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] | A titanosaur. | |||
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. | ||||||
Titanosauriform [11] | 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 | "Vertebrae" | Previously considered a Noasaurid now considered an indeterminate Abelisaurid [12] | |||
Indosaurus | I. matleyi | Bara Simla | Partial skeleton, including a partial skull. [13] | An abelisaur. | ||
Indosuchus | I. raptorius | Bara Simla | Cranial remains, including two braincases, as well as a nearly complete skeleton. [13] | An abelisaurid theropod. | ||
Ornithomimoides | O. barasimlensis | Bara Simla | "Vertebrae." [14] | An abelisaurid [15] | ||
O. mobilis | Bara Simla | "Vertebrae" [14] | ||||
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. [13] | A noasaurid | ||
Noasauridae | Indeterminate | A partial dentary [15] | A noasaurid. | |||
Coeluroides | C. largus | Bara Simla | "Isolated vertebrae." [14] | A Indeterminate theropod also known from Dabrazhin Formation of Kazakhstan | ||
Dryptosauroides | D. grandis | Bara Simla | "Vertebrae." [14] | |||
Jubbulpuria | J. tenuis | "Vertebrae." [14] | Likely junior synonym of Laevisuchus [15] | |||
Lametasaurus | L. indicus | Bara Simla | "Sacrum, ilia, tibia." [14] "Sacrum, ilia, tibia, spines, armor." [16] | |||
? Megalosaurus | Referred to as the 'E' morphotype | A solitary tooth. [17] | Originally identified as belonging to Megalosaurus, however may instead represent a troodontid. [18] | |||
Orthogoniosaurus | O. matleyi | Bara Simla | "Tooth" [14] | |||
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. [19] | Described as a nodosaurid, but the limb bones are titanosaurian. [20] | ||
Brachypodosaurus | B. gravis | Chota Simla Hill | "Humerus." [21] | May not be dinosaurian | ||
Ceratopsia? | Indeterminate | Kheda | Horncore base. | Originally described as a ceratopsian horncore, [22] but likely represents a theropod limb element or a dorsal rib of a theropod or a titanosauriform. [23] | ||
Deltapodus [24] | sp. | Jetholi | Solitary footprint. | Possibly a Late Cretaceous Stegosaur, Like Dravidosaurus. | ||
Hypsilophodontidae? [25] | Indeterminate. | Vikarabad. | Teeth. | Hypsilophodontidae is not a natural grouping. | ||
Ornithischia [26] | Indeterminate | Indeterminate Ornithischian. | ||||
Spheroolithus ? | sp. | Polgaon, Tidkepar | Egg fossils. | Questionably assigned to this genus [27] |
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
---|---|---|---|---|---|---|
Madtsoia | M. pisdurensis [28] | Upper | A madtsoiid snake. | |||
Sanajeh | S. indicus | A skull, precloaca vertebrae and ribs. | A madtsoiid snake. |
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
---|---|---|---|---|---|---|
Dyrosauridae [29] [25] [30] | Indeterminate. | Kisalpuri and Vikarabad. | Vertebrae, eggs and teeth. | Non-Phosphatosaurinae Dyrosaurid Crocodylomorphs. | ||
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
---|---|---|---|---|---|---|
Jainemys | J. pisdurensis | A bothremydid side-necked turtle. | ||||
Pelomedusidae [31] [32] | Indeterminate | A 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. sp. | ||
Paludina | P. deccanensis | ||
Lymnaea | L. subulata | ||
Unio | U. 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.
The Lance (Creek) Formation is a division of Late Cretaceous rocks in the western United States. Named after Lance Creek, Wyoming, the microvertebrate fossils and dinosaurs represent important components of the latest Mesozoic vertebrate faunas. The Lance Formation is Late Maastrichtian in age, and shares much fauna with the Hell Creek Formation of Montana and North Dakota, the Frenchman Formation of southwest Saskatchewan, and the lower part of the Scollard Formation of Alberta.
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.
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.
The Judith River Formation is a fossil-bearing geologic formation in Montana, and is part of the Judith River Group. It dates to the Late Cretaceous, between 79 and 75.3 million years ago, corresponding to the "Judithian" land vertebrate age. It was laid down during the same time period as portions of the Two Medicine Formation of Montana and the Oldman Formation of Alberta. It is an historically important formation, explored by early American paleontologists such as Edward Drinker Cope, who named several dinosaurs from scrappy remains found here on his 1876 expedition. Modern work has found nearly complete skeletons of the hadrosaurid Brachylophosaurus.
Madtsoia is an extinct genus of madtsoiid snakes. It is known from the Eocene of Argentina, the Paleocene of Brazil, the Late Cretaceous (Maastrichtian) of India, and the Late Cretaceous (Maastrichtian) of Madagascar. The type species was the largest with an estimated length of 9–10 m (30–33 ft), and the other three species were smaller. A 5.1 m (17 ft) long M. madagascariensis would have weighed 50 kg (110 lb), but an isolated specimen suggests that this species reached 8 m (26 ft) in maximum length.
The Javelina Formation is a geological formation in Texas. Dating has shown that the strata date to the Maastrichtian stage of the Late Cretaceous, approximately 70 to 66.5 million years old. The middle part of the formation has been dated to about 69 million years ago plus or minus 1 million years and the top situated near the Cretaceous–Paleogene boundary, dated to 66 Ma ago. Dinosaur remains are among the fossils that have been recovered from the formation.
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 phylogenetic analysis found Aoniraptor, Bahariasaurus, Deltadromeus, and Gualicho to form a monophyletic clade as the sister taxon to Elaphrosaurus near 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.
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 70 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.
Deccanolestes is a scansorial, basal Euarchontan from the Late Cretaceous (Maastrichtian) and Paleocene Intertrappean Beds of Andhra Pradesh, India. It may be closely related to Sahnitherium. Deccanolestes has been referred to Palaeoryctidae in the past, but recent evidence has shown that it is either the most basal Euarchontan, as the earliest known Adapisoriculid, or as a stem-afrotherian.
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 several spinosaurid taxa known from the Iberian peninsula, the others being Iberospinus, Protathlitis, ‘’Baryonyx’’, Riojavenatrix, and Vallibonavenatrix.
Avashishta bacharamensis is an extinct genus of a possibly late surviving haramiyid from the Maastrichtian Lameta formation of India. It is known from a solitary molariform tooth. It might represent the last known non-mammalian synapsid.