| Titanosaurus | |
|---|---|
 | |
| Titanosaurus indicus holotypic distal caudal vertebra | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Macronaria |
| Clade: | †Titanosauria |
| Genus: | †Titanosaurus Lydekker, 1877 |
| Type species | |
| †Titanosaurus indicus Lydekker, 1877 | |
| Other species | |
| Synonyms | |
| |
Titanosaurus (/taɪˌtænəˈsɔːrəs/;lit. 'titanic lizard') is adubiousgenus ofsauropoddinosaurs, first described byRichard Lydekker in 1877.[1] It is known from theMaastrichtian (Upper Cretaceous)Lameta andKallakurichi Formations ofIndia.[2]
Titanosaurus, literally meaning 'titanic lizard', was named after theTitans of Greek mythology.
Titanosaurus was the first Indian dinosaur to be named and properly described, having been recorded for the first time in 1877. The type species,T. indicus, was named in 1877,[1][3] and the second species,T. blanfordi, was named in 1879.[4] Both species were named byRichard Lydekker.[1][4]T. indicus andT. blanfordi are 70 million years old.
Both species are known from theLameta Formation,[5] while indeterminate remains assigned toTitanosaurus have also been collected from theKallakurichi Formation.[6]
Theholotype vertebrae ofTitanosaurus indicus were discovered during an exploration toJabalpur in 1828 by CaptWilliam Henry Sleeman of theEast India Company army. He was one among many explorations for fossils initially carried out by army personnel, medical doctors and priests who chanced upon them just by being "fairly literate and mobile at the time". He stumbled across the vertebrae on Bara Simla Hill near a British Army gun carriage workshop while searching for petrified wood. Sleeman, employed by theBengal Army, regarded the bones as curiosities. He gave two vertebral pieces to surgeon G. G. Spilsbury, who had a practice in Japalpur and who also excavated a bone himself. Spilsbury sent the fossils in 1832 to theantiquarianJames Prinsep inCalcutta, who realised that they were fossilised bones and then sent them back to Sleeman.[7] In 1862,Thomas Oldham, the first director of the newly established Geological Survey of India, transferred the vertebrae from Japalpur to Calcutta and added them to the collection of theIndian Museum. There, the bones were studied by the Survey's supervisor,Hugh Falconer, who concluded that they were reptilian bones.[8] After Falconer's death, in 1877,Richard Lydekker described the vertebrae as a new species of reptile known asTitanosaurus indicus.[1]
The known remains ofT. indicus were generally considered to be lost and untraceable by the end of the twentieth century; in 2010 Matthew Carrano therefore established a cast based on illustrations Lydekker made in 1877, as a replacement plastotype, with the inventory number NHMUK 40867. However, that turned out to be a bit premature. In the early twenty-first century, Indian paleontologistDhananjay Mohabey understood that such specimens were lost only because no serious inventory of the collections had been carried out for generations.[5] He therefore started theStudy of Late Cretaceous Tetrapod fossils from Lameta Formation project with support from theUniversity of Michigan, with one of the main goals of locating lost specimens.[5] In this context, he and Subhasis Sengupta recovered one of the holotype vertebra on 25 April 2012.[9] It turned out to be in a batch of fossils that had been left behind by Lydekker in 1878 that had been lost up until then, which is why no official inventory number of the GSI had been assigned to it.[10]
Part of the fossils that Lydekker assigned to the type specimen ofT. indicus, that formed a series ofsyntypes, was a 1.5 metres (4.9 ft) long femur that had been excavated at the same location in 1871 or 1872 byHenry Benedict Medlicott – specimen GSI K22/754.[1] In 1933 this was reassigned byCharles Alfred Matley andFriedrich von Huene toAntarctosaurusseptentrionalis,[11] which was moved to the new genusJainosaurus in 1995.[12]
