By: Charles Choi, LiveScience Contributor
Published: 01/23/2013 06:51 PM EST on LiveScience
An advanced member of the largest group of dinosaurs ever to walk the Earth still had a relatively puny brain, researchers say.
The scientists analyzed the skull of 70-million-year-old fossils of the giant dinosaur Ampelosaurus, discovered in 2007 in Cuenca, Spain, in the course of the construction of a high-speed rail track connecting Madrid with Valencia. The reptile was a sauropod, long-necked, long-tailed herbivores that were the largest creatures ever to stride the Earth. More specifically, Ampelosaurus was a kind of sauropod known as a titanosaur, many if not all of which had armorlike scales covering their bodies.
Sauropod skulls are typically fragile, and few have survived intact enough for scientists to learn much about their brains. By scanning the interior of the skull via CT imaging, the researchers developed a 3-D reconstruction of Ampelosaurus' brain, which was not much bigger than a tennis ball.
Despite being the fruit of a long evolution, the brain of the plant-eating dinosaur called Ampelosaurus sported was tiny, shown here in a 3D reconstruction.
"This saurian may have reached 15 meters (49 feet) in length; nonetheless its brain was not in excess of 8 centimeters (3 inches)," study researcher Fabien Knoll, a paleontologist at Spain's National Museum of Natural Sciences, said in a statement. [Gallery: Stunning Illustrations of Dinosaurs]
The first sauropods appeared about 160 million years earlier than this fossil.
"We don't see much expansion of brain size in this group of animals as they go through time, unlike a lot of mammalian and bird groups, where you see increases in brain size over time," researcher Lawrence Witmer, an anatomist and paleontologist at Ohio University, told LiveScience. "They apparently hit on something and stuck with it — expansion of brain size over time wasn't a major focus of theirs."
For years, scientists have wondered how the largest land animals ever lived with such tiny brains. "Maybe we should flip that question on their end — maybe we shouldn't ask how they could function with tiny brains, but what are many modern animals doing with such ridiculously large brains. Cows may be triple-Einsteins compared to most dinosaurs, but why?" Witmer said.
Their computer model also revealed the ampelosaur had a small inner ear.
"Part of the inner ear is associated with hearing, so the fact it had a small inner ear means it probably wasn't all that good at hearing airborne sounds," Witmer said. "It probably used a kind of hearing we don't think much about, which depends on sounds transmitted through the ground."
The inner ear is also responsible for balance and equilibrium, Witmer said.
"Given what we know about its inner ear, Ampelosaurus probably didn't put a real premium on rapid, quick jerky eye or head movements, which makes sense — these are relatively large, slow-moving, plant-eating animals," he said.
Knoll and his colleagues had previously developed 3-D reconstructions of another sauropod, Spinophorosaurus nigeriensis. In contrast to Ampelosaurus, Spinophorosaurus had a fairly developed inner ear.
"It is quite enigmatic that sauropods show such a diverse inner ear morphology whereas they have a very homogenous body shape," Knoll said. "More investigation is definitely required."
Currently scientists are debating whether sauropods held their heads near the ground, grazing on low vegetation, or high up like giraffes to browse on high leaves. "It could be that learning more about the inner ear could tell us what sauropod neck posture was like," Witmer said.
The scientists detailed their findings online Jan. 23 in the journal PLOS ONE.
Follow LiveScience on Twitter @livescience. We're also on Facebook & Google+.
Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Our 2024 Coverage Needs You
It's Another Trump-Biden Showdown — And We Need Your Help
The Future Of Democracy Is At Stake
Our 2024 Coverage Needs You
Your Loyalty Means The World To Us
As Americans head to the polls in 2024, the very future of our country is at stake. At HuffPost, we believe that a free press is critical to creating well-informed voters. That's why our journalism is free for everyone, even though other newsrooms retreat behind expensive paywalls.
Our journalists will continue to cover the twists and turns during this historic presidential election. With your help, we'll bring you hard-hitting investigations, well-researched analysis and timely takes you can't find elsewhere. Reporting in this current political climate is a responsibility we do not take lightly, and we thank you for your support.
Contribute as little as $2 to keep our news free for all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
The 2024 election is heating up, and women's rights, health care, voting rights, and the very future of democracy are all at stake. Donald Trump will face Joe Biden in the most consequential vote of our time. And HuffPost will be there, covering every twist and turn. America's future hangs in the balance. Would you consider contributing to support our journalism and keep it free for all during this critical season?
HuffPost believes news should be accessible to everyone, regardless of their ability to pay for it. We rely on readers like you to help fund our work. Any contribution you can make — even as little as $2 — goes directly toward supporting the impactful journalism that we will continue to produce this year. Thank you for being part of our story.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
It's official: Donald Trump will face Joe Biden this fall in the presidential election. As we face the most consequential presidential election of our time, HuffPost is committed to bringing you up-to-date, accurate news about the 2024 race. While other outlets have retreated behind paywalls, you can trust our news will stay free.
But we can't do it without your help. Reader funding is one of the key ways we support our newsroom. Would you consider making a donation to help fund our news during this critical time? Your contributions are vital to supporting a free press.
Contribute as little as $2 to keep our journalism free and accessible to all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
As Americans head to the polls in 2024, the very future of our country is at stake. At HuffPost, we believe that a free press is critical to creating well-informed voters. That's why our journalism is free for everyone, even though other newsrooms retreat behind expensive paywalls.
Our journalists will continue to cover the twists and turns during this historic presidential election. With your help, we'll bring you hard-hitting investigations, well-researched analysis and timely takes you can't find elsewhere. Reporting in this current political climate is a responsibility we do not take lightly, and we thank you for your support.
Contribute as little as $2 to keep our news free for all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
Dear HuffPost Reader
Thank you for your past contribution to HuffPost. We are sincerely grateful for readers like you who help us ensure that we can keep our journalism free for everyone.
The stakes are high this year, and our 2024 coverage could use continued support. Would you consider becoming a regular HuffPost contributor?
Dear HuffPost Reader
Thank you for your past contribution to HuffPost. We are sincerely grateful for readers like you who help us ensure that we can keep our journalism free for everyone.
The stakes are high this year, and our 2024 coverage could use continued support. If circumstances have changed since you last contributed, we hope you'll consider contributing to HuffPost once more.
Support HuffPostAlready contributed? Log in to hide these messages.