Kallamedu Formation

Kallamedu Formation
Stratigraphic range: Maastrichtian to Danian ~70.6–65.5 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Ariyalur Group
Underlies	Niniyur Formation
Overlies	Archean Basement
Thickness	Variable, typically 5–5,000 km (3.1–3,106.9 mi)
Lithology
Primary	Claystone, siltstone limestone
Other	Conglomerate
Location
Coordinates	11.6962°N 79.4127°E / 11.6962; 79.4127
Country	India
Extent	Kallamedu
Type section
Named for	Kallamedu village

The Kallamedu Formation is a Late Cretaceous (Maastrichtian) geologic formation located in the Ariyalur district of Tamil Nadu, India that forms part of the Ariyalur Group.^[1] It dates to the Maastrichtian of the Late Cretaceous. Dinosaur remains and petrified wood samples are among the known fossils recovered from this formation.^[2]

Lithology

The Kallamedu Formation likely represented a fluvial environment. It is composed of siltstones, clays and sandstones. The high organic carbon content of some of the rocks are consistent with a swamp.^[3]

Paleofauna

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.

Dinosaurs

Dinosaurs from the Kallamedu Formation
Genus	Species	Material	Notes
Abelisauridae indet.[4]		"Disassociated remains" and teeth.
Carnosauria indet.?[5]		"Fragmentary remains"	Carnosauria was often used as a wastebasket taxon.
Troodontidae indet.[4]		One isolated tooth (DUGF/52).
Bruhathkayosaurus[5][6]	B. matleyi	ilium and ischium, femur, tibia, radius and part of a vertebra (specifically a platycoelous caudal centrum). Remains no longer exist	Initially described as a Theropod, it was reclassified as a Titanosaur.
Sauropoda	Indeterminate.[7][8]	"Fragmentary remains."
Titanosauria	Indeterminate.[9]	Solitary egg.
Titanosauria	Indeterminate.[10]	Ten large sauropod bones, some of which could be identified as a humerus or femur, proximal end of a femur and scapula. All the bones pertain to the limbs.	Similar in size to Bruhathkayosaurus.[6]
Fusioolithus[9]	F. baghensis	Dinosaur eggs.
?Camarasauridae[11]	Indeterminate.	Vertebrae.	Camarasaurids are not known from the cretaceous.
?Stegosauria[12]	Indeterminate.	Misinterpreted sauropod bone.	Other more plausible Stegosaur material is known from Cretaceous India.

Crocodylomorphs

Crocodylomorphs from the Kallamedu Formation
Genus	Species	Material	Notes
Crocodilia[13]	Indeterminate	Teeth.
Simosuchus [13]	cf. Simosuchus sp.	Teeth.	Notosuchian Related to Simosuchus.

Turtles

Turtle from the Kallamedu Formation
Genus	Species	Material	Notes
Kurmademys [14]	K. kallamedensis	Nearly complete skull.	A Side-necked Turtle.
Testudines[13]	Indeterminate	Several fragmentary pieces of carapace and one vetebral element.	Too fragmentary to compare with Kurmademys.

Fish

Fish from the Kallamedu Formation
Genus	Species	Material	Notes
Lepisosteidae[13]	Indeterminate.	Scales.	Similar scales are known from the Intertrappean Beds.

Amphibians

Amphibians from the Kallamedu Formation
Genus	Species	Material	Notes
Anura[13]	Indeterminate.	Fragmentary ilium.

References

1. Memoirs of the Geological Survey of India. Oxford University. 1865. pp. 107–140.
2. Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Cretaceous, Asia)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 593–600. ISBN 0-520-24209-2.
3. https://www.researchgate.net/publication/263426844_SEDIMENTOLOGICAL_STUDIES_OF_KALLAMEDU_FORMATION_IN_ARIYALUR_AREA_TAMIL_NADU_INDIA
4. Goswami, A.; Prasad, G. V. R.; Verma, O.; Flynn, J. J.; Benson, R. B. J. (2013). "A troodontid dinosaur from the latest Cretaceous of India". Nature Communications. 4: 1703. Bibcode:2013NatCo...4.1703G. doi:10.1038/ncomms2716. PMID 23591870.
5. Yadagiri, P. and Ayyasami, K. (1987). "A carnosaurian dinosaur from the Kallamedu Formation (Maestrichtian horizon), Tamilnadu." In M.V.A. Sastry, V.V. Sastry, C.G.K. Ramanujam, H.M. Kapoor, B.R. Jagannatha Rao, P.P. Satsangi, and U.B. Mathur (eds.), Three Decades of Development in Palaeontology and Stratigraphy in India. Volume 1. Precambrian to Mesozoic. Geological Society of India Special Publication, 11(1): 523–528.
6. Pal, Saurabh; Ayyasami, Krishnan (May 2022). "The lost titan of Cauvery". Geology Today. 38 (3): 112–116. doi:10.1111/gto.12390. ISSN 0266-6979.
7. R. Lydekker. (1877). Notices of new and other Vertebrata from Indian Tertiary and Secondary rocks. Records of the Geological Survey of India 10(1):30–43
8. C. R. Narayana Rao and L. Rama Rao. 1930. The limb bones of a sauropodous dinosaur. Proceedings of the Indian Science Congress, Allahabad 17:330.
9. Dhiman, Harsha; Prasad, Guntupalli V. R.; Goswami, Anjali (2018). "Parataxonomy and palaeobiogeographic significance of dinosaur eggshell fragments from the Upper Cretaceous strata of the Cauvery Basin, South India". Historical Biology: 1–13. doi:10.1080/08912963.2018.1450408. S2CID 89969203.
10. Matley, 1929. The Cretaceous Dinosaurs of the Trichinopoly district and the rocks associated with them. Rec. Geof. Surv. India. Vol. 61 (4):337-349.
11. C. R. Narayana Rao and L. Rama Rao. 1930. Some dinosaurian vertebrae. Proceedings of the Indian Science Congress, Allahabad 17:329.
12. Peter M. Galton; Krishnan Ayyasami (2017). "Purported latest bone of a plated dinosaur (Ornithischia: Stegosauria), a "dermal plate" from the Maastrichtian (Upper Cretaceous) of southern India". Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 285 (1): 91–96. doi:10.1127/njgpa/2017/0671.
13. Prasad, G. V. R., Verma, O., Flynn, J. J. & Goswami, A. (2013) A new Late Cretaceous vertebrate fauna from the Cauvery basin, South India: implications for Gondwanan palaeobiogeography. Journal of Vertebrate Paleontology.
14. Gaffney, Eugene S; Chatterjee, Sankar; Rudra, Dhiraj K. (2001). "Kurmademys, a new side-necked turtle (Pelomedusoides: Bothremydidae) from the Late Cretaceous of India" (pdf). American Museum Novitates (3321): 1–16. doi:10.1206/0003-0082(2001)321<0001:kansnt>2.0.co;2. hdl:2246/2938. S2CID 53980146.