Dino Intelligence: Dim to Somewhat Smart

Jan. 4, 2008 -- A 1997 episode of "Star Trek: Voyager" featured a group of extraterrestrial dinosaurs that managed to survive Earth's mass extinction event 65 million years ago. Safe on another planet, they evolved into a highly intelligent new "race" called the Saurians.

Such impressive dinosaur intelligence may exist in fiction, but new research is shaking up preconceived notions about just how smart many dinos actually were. The truth seems to be that these now-extinct animal wonders ran the intellectual gamut from slow-witted to somewhat smart.

Reconstructing Dinosaur Brains

Made of soft tissue, brain matter isn't ideal for historical preservation. The organic matter that made up dinosaur brains decayed millions of years ago. Paleontologists, however, are recreating the basic features of dino brains based on endocraniums, or the inside surfaces of dinosaur skulls.

A new paper published in this month's Palaeoworld, for example, describes the basic endocranial contents, and activity, of Psittacosaurs. These two-footed dinosaurs possessed unique parrot-like beaks and occurred in the Early Cretaceous period in East Asia around 123 million years ago.

Ke-Qin Gao and his colleagues CT scanned three near-complete Psittacosaur skulls from China. During this process, a thin X-ray beam produces images in slices, which can be virtually stacked together to reveal objects in detailed 3-D.

"The 3-D image of the endocast serves as the mold of a dinosaur brain, from which we can identify the brain structures," Gao, a researcher at Peking University's School of Earth and Space Sciences, told Discovery News.

EQ Linked to IQ

Gao explained that he and other scientists use an Encephalization Quotient, or EQ, to speculate upon the complexity, or lack thereof, of brain activity in dinosaurs. The EQ is a ratio of brain mass to body size. When it's used on existing creatures, it seems to provide an accurate picture of overall brain power within a species. Human EQ has been rated between 6.0 and 8.0.

Before the new study, paleontologists thought that Psittacosaurus, along with their ceratopsian relatives, had tiny brains and low EQ's. A 1996 Journal of Earth Sciences paper by D.A. Russell and X.J. Xhao mentioned that "the small brain size of Psittacosaurus implies a very restrictive behavioral repertoire relative to that of modern mammals of similar body size." In other words, they believed these dinosaurs were rather dumb.

In fact, the latest findings instead rate Psittacosaurus as having an EQ of 0.31, which is not brilliant, but not bad. It even puts the smallish parrot-beaked dinos ahead of protoceratops, with its 0.19 EQ, and 0.11-EQ triceratops. Both were later, distant relatives of Psittacosaurus.

True Bird Brains

Paleontologists are reevaluating their figures because traditionally it was thought that brain size in dinosaurs mirrored that of reptiles, meaning the brain occupied around 50 percent of the endocranial volume. The marks on the inside of dino skulls, however, suggest dinosaur brains more closely matched the size of bird and mammal brains, at least in the way that the grey matter filled the endocranial cavity.

Rebekah Wright, a researcher in the Department of Geosciences at the University of Arizona, believes dinosaur brains occupied "the entire brain case."

"Because it is now accepted that birds are the closest relatives to dinosaurs, it is reasonable to believe that dinosaur intelligence should be modeled on that of birds rather than reptiles," she said.

The Smartest Dinos

Gao and his team analyzed their own data, as well as that of prior researchers, to come up with a list for Discovery showing how dinosaurs rate in terms of EQ. A high rating correlates to behavioral complexity, whereas a low rating suggests a more simple set of behaviors. It's like comparing a 1977 Apple II computer with a new iMac. Both work, but the latter builds on the basic functions to perform additional skills and in a more complex way.

Ornithomimids top the dino EQ chart with a 0.8 rating. These beast-footed, two-legged dinosaurs bore a passing resemblance to modern ostriches. Fleet footed and baring powerful claws, they were probably among the fastest of all dinosaurs.