Scientists have discovered that even the most advanced members of the largest group of dinosaurs ever to walk the Earth still had relatively tiny brains, not more than 3 inches in size.
Researchers analysed the skull of 70-million-year-old fossils of the giant dinosaur Ampelosaurus, discovered in 2007 in Cuenca, Spain.
The reptile - a sauropod - had a long-neck, long-tail and was herbivorous, making them the largest creatures ever to stride the Earth.
Ampelosaurus was a kind of sauropod known as a titanosaur, many if not all of which had armour-like scales covering their bodies, LiveScience reported.
Sauropod skulls are typically fragile, and few have survived intact enough for scientists to learn much about their brains.
By taking scans of the interior of their skull via CT imaging, the researchers developed a 3-D reconstruction of Ampelosaurus’ brain, which was not much bigger than a tennis ball.
“This saurian may have reached 15 meters (49 feet) in length; nonetheless its brain was not in excess of 8 centimetres (3 inches),” study researcher Fabien Knoll, a paleontologist at Spain’s National Museum of Natural Sciences, said in a statement.
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, said.
“They apparently hit on something and stuck with it — expansion of brain size over time wasn’t a major focus of theirs,” said Witmer.
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.
Computer model of dinosaur also revealed the ampelosaur had a small inner ear.
The study was published in the journal PLOS ONE.