Unveiling the Titanosaur, which may be the world’s largest dinosaur

A 37-meter-long "prehistoric lawnmower" fills a room at the Natural History Museum.

NEW YORK—Today, the American Museum of Natural History dropped the curtain to reveal one of the biggest paleontological finds of recent years. Everything in that sentence is literal—the museum lowered a curtain to reveal a full-sized cast of the Titanosaur, a species that may be the largest dinosaur ever discovered.

The find itself made news when images came out of paleontologist Diego Pol lying on the femur of the skeleton, which is roughly the size of a sofa (though far less comfortable). Since then, the team from the Museo Paleontologico Egidio Feruglio (MPEF) has excavated more than 200 bones, representing 70 percent of the skeleton. Four of those bones (each over a meter long) are also on display at the exhibit. The skeleton on display is made of lightweight fiberglass casts, as the actual bones would weigh far too much to support—the femur alone is roughly 500kg. It's the first outside of the MPEF.

The partnership between MPE and the AMNH was a natural one, as Pol got his PhD there. And he was back on hand for the Titanosaur's unveiling.

Since this individual belongs to a species that hasn't been formally described, there's no official name to give it. They do know, however, that it's not a mature adult—certain bones in these animals fuse when growth stops, which didn't happen here. The researchers on hand said that they'd be able to count features on certain bones and eventually estimate its actual age.

Whatever its age was, it clearly grew up fast. Pol said that the largest sauropod eggs were roughly the size of a volleyball. This young adult was roughly 37 meters long (122 feet) and weighed in at an estimated 63 metric tons.

If you'd imagine proportions like this would make for an impressive display, you'd be absolutely right. The skeleton filled an entire room that could easily fit hundreds of people, and it was arranged so that its head jutted out the doorway and into the hall beyond. From a distance, everything looks roughly proportional, so it's difficult to appreciate just how big everything is. It's only when you drop your gaze low enough to see how the legs compare to full grown people that the size of it is really driven home.

While the species hasn't been described yet, researchers already know a fair bit about it based on the large number of bones and comparison to other species of Titanosaur. Mike Novacek, the AMNH's curator of the Division of Paleontology, told us a little about them. This particular group is distinctive in part because of its size, but it also has skeletal features such as long neck vertebrae and a thick tail.

It also has distinctive teeth. Although they're not sharp, they're pointier than you'd expect from a herbivore. "The teeth worked like big rakes," Novacek told Ars, adding that the dinosaur simply obtained as much foliage as possible but didn't actually chew it. And, while sauropods are often depicted with their necks nearly vertical, they simply couldn't flex that way—Novacek said that they were generally just held horizontally.

To eat, scientists surmise, the animal moved its neck across a large arc, then moved slightly forward and repeated the process—Novacek called them "prehistoric lawnmowers." In the later parts of the Cretaceous, the site the animals were in (present-day Patagonia) probably looked a lot like the African savannah, although with a very different collection of plants than you'd find there now. In fact, most of the plants at the time probably had lower nutritional content than today's flowering plants, forcing the animal's feeding to be hyper-efficient.

We'll probably learn a lot more about this Titanosaur (including its name) when it's formally described. But in the mean time, if you're passing through New York, it's worth spending some time to marvel at it.