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.
Nearly matching ornithomimids in mental swiftness, according to Gao, were the troodontids, at 0.7 EQ. Troodontids were small to medium-sized long-legged dinosaurs with sickle-like claws. They too shared many characteristics with modern-day birds.
Iguanodons, at 0.5 EQ, and hadrosaurids at 0.47 EQ round out the more complex-behaving dino group. "Complexity" for dinos was also linked to birds, as these more sophisticated animals tended to nest, follow bird-like sleeping behaviors and to engage in greater parental doting. Such behaviors, Gao said, "are evolved among those smart animals under the control of a powerful brain."
The researchers were surprised to discover that many top predator dinosaurs, such as Tyrannosaurus rex and allosaurids, had lower EQ values than iguanodons and hadrosaurids.
"I guess that we have to say it is not the body size, but the relative brain size that reflects how well the dinosaur species adapted to their living environment," Gao explained. "It is all about the survival of the fittest."
Slow-Witted Dinosaurs
Brawn definitely did not indicate dino braininess. Wright concluded that many big dinosaurs fell "below the (existing ground bird EQ) range and the sauropods remain the least intelligent."
At the very bottom of the EQ ratings is Diplodocus, with a meager 0.05 EQ. One of the longest known dinosaurs, Diplodocus could measure around 90 feet in length. Twenty feet of that was neck, topped off with a tiny head and an even tinier brain case.
This Jurassic dino predated some of the more complex-behaving earlier dinosaurs. Thinking again of technological innovations, it seems that evolution can produce brainier models as time goes on. Thomas Wagner, program director for the National Science Foundation's Antarctic Earth Sciences fund, explained the phenomenon to Discovery News.
"Think of it like this," Wagner said. "Crylophosaurusellioti (a recently discovered Antarctic dino), at 185 million years old, was a distant ancestor to T. rex, which died out 65 million years ago. I can imagine it would have gotten a lot more sophisticated in 120 million years."
Star Trek Truth?
Dale Russell, curator of vertebrate fossils at the National Museums of Canada, also theorizes that intelligence may improve over evolutionary time. In the 1980's, he modeled what might have happened if troodon, a genus of a relatively small, bird-like dinosaur from the Late Cretaceous Period, had survived the K-T extinction event.
Not unlike the Star Trek Saurians, Russell's modern day troodons would have stood upright -- to hold and balance their brain-heavy heads -- and would have had big eyes, the better with which to see, and shoulders that could have permitted throwing objects.
While history stopped troodon evolution dead in its tracks, modern science is revealing that many dinosaurs were not complete airy boneheads, as their now-empty skulls suggest. As Wright concluded, "Dinosaurs were not nearly as intellectually challenged as once thought."
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