Between 1860 and 1870, geologistWilliam Thomas Blanford had found twosauropod middle caudal vertebrae nearPisdura (one vertebra, GSI 2195, became the type specimen). In 1879, they were named by Lydekker as a second species ofTitanosaurus,T. Blanfordi,[4] which according to current rules should be written asTitanosaurus blanfordi. Of the two fossils, making up specimen GSI IM K27 / 501, the second, smaller vertebra was split off byvon Huene in 1929 and assigned toTitanosaurus araukanicus (nowLaplatasaurus).[13][14]
Upchurch & Wilson concluded in their 2003 revision that this assignment was unfounded, although there is indeed no evidence beyond their origin that the two vertebrae have anything to do with each other.[15] The large vertebra, strongly procoel, convex in front, is distinguished by a square cross-section, the lack of a trough on the underside and elongated proportions. These features are also found in other titanosaurs, although not found in India – the latter, however, was insufficient reason for Upchurch & Wilson not to speak of anomen dubium.[15]
The holotype vertebrae ofT. blanfordi were also missing for years and were rediscovered in 2012 by Dhananjay Mohabey and Subhasis Sengupta at the same location as the holotype ofT. indicus.[10]
Wilson & Upchurch (2003) treatedTitanosaurus as anomen dubium ("dubious name") because they noted that the originalTitanosaurus specimens cannot be distinguished from those of related animals.[15]
As the type genus ofTitanosauria,Titanosaurus at times became awastebasket taxon for a number of titanosaurs, including those not just from India but also southernEurope,Laos, andSouth America. Only two among these, however, are currently considered species ofTitanosaurus:T. indicus andT. blandfordi, both of which are considerednomina dubia.
Other species formerly referred to this genus include:
Titanosaurus indicus has been found in the Lameta Formation, a rock unitradiometrically dated to the Maastrichtianage of the latest Cretaceous representing anarid orsemi-arid landscape with a river flowing through it–probably providing shrub cover near the water–which formed between episodes of volcanism in theDeccan Traps.[19][20][21][22]Titanosaurus likely inhabited what is now the Narmada River Valley. The formation is known for being a sauropod nesting site, yielding several dinosaur eggs, and sauropod herds likely chose sandy soil for nesting;[23] though eggs belonging to largetheropods have been found.[24] Sauropodcoprolite remains indicate they lived in a forested landscape, consuming plants such asPodocarpus,Araucaria, andCheirolepidiaceaeconifers;cycads;palm trees; earlygrass; andCaryophyllaceae,Sapindaceae, andAcanthaceae flowering plants.[25]Ferns were also common in India withOsmundaceae,Schizaeales,Dicksoniaceae,Gleicheniaceae andSalviniales being found.[26] The prehistoric snakeSanajeh mainly raided the nests of sauropods for eggs.[27]
India, by the Late Cretaceous, had separated from Madagascar and South America during the break-up of Gondwana, andTitanosaurus lived on an isolated island, likely causingendemism and unique characteristics not seen in other abelisaurids.[22][28] However, despite being an island, there is no evidence of endemic animals with unique traits from Late Cretaceous India, perhaps indicating a continued connection to other parts of the world, likely Africa due to its closer proximity to India than other continents.[29] The similarity between European and Indian sauropodegg taxa suggests an inter-continental migration of animals between India, Europe, and South America during the Cretaceous, despite water barriers.[30]
Several dinosaurs have been described from the Lameta Formation, such as thenoasaurid theropodLaevisuchus;abelisauridsIndosaurus,Indosuchus,Lametasaurus,Rahiolisaurus, andRajasaurus; and the other titanosaurian sauropodsJainosaurus, andIsisaurus. The diversity of abelisauroid and titanosaurian dinosaurs in Cretaceous India indicates they shared close affinities to the dinosaur life of the other Gondwanan continents, which had similar inhabitants.[31][32] The dinosaurs in India probably all went extinct due to volcanic activity around 350,000 years before theCretaceous–Paleogene boundary.[33]
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