Bayan Mandahu Formation - AbsoluteAstronomy.com

The Bayan Mandahu Formation (or Wulansuhai Formation) is a geological unit of "redbeds" located near the village of Bayan Mandahu in Inner Mongolia

Inner Mongolia

Inner Mongolia is an autonomous region of the People's Republic of China, located in the northern region of the country. Inner Mongolia shares an international border with the countries of Mongolia and the Russian Federation...

, China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

(Gobi Desert

Gobi Desert

The Gobi is a large desert region in Asia. It covers parts of northern and northwestern China, and of southern Mongolia. The desert basins of the Gobi are bounded by the Altai Mountains and the grasslands and steppes of Mongolia on the north, by the Hexi Corridor and Tibetan Plateau to the...

) and dates from the Late Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

Period. Laid down in the early Campanian

Campanian

The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...

, possibly starting in the latest Santonian

Santonian

The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series. It spans the time between 85.8 ± 0.7 mya and 83.5 ± 0.7 mya...

, it is dated somewhat uncertainly at about 84-75 mya (million years ago).

The paleoenvironment it preserves was semi-arid

Arid

A region is said to be arid when it is characterized by a severe lack of available water, to the extent of hindering or even preventing the growth and development of plant and animal life...

and characterized by alluvial

Alluvium

Alluvium is loose, unconsolidated soil or sediments, eroded, deposited, and reshaped by water in some form in a non-marine setting. Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel...

(stream-deposited) and eolian (wind-deposited) sediments. The formation is known for its vertebrate

Vertebrate

Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...

fossils, most of which are preserved in unstructured sandstone, indicating burial by wind-blown sandstorms

Dust storm

A dust / sand storm is a meteorological phenomenon common in arid and semi-arid regions. Dust storms arise when a gust front or other strong wind blows loose sand and dirt from a dry surface. Particles are transported by saltation and suspension, causing soil to move from one place and deposition...

Fauna

The fauna

Fauna

Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...

of the Bayan Mandahu is very similar in composition to the nearby Djadochta Formation

Djadochta Formation

The Djadochta Formation is situated in central Asia and dates from the Late Cretaceous Period. Laid down in the early Campanian, possibly starting in the latest Santonian, it is dated somewhat uncertainly at about 84-75 mya...

, and the two may have been deposited at roughly the same time. These two formations share many of the same genera

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

, but differ in the makeup of species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

. 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.

Crocodylomorphs

Crocodylomorphs of the Bayan Mandahu Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes
Shamosuchus Shamosuchus Shamosuchus is an extinct genus of neosuchian crocodile that lived during the Late Cretaceous period in what is now the Gobi desert of Mongolia, approximately 85 to 65 million years ago. The teeth were adapted to crush bivalves, gastropods and other animals with a shell or exoskeleton . The genus...					A mesoeucrocodylia Mesoeucrocodylia Mesoeucrocodylia is the name of the clade that includes Eusuchia and the paraphyletic group Mesosuchia. The group appeared during the Early Jurassic, and continues to the present day.... n.

Lizards

An amphisbaenia

Amphisbaenia

The Amphisbaenia are a usually legless suborder of squamates closely related to lizards and snakes. As many species possess a pink body coloration and scales arranged in rings, they have a superficial resemblance to earthworms. They are very poorly understood, due to their burrowing lifestyle...

n species is known from the formation. An iguania

Iguania

Iguania is the suborder of Squamata that contains the iguanas, chameleons, agamids, and "New World lizards" such as anoles and Phrynosomatidae...

n species is known from the formation.

Lizard Lizard Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains... s of the Bayan Mandahu Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes
Adamisaurus	A. magnidentatus				An agamid.
Bainguis					A diploglossan.
Telmasaurus Telmasaurus Telmasaurus is an extinct genus of varanoid lizard from the Late Cretaceous of Mongolia. Fossils have been found from the Djadokha and Barun Goyot Formations that date between the early and middle Campanian stage from approximately 80 to 75 million years ago. The type species T...					A monitor lizard Monitor lizard Monitor lizards are usually large reptiles, although some can be as small as in length. They have long necks, powerful tails and claws, and well-developed limbs. Most species are terrestrial, but arboreal and semiaquatic monitors are also known... .

Mammals

A taeniolabidoidea

Taeniolabidoidea

Taeniolabidoidea is a group of extinct mammals known from North America and Asia. They were the largest members of the also extinct order Multituberculata. Lambdopsalis even provides direct fossil evidence of mammalian fur in a fairly good state of preservation for a 60-million-year-old animal...

multituberculate is known from the formation.

Mammal Mammal Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young... s of the Bayan Mandahu Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes
Kennalestes Kennalestes Kennalestes gobiensis is an extinct species of insectivoreous mammal resembling a shrew. It was a common mammal in Mongolia during the Cretaceous period, found in both the Bayan Mandahu Formation and Djadochta Formation....	K. gobiensis				A placental Eutheria Eutheria is a group of mammals consisting of placental mammals plus all extinct mammals that are more closely related to living placentals than to living marsupials . They are distinguished from noneutherians by various features of the feet, ankles, jaws and teeth... . Also present in the Djadochta Formation Djadochta Formation The Djadochta Formation is situated in central Asia and dates from the Late Cretaceous Period. Laid down in the early Campanian, possibly starting in the latest Santonian, it is dated somewhat uncertainly at about 84-75 mya... .
Kryptobaatar Kryptobaatar Kryptobaatar and also known as Gobiaatar, Gobibaatar or Tugrigbaatar is an extinct mammalian genus dating from the Upper Cretaceous Period and identified in Central Asia...	K. mandahuensis			The most common mammal in this formation.	A multituberculate.

Ornithischians

Ornithischian dinosaur Dinosaur Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of... s of the Bayan Mandahu Formation
Genus	Species	Location	Abundance	Notes	Images
Hadrosauridae indet.	Indeterminate	Bayan Mandahu		A hadrosaurid.
Magnirostris Magnirostris Magnirostris, from the Latin "magnus" 'large' and "rostrum" 'beak', is the name given to a genus of dinosaur from the Late Campanian epoch in the Late Cretaceous. It was a ceratopsian which lived in Inner Mongolia in China...	M. dodsoni	Bayan Mandahu		A ceratopsia Ceratopsia Ceratopsia or Ceratopia is a group of herbivorous, beaked dinosaurs which thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. The earliest known ceratopsian, Yinlong downsi, lived between 161.2 and 155.7... n.
Pinacosaurus Pinacosaurus Pinacosaurus is a genus of medium-sized ankylosaur dinosaurs that lived from the late Santonian to the late Campanian stages of the late Cretaceous Period , in Mongolia and China...	P. mephistocephalus	Bayan Mandahu	"Skull, postcranial skeleton, osteoderms."	An ankylosaur Ankylosauridae An ankylosaurid is a member of the Ankylosauridae family of armored dinosaurs that evolved 125 million years ago and became extinct 65 million years ago during the Cretaceous-Tertiary extinction event... .
Protoceratops Protoceratops Protoceratops is a genus of sheep-sized herbivorous ceratopsian dinosaur, from the Upper Cretaceous Period of what is now Mongolia. It was a member of the Protoceratopsidae, a group of early horned dinosaurs...	P. hellenikorhinus	Bayan Mandahu	"Complete skull."	A ceratopsian.
?Udanoceratops Udanoceratops Udanoceratops is a genus of ceratopsian dinosaur. It lived during the Late Cretaceous Period in the late Santonian or early Campanian faunal stages...	Indeterminate	Bayan Mandahu		A giant ceratopsian.

Saurischians

Saurischia Saurischia Saurischia meaning 'lizard' and ischion meaning 'hip joint') is one of the two orders, or basic divisions, of dinosaurs. In 1888, Harry Seeley classified dinosaurs into two orders, based on their hip structure... n dinosaur Dinosaur Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of... s of the Bayan Mandahu Formation
Genus	Species	Location	Abundance	Notes	Images
cf. Gobipteryx Gobipteryx Gobipteryx is the name given to a genus of enantiornithine bird from the Late Cretaceous Period. Its fossils were found in the Barun Goyot Formation in the Gobi Desert, Mongolia and first described in 1976 from two fragmentary skulls...	Indeterminate			Eggs similar to those attributed to Gobipteryx minuta from the Djadochta Formation Djadochta Formation The Djadochta Formation is situated in central Asia and dates from the Late Cretaceous Period. Laid down in the early Campanian, possibly starting in the latest Santonian, it is dated somewhat uncertainly at about 84-75 mya... .
Linheraptor Linheraptor Linheraptor is a genus of dromaeosaurid dinosaur which lived in what is now China in the Late Cretaceous. It was named by Xu Xing and colleagues in 2010, and contains the species Linheraptor exquisitus. This bird-like dinosaur was less than 2 m long and was found in Inner Mongolia...	L. exquisitus	Bayan Mandahu		A dromaeosaurid
Linhevenator Linhevenator Linhevenator is a genus of short-armed troodontid theropod dinosaur from the Late Cretaceous Bayan Mandahu Formation of Bayan Mandahu, Inner Mongolia, China....	L. tani	Bayan Mandahu		A troodontid
Machairasaurus Machairasaurus Machairasaurus is a genus of oviraptorid dinosaur which was found in the Bayan Mandahu Formation, China during the late Cretaceous period. It was first named by Nicholas R. Longrich, Philip J. Currie and Dong Zhi-Ming in 2010 and the type species is Machairasaurus leptonychus....	M. leptonychus	Bayan Mandahu		An oviraptorid
Oviraptoridae Oviraptoridae Oviraptoridae is a group of bird-like, herbivorous and omnivorous maniraptoran dinosaurs. Oviraptorids are characterized by their toothless, parrot-like beaks and, in some cases, elaborate crests. They were generally small, measuring between one and two metres long in most cases, though some... indet.	Indeterminate	Bayan Mandahu		An oviraptorid.
Sauropoda Sauropoda Sauropoda , or the sauropods , are an infraorder of saurischian dinosaurs. They had long necks, long tails, small heads , and thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land... indet.	Indeterminate	Bayan Mandahu		A sauropod.
cf. Saurornithoides Saurornithoides Saurornithoides is a genus of troodontid maniraptoran dinosaur, living during the Late Cretaceous period. These creatures were predators, which could run fast on their hind legs and had excellent sight and hearing...	Indeterminate	Bayan Mandahu		A troodontid Troodontidae Troodontidae is a family of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and scrappy and they have therefore been allied, at various times, with many dinosaurian lineages... similar to Saurornithoides mongoliensis from the Djadochta Formation.
Tyrannosauridae Tyrannosauridae Tyrannosauridae is a family of coelurosaurian theropod dinosaurs which comprises two subfamilies containing up to six genera, including the eponymous Tyrannosaurus. The exact number of genera is controversial, with some experts recognizing as few as three... indet.	Indeterminate	Bayan Mandahu		A tyrannosaurid.
Velociraptor Velociraptor Velociraptor is a genus of dromaeosaurid theropod dinosaur that existed approximately 75 to 71 million years ago during the later part of the Cretaceous Period. Two species are currently recognized, although others have been assigned in the past. The type species is V. mongoliensis; fossils...	V. mongoliensis			Misclassified, only present in the Djadochta Formation Djadochta Formation The Djadochta Formation is situated in central Asia and dates from the Late Cretaceous Period. Laid down in the early Campanian, possibly starting in the latest Santonian, it is dated somewhat uncertainly at about 84-75 mya... .
	V. osmolskae	Bayan Mandahu		A dromaeosaurid.

Turtles

Turtle Turtle Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield... s of the Bayan Mandahu Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes
Basilemys					A softshell turtle.

Fauna

Crocodylomorphs

Lizards

Mammals

Ornithischians

Saurischians

Turtles

See also