New Titanosaur: Big Body, Small Brain, Major Appetite

A new titanosaur dig includes one of the best dinosaur skulls ever discovered, allowing researchers to reconstruct everything from the dino’s intellect -- or lack thereof -- to its senses and head posture.

Named Sarmientosaurus musacchioi, the new, small-brained dino had good eyesight, hearing tuned to low frequencies, and habitually held its head with its snout facing downward, according to a paper published in the journal PLOS ONE. The head was at the end of a long neck and featured a mouth full of sharp teeth.

The researchers believe that the plant-eating dinosaur lived life basically like a giant weed whacker, sweeping its neck over the ground to find plants that it would grab, but not chew.

“Sarmientosaurus had powerful teeth … but those teeth did not chew,” lead author Rubén Martínez of the Laboratorio de Paleovertebrados of the Universidad Nacional de la Patagonia San Juan Bosco told Discovery News. “(The teeth) would only cut the leaves and the dinosaur would eat them with almost no chewing.”

Co-author Lawrence Witmer of the Ohio University Heritage College of Osteopathic Medicine added that the dinosaur “had a large feeding envelope. When you’re as large as these sauropods were, being able to scarf down a lot of food without having to move saves a lot of energy.”

Witmer estimates that the dinosaur, which lived roughly 95 million years ago, was about 40–50 feet long and weighed 8–12 tons. He and his colleagues consider it to have been a modest-sized titanosaur, given that others could grow to 90 feet in length and weigh as much as 50 tons. They were the largest animals ever to walk the earth.

The new species was excavated in southern Chubut Province, Argentina, near the town of Sarmiento, for which the dino was named. The species name also honors the late paleontologist Eduardo Musacchio, who was a friend of Martínez and other members of the team.

Of the 60 plus species of titanosaur that have been discovered so far, only four are represented by nearly or even reasonably complete skulls. They include Nemegtosaurus, Rapetosaurus, Tapuiasaurus, and now, possibly with the best preserved skull of all, Sarmientosaurus.

The dino certainly did not have a lot of brain matter to weigh down its head. The researchers estimate that the creature's brain was the size of a lime. Witmer said that “Sarmientosaurus certainly was no Einstein and was governed mostly by instinct. It probably had enough intelligence to have some fairly complicated behaviors, but this was not a clever animal by any means.”

At least it could see and hear predators, like the meat-eating Megaraptor. Its cochlear duct was different from that of most other known titanosaurs, and enabled it to hear low-frequency sounds spread out over long distances. Witmer said the ability “could have helped the animals keep track of others in the herd as they spread out over the countryside.”

He added that it might have been a primitive trait inherited from its ancestors. Sarmientosaurus appears to have been an intermediate species on the titanosaur family tree, providing a unique glimpse at evolution in action when compared with additional dinosaurs in the group.

The dinosaur’s well-preserved inner ear, revealed via CT scanning, reveals that it habitually held its snout pointing downward with its eyes directed forward.

As for its long neck, Martínez said that the bones in it were extremely light and nearly hollow with up to 80 percent air.

It's the first non-bird dinosaur to preserve a bizarre structure in the neck that the researchers interpret to have been a long bony tendon. The scientists support the widely held view, however, that birds evolved from two-legged, meat-eating dinosaurs similar to Velociraptor and not from large plant-eaters like Sarmientosaurus.

They suspect that other plant-eating dinosaurs, known as sauropods, had the bony tendon, but that, for some reason, it didn't fossilize in them the way that it did in the Sarmientosaurus remains.

Read more at Discovery News