| Named By: | P. Yadagiri & K. Ayyasami in 1989 |
| Time Period: | Late Cretaceous, 70 Ma |
| Location: | India - Kallemedu Formation |
| Size: | Uncertain since original fossil are now gone and estimates vary considerably |
| Diet: | Herbivore |
| Fossil(s): | Description based upon hip, and leg bones, but these are now lost to science and only the original description and line drawings remain |
| Classification: | | Chordata | Reptilia | Dinosauria | Saurischia | Sauropoda | Titanosauria | |
Bruhathkayosaurus (meaning "huge bodied lizard") is a dinosaur, with remains found in India, claimed by some researchers to have been the largest dinosaur that ever lived. Estimates of size exceed the titanosaur Argentinosaurus, as longer than 35 metres (115 ft) and weighing over 80-100 tons. The accuracy of this claim, however, has been mired in controversy and debate. All the estimates are based on Yadagiri and Ayyasami's 1989 paper, which announced the find (see below: Size estimates).
The authors originally classified the dinosaur as a theropod, a member of a large group of bipedal, mostly carnivorous dinosaurs that includes Tyrannosaurus, but several unpublished opinions, beginning in 1995, suggested that the remains actually belonged to a sauropod (probably a titanosaur), a member of a very different group of quadrupedal, herbivorous dinosaurs with long necks and tails. In 2006, the first published reference to Bruhathkayosaurus as a sauropod appeared in a survey of Malagasy vertebrates by David Krause and colleagues.
Until the remains are properly described, the validity of the genus and any size estimates will be questionable. It is possible that the only known remains of Bruhathkayosaurus have been lost to monsoon flooding. Thus the only remaining evidence is likely the very simple and indistinct line-drawings of the bones.