Lameta Formation

The Lameta Formation, also known as the Infratrappean Beds (not to be confused with the contemporaneous Intertrappean Beds), is a sedimentary geological formation found in Madhya Pradesh, Gujarat, Maharashtra, Telangana, and Andhra Pradesh, India, associated with the Deccan Traps.^[1] It is of the Maastrichtian age (Late Cretaceous), and is notable for its dinosaur fossils.

Lameta Formation
Stratigraphic range: Maastrichtian ~70–66 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Exposure of the Lameta Formation at its type locality of Lameta
Type	Geological formation
Underlies	Intertrappean Beds, Deccan Traps deposits
Overlies	Jabalpur Group or Precambrian Basement
Area	5,000 km2 (1,900 sq mi)
Thickness	Variable, typically 18–45 m (59–148 ft)
Lithology
Primary	Claystone, sandstone limestone
Other	Conglomerate
Location
Coordinates	23.2°N 80.0°E / 23.2; 80.0
Approximate paleocoordinates	24.7°S 63.2°E / -24.7; 63.2
Region	Western India
Country	India
Extent	Madhya Pradesh, Gujarat, Maharashtra, Andhra Pradesh, Telangana
Type section
Named for	Lameta Ghat
Lameta Formation (India)

History

The first fossils found in the Lameta Formation were discovered between 1917 and 1919.^[2]

The Lameta Formation was first identified in 1981 by geologists working for the Geological Survey of India (GSI), G. N. Dwivedi and Dhananjay Mahendrakumar Mohabey, after being given limestone structures–later recognised as dinosaur eggs–by workers of the ACC Cement Quarry in the village of Rahioli near the city Balasinor in the Gujarat state of western India.^[3]

Lithology

Paleoart of the Deccan trap illustrating the paleoenvironment of Lameta formation

The formation is underlain by the Lower Cretaceous sedimentary "Upper Gondwana Sequence" also known as the Jabalpur Formation, and is overlain by the Deccan Traps basalt. The Lameta Formation is only exposed at the surface as small isolated outcrops associated with the Satpura Fault. The lithology of the formation, depending on the outcrop, consists of alternating clay, siltstone and sandstone facies, deposited in fluvial and lacustrine conditions. The environment at the time of deposition has alternatively been considered semi-arid, or tropical humid.^[4][5]

Fossil content

Many dubious names have been created for isolated bones, but several genera of dinosaurs from these rocks are well-supported, including the titanosaur sauropods Isisaurus and Jainosaurus and the Abelisaurs Indosaurus, Indosuchus, and Rajasaurus and Noasaurids Laevisuchus.^[6] Synapsids are also known form the formation, such as the possibly late surviving Avashishta,possibly the last known non- mammalian synapsid the possibly youngest known stegosaurian ichnogenus Deltapodus, madtsoiid snakes and other fossils.

Dinosaurs

Dinosaurs of Lameta Formation in which a group of Rajasaurus (Middle) hunting an Isisaurus (Middle) with an Indosuchus (bottom left) watching it with her chicks and a Laevisuchus (Bottom right) running with two Jainosaurus (Top Left) in the background

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

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Ankylosauria?	Indeterminate	Rahioli		Isolated vertebrae, scapulocoracoid, humerus, femur, and several armor fragments such as hollow lateral spikes and solid dorsal scutes.[7]	Described as a nodosaurid, but the limb bones are titanosaurian.[8]
Brachypodosaurus	B. gravis	Chota Simla Hill		"Humerus."[9]	May not be dinosaurian
Ceratopsia?	Indeterminate	Kheda		Horncore base.	Originally described as a ceratopsian horncore,[10] but likely represents a theropod limb element or a dorsal rib of a theropod or a titanosauriform.[11]
Deltapodus[12]	sp.	Jetholi		Solitary footprint.	A Possible Late Cretaceous Stegosaur, Like Dravidosaurus.
Hypsilophodontidae?[13]	Indeterminate.	Vikarabad.		Teeth.	Hypsilophodontidae is not a natural grouping.
Ornithischia[14]	Indeterminate	Kheda		Braincase.	Indeterminate Ornithischian.
Spheroolithus?	sp.	Polgaon, Tidkepar		Egg fossils.	Questionably assigned to this genus[15]

Sauropods

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Isisaurus	I. colberti	Dongargaon Hill		Holotype skeleton consists of cervical, dorsal, sacral, caudal vertebrae, ribs, pelvis, scapula, coracoid, left forelimb, and other bones. Other specimens such as skull, hindlimb, and foot bones are unknown.	A titanosaur.
Jainosaurus	J. septentrionalis	Bara Simla		"Basicranium and partial postcranial skeleton."[16]	A titanosaur.
Titanosaurus	T. blanfordi	Panchgaon Pisdura Hill		Caudal vertebrae.[17]	A dubious genus of titanosaur.[18]	T. blanfordi holotype distal caudal vertebra
	T. indicus	Pisdura Hill		Teeths, Caudal vertebrae and chevron.[19]		''T. indicus holotypic distal caudal vertebra
Megaloolithus[20]	M. cylindricus	Chui Hill, Bara Simla, Nand region, Pavan, Ghorpend, Bagh Caves, Dhar, Indwan, Kadwal, Dholiya Raipuriya village, Akhada village, Jhaba village, Padlya village, Jhabua, Dohad, Jhalod, Garadi, Kheda, Rahioli, Dholi Dungri.		Sauropod egg fossils
	M. dhoridungriensis
	M. jabalpurensis
	M. khempurensis
	M. megadermus
	M. problematica
	M. walpurensis
	M. sp.
Titanosauriform[21]	Indeterminate	Ukala.		Dorsal vertebrae, parts of illia and pelvis and limb bones.	A titanosauriform.

