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Karai Formation

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Coordinates: 11°00′N 78°54′E / 11.0°N 78.90°E / 11.0; 78.90
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Karai Formation
Stratigraphic range: Albian to Turonian
~105.5–89.3 Ma
TypeGeological formation
Sub-unitsOdiyam & Kunnam Members
UnderliesUnconformity with the Kulakkalnattam formation
OverliesUttatur Group
Lithology
PrimaryMudstone
Location
Coordinates11°00′N 78°54′E / 11.0°N 78.90°E / 11.0; 78.90
RegionTamil Nadu, Cauvery basin
Country India
[[File:.
Karai Formation is located in India
Karai Formation
Karai Formation (India)
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The Karai Formation is a Mesozoic (Albian to Turonian) geologic formation in India. Fossilized ichthyosaur remains and shark teeth have been reported from this formation.[1]

Paleobiota

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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.

Ichthyosaurs

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Ichthyosaurs from the Karai Formation
Genus Species Location Material Notes Images
Ichthyosauria indet.[2] Vertebrae. Previously known as "Platypterygius indicus".[3]
Ichthyosaurus[4] I. indicus A few complete and one partially complete vertebrae. Considered a nomen dubium.[5]
Ichthyosauria indet.[6]
  • Six adult teeth (DUGF/41-45)
  • One juvenile tooth (DUGF/46)
  • Seven partial vertebrae.
 Was tentatively assigned to P. indicus. It is similar to other species of Platypterygius.[1] It was later noted that only one of the teeth can be assigned to Platypterygiinae.[6]
Platypterygius P. sp. indet. An Anterior caudal vertebra. A Platypterygiine ichthyosaur.[7]

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Chondrichthyans from the Karai Formation
Genus Species Location Material Notes Images
Protosqualus P. sp. One incomplete tooth. A Squalid shark.[1]
Gladioserratus G. magnus One lower lateral tooth. A Hexanchid shark.[1]
?Notidanodon ?N. sp. One tooth fragment. A Hexanchid shark.[1]
Cretalamna C. appendiculaia Twenty-five teeth. An Otodontid shark.[1]
Dwardius D. sudindicus Over a hundred teeth. A Lamniform shark.[1]
?Eostriatolamia ?E. sp. One upper lateral tooth and a cusp of an anterior tooth. An Odontaspidid shark.[1]
Squalicorax S. aff. baharijensis Five complete and two fragmentary teeth. An Anacoracid shark.[1]
Cretodus C. longiplicatus Fifteen teeth. A Lamniform shark.[1]

Mollusk

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Mollusks from the Karai Formation
Genus Species Location Material Notes Images
Acanthoceras A. rhotomagense An Acanthoceratidae Ammonite.
Calycoceras
  • C. asiaticum
  • C. naviculare
 An Acanthoceratidae Ammonite.
Pseudocalycoceras
  • P. harpax
  • sp.
 An Acanthoceratidae Ammonite.
Kunnamiceras K. tropicum An Acanthoceratidae Ammonite.
Eucalycoceras E. pentagonum An Acanthoceratidae Ammonite.
Lotzeites L. aberrans An Acanthoceratidae Ammonite.
Desmoceras
  • D. latidorsatum
  • sp.
 A Desmoceratidae Ammonite.
Sciponoceras sp. A Baculitidae Ammonite.
Phylloceras P. seresitense A Phylloceratidae Ammonite.
Holcodiscoides H. elegans A Kossmaticeratidae Ammonite.
Cymatoceras C. huxleyanum A Nautilidae.
Eutrephoceras E. justum A Nautilidae.
Pycnodonte P. vesicularis An Oyster.

References

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  1. ^ a b c d e f g h i j https://www.researchgate.net/publication/233085546_Marine_Vertebrates_from_the_%27Middle%27_Cretaceous_Early_Cenomanian_of_South_India
  2. ^ Fischer, Valentin; Bardet, Nathalie; Benson, Roger B. J.; Arkhangelsky, Maxim S.; Friedman, Matt (2016-03-08). "Extinction of fish-shaped marine reptiles associated with reduced evolutionary rates and global environmental volatility". Nature Communications. 7 (1): 10825. Bibcode:2016NatCo...710825F. doi:10.1038/ncomms10825. ISSN 2041-1723. PMC 4786747. PMID 26953824.
  3. ^ Foote, Robert Bruce; Lydekker, Richard (1874). Indian Tertiary and post Tertiary Vertebrata. Calcutta: Geological Survey Office [etc., etc.] doi:10.5962/bhl.title.125505.
  4. ^ Lydekker, R. (July 1888). "VI.—Note on the Classification of the Ichthyopterygia (with a Notice of Two New Species)". Geological Magazine. 5 (7): 309–314. Bibcode:1888GeoM....5..309L. doi:10.1017/s0016756800181968. ISSN 0016-7568.
  5. ^ https://www.redalyc.org/pdf/505/50510405.pdf
  6. ^ a b Fischer, Valentin (2016-10-20). "Taxonomy ofPlatypterygius campylodonand the diversity of the last ichthyosaurs". PeerJ. 4: e2604. doi:10.7717/peerj.2604. ISSN 2167-8359. PMC 5075704. PMID 27781178.
  7. ^ Ayyasami, K.; Elamparuthi, S.; Gowtham, B. (2016-06-01). "An ichthyosaur vertebra from the Cretaceous (Middle Cenomanian) Karai Formation, southern India". Journal of the Geological Society of India. 87 (6): 706–708. Bibcode:2016JGSI...87..706A. doi:10.1007/s12594-016-0442-5. ISSN 0974-6889.
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