Bissekty Formation

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Bissekty Formation Stratigraphic range: Turonian–Coniacian
Type	Geological formation
Underlies	Aitym Formation
Overlies	Dzheirantui Formation
Lithology
Primary	Sandstone
Other	Conglomerate
Location
Region	Asia
Country	Uzbekistan

The Bissekty Formation (sometimes referred to as Bissekt) is situated in the Kyzyl Kum desert of Uzbekistan, and dates from the late Cretaceous Period. Laid down in the early the Turonian to Coniacian stages, it is dated to about 90-85 ma (million years ago).

The Bissekty Formation is characterised by a mix of marine, brackish, freshwater, and terrestrial animal fossils. This stands in contrast the strictly marine fossils found in the underlying Dzheirantui Formation, and indicates that the Bissekty was formed during the regression of a saltwater sea. The coastline expanded inland again in the upper portion of the Bissekty, represented by a proportional increase of fully aquatic species, which were almost completely absent from the middle period of the formation. Semi-aquatic species remained abundant during this middle period, and the geology of the formations indicates that a braided river system took the place of the coastline. Eventually the area was again completely underwater, during the time period represented by the later Aitym Formation, which preserves coastal marine sediments.^[1]

Invertebrate paleofauna

An indeterminate species of marine coral.

Arthropods

Arthropods of the Bissekty Formation
Genus	Species	Location	Stratigraphic Position	Abundance	Notes
Linuparus	Linuparus dzheirantuiensis			Marine.	A spiny lobster.

Molluscs

An indeterminate species of marine placenticeratid ammonite. An indeterminate species of marine teredinid shipworm. An indeterminate marine trigoniid bivalve. An indeterminate marine veneroid bivalve.

Molluscs of the Bissekty Formation
Genus	Species	Location	Stratigraphic Position	Abundance	Notes
Crassatelites	Indeterminate				A marine crassatellid bivalve.
Mytiloides	Mytiloides labiatus				a marine inoceramid bivalve.
Plagiostoma	Indeterminate				A marine limoid bivalve.
Quadratotrigonia	Indeterminate				A marine trigoniid bivalve.
Xylophaga	Indeterminate				An indeterminate species of marine shipworm.

Vertebrate paleofauna

The Bissekty Formation is notable for preserving the most abundant Turonian land animal fossils in Eurasia, and the most diverse fauna of Late Cretaceous eutherians (placental mammals and relatives) in the world.^[1]

Listings and accompanying information are based on a survey of the Bissekty Formation published by Cory Redman and Lindsey Leighton in 2009 unless otherwise noted.^[1] Aquatic and semi-aquatic species are restricted to freshwater unless otherwise noted.

Amphibians

An indeterminate species of salamander-like albanerpetontid amphibian. An indeterminate gobiatid species.

Amphibians of the Bissekty Formation
Genus	Species	Location	Stratigraphic Position	Abundance	Notes
Aralobatrachus	Aralobatrachus robustus				A frog.
Eoscapherpeton	Eoscapherpeton asiaticum				A scapherpetontid salamander.
Gobiates	Gobiates sosedkoi				A gobiatid frog.
Gobiates	Gobiates spp.				Additional indeterminate species of Gobiates.
Itemirella	Itemirella cretacea				A possible discoglossid frog.
Kizylkuma	Kizylkuma antiqua				A possible discoglossid frog. Marine.
Mynbulakia	Mynbulakia surgai				A batrachosauroidid salamander.

Cartilaginous fish

Cartilaginous fishes of the Bissekty Formation
Genus	Species	Location	Stratigraphic Position	Abundance	Notes	Images
Cretodus	Cretodus crassidens				A cretoxyrhinid. Marine.	Scapanorhynchus rhaphiodon
Heterodontus	Indeterminate				A bullhead shark. Marine.
Hispidaspis	Indeterminate				A sand shark. Tolerant of brackish water.
Hybodus	Indeterminate				A hybodontid. Tolerant of brackish water.
Ischyrhiza	Ischyrhiza serra				A sclerorhynchid. Tolerant of brackish water.
Myledaphus	Myledaphus tritus				A rhinobatoid. Tolerant of brackish water.
Polyacrodus	Indeterminate				A polyacrodontid. Tolerant of brackish water.
Scapanorhynchus	Scapanorhynchus rhaphiodon				A goblin shark. Tolerant of brackish water.

