Isisaurus Temporal range: Late Cretaceous (Maastrichtian), | |
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Life restoration | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | † Sauropodomorpha |
Clade: | † Sauropoda |
Clade: | † Macronaria |
Clade: | † Titanosauria |
Clade: | † Lithostrotia |
Genus: | † Isisaurus Wilson & Upchurch, 2003 |
Species: | †I. colberti |
Binomial name | |
†Isisaurus colberti (Jain & Bandyopadhyay, 1997) | |
Synonyms | |
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Isisaurus (named after the Indian Statistical Institute) 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.
The type specimen of Isisaurus colberti, ISI R 335/1-65, was originally described and named as Titanosaurus colberti by Sohan Lal Jain and Saswati Bandyopadhyay in 1997. The specific name honours Edwin Harris Colbert. [1] [2] In 2003, the fossils were designated as belonging to its own genus by Wilson and Upchurch. [3] The generic name, "Isisaurus," combines a reference to the Indian Statistical Institute (ISI) with the Greek "saurus," meaning "lizard." It had a short, vertically directed neck and long forelimbs,[ citation needed ] making it considerably different from other sauropods. The humerus is 148 centimetres long. [1]
The site locality is Dongargaon Hill, which is in a Maastrichtian crevasse splay claystone in the Lameta Formation of India. [2] Dongargaon Hill (20.212318N,79.090709E) is located near Warora, in Chandrapur District, Maharashtra.
A braincase referrable to the species is known from the Pab Formation of Pakistan, which is equivalent in age to the Lameta Formation. [4]
Isisaurus is known from better remains than many other titanosaurs that were known at the time of its description. Much of its postcranial skeleton is known. The skeletal material found by Jain and Bandyopadhyay between 1984 and 1986 was "in associated and mostly articulated condition." The holotype includes cervical, dorsal, sacral and caudal vertebrae, ribs, pelvis, scapula, coracoid, left forelimb and other bones. No skull, hindlimb, or foot bones are known. [1] Since the original description of Isisaurus, unrelated titanosaur fossils belonging to more complete individuals have been discovered elsewhere. [5] [6]
Isisaurus was a medium-sized sauropod, with some estimates of its body length up to 18 metres (59 ft) long and weighing 15 metric tons (17 short tons). [7] The angle between the occipital bone and occipital condyle in Isisaurus and the fellow Indian titanosaur Jainosaurus is different. In the specimen from Dongargaon it is equal to 120°. In that matter, the cranium of Isisaurus resembles the skulls of Diplodocus and Apatosaurus (genera belonging to the Diplodocidae), but the bone modifications are different. [8]
While Isisaurus has consistently been considered to be a titanosaurian sauropod, its exact placement within this clade and its relationships with other titanosaurs has been controversial and problematic. Most analyses have recovered it with close affinities to taxa such as Rapetosaurus or the Saltasauridae. Various alternative positions suggested in that past are displayed in the following cladograms:
Isisaurus was placed within Opisthocoelicaudiinae by Curry-Rogers in 2005. [9]
The cladogram below follows Zaher et al. (2011). [10]
In 2017, Isisaurus was recovered as the sister taxon to Tapuiasaurus . [11]
In 2021, Isisaurus was placed as the sister taxon to Arackar . The cladogram from Rubilar-Rogers et al. (2021) is shown below: [12]
Fungus in coprolites believed to have been voided by Isisaurus indicate that it ate leaves from several species of tree, since these fungi are known to be pathogens which infect tree leaves. [13]
Isisaurus lived in the area belonging nowadays to India during the Maastrichtian age of the Cretaceous period. [14] [15] Its remains are the most complete among the Cretaceous dinosaurs known from that region. [16] Khosla et al. (2003) listed the following Indian sauropods: [17]
Wilson et al. (2009) listed only two Indian titanosaurs, Isisaurus and its distant relative, Jainosaurus. Isisaurus and Jainosaurus lived sympatrically in the area of middle and western India. Isisaurus fossils have also been reported from western Pakistan. [8]
Other dinosaurs, including the abelisaurs Indosuchus , Rahiolisaurus , and Rajasaurus , also existed in the Lameta Formation.
Titanosaurs were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thriving at the time of the extinction event at the end of the Cretaceous. This group includes some of the largest land animals known to have ever existed, such as Patagotitan—estimated at 37 m (121 ft) long with a weight of 69 tonnes —and the comparably-sized Argentinosaurus and Puertasaurus from the same region.
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.
Nemegtosauridae is a family of titanosaurian sauropod dinosaurs based on their diplodocid-like skulls. Only three species are known: Nemegtosaurus, Quaesitosaurus and possibly Tapuiasaurus, each from the Cretaceous.
