Bayan Mandahu Formation

Bayan Mandahu Formation Stratigraphic range: Campanian, 75–71 Ma PreЄ Є O S D C P T J K Pg N ↓
Type	Geological formation
Lithology
Primary	Sandstone
Location
Region	Asia
Country	China
Type section
Named for	Bayan Mandahu, Inner Mongolia

The Bayan Mandahu Formation (or Wulansuhai Formation) is a geological unit of "redbeds" located near the village of Bayan Mandahu in Inner Mongolia, China Asia (Gobi Desert) and dates from the late Cretaceous Period. Laid down in the Campanian, it is dated somewhat uncertainly to between 75-71 mya (million years ago).^[1]

The paleoenvironment it preserves was semi-arid and characterized by alluvial (stream-deposited) and eolian (wind-deposited) sediments. The formation is known for its vertebrate fossils, most of which are preserved in unstructured sandstone, indicating burial by wind-blown sandstorms.^[2]

Fauna

The fauna of the Bayan Mandahu is very similar in composition to the nearby Djadochta Formation, and the two may have been deposited at roughly the same time. These two formations share many of the same genera, but differ in the makeup of species. For example, the most common mammal in the Djadochta is Kryptobaatar dashzevegi, while in the Bayan Mandahu, it is the closely related Kryptobaatar mandahuensis. Similarly, the dinosaur fauna of the Djadochta includes Protoceratops andrewsi and Velociraptor mongoliensis, while the Bayan Mandahu contains Protoceratops hellenikorhinus and Velociraptor osmolskae.^[1]

Crocodylomorphs

Crocodylomorphs of the Bayan Mandahu Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes
Shamosuchus[2]					A mesoeucrocodylian.

Lizards

An amphisbaenian species is known from the formation.^[2] An iguanian species is known from the formation.^[2]

Lizards of the Bayan Mandahu Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes
Adamisaurus[2]	A. magnidentatus[2]				An agamid.
Bainguis[2]					A diploglossan.
Telmasaurus[2]					A monitor lizard.

Mammals

A taeniolabidoidea multituberculate is known from the formation.^[2]

Mammals of the Bayan Mandahu Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes
Kennalestes[2]	K. gobiensis[2]				A placental. Also present in the Djadochta Formation.
Kryptobaatar	K. mandahuensis			The most common mammal in this formation.[1]	A multituberculate.

Ornithischians

Ornithischian dinosaurs of the Bayan Mandahu Formation
Genus	Species	Location	Abundance	Notes	Images
Hadrosauridae indet.[3]	Indeterminate[3]	Bayan Mandahu[3]		A hadrosaurid.	Magnirostris Pinacosaurus
Magnirostris[1]	M. dodsoni[1]	Bayan Mandahu[3]		A ceratopsian.
Pinacosaurus[1]	P. mephistocephalus[1]	Bayan Mandahu[3]	"Skull, postcranial skeleton, osteoderms."[4]	An ankylosaur.
Protoceratops[1]	P. hellenikorhinus[1]	Bayan Mandahu[3]	"Complete skull."[5]	A ceratopsian.
?Udanoceratops[2]	Indeterminate[2]	Bayan Mandahu[3]		A giant ceratopsian.

Saurischians

Saurischian dinosaurs of the Bayan Mandahu Formation
Genus	Species	Location	Abundance	Notes	Images
cf. Gobipteryx[2]	Indeterminate			Eggs similar to those attributed to Gobipteryx minuta from the Djadochta Formation.
Linheraptor[6]	L. exquisitus[6]	Wulansuhai[3]		A dromaeosaurid
Linhevenator[7]	L. tani[7]	Wulansuhai[7]		A troodontid
Philovenator	P. curriei	Wulansuhai		A troodontid
Wulatelong	W. gobiensis	Wulansuhai		An oviraptorosaur
Linhenykus	L. monodactylus	Wulansuhai		An alvarezsaurid
Machairasaurus	M. leptonychus	Bayan Mandahu[3]		An oviraptorid
Oviraptoridae indet.[3]	Indeterminate[3]	Bayan Mandahu[3]		An oviraptorid.
Sauropoda indet.[3]	Indeterminate[3]	Bayan Mandahu[3]		A sauropod.
Tyrannosauridae indet.[3]	Indeterminate[3]	Bayan Mandahu[3]		A tyrannosaurid.
Velociraptor[2]	V. mongoliensis[2]			Misclassified, only present in the Djadochta Formation.
	V. osmolskae	Bayan Mandahu[3]		A dromaeosaurid.

Turtles

Turtles of the Bayan Mandahu Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes
Basilemys[2]					A softshell turtle.

See also

• Barun Goyot Formation
• List of fossil sites (with link directory)
• Nemegt Formation
• List of dinosaur-bearing rock formations

References

1. Godefroit, Pascal; Currie, Philip J.; Li, Hong; Shang, Chang Yong; Dong, Zhi-ming (2008). "A new species of Velociraptor (Dinosauria: Dromaeosauridae) from the Upper Cretaceous of northern China". Journal of Vertebrate Paleontology 28 (2): 432–438. doi:10.1671/0272-4634(2008)28[432:ANSOVD]2.0.CO;2.
2. Jerzykiewicz, T.; Currie, P.J.; Eberth, D.A.; Johnston, P.A.; Koster, E.H.; Zheng J. (1993). "Djadokhta correlative strata in Chinese Inner Mongolia: An overview of the stratigraphy, sedimentary geology, and paleontology and comparisons with the type locality in the pre-Altai Gobi.". Canadian Journal of Earth Sciences 30: 2180–2195. doi:10.1139/e93-190. [printed early 1994]
3. Nicholas R. Longrich, Philip J. Currie, Dong Zhi-Ming (2010). "A new oviraptorid (Dinosauria: Theropoda) from the Upper Cretaceous of Bayan Mandahu, Inner Mongolia". Palaeontology 53 (5): 945–960. doi:10.1111/j.1475-4983.2010.00968.x.
4. "Table 17.1," in Weishampel, et al. (2004). Page 364.
5. "Table 22.1," in Weishampel, et al. (2004). Page 480.
6. Xu, X., Choinere, J., Pittman, M., Tan, Q., Xiao, D., Li, Z., Tan, L., Clark, J., Norell, M., Hone, D.W.E. and Sullivan, C. (In press). "A new dromaeosaurid (Dinosauria: Theropoda) from the Upper Cretaceous Wulansuhai Formation of Inner Mongolia, China." Zootaxa, in press.
7. Xu X., Tan Q., Sullivan, C., Han F., Xiao D. (2011) A Short-Armed Troodontid Dinosaur from the Upper Cretaceous of Inner Mongolia and Its Implications for Troodontid Evolution. PLoS ONE 6(9): e22916. doi:10.1371/journal.pone.0022916 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0022916