Karai Formation

Last updated
Karai Formation
Stratigraphic range: Albian to Turonian
~105.5–89.3  Ma
Type Geological formation
Sub-units Odiyam & Kunnam Members
UnderliesUnconformity with the Kulakkalnattam formation
Overlies Uttatur Group
Lithology
Primary Mudstone
Location
Coordinates 11°00′N78°54′E / 11.0°N 78.90°E / 11.0; 78.90
Region Tamil Nadu, Cauvery basin
Country India
India relief location map.jpg
Cyan pog.svg
Karai Formation (India)

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]

Contents

Paleobiota

Color key
Taxon Reclassified taxonTaxon falsely reported as presentDubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Ichthyosaurs

Ichthyosaurs from the Karai Formation
GenusSpeciesLocationMaterialNotesImages
Ichthyosauria indet. [2] Vertebrae.Previously known as " Platypterygius indicus". [3]
Ichthyosaurus [4] I. indicusA 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]

Chondrichthyans

Chondrichthyans from the Karai Formation
GenusSpeciesLocationMaterialNotesImages
Protosqualus P. sp.One incomplete tooth.A Squalid shark. [1]
Gladioserratus G. magnusOne lower lateral tooth.A Hexanchid shark. [1]
 ? Notidanodon  ?N. sp.One tooth fragment.A Hexanchid shark. [1]
Cretalamna C. appendiculaiaTwenty-five teeth.An Otodontid shark. [1]
Dwardius D. sudindicusOver 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. baharijensisFive complete and two fragmentary teeth.An Anacoracid shark. [1]
Cretodus C. longiplicatusFifteen teeth.A Lamniform shark. [1]

Mollusk

Mollusks from the Karai Formation
GenusSpeciesLocationMaterialNotesImages
Acanthoceras A. rhotomagenseAn Acanthoceratidae Ammonite.
Calycoceras
  • C. asiaticum
  • C. naviculare
An Acanthoceratidae Ammonite.
Pseudocalycoceras
  • P. harpax
  • sp.
An Acanthoceratidae Ammonite.
Kunnamiceras K. tropicumAn Acanthoceratidae Ammonite.
Eucalycoceras E. pentagonumAn Acanthoceratidae Ammonite.
Lotzeites L. aberransAn Acanthoceratidae Ammonite.
Desmoceras
  • D. latidorsatum
  • sp.
A Desmoceratidae Ammonite.
Sciponoceras sp.A Baculitidae Ammonite.
Phylloceras P. seresitenseA Phylloceratidae Ammonite.
Holcodiscoides H. elegansA Kossmaticeratidae Ammonite.
Cymatoceras C. huxleyanumA Nautilidae.
Eutrephoceras E. justumA Nautilidae.
Pycnodonte P. vesicularisAn Oyster.

References

  1. 1 2 3 4 5 6 7 8 9 10 Underwood, Charlie J.; Goswami, Anjali; Prasad, G. V. R.; Verma, Omkar; Flynn, John J. (May 2011). "Marine vertebrates from the 'middle' Cretaceous (early Cenomanian) of South India". Journal of Vertebrate Paleontology. 31 (3): 539–552. doi:10.1080/02724634.2011.574518.
  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. Marta Fernández (2003). "Reseña de "Handbook of Paleoherpetology. Part 8. Ichthyopterygia" de C. Mcgowan and R. Motani" (PDF). Geologica Acta. 1 (4): 363–364.
  6. 1 2 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.