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 | |
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Stratigraphic range: Maastrichtian ~ | |
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°12′N 80°00′E / 23.2°N 80.0°E |
Approximate paleocoordinates | 24°42′S 63°12′E / 24.7°S 63.2°E |
Region | Western India |
Country | India |
Extent | Madhya Pradesh, Gujarat, Maharashtra, Andhra Pradesh, Telangana |
Type section | |
Named for | Lameta Ghat |
Lameta Formation (India) |
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 Rajasaurus and 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.
Color key
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Notes Uncertain or tentative taxa are in small text; |
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] | ||||
T. indicus | "Teeth"[9] | |||||
Megaloolithus[10] | M. cylindricus | Sauropod egg fossils | ||||
M. dhoridungriensis | ||||||
M. jabalpurensis | ||||||
M. khempurensis | ||||||
M. megadermus | ||||||
M. problematica | ||||||
M. walpurensis | ||||||
M. sp. |
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
---|---|---|---|---|---|---|
Compsosuchus | C. solus | "Vertebrae" | Previously considered a Noasaurid now considered an indeterminate Abelisaurid[11] | |||
Coeluroides | C. largus | Bara Simla | "Isolated vertebrae."[12] | A Indeterminate theropod also known from Dabrazhin Formation of Kazakhstan | ||
Dryptosauroides | D. grandis | Bara Simla | "Vertebrae."[12] | |||
Indosaurus | I. matleyi | Bara Simla | Partial skeleton, including a partial skull.[13] | |||
Indosuchus | I. raptorius | Bara Simla | Cranial remains, including two braincases, as well as a nearly complete skeleton.[13] | An abelisaurid theropod. | ||
Jubbulpuria | J. tenuis | "Vertebrae."[12] | Likely junior synonym of Laevisuchus[14] | |||
Lametasaurus | L. indicus | Bara Simla | "Sacrum, ilia, tibia."[12] "Sacrum, ilia, tibia, spines, armor."[15] | |||
Laevisuchus | L. indicus | Bara Simla | Only vertebrae.[13] | A noasaurid | ||
Ornithomimoides | O. barasimlensis | Bara Simla | "Vertebrae."[12] | An abelisaurid[14] | ||
O. mobilis | Bara Simla | "Vertebrae"[12] | ||||
Orthogoniosaurus | O. matleyi | Bara Simla | "Tooth"[12] | |||
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. | ||
Noasauridae | Indeterminate | A partial dentary[14] | A noasaurid. |
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
---|---|---|---|---|---|---|
Brachypodosaurus | B. gravis | "Humerus."[16] | May not be dinosaurian | |||
Spheroolithus? | Sp. | Polgaon,
Tidkepar |
Egg fossils | Questionably assigned to this genus[17] | ||
Deltapodus[18] | Solitary footprint | Possibly a Late Cretaceous Stegosaur, Like Dravidosaurus | ||||
Ankylosauria | Indeterminate | Rahioli | Isolated vertebrae, scapulocoracoid, humerus, femur, and several armor fragments such as hollow lateral spikes and solid dorsal scutes.[19] | Possibly a nodosaurid. |
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
---|---|---|---|---|---|---|
Sanajeh | S. indicus | A skull, precloaca vertebrae and ribs. | A madtsoiid snake | |||
Madtsoia | M. pisdurensis[20] | A madtsoiid snake |
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
---|---|---|---|---|---|---|
Jainemys | J. pisdurensis | A bothremydid side-necked turtle |
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
---|---|---|---|---|---|---|
Avashishta | A. bacharamensis | A Haramiyida Mammal |
Genus | Species | Location | Notes |
---|---|---|---|
Mollusca | Indeterminate | ||
Gastropoda | Indeterminate | ||
Viviparus | V. normalis | ||
Physa | P. normalis
sp. |
||
Paludina | P. deccanensis | ||
Lymnaea | L. subulata | ||
Unio | U. deccanensis
sp. |