Bissekty Formation

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Bissekty Formation
Stratigraphic range: TuronianConiacian
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[edit]

An indeterminate species of marine coral.

Arthropods[edit]

Arthropods of the Bissekty Formation
Genus Species Location Stratigraphic Position Abundance Notes

Linuparus

Linuparus dzheirantuiensis

Marine.

A spiny lobster.

Molluscs[edit]

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[edit]

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[edit]

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 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[edit]

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[edit]

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[edit]

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[edit]

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.

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[edit]

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

B. kysylkumensis[2]

A hadrosaur

Bissektipelta

B. archibaldi[3]

"Partial skull."[4]

An ankylosaur

Levnesovia

L. transoxiana

"Braincases."

An hadrosauroid

Cionodon

C. kyslkumensis

"Fragmentary dentary, vetebrae, tibia."[5]

Gilmoreosaurus

G. kysylkumensis

Reclassified as Bactrosaurus

Turanoceratops[2]

T. tardabilis[2]

A ceratopsian[6]

Plesiosaurs[edit]

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[edit]

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[edit]

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[edit]

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

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[edit]

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]

Catenoleimus

C. anachoretus

A possible enantiornithine.

Enantiornis[2]

E. martini[2]

"Coracoid."[19]

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]

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]

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]

Z. logunovi[2]

"Synsacrum."[21]

Turtles[edit]

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[edit]

  1. ^ a b c 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. ^ a b c d e f g h i j k l m n o p q r s "Dinosaur distribution (Bissekty Formation)." Weishampel, et al. (2004). Pg. 594.
  3. ^ a b 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.
  4. ^ "Table 17.1," in Weishampel, et al. (2004). Page 367.
  5. ^ "Table 20.1," in Weishampel, et al. (2004). Page 442.
  6. ^ Sues, H.-D., and Averianov, A. (2009). "Turanoceratops tardabilis—the first ceratopsid dinosaur from Asia." Naturwissenschaften, doi:10.1007/s00114-009-0518-9.
  7. ^ a b c 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].
  8. ^ Averianov. (2007). "Theropod dinosaurs from Late Cretaceous deposits in the northeastern Aral Sea region, Kazakhstan." Cretaceous Research, .
  9. ^ 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.
  10. ^ "Table 6.1," in Weishampel, et al. (2004). Page 139.
  11. ^ "Table 8.1," in Weishampel, et al. (2004). Page 166.
  12. ^ "Table 10.1," in Weishampel, et al. (2004). Page 199.
  13. ^ "Table 9.1," in Weishampel, et al. (2004). Page 185.
  14. ^ a b c d "Table 11.1," in Weishampel, et al. (2004). Page 212.
  15. ^ 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. ^ a b "Table 11.1," in Weishampel, et al. (2004). Page 216.
  17. ^ Averianov, A.O.; 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. 
  18. ^ a b c d e f g h 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. ^ a b c d "Table 11.1," in Weishampel, et al. (2004). Page 213.
  20. ^ 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. ^ a b c "Table 11.1," in Weishampel, et al. (2004). Page 214.