Want to know how well a dinosaur could see, hear and smell? Get