| Lameta Formation | |
| Type: | Geological formation |
| Age: | Maastrichtian ~ |
| Period: | Maastrichtian |
| Prilithology: | Claystone, sandstone limestone |
| Otherlithology: | Conglomerate |
| Region: | Western India |
| Country: |  India |
| Coordinates: | 23.2°N 80°W |
| Paleocoordinates: | -24.7°N 63.2°W |
| Underlies: | Intertrappean Beds, Deccan Traps deposits |
| Overlies: | Jabalpur Group or Precambrian Basement |
| Thickness: | Variable, typically 18m-45mm (59feet-148feetm) |
| Extent: | Madhya Pradesh, Gujarat, Maharashtra, Andhra Pradesh, Telangana |
| Area: | 5000km2 |
| Namedfor: | Lameta Ghat |
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.
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]
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]
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 Rajasaurusand Noasaurids Laevisuchus.[6] Mammals are also known form the formation, such as the possibly late surviving Avashishta, the possibly youngest know stegosaurian Deltapodus, madtsoiid snakes and other fossils.
| 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."[7] | A titanosaur. | ||
| Titanosaurus | T. blanfordi |
| Caudal vertebrae.[8] | A titanosaur. | ||
| T. indicus | Pisdura Hill | Teeths, Caudal vertebrae and chevron.[9] | ||||
| Megaloolithus | 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[10] | Indeterminate | Ukala. | Dorsal vertebrae, parts of illia and pelvis and limb bones. | A titanosauriform. | ||
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Compsosuchus | C. solus | Bara Simla | "Vertebrae" | Previously considered a Noasaurid now considered an indeterminate Abelisaurid[11] | ||
| Indosaurus | I. matleyi | Bara Simla | Partial skeleton, including a partial skull. | An abelisaur. | ||
| Indosuchus | I. raptorius | Bara Simla | Cranial remains, including two braincases, as well as a nearly complete skeleton. | An abelisaurid theropod. | ||
| Ornithomimoides | O. barasimlensis | Bara Simla | "Vertebrae." | An abelisaurid | ||
| O. mobilis | Bara Simla | "Vertebrae" | ||||
| 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. | ||
| Laevisuchus | L. indicus | Bara Simla | Only vertebrae.[12] | |||
| Noasaurinae | Indeterminate | A partial dentary | A noasaurid noasaurine. | |||
| Coeluroides | C. largus | Bara Simla | "Isolated vertebrae."[13] | A Indeterminate theropod also known from Dabrazhin Formation of Kazakhstan | ||
| Dryptosauroides | D. grandis | Bara Simla | "Vertebrae." | |||
| Jubbulpuria | J. tenuis | Bara Simla | "Vertebrae." | Likely junior synonym of Laevisuchus[14] | ||
| Lametasaurus | L. indicus | Bara Simla | "Sacrum, ilia, tibia." "Sacrum, ilia, tibia, spines, armor."[15] | |||
| ?Megalosaurus | Referred to as the 'E' morphotype | A solitary tooth.[16] | Originally identified as belonging to Megalosaurus, however may instead represent a troodontid.[17] | |||
| Orthogoniosaurus | O. matleyi | Bara Simla | "Tooth" | |||
| 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. | Described as a nodosaurid, but the limb bones are titanosaurian.[18] | |||
| Brachypodosaurus | B. gravis | Chota Simla Hill | "Humerus."[19] | May not be dinosaurian | |||
| Ceratopsia? | Indeterminate | Kheda | Horncore base. | Originally described as a ceratopsian horncore,[20] but likely represents a theropod limb element or a dorsal rib of a theropod or a titanosauriform.[21] | |||
| Deltapodus[22] | sp. | Jetholi | Solitary footprint. | A Late Cretaceous Stegosaur, Like Dravidosaurus. | |||
| Hypsilophodontidae? | Indeterminate. | Vikarabad. | Teeth. | Hypsilophodontidae is not a natural grouping. | |||
| Ornithischia[23] | Indeterminate | Kheda | Braincase. | Indeterminate Ornithischian. | |||
| Spheroolithus? | sp. | Polgaon,Tidkepar | Egg fossils. | Questionably assigned to this genus |
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images | |
|---|---|---|---|---|---|---|---|
| Madtsoia | M. pisdurensis[24] | Pidura Hill | Upper | A madtsoiid snake. | |||
| Sanajeh | S. indicus | Dholi Dungri | A skull, precloaca vertebrae and ribs. | A madtsoiid snake. |
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images | |
|---|---|---|---|---|---|---|---|
| Jainemys | J. pisdurensis | Pisdura hill | A bothremydid side-necked turtle. | ||||
| Pelomedusidae[28] [29] | Indeterminate | A turtle. |
| Genus | Species | Location | Notes |
|---|---|---|---|
| Mollusca | Indeterminate | ||
| Gastropoda | Indeterminate | ||
| Viviparus | V. normalis | ||
| Physa | P. sp. | ||
| Paludina | P. deccanensis | ||
| Lymnaea | L. subulata | ||
| Unio | U. sp. | ||