Titanosaurus is a dubious genus of sauropod dinosaurs, first described by Richard Lydekker in 1877. It is known from the Maastrichtian Lameta Formation of India.
Antarctosaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. The type species, Antarctosaurus wichmannianus, and a second species, Antarctosaurus giganteus, were described by prolific German paleontologist Friedrich von Huene in 1929. Three additional species of Antarctosaurus have been named since then but later studies have considered them dubious or unlikely to pertain to the genus.
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.
Alamosaurus is a genus of opisthocoelicaudiine titanosaurian sauropod dinosaurs containing a single known species, Alamosaurus sanjuanensis, from the Maastrichtian age of the Late Cretaceous period in what is now southwestern North America. Isolated vertebrae and limb bones indicate that it reached sizes comparable to Argentinosaurus and Puertasaurus, which would make it the absolute largest dinosaur known from North America. Its fossils have been recovered from a variety of rock formations spanning the Maastrichtian age. Specimens of a juvenile Alamosaurus sanjuanensis have been recovered from only a few meters below the Cretaceous-Paleogene boundary in Texas, making it among the last surviving non-avian dinosaur species. Alamosaurus is the only known sauropod to have inhabited North America after their nearly 30-million year absence from the North American fossil record and probably represents an immigrant from South America.
Ampelosaurus is a titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now France. Its type species is A. atacis, named by Le Loeuff in 1995. Its remains were found in a level dating from 71.5 million years ago representing the early Maastrichtian.
Adamantisaurus is a poorly-known genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. It is only known from six tail vertebrae but, as a sauropod, it can be assumed that this dinosaur was a very large animal with a long neck and tail.
Jeffrey A. Wilson, also known as JAW, is a paleontologist and professor of geological sciences and assistant curator at the Museum of Paleontology at the University of Michigan.
Laplatasaurus is a genus of titanosaurian sauropod dinosaur that lived during the Late Cretaceous in South America, with the holotype and only known specimen found in the Anacleto Formation.
Saltasauridae is a family of armored herbivorous sauropods from the Upper Cretaceous. They are known from fossils found in South America, Africa, Asia, North America, and Europe. They are characterized by their vertebrae and feet, which are similar to those of Saltasaurus, the first of the group to be discovered and the source of the name. The last and largest of the group and only one found in North America, Alamosaurus, was thirty-four metres in length and one of the last sauropods to go extinct.
The Lameta Formation, also known as the Infratrappean Beds, is a sedimentary geological formation found in Madhya Pradesh, Gujarat, Maharashtra, Telangana, and Andhra Pradesh, India, associated with the Deccan Traps. It is of the Maastrichtian age, and is notable for its dinosaur fossils
Lithostrotia is a clade of derived titanosaur sauropods that lived during the Early Cretaceous and Late Cretaceous. The group was defined by Upchurch et al. in 2004 as the most recent common ancestor of Malawisaurus and Saltasaurus and all the descendants of that ancestor. Lithostrotia is derived from the Ancient Greek lithostros, meaning "inlaid with stones", referring to the fact that many known lithostrotians are preserved with osteoderms. However, osteoderms are not a distinguishing feature of the group, as the two noted by Unchurch et al. include caudal vertebrae with strongly concave front faces (procoely), although the farthest vertebrae are not procoelous.
Sohan Lal Jain is an Indian paleontologist, who worked for 33 years at the Indian Statistical Institute, Kolkata. The large herbivorous sauropod dinosaur genus Jainosaurus, was named in his honour after it was identified as a distinct genus although initially thought to be a species of Antarctosaurus. His other major contributions to paleontology were in the study of sauropod braincases and some fossil turtles.
Pitekunsaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Anacleto Formation of Neuquén, Argentina. It was described by L. Filippi and A. Garrido in 2008. The type species is P. macayai. The generic name is derived from Mapudungun pitekun, meaning "to discover", the epitheton honours the discoverer, oil company explorer Luis Macaya, who found the fossil in April 2004.
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.
Aeolosaurini is an extinct clade of titanosaurian dinosaurs known from the Cretaceous period of Argentina and Brazil. Rodrigo M. Santucci and Antonio C. de Arruda-Campos (2011) in their cladistic analysis found Aeolosaurus, Gondwanatitan, Maxakalisaurus, Panamericansaurus and Rinconsaurus to be aeolosaurids.
Saltasaurinae is a subfamily of titanosaurian sauropods known from the late Cretaceous period of South America, India and Madagascar.
Vahiny is an extinct genus of titanosaur sauropod dinosaur known from the Late Cretaceous of the Maevarano Formation, northwestern Madagascar. It contains a single species, Vahiny depereti.
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