Jainosaurus

*Jainosaurus septentrionalis*

**Jainosaurus** is a Primitive Titanosaur from late Cretaceous India. It was 70.5 feet (21.5 meters) and weighed 3 tons (6,000 lbs). A giant Sauropod from the end of the Age of Dinosaurs in India, once thought to be a species of Antarctosaurus.

## Etymology

The specific name of *J. septentrionalis* means "northern" in Latin, a reference to the fact that the species was discovered on the Northern hemisphere whereas *Antarctosaurus* means "saurian from the Southern hemisphere" because its type species *Antarctosaurus wichmannianus* was found in Argentina. The generic name honours the Indian paleontologist Sohan Lal Jain, who worked on the cranial nerve impressions in the skull; and in 1982 published a study about the results. Ironically, Jain himself considered the remains synonymous with *Titanosaurus* in the 1997 description of *Isisaurus*. However, Wilson and Upchurch (2003) rejected the synonymy of *Jainosaurus* and *Titanosaurus* due to the dubious status of the latter.

## History

The type species of *Jainosaurus*, *J. septentrionalis* has a long and complex taxonomic history closely connected to the history of the problematic genera *Titanosaurus* and *Antarctosaurus*. The first known remains attributable to *Jainosaurus*, the humerus GSI K22/754, was discovered in 1871 or 1872 by Henry Benedict Medlicott, and the holotype remains were found by Charles Alfred Matley between 1917 and 1920 near Jabalpur in the Lameta Formation. These were named *Antarctosaurus septentrionalis* by Friedrich von Huene and Matley in 1933.

In 1995 Adrian Paul Hunt *et al.*, believing *Antarctosaurus* to belong to Dicraeosauridae, made the clearly titanosaurian *Antarctosaurus septentrionalis* the type species of a new genus, *Jainosaurus*, and determined that the braincase, GSI IM K27/497, should be the lectotype. *Jainosaurus* was further distinguished from *Antarctosaurus* by details of the braincase.

In 2009, Jeffrey Wilson and others made a detailed reassessment of *Jainosaurus septentrionalis* and confirmed its validity. The postcrania, which had been assumed lost, were shown to be largely present in the collection of the Geological Survey of India at Calcutta. They include: dorsal rib fragments (GSI K20/326, K27/425); a caudal vertebra (GSI K20/317), four chevrons (GSI K27/492–494, 496), the left and right scapula (only a cast still extant); a sternal plate (GSI K20/647); a humerus (lacking an inventory number), a radius (GSI K27/490) and an ulna (GSI K27/491). In 1996 Sankar Chatterjee referred a second braincase to the species: ISI R162. Some material from Pakistan also possibly belongs to *Jainosaurus*.

Wilson e.a. concluded that *Jainosaurus* is a valid taxon, clearly distinguishable from *Isisaurus*. It would have been a fairly derived member of the Titanosauria, more closely related to South American forms like *Pitekunsaurus*, *Muyelensaurus* and *Antarctosaurus* than to *Isisaurus* or *Rapetosaurus*.

## JPInstitute.com Description

Jainosaurus was a large, long-necked plant-eater that lived in India. It was a titanosaur, the same family as Argentinosaurus. These giants were among the last dinosaurs to live on Earth.

There is some discussion, based on the paucity of remains for Jainosaurus, that this dinosaur is a Titanosaurus. It has been suggested that the distinctions between Jainosaurus and Titanosaurus are related to gender and not genus.

## Links

http://web.archive.org/web/20040420195456fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_jaino.html#