Crocodylomorphs

Crocodylomorphs of the Bissekty Formation
Genus	Species	Location	Stratigraphic Position	Abundance	Notes
Kansajsuchus	Kansajsuchus borealis				A possible goniopholidid mesoeucrocodylian.
Shamosuchus	Indeterminate				A goniopholidid mesoeucrocodylian tolerant of brackish water.
Tadzhikosuchus	Tadzhikosuchus macrodentis				A possible alligatoroid eusuchian.
Zholsuchus	Zholsuchus procevus				A possible mesoeucrocodylian.
Zhyrasuchus	Zhyrasuchus angustifrons				A possible eusuchian.

Lizards

An indeterminate gekkonid. An indeterminate priscagamid. An indeterminate scincid.

Lizards of the Bissekty Formation
Genus	Species	Location	Stratigraphic Position	Abundance	Notes
Buckantaus	Buckantaus crassidens				A macrocephalosaurid.
Ekshmer	Ekshmer bissektensis				A priscagamid.

Mammals and other therapsids

An unnamed genus and species of zhelestid ungulatomorph.

Mammaliaformes of the Bissekty Formation
Genus	Species	Location	Stratigraphic Position	Abundance	Notes
Aspanlestes	Aspanlestes aptap				A zhelestid.
Daulestes	Daulestes inobservabilis				An asioryctitherian.
	Daulestes kezbe				An asioryctitherian.
	Daulestes kulbeckensis				An asioryctitherian.
	Unnamed				An unnamed species of Daulestes.
Kulbeckia	Kulbeckia kulbecke				A zalambdalestid.
Kulbeckia	Unnamed				An unnamed smaller species of Kulbeckia.
Paranyctoides	Paranyctoides aralensis				A eutherian.
Parazhelestes	Parazhelestes mynbulakensis				A zhelestid.
Parazhelestes	Parazhelestes robustus				A zhelestid.
Shalbaatar	Shalbaatar bakht				A symmetrodont.
Sulestes	Sulestes karakshi				A deltatheroid.
Uzbekbaatar	Uzbekbaatar kizylkumensis				A cimolodont.
Zhelestes	Zhelestes temirkazyk				A zhelestid.

Ornithischians

Indeterminate hadrosaurid remains are known from the Bissekty Formation.^[2]

Color key

Taxon	Reclassified taxon	Taxon falsely reported as present	Dubious taxon or junior synonym	Ichnotaxon	Ootaxon	Morphotaxon

Notes
Uncertain or tentative taxa are in small text; ~~crossed out~~ taxa are discredited.

Ornithischians reported from the Bissekty Formation
Genus	Species	Location	Stratigraphic position	Material	Description	Images
Amtosaurus	A. archibaldi^[2]				Reclassified as Bissektipelta^[3]	Bactrosaurus
Bactrosaurus	B. kysylkumensis^[2]				A hadrosaur
Bissektipelta	B. archibaldi^[3]			"Partial skull."^[4]	An ankylosaur
Cionodon	C. kyslkumensis			"Fragmentary dentary, vetebrae, tibia."^[5]
Gilmoreosaurus	G. kysylkumensis				Reclassified as Bactrosaurus
Turanoceratops^[2]	T. tardabilis^[2]				A ceratopsian^[6]

Plesiosaurs

Plesiosaurs of the Bissekty Formation
Genus	Species	Location	Stratigraphic Position	Abundance	Notes	Images
?Plesiosaurus	P.? sp.				A possible species of Plesiosaurus. Marine, possibly tolerant of brackish water.

Pterosaurs

Pterosaurs of the Bissekty Formation
Genus	Species	Location	Stratigraphic Position	Abundance	Notes	Images
Azhdarcho	Azhdarcho lancicollis	Dzhara-Kuduk	Taykarshinskaya unit		An azhdarchid

Ray-finned fish

An indeterminate acipenserid. An indeterminate albulid (bonefish) species. An indeterminate albulid (bonefish) species. An indeterminate pholidophoriform species.

Ray-finned fish of the Bissekty Formation
Genus	Species	Location	Stratigraphic Position	Abundance	Notes	Images
Aidachar	Aidachar paludalis				An ichthyodectiform tolerant of brackish water.	A living Amia.
Amia ♥	Amia limosa				A bowfin tolerant of brackish water.
Atractosteus	Atractosteus turanensis				A gar tolerant of brackish water.
Belonostomus	Belonostomus aciculifer				An aspidorhynchid.
Psephuroides	Psephuroides kazakhorum				A paddlefish.

