Lameta Formation | |
---|---|
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′N80°00′E / 23.2°N 80.0°E |
Approximate paleocoordinates | 24°42′S63°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 |
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 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
| 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. | ||
Rajasaurus is a genus of carnivorous abelisaurid theropod dinosaur from the Late Cretaceous of India, containing one species: Rajasaurus narmadensis. The bones were excavated from the Lameta Formation in the Gujarat state of Western India, probably inhabiting what is now the Narmada River Valley. It was formally described by palaeontologist Jeffrey A. Wilson and colleagues in 2003 based on a partial skeleton comprising the braincase, spine, hip bone, legs, and tail–a first for an Indian theropod. The dinosaur likely measured 6.6 metres (22 ft), and had a single horn on the forehead which was probably used for display and head-butting. Like other abelisaurids, Rajasaurus was probably an ambush predator.
Jainosaurus is a genus of titanosaurian sauropod dinosaur of India and wider Asia, which lived in the Maastrichtian. It is thought to have been about the same size as its contemporary relative Isisaurus, measuring 18 metres (59 ft) long and weighing 15 metric tons. The humerus of the type specimen is 134 centimetres long.
Dravidosaurus is a controversial taxon of Late Cretaceous reptiles, variously interpreted as either a ornithischian dinosaur or a plesiosaur. The genus contains a single species, D. blanfordi, known from mostly poorly preserved fossils from the Coniacian of southern India.
Deltadromeus is a genus of theropod dinosaur from the Aoufous Formation of Morocco.
Brachypodosaurus is a dubious genus of dinosaur, possibly an ornithischian, from the Late Cretaceous Lameta Formation (Maastrichtian) in India.
Indosaurus is a genus of carnivorous theropod dinosaur that lived in what is now India, about 69 to 66 million years ago during the Maastrichtian division of the Late Cretaceous.
Compsosuchus is a dubious genus of abelisauroid dinosaur from the Late Cretaceous Lameta Formation of India.
Isisaurus is a genus of titanosaurian dinosaur from the Late Cretaceous Lameta Formation of India and Pab Formation of Pakistan. The genus contains a single species, Isisaurus colberti.
Laevisuchus is a genus of theropod dinosaur from the Late Cretaceous. Its remains were discovered by Charles Alfred Matley near Jabalpur in Maastrichtian "Carnosaur Bed" deposits in the Lameta Formation in Madhya Pradesh, central India, and were named and described by paleontologists Friedrich von Huene and Matley in 1933.
Lametasaurus named for the Lameta Formation, Jabalpur, India, is the generic name given to a possibly chimeric dinosaur species. The type species is L. indicus.
Ornithomimoides is a dubious genus of theropod dinosaur, from the Late Cretaceous Lameta Formation of India. Two species have been identified, the type species O. mobilis and O. barasimlensis, were named by von Huene in 1932 and were described by Matley in 1933 though they are known only from isolated vertebrae. O. barasimlensis is known from five dorsal vertebrae, and O. mobilis from four smaller vertebrae, found at the same location.
Orthogoniosaurus was a genus of theropod dinosaur from the late Maastrichtian-age Upper Cretaceous Lameta Formation of Jabalpur, India. It is based on one small, fragmentary tooth.
The Maevarano Formation is a Late Cretaceous sedimentary rock formation found in the Mahajanga Province of northwestern Madagascar. It is most likely Maastrichtian in age, and records a seasonal, semiarid environment with rivers that had greatly varying discharges. Notable animal fossils recovered include the theropod dinosaur Majungasaurus, the early bird Vorona, the paravian Rahonavis, the titanosaurian sauropod Rapetosaurus, and the giant frog Beelzebufo.
The Lecho Formation is a geological formation in the Salta Basin of the provinces Jujuy and Salta of northwestern Argentina. Its strata date back to the Early Maastrichtian, and is a unit of the Salta Group. The fine-grained bioturbated sandstones of the formation were deposited in a fluvial to lacustrine coastal plain environment.
Bahariasauridae is a potential family of averostran theropods that might include a handful of African and South American genera, such as Aoniraptor, Bahariasaurus, Deltadromeus, and Gualicho. The placement of these theropods is controversial, with some studies placing them as basal ceratosaurs possibly related to Noasauridae, others classifying them as megaraptorans, basal neovenatorids, or basal coelurosaurs. There is also a possibility the group might not be monophyletic, as a monograph on the vertebrate diversity in the Kem Kem Beds published in 2020 found Bahariasaurus to be nomen dubium. In the same paper Deltadromeus is classified as an noasaurid, a result also recovered by some previous studies. A 2024 analysis found Aoniraptor, Bahariasaurus, Deltadromeus, Elaphrosaurus and Gualicho to form a monophyletic clade at the base of Ceratosauria.
The Intertrappean Beds are a Late Cretaceous and Early Paleocene geologic formation in India. The beds are found as interbeds between Deccan Traps layers, including the slightly older Lameta Formation. The formation spans the Cretaceous–Paleogene boundary, with a stratigraphic range of only a few hundred thousand years before and after the boundary, and a significant debate exists about whether specific sites belong to the Cretaceous or the Paleocene.
Sanajeh is a genus of late Cretaceous madtsoiid snake from western India. A fossil described in 2010 from the Lameta Formation was found coiled around an egg and an adjacent skeleton of a 50 cm (19 in) long sauropod dinosaur hatchling. This suggests that the snake preyed on hatchling sauropods at nesting sites.
Rahiolisaurus is a genus of abelisaurid theropod dinosaur which existed in India during the Late Cretaceous period. It was described in 2010, based on fossils recovered from the Lameta Formation in the Indian state of Gujarat. These fossils include elements from at least seven different individuals and are believed to have been from the Maastrichtian stage, sometime between 72.1 and 66 million years ago, making it one of the last non-avian dinosaurs known in the fossil record. Despite representing a variety of different growth stages, all recovered fossils from the locality indicate a single species, the type species Rahiolisaurus gujaratensis.
Camarillasaurus is a genus of theropod dinosaur from the Early Cretaceous period (Barremian) of Camarillas, Teruel Province, in what is now northeastern Spain. Described in 2014, it was originally identified as a ceratosaurian theropod, but later studies suggested affinities to the Spinosauridae. If it does represent a spinosaur, Camarillasaurus would be one of five spinosaurid taxa known from the Iberian peninsula, the others being Iberospinus, Protathlitis, Riojavenatrix, and Vallibonavenatrix.
This timeline of ceratosaur research is a chronological listing of events in the history of paleontology focused on the ceratosaurs, a group of relatively primitive, often horned, predatory theropod dinosaurs that became the apex predators of the southern hemisphere during the Late Cretaceous. The nature and taxonomic composition of the Ceratosauria has been controversial since the group was first distinguished in the late 19th century. In 1884 Othniel Charles Marsh described the new genus and species Ceratosaurus nasicornis from the Late Jurassic Morrison Formation of the western United States. He felt that it belonged in a new family that he called the Ceratosauridae. He created the new taxon Ceratosauria to include both the Ceratosauridae and the ostrich-like ornithomimids. The idea of the Ceratosauria was soon contested, however. Later that same decade both Lydekker and Marsh's hated rival Edward Drinker Cope argued that the taxon was invalid.