Theropods

Abelisaurs

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Abelisauroidea	Indeterminate			Multiple specimens.[22]	Could be referred to Abelisauridae or Noasauridae.[23]	Rajasaurus Indosuchus Rahiolisaurus
Abelisauridae	Indeterminate			Multiple specimens.	Include form similar to Majungasaurus and forms similar to Carnotaurus.[22]
Compsosuchus	C. solus	Bara Simla		"Vertebrae"	Previously considered a Noasaurid now considered an indeterminate Abelisaurid[24]
Indosaurus	I. matleyi	Bara Simla		Partial skeleton, including a partial skull.[25]	An abelisaur.
Dryptosauroides	D. grandis	Bara Simla		"Vertebrae."[26]
Ellipsoolithus[27]	E. khedaensis	Kheda		Eggs	Theropod egg fossils.
Indosuchus	I. raptorius	Bara Simla		Cranial remains, including two braincases, as well as a nearly complete skeleton.[25]	An abelisaur.
Ornithomimoides	O. barasimlensis	Bara Simla		"Vertebrae."[26]	An abelisaurid[28]
	O. mobilis	Bara Simla		"Vertebrae"[26]
Orthogoniosaurus	O. matleyi	Bara Simla		"Tooth"[26]	An abelisaurid.[29]
Rahiolisaurus	R. gujaratensis	Rahioli Village		Cervical, dorsal, sacral, and caudal vertebrae, portions of pectoral and pelvic girdles, and several hind limb bones of different individuals.	An abelisaurid.
Rajasaurus	R. narmadensis	Temple Hill, Rahioli		A partial skeleton consists of maxillae, premaxillae, braincase, and quadrate bone on the skull; and spine, hip bone, legs, and tail in post-cranial remains.	An abelisaurid.

Noasaurids

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Laevisuchus	L. indicus	Bara Simla		Only vertebrae.[25]	A noasaurid.
Noasaurinae	Indeterminate	Pisdura Hill		A partial dentary.[28]	A noasaurine noasaurid.
Noasauridae	Indeterminate			Multiple specimens.[22]	May include femora from very large individuals.[23]

Other Theropods

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Coeluroides	C. largus	Bara Simla		"Isolated vertebrae."[26]	A Indeterminate theropod also known from Dabrazhin Formation of Kazakhstan
Jubbulpuria	J. tenuis	Bara Simla		"Vertebrae."[26]	Likely junior synonym of Laevisuchus[28]
?Megalosaurus	Referred to as the 'E' morphotype	Rahioli		A solitary tooth.[30]	Originally identified as belonging to Megalosaurus, however may instead represent a troodontid.[31]
Ornithomimidae?[32]	Indeterminate	Bara Simla			Ceratosaurian taxa from the Lameta Formation have been erroneously referred to ornithomimdae.
Theropoda	Indeterminate			Cervical vertebra.	Initially described as allosauroid. Not an abelisaurid, possibly representing a member of a clade outside of abelisauroidea.[22]
Trachoolithus[33]	T. faticanus	Bara Simla		Eggs.	Theropod egg fossils.

Indeterminate or chimaeric taxa

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
"Dubeynarainsaurus"	"D. sahni"	Sirolkhal		"Partial dentary with associated teeth."[34]	May instead be a later cretaceous pterosaur,[35] proposed to be either belonging to the Infratrappean or Intertrappean beds, although if it were a pterosaur it would not be Maastrichtian.[36]
Lametasaurus	L. indicus	Bara Simla		"Sacrum, ilia, tibia."[26] "Sacrum, ilia, tibia, spines, armor."[37]	Includes crocodylomorph, titanosaur and possibly ankylosaur material.[8] Also includes abelisaurid material now removed from the type.[3]

Reptiles

Snakes

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Madtsoia	M. pisdurensis[38]	Pidura Hill	Upper		A madtsoiid snake.
Sanajeh	S. indicus	Dholi Dungri		A skull, precloaca vertebrae and ribs.	A madtsoiid snake.	Sanajeh about to attack a titanosaur hatchling

Crocodylomorphs

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Dyrosauridae[39][13][40]	Indeterminate.	Kisalpuri and Vikarabad.		Vertebrae, eggs and teeth.	Non-Phosphatosaurinae Dyrosaurid Crocodylomorphs.

Turtles

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Jainemys	J. pisdurensis	Pisdura hill			A bothremydid side-necked turtle.
Pelomedusidae[41][42]	Indeterminate				A turtle.

Mammals

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Avashishta	A. bacharamensis[43]	Bacharam			A Haramiyida Mammal.

Mollusca

Genus	Species	Location	Notes
Mollusca	Indeterminate
Gastropoda	Indeterminate
Viviparus	V. normalis
Physa	P. sp.
Paludina	P. deccanensis
Lymnaea	L. subulata
Unio	U. sp.

See also

• List of dinosaur-bearing rock formations
• Geology of India
• Deccan Traps
• Maevarano Formation, contemporaneous fossiliferous formation of Madagascar
• Intertrappean Beds contemporaneous formation in India, also known for its fossils