Theropods

A possible oviraptorosaur, known from a single forelimb claw.^[7] An unnamed ornithomimosaur, known from fragmentary remains.^[8] An indeterminate tyrannosaurid species, known from isolated teeth.^[9]

Theropod dinosaurs reported from the Bissekty Formation
Genus	Species	Location	Stratigraphic position	Material	Description	Images
Alectrosaurus sp.					Fragmentary remains which may belong to juvenile Alectrosaurus, a tyrannosaurid.^[7]	Archaeornithomimus
Archaeornithomimus	A. bissektensis			"Metatarsals."^[10]	A possible species of Archaeornithomimus, an ornithomimosaur.
Caenagnathasia	C. martinsoni			"[Two] partial mandibles."^[11]	An oviraptorosaur.
Euronychodon	E. asiaticus			A tooth.^[12]^[13]
cf. Gallimimus sp.					A possible ornithomimosaur or oviraptorosaur.^[7]
Horezmavis	H. eocretacea^{[citation needed]}				A possible gruiform.
Itemirus	I. medullaris				A velociraptorine
Kuszholia^[14]	K. mengi^[14]			"[Two] synsacra."^[14]
Paronychodon	Paronychodon asiaticus				A troodontid, known from isolated teeth. (Originally Euronychodon asiaticus)^[15] A possible second species of Paronychodon is also known from the Bissekty Formation.
Richardoestesia	R. asiatica				A possible dromaeosaurid.
Platannavis^[2]	P. nana^[2]			"Sacrum."^[16]
Urbacodon sp.					A troodontid, known from isolated teeth.^[17]
Zhyraornis	Z. kashkarovi				A possible ornithurine.

Enantiornithines

Color key

Taxon	Reclassified taxon	Taxon falsely reported as present	Dubious taxon or junior synonym	Ichnotaxon	Ootaxon	Morphotaxon

Notes
Uncertain or tentative taxa are in small text; ~~crossed out~~ taxa are discredited.

Enantiornithines reported from the Bissekty Formation
Genus	Species	Location	Stratigraphic position	Material	Description	Images
Abavornis	A. bonaparti			Known from a partial coracoid.^[18]	A possible enantiornithine.^[18] A possible second species of Abavornis in the Bissekty Formation is known from a partial coracoid.^[18]	Enantiornis
Catenoleimus	C. anachoretus				A possible enantiornithine.
Enantiornis^[2]	E. martini^[2]			"Coracoid."^[19]
Enantiornis^[2]	E. walkeri^[2]			"Coracoid."^[19]
Explorornis	E. nessovi				An enantiornithine. Possible third and fourth species of Explorornis in the Bissekty Formation are known from partial coracoids.^[18]
Explorornis	E. walkeri
Ichthyornis	I. minusculus			"Dorsal vertebra."^[16]	An enantiornithine originally but incorrectly identified as a species of Ichthyornis.^[20]
Incolornis	I. martini			Known from a partial coracoid.^[18]	A possible enantiornithine.^[18]
Incolornis	I. silvae			Known from a partial coracoid.^[18]	A possible enantiornithine.^[18]
Kizylkumavis^[2]	K. cretacea^[2]			"Distal humerus."^[19]	An enantiornithine.
Kuszholia	K. mengi			"[Two] synsacra."^[14]	An enantiornithine.
Lenesornis^[2]	L. maltshevskyi^[2]			"Synsacrum."^[19]	A possible enantiornithine.
cf. Nanantius					An enantiornithine, similar to Nanantius eos.
Sazavis^[2]	S. prisca^[2]			"Distal tibiotarsus."^[21]	An enantiornithine.
Zhyraornis^[2]	Z. kashkarovi^[2]			"Synsacrum."^[21]
Zhyraornis^[2]	Z. logunovi^[2]			"Synsacrum."^[21]

Turtles

An indeterminate trionychid (soft-shell) turtle species that was tolerant of brackish water.

Turtles of the Bissekty Formation
Genus	Species	Location	Stratigraphic Position	Abundance	Notes
"Adocus"	"Adocus" aksary				An adocid tolerant of brackish water.
Anatolemys	Indeterminate				A "macrobaenid" tolerant of brackish water.
Khunnuchelys	Khunnuchelys kizylkumensis				A trionychid tolerant of brackish water.
Lindholmemys	Lindholmemys elegans				A "lindholmemydid" tolerant of brackish water.
Shachemys	Shachemys ancestralis				An adocid tolerant of brackish water.

