Bissekty Formation

The Bissekty Formation (sometimes referred to as Bissekt) is a geologic formation and Lagerstätte which crops out in the Kyzyl Kum desert of Uzbekistan, and dates to the Late Cretaceous Period. Laid down in the mid to late Turonian, it is dated to about 92 to 90 Ma (million years ago).[1]

Bissekty Formation
Stratigraphic range: Mid-Late Turonian
~92–90 Ma
TypeGeological formation
UnderliesAitym Formation
OverliesDzheirantui Formation
Thicknessup to 80 m (260 ft)
Lithology
PrimarySandstone
OtherConglomerate, mudstone, siltstone
Location
Coordinates42°06′N 62°42′E / 42.1°N 62.7°E / 42.1; 62.7Coordinates: 42°06′N 62°42′E / 42.1°N 62.7°E / 42.1; 62.7
Approximate paleocoordinates36°48′N 57°00′E / 36.8°N 57.0°E / 36.8; 57.0
RegionNavoiy & Xorazm Regions
Country Uzbekistan
ExtentKyzylkum Desert
Bissekty Formation is located in Uzbekistan
Bissekty Formation
Bissekty Formation
Bissekty Formation (Uzbekistan)

DescriptionEdit

The lithology of the sediment largely consists of cross bedded sandstones with interbeds of massive sandstone, well cemented intraformational conglomerate, siltstones and mudstones. Most of the fossils are found as clasts within the conglomerates.[2]

Fossil contentEdit

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.[2]

VertebratesEdit

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.[2]

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.[2] Aquatic and semi-aquatic species are restricted to freshwater unless otherwise noted.

AmphibiansEdit

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 A. robustus A frog
Eoscapherpeton E. asiaticum A scapherpetontid salamander
Gobiates G. sosedkoi A gobiatid frog
Gobiates spp. Additional indeterminate species of Gobiates
Itemirella I. cretacea A possible discoglossid frog
Kizylkuma K. antiqua A possible discoglossid marine frog
Mynbulakia M. surgai A batrachosauroidid salamander

Cartilaginous fishEdit

Cartilaginous fishes of the Bissekty Formation
Genus Species Location Stratigraphic position Abundance Notes Images
Cretodus C. crassidens A marine cretoxyrhinid
Heterodontus Indeterminate A marine bullhead shark
Hispidaspis Indeterminate A sand shark tolerant of brackish water
Hybodus Indeterminate A hybodontid tolerant of brackish water
Ischyrhiza I. serra A sclerorhynchid tolerant of brackish water
Myledaphus M. tritus A rhinobatoid tolerant of brackish water
Polyacrodus Indeterminate A polyacrodontid tolerant of brackish water
Scapanorhynchus S. rhaphiodon A goblin shark tolerant of brackish water

CrocodylomorphsEdit

Crocodylomorphs of the Bissekty Formation
Genus Species Location Stratigraphic position Abundance Notes
Kansajsuchus K. borealis A possible goniopholidid mesoeucrocodylian
Tadzhikosuchus T. macrodentis A possible alligatoroid eusuchian
Zholsuchus Z. procevus A possible mesoeucrocodylian
Zhyrasuchus Z. angustifrons A possible eusuchian

LizardsEdit

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

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

Mammals and other therapsidsEdit

Mammaliaformes of the Bissekty Formation
Genus Species Location Stratigraphic position Abundance Notes
Aspanlestes A. aptap A zhelestid
Bulaklestes B. kezbe An asioryctitherian
Daulestes D. inobservabilis An asioryctitherian
D. kulbeckensis An asioryctitherian
Eoungulatum E. kudukensis A zhelestid
Kulbeckia K. kulbecke A zalambdalestid
Paranyctoides P. quadrans An eutherian
Parazhelestes P. mynbulakensis A zhelestid
P. robustus A zhelestid
Shalbaatar S. bakht A symmetrodont
Sulestes S. karakshi A deltatheroid
Uchkudukodon U. nessovi An asioryctitherian
Uzbekbaatar U. kizylkumensis A cimolodont
Zhelestes Z. temirkazyk A zhelestid

OrnithischiansEdit

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[3] Reclassified as Bissektipelta[4]
Bissektipelta B. archibaldi[4] "Partial skull."[5] An ankylosaur
Cionodon C. kyslkumensis "Fragmentary dentary [=maxilla], vetebrae, tibia."[6] Nomen dubium
Gilmoreosaurus G. arkhangelskyi Nomen dubium
Levnesovia L. transoxiana "Braincases" A hadrosauroid
Turanoceratops[3] T. tardabilis[3] A ceratopsian[7]

PlesiosaursEdit

Plesiosaurs of the Bissekty Formation
Genus Species Location Stratigraphic position Abundance Notes Images
Plesiosauria Indeterminate Marine, possibly tolerant of brackish water

PterosaursEdit

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

Ray-finned fishEdit

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 A. paludalis An ichthyodectiform tolerant of brackish water
Amia Extant A. limosa A bowfin tolerant of brackish water
 
A living Amia.
Atractosteus A. turanensis A gar tolerant of brackish water
Belonostomus B. aciculifer An aspidorhynchid
Psephuroides P. kazakhorum A paddlefish

TheropodsEdit

An unnamed ornithomimosaur, known from fragmentary remains.[8] An indeterminate tyrannosaurid species, known from isolated teeth.[9] A neovenatorid is in the process of being described.

Non-Enantiornithine Theropod dinosaurs of the Bissekty Formation
Genus Species Location Stratigraphic position Material Description Images
"Archaeornithomimus" A. bissektensis "Metatarsals"[10] A dubious ornithomimosaur
Caenagnathasia C. martinsoni "[Two] partial mandibles"[11] An elmisaurine caenagnathid
Euronychodon E. asiaticus A possible troodontid based on isolated teeth[12][13][14]
Itemirus I. medullaris A velociraptorine
Kuszholia[15] K. mengi[15] "[Two] synsacra"[15]
Platanavis[3] P. nana[3] "Sacrum"[16]
Therizinosauroidea spp.[17] Indeterminate Partial crania also preserving some teeth and some postcranial elements including pedal bones (from multiple individuals) At least two different therizinosauroids
Timurlengia[18] T. euotica Two braincases, dentary, and miscellaneous postcranial elements (from multiple individuals) A non-tyrannosaurid tyrannosauroid
Urbacodon Unnamed species A troodontid, known from isolated teeth[19]
Zhyraornis Z. kashkarovi A possible ornithurine
EnantiornithinesEdit
Enantiornithines of the Bissekty Formation
Genus Species Location Stratigraphic position Material Description Images
Abavornis A. bonaparti Known from a partial coracoid[20] A possible enantiornithine.[20] A possible second species of Abavornis in the Bissekty Formation is known from a partial coracoid.[20]
Catenoleimus C. anachoretus A possible enantiornithine
Explorornis E. nessovi An enantiornithine. Possible third and fourth species of Explorornis in the Bissekty Formation are known from partial coracoids.[20]
E. walkeri "Coracoid"[21]
Ichthyornis I. minusculus "Dorsal vertebra"[16] An enantiornithine originally but incorrectly identified as a species of Ichthyornis.[22]
Incolornis I. martini Known from a partial coracoid[20] A possible enantiornithine[20]
I. silvae Known from a partial coracoid[20] A possible enantiornithine[20]
Kizylkumavis[3] K. cretacea[3] "Distal humerus"[21] An enantiornithine
Kuszholia K. mengi "[Two] synsacra"[15] An enantiornithine
Lenesornis[3] L. maltshevskyi[3] "Synsacrum"[21] A possible enantiornithine
cf. Nanantius An enantiornithine, similar to Nanantius eos
Sazavis[3] S. prisca[3] "Distal tibiotarsus"[23] An enantiornithine
Zhyraornis[3] Z. kashkarovi[3] "Synsacrum"[23]
Z. logunovi[3] "Synsacrum"[23]

TurtlesEdit

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 K. kizylkumensis A trionychid tolerant of brackish water
Lindholmemys L. elegans A "lindholmemydid" tolerant of brackish water
Shachemys S. ancestralis An adocid tolerant of brackish water

InvertebratesEdit

An indeterminate species of marine coral.

ArthropodsEdit

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

MolluscsEdit

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 M. 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

ReferencesEdit

  1. ^ Averianov, Alexander; Sues, Hans-Dieter (April 2012). "Skeletal remains of Tyrannosauroidea (Dinosauria: Theropoda) from the Bissekty Formation (Upper Cretaceous: Turonian) of Uzbekistan". Cretaceous Research. 34: 284–297. doi:10.1016/j.cretres.2011.11.009. ISSN 0195-6671.
  2. ^ a b c d Redman & Leighton, 2009
  3. ^ a b c d e f g h i j k l m n "Dinosaur distribution (Bissekty Formation)." Weishampel, et al. (2004). Pg. 594.
  4. ^ a b Averianov, 2002
  5. ^ "Table 17.1," in Weishampel, et al. (2004). Page 367.
  6. ^ "Table 20.1," in Weishampel, et al. (2004). Page 442.
  7. ^ Sues & Averianov, 2009
  8. ^ Sues & Averianov, 2016
  9. ^ Archibald, James David; Sues, Hans-Dieter; Averianov, Alexander; King, Chris; Ward, David John; Tsaruk, Oleg; Danilov, Igor; Rezvyi, Anton; Veretennikov, Boris; Khodjaev, Anvar (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. ^ 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].
  15. ^ a b c d "Table 11.1," in Weishampel, et al. (2004). Page 212.
  16. ^ a b "Table 11.1," in Weishampel, et al. (2004). Page 216.
  17. ^ Sues, H.-D.; Averianov, A. (2016). "Therizinosauroidea (Dinosauria: Theropoda) from the Upper Cretaceous of Uzbekistan". Cretaceous Research. 59: 155–178. doi:10.1016/j.cretres.2015.11.003.
  18. ^ Stephen L. Brusatte; Alexander Averianov; Hans-Dieter Sues; Amy Muir; Ian B. Butler (2016). "New tyrannosaur from the mid-Cretaceous of Uzbekistan clarifies evolution of giant body sizes and advanced senses in tyrant dinosaurs". Proceedings of the National Academy of Sciences of the United States of America. 113 (13): 3447–3452. doi:10.1073/pnas.1600140113. PMC 4822578. PMID 26976562.
  19. ^ 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.
  20. ^ 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.
  21. ^ a b c "Table 11.1," in Weishampel, et al. (2004). Page 213.
  22. ^ 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.
  23. ^ a b c "Table 11.1," in Weishampel, et al. (2004). Page 214.

BibliographyEdit

Further readingEdit