Titanosaurus

Titanosaurus Temporal range: Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Titanosaurus indicus holotypic distal caudal vertebra
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	†Sauropodomorpha
Clade:	†Sauropoda
Clade:	†Macronaria
Clade:	†Titanosauria
Genus:	†Titanosaurus Lydekker, 1877
Type species
†Titanosaurus indicus Lydekker, 1877
Other species
†T. blanfordi Lydekker, 1879
Synonyms
Titanosaurus blandfordi (sic) Tritonausaurus (sic) Tritonosaurus (sic)

Titanosaurus (

Titanosaurus, literally meaning 'titanic lizard', was named after the mythological

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][2] and the second species, T. blanfordi, was named in 1879.^[3] Both species were named by Richard Lydekker.^[1][3] T. indicus and T. blanfordi are 70 million years old.

A report in PLOS One published by Dhiman et al. (2023) reported that 92 titanosaur clutches were found in Dhar District, Madhya Pradesh, India. There were 256 eggs in three clutch patterns (viz. circular, combination, linear) that are assignable to six oospecies,^[4] which were likely laid by Titanosaurus.

Titanosaurus indicus

The

The known remains of T. 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 paleontologist Dhananjay Mohabey understood that such specimens were lost only because no serious inventory of the collections had been carried out for generations.^[7] He therefore started the Study of Late Cretaceous Tetrapod fossils from Lameta Formation project with support from the University of Michigan, with one of the main goals of locating lost specimens.^[7] In this context, he and Subhasis Sengupta recovered one of the holotype vertebra on 25 April 2012.^[8] 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.^[9]

Part of the fossils that Lydekker assigned to the type specimen of T. indicus, that formed a series of syntypes, was a 1.5 metres (4.9 ft) long femur that had been excavated at the same location in 1871 or 1872 by Henry Benedict Medlicott - specimen GSI K22/754.^[1] In 1933 this was reassigned by Charles Alfred Matley and Friedrich von Huene to Antarctosaurus septentrionalis,^[10] which was moved to the new genus Jainosaurus in 1995.^[11]

Titanosaurus blanfordi

Between 1860 and 1870, geologist

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.[14] 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 a nomen dubium.^[14]

The holotype vertebrae of T. blanfordi were also missing for years and were rediscovered in 2012 by Dhananjay Mohabey and Subhasis Sengupta at the same location as the holotype of T. indicus.^[9]

Classification

Wilson and Upchurch (2003) treated Titanosaurus as a nomen dubium ("dubious name") because they noted that the original Titanosaurus specimens cannot be distinguished from those of related animals.^[14]

Species

As the type genus of Titanosauria, Titanosaurus at times became a wastebasket taxon for a number of titanosaurs, including those not just from India but also southern Europe, Laos, and South America. Only two among these, however, are currently considered species of Titanosaurus: T. indicus and T. blandfordi, both of which are considered nomina dubia.

Other species formerly referred to this genus include:

• "Titanosaurus" rahioliensis - Described based on teeth, this species is now considered an indeterminate
  neosauropod as it shows similarities to Nigersaurus teeth^[14]
• "Titanosaurus" colberti - This species was the most well-known species of Titanosaurus, but has been moved into its own genus, Isisaurus.^[14][15]
• "Titanosaurus" australis - Known from relatively complete remains, but has been renamed Neuquensaurus.^[14]
• "Titanosaurus" nanus - A small species found to be non diagnostic, and hence a nomen dubium.^[14]
• "Titanosaurus" robustus - Now referred to Neuquensaurus.^[14]
• "Titanosaurus" madagascariensis - nomen dubium; UCB 92305 apparently related to Vahiny, while UCM 92829 has been reassigned to Rapetosaurus.^[14]
• "Titanosaurus" falloti - This large species, native to Laos, has disputed affinities. It has been considered synonymous with Tangvayosaurus and Huabeisaurus, but the remains are too fragmentary to be sure.^[14][16][17]
• "Titanosaurus" valdensis - Referred to a new genus, Iuticosaurus, but still considered a nomen dubium.^[14]
• "Titanosaurus" lydekkeri - Also referred to Iuticosaurus, but its relation to I. valdensis is uncertain.^[14]
• "Titanosaurus" dacus - A dwarf titanosaur; now moved to the genus Magyarosaurus.^[14]

References