References

↑ 1.0 1.1 1.2 Redman, C.M. and Leighton, L.R. (2009). "Multivariate faunal analysis of the Turonian Bissekty Formation: Variation in the degree of marine influence in temporally and spatially averaged fossil assemblages." PALAIOS, 24(1): 18-26. doi:10.2110/palo.2007.p07-072r Supplementary information including faunal tables.
↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 "Dinosaur distribution (Bissekty Formation)." Weishampel, et al. (2004). Pg. 594.
↑ 3.0 3.1 Aviarianov, A.O. (2002). "An ankylosaurid (Ornithischia: Ankylosauria) from the Upper Cretaceous Bissekty Formation of Uzbekistan." Bull. Inst. Roy. Sci. Nat. Belg. Sci. Terre, 72: 97-110.
↑ "Table 17.1," in Weishampel, et al. (2004). Page 367.
↑ "Table 20.1," in Weishampel, et al. (2004). Page 442.
↑ Sues, H.-D., and Averianov, A. (2009). "Turanoceratops tardabilis—the first ceratopsid dinosaur from Asia." Naturwissenschaften, doi:10.1007/s00114-009-0518-9.
↑ 7.0 7.1 7.2 Nesov, A. (1995). "Dinosaurs of Northern Eurasia: new data about assemblages, ecology and paleobiogeography." Scientific Research Institute of the Earth's Crust. St. Petersburg State University, St. Petersburg, Russia: 156 pp. + 14 pl. [in Russian with short English, German, and French abstracts].
↑ Averianov. (2007). "Theropod dinosaurs from Late Cretaceous deposits in the northeastern Aral Sea region, Kazakhstan." Cretaceous Research, .
↑ Archibald, Sues, Averianov, King, Ward, Tsaruk, Danilov, Rezvyi, Vereterunikov and Khodjaev. (1998). "Precis of the Cretaceous paleontology, biostratigtaphy and sedimentology at Dzharakuduk (Turonian?-Santonian), Kyzylkum Desert, Uzbekistan." Bulletin of the New Mexico Museum of Natural History and Science, 14: 21-27.
↑ "Table 6.1," in Weishampel, et al. (2004). Page 139.
↑ "Table 8.1," in Weishampel, et al. (2004). Page 166.
↑ "Table 10.1," in Weishampel, et al. (2004). Page 199.
↑ "Table 9.1," in Weishampel, et al. (2004). Page 185.
↑ 14.0 14.1 14.2 14.3 "Table 11.1," in Weishampel, et al. (2004). Page 212.
↑ Nesov, A. (1995). Dinozavri severnoi Yevrasii: Novye dannye o sostave kompleksov, ekologii i paleobiogeografii [Dinosaurs of Northern Eurasia: new data about assemblages, ecology and paleobiogeography]. Scientific Research Institute of the Earth's Crust, St. Petersburg State University, St. Petersburg, Russia: 156 pp. + 14 pl. [in Russian with short English, German, and French abstracts].
↑ 16.0 16.1 "Table 11.1," in Weishampel, et al. (2004). Page 216.
↑ Averianov, A.O.; and Sues, H.-D. (2007). "A new troodontid (Dinosauria: Theropoda) from the Cenomanian of Uzbekistan, with a review of troodontid records from the territories of the former Soviet Union". Journal of Vertebrate Paleontology 27 (1): 87–98. doi:10.1671/0272-4634(2007)27[87:ANTDTF]2.0.CO;2. Cite uses deprecated parameters (help)
↑ 18.0 18.1 18.2 18.3 18.4 18.5 18.6 18.7 Panteleev. (1998). "New species of enantiornithines (Aves: Enantiornithes) from the Upper Cretaceous of Central Kyzylkum." Russkii Ornitologicheskii Zhurnal, Ekspress-vy.pvsk 35: 3-15.
↑ 19.0 19.1 19.2 19.3 "Table 11.1," in Weishampel, et al. (2004). Page 213.
↑ Kurochkin. (1996). "A new Enantiornithid of the Mongolian Late Cretaceous, and a general appraisal of the Infraclass Enantiornithes (Aves)." Russian Academy of Sciences, special issue: 50pp.
↑ 21.0 21.1 21.2 "Table 11.1," in Weishampel, et al. (2004). Page 214.

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