The Bayan Shireh Formation (also known as Bayanshiree Svita or the Baynshirenskaya Formation) is a geological formation in Burkhant, Mongolia

Mongolia

Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...

, that dates to the late Cretaceous

Late Cretaceous

The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...

 period. The exact age is uncertain, with two competing hypotheses; based on comparisons with other formations, the Bayan Shireh 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"...

 seems to correspond best with the Turonian

Turonian

The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...

 through 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 ...

 stages of the Late Cretaceous, about 93 to 80 million years ago. However, examination of the magnetostratigraphy

Magnetostratigraphy

Magnetostratigraphy is a geophysical correlation technique used to date sedimentary and volcanic sequences. The method works by collecting oriented samples at measured intervals throughout the section. The samples are analyzed to determine their characteristic remanent magnetization , that is, the...

 of the formation seems to confirm that the entire Bayan Shireh lies within the Cretaceous Long Normal, which lasted only until the end of the 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...

 stage, giving a possible Cenomanian

Cenomanian

The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...

 through Santonian age, or between 98 and 83 million years ago. The fauna of this formation is similar to the nearby Iren Dabasu Formation

Iren Dabasu Formation

The Iren Dabasu Formation is a Mesozoic geologic formation. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.-Ornithischians:-Saurischians:-References:...

.

Theropod dinosaurs

Theropods reported from the Bayan Shireh Formation
Genus	Species	Location	Stratigraphic Position	Material	Notes	Images
Achillobator Achillobator Achillobator is a genus of dromaeosaurid theropod dinosaur from the late Cretaceous Period of what is now Mongolia, about 90 million years ago. It was probably an active bipedal predator, hunting with the large sickle-shaped claw on the second toe of each hind foot...				"Partial skull and fragmentary postcrania."	a giant dromaeosaur
Alectrosaurus Alectrosaurus Alectrosaurus is a genus of tyrannosaurid theropod dinosaur from the Late Cretaceous Period of Inner Mongolia. It was a bipedal carnivore with a body shape similar to its much larger relative, Tyrannosaurus rex...					a tyrannosaur. Also present in the Iren Dabasu Formation Iren Dabasu Formation The Iren Dabasu Formation is a Mesozoic geologic formation. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.-Ornithischians:-Saurischians:-References:...
Enigmosaurus Enigmosaurus Enigmosaurus is a genus of therizinosauroid theropod dinosaur from the Late Cretaceous of Mongolia, central Asia...				"Incompletely preserved pelvis."	a therizinosaur
Erlikosaurus Erlikosaurus Erlikosaurus is a genus of herbivorous theropod dinosaur from the late Cretaceous Period, belonging to the Therizinosauridae. Its fossils, a skull and some post-cranial fragments, were found in the Bayan Shireh Formation of Mongolia, dating to around 90 million years ago.-Discovery and naming:The...				"Skull, pes, [and a] fragmentary postcranium."	a therizinosaur
Garudimimus Garudimimus Garudimimus is a basal ornithomimosaurian theropod dinosaur from the Upper Cretaceous of Mongolia.-Discovery and naming:...				"Skull with associated incomplete postcranium."	an ornithomimosaur
Segnosaurus Segnosaurus Segnosaurus is a genus of herbivorous theropod dinosaur belonging to the Therizinosauridae from the Cretaceous of Mongolia.-Discovery and naming:...				"[Three] specimens, including mandible pelvis, hindlimb, scapulocoracoid, incomplete forelimb, [and] fragmentary vertebrae."	a therizinosaur

Ornithischian dinosaurs

Ornithischians reported from the Bayan Shireh Formation
Genus	Species	Location	Stratigraphic Position	Material	Notes	Images
Amtosaurus Amtosaurus Amtosaurus is a genus of ornithischian dinosaur based on a fragmentary skull collected from the Upper Cretaceous Bayanshiree Svita Formation of Mongolia and originally believed to represent an ankylosaurid. Hadrosaurid affinities have also been suggested...	A. magnus			"Fragmentary skull."
Graciliceratops Graciliceratops Graciliceratops is a Ceratopsian dinosaur first described by paleontologist Paul Sereno in 2000. It is known from the Late Cretaceous period and its fossils were found in Mongolia...			Sheeregeen Gashoon beds	"Partial skull, skeleton."	A primitive ceratopsian, also present in the Minhe Formation Minhe Formation -References:* Molnar, R. E., 2001, Theropod paleopathology: a literature survey: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 337-363....
Maleevus Maleevus Maleevus is a genus of ankylosaurid dinosaur that is known only from the jawbone and part of the skull discovered in 1952 by Soviet palaeontologist Evgenii Aleksandrovich Maleev. It has been estimated that Maleevus was about 6 meters long...			Sheeregeen Gashoon beds		an ankylosaur
Microceratus			Sheeregeen Gashoon beds		A primitive ceratopsian, also present in the Minhe Formation Minhe Formation -References:* Molnar, R. E., 2001, Theropod paleopathology: a literature survey: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 337-363....
Talarurus Talarurus Talarurus is a genus of hippopotamus-sized ankylosaurid dinosaur with heavy armour and a club tail. It was named by Evgeny Maleev in 1952.-Age and location:...				"More than [five] specimens, including [two] partial skulls, nearly complete skeleton, osteoderms."	an ankylosaur
Tsagantegia Tsagantegia Tsagantegia is a genus of medium-sized ankylosaurid dinosaur from the Upper Cretaceous Mongolia, during the Cenomanian stage.The holotype specimen , a complete skull, was recovered from the Bayan Shireh Formation , at the Tsagan-Teg locality, Dzun-Bayan, in the southeastern Gobi Desert, Mongolia...				"Skull."	an ankylosaur