The biggest creatures to ever walk the Earth had brains smaller than ours. A recent study has shown that those massive dinosaurs with long necks that grazed on vegetation, known as sauropods, actually had relatively tiny brains. Fabien Knoll, from the National Museum of Natural Sciences in Spain, and Lawrence Witmer from Ohio University, analyzed the fossils from a sauropod known as Ampelosaurus, a type of titanosaur, a particularly large sauropod. The fossils had been lying in Cuenca, Spain for 70 million years before being discovered in 2007 during the construction of a railroad track. Knoll and Witmer were pleasantly surprised to find that the Ampelosaurus skull was relatively intact, a rarity for fragile Sauropod skulls. The researchers used CT scanning to determine how big and what shape the brain cavity was. Their technology estimated Ampelosaurus’ brain to be about 3 inches in diameter; it’s body, however, was a whopping 50 feet long. The human brain measures approximately 6 inches. That means our brains are almost twice as big, and our bodies approximately 1/8 as long (and a much smaller proportion in weight), than this monstrous sauropod.

Scientists are still unsure about why Ampelosaurus had such a miniscule brain compared to its enormous body. Perhaps they just didn’t need that much brain. Sauropods had incredibly long necks in order to reach around and up, to find hard-to-reach leaves and branches to munch on. The lengthy neck had to support the head, so a heavy brain wouldn’t have been very efficient.

The study also found that Ampelosaurus’ inner ear was smaller than expected. This beast’s inner ear, which controls an organism’s balance, wasn't very developed and was probably not doing that much work. The researchers say Ampelosaurus most likely moved with deliberate, slow motion and couldn’t jerk its head around quickly. Other sauropods, however, have much more developed inner ears and probably could balance with more ease than Ampelosaurus. Scientists hope to further study inner ear and skull morphology and learn more about the evolutionary progression and branching of the sauropod family.

Read on at

The original research was published in the journal PLoS ONE. The Paleontological Research Institution, Ithaca, New York, is pleased to sponsor Paleontology content for This View of Life. Founded in 1932, PRI has outstanding programs in research, collections, and publications, and is a national leader in development of informal Earth science education resources for educators and the general public.