Karai Formation

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]

Karai Formation
Stratigraphic range: Albian to Turonian ~105.5–89.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Sub-units	Odiyam & Kunnam Members
Underlies	Unconformity with the Kulakkalnattam formation
Overlies	Uttatur Group
Lithology
Primary	Mudstone
Location
Coordinates	11.0°N 78.90°E / 11.0; 78.90
Region	Tamil Nadu, Cauvery basin
Country	India
Karai Formation (India)

Paleobiota

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

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]

Chondrichthyans

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

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.