planinychus |
"Incomplete postcranium."[10] |
An ornithomimid. | ||||
|
Bagaraatan ostromi |
"Fragmentary skull and associated postcranium."[11] |
A coelurosaur or uncertain classification. | ||||
|
Deinocheirus mirificus[4] |
"Forelimb elements."[10] |
A giant ornithomimosaur. | ||||
|
Gallimimus bullatus[4] |
"[Three] nearly complete skeletons, complete postcranium, skull with associated frgamentary postcranium, [and] other fragmentary postcrania."[10] |
An ornithomimid. | ||||
|
Mononykus olecranus |
An alvarezsaurid. | |||||
|
Tarbosaurus bataar[4] |
A tyrannosaur. Articulated skeletons are unusually common here. May also be present in the Djadochta Formation. |
|||||
|
Therizinosaurus cheloniformis[4] |
|
|
"Forelimb elements [and a] referred hindlimb."[12] |
|||
Invertebrates
| Invertebrates of the Nemegt Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic Position | Abundance | Notes | |
| An ostracod. | ||||||
Mammals
| Mammals of the Nemegt Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic Position | Abundance | Notes | Images |
|
Buginbaatar transaltaiensis |
||||||
Ornithischians
| Ornithischians of the Nemegt Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic Position | Material | Notes | Images |
|
Barsboldia sicinskii |
"Sacrum [and] pelvis."[13] |
A hadrosaurid. | ||||
|
Homalocephale calathoceros |
A pachycephalosaur. | |||||
|
P. prenes |
"Complete skull with associated partial postcranium."[14] |
|||||
|
Saurolophus angustirostris |
"At least [fifteen] specimens, including articulated skull and postcranial skeleton."[13] |
A hadrosaurid. | ||||
|
Tarchia gigantea |
An ankylosaur, also found in the Barun Goyot Formation. | |||||
Sauropods
| Sauropods reported from the Nemegt Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic Position | Material | Notes | Images |
|
Nemegtosaurus mongoliensis |
"Skull."[15] |
A titanosaur. | ||||
|
Opisthocoelicaudia skarzynskii |
"Skeleton lacking skull and cervical series."[16] |
A titanosaur. |
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Fossil Eggs
| Fossil eggs found in the Nemegt Formation | ||||||
|---|---|---|---|---|---|---|
| Oogenus | Oospecies | Location | Stratigraphic Position | Material | Notes | Images |
|
Laevisoolithus sochavai |
"Whole egg with partly broken pole"[17] |
Laid by a bird or small theropod.[17] | ||||
|
Subtiliolithus microtuberculatus[17] |
"Eggshel fragments"[17] |
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References
- ^ Sulliban, R.M. (2006). "A taxonomic review of the Pachycephalosauridae (Dinosauria: Ornithischia)." Pp. 347-366 in Lucas, S.G. and Sullivan, R.M. (eds.), Late Cretaceous vertebrates from the Western Interior. New Mexico Museum of Natural History and Science Bulletin 3.
- ^ a b c d e "Table 8.1," in Weishampel, et al. (2004). Page 167.
- ^ a b "Table 8.1," in Weishampel, et al. (2004). Page 166.
- ^ a b c d e f g h i j k l m Barsbold, R. (1983). "Carnivorous dinosaurs from the Cretaceous of Mongolia [in Russian]." Trudy, Sovmestnaâ Sovetsko−Mongol’skaâ paleontologičeskaâ èkspediciâ, 19: 1–120.
- ^ "Table 10.1," in Weishampel, et al. (2004). Page 198.
- ^ a b c "Table 9.1," in Weishampel, et al. (2004). Page 185.
- ^ "Table 11.1," in Weishampel, et al. (2004). Page 213.
- ^ "Table 11.1," in Weishampel, et al. (2004). Page 215.
- ^ Norell, M.A.; Makovicky, P.J., Bever, G.S., Balanoff, A.M., Clark, J.M., Barsbold, R. and Rowe, T. (2009). "A Review of the Mongolian Cretaceous Dinosaur Saurornithoides (Troodontidae: Theropoda)". American Museum Novitates 3654: 63.
- ^ a b c "Table 6.1," in Weishampel, et al. (2004). Page 138.
- ^ "Table 5.1," in Weishampel, et al. (2004). Page 112.
- ^ "Table 7.1," in Weishampel, et al. (2004). Page 152.
- ^ a b "Table 20.1," in Weishampel, et al. (2004). Page 441.
- ^ "Table 21.1," in Weishampel, et al. (2004). Page 465.
- ^ "Table 13.1," in Weishampel, et al. (2004). Page 263.
- ^ "Table 13.1," in Weishampel, et al. (2004). Page 270.
- ^ a b c d e f K. E. Mikhailov. 1991. Classification of fossil eggshells of amniotic vertebrates. Acta Palaeontologica Polonica 36(2):193-238
See also
- Barun Goyot Formation
- Djadochta Formation
- List of fossil sites
- Nemegt Basin
- List of dinosaur-bearing rock formations
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