Where The New Titanosaur Weighs in Among the Biggest Dinosaurs Ever

This titanosaur likely reached lengths of 122 feet and weighed up to seven tons, as much as 10 African elephants, and was unveiled January 14 at New York's American Museum of Natural History. AMNH

The American Museum of Natural History (AMNH) in Manhattan unveiled what may be the largest known dinosaur in the world on Thursday morning, known for now simple as the titanosaur. The creature is believed to have reached lengths of 122 feet long and weighed 70 tons—equal to 10 African elephants. The cast of its skeleton is so big that the animal's 39-foot-long neck sticks out of the entrance of room in which it is housed, cheekily peering at approaching visitors. Its back would've reached 20 feet in the air, and it easily could have had a looked into a fourth-story window by raising its small head.

Researchers have uncovered more than 220 bones of six different titanosaurs at a rural location in Argentina, and they believe they have now found about 70 percent of the animal's complete skeleton, says Diego Pol, with the Museum of Paleontology Egidio Feruglio, in the Patagonia region of Argentina. The shape of the rest of the bones on display, which are all plaster-like casts (as the bones are too heavy to exhibit), were inferred from the shape of related dinosaurs.

"Certainly we think this is the biggest dinosaur," Pol says, while acknowledging that estimations of lengths are difficult to make from skeletons.

Workers install the titanosaur cast in the Miriam and Ira D. Wallach Orientation Center at the American Museum of Natural History. AMNH/D.Finnin

Over the years, as our knowledge about dinosaurs has grown, the designation of "largest dinosaur" has shifted a few times. Today, it's still a controversial subject. The AMNH's recent find is so new that it doesn't yet have a scientific name. In addition, there are several species of "titanosaurs," so it can all get a bit confusing. To help sort it out, here's a look at some of the strongest contenders for biggest dino ever over the years.

Amphicoelias fragillimus

In the late 1800s, famed paleontologist Edward Drinker Cope described finding a single dinosaur vertebra in central Colorado, which allegedly measured 5 feet in length. Cope and his team estimated that would mean an adult of the species, named Amphicoelias fragillimus, would've reached a length of 190 feet. This bone was supposedly shipped to the AMNH around 1897, and there is a brief description of the bone in the organization's archive. But when the museum's collection was reviewed by two scientists in 1921, they found no trace of it, writing "the type of this species has not been found in the Cope Collection, and its characters cannot be clearly determined." Many now think that the bone never existed or wasn't properly described.


Beginning in the 1970s, scientists made a number of new discoveries, challenging the idea of what was the biggest known dinosaur. All of the species to follow (at least the ones that have held up to scrutiny) are classified as sauropods, a type of long-necked, long-tailed herbivore.

The so-called Ultrasaurus was discovered in 1979 and briefly thought to be the biggest dino, reaching lengths of 90 feet and a weight of 180 tons. But it was later revealed that the bones of the proposed species actually came from an Brachiosaurus and a Supersaurus, which were jumbled together in a quarry.

Paleontologist James Jensen stands by forefoot of Ultrasaurus. James Jenson / public domain


The reputation of the Supersaurus has held up better. Initially estimated to be between 115 and 147 feet long, it's now thought to have measured about 110 feet in length, and coming in at a light (for its size) 45 tons.


In 1991, paleontologist David Gillette said he'd identified the largest of the sauropods, with a length between 127 and 170 feet. Further examination revealed that Gillette had overestimate the size: He was basing his numbers in part on a vertebrae he thought came from near the tail but should've actually been placed closer to the hips. That reduced the estimated size to a (still massive) 110 feet. By 2004, scientists agreed that Seismosaurus was just very large type of Diplodocus. It's likely length has since been downgraded to an estimated 108 feet.


The incomplete skeleton of this behemoth was discovered in Argentina in 1991, and thought to reach lengths above 100 feet, perhaps as long as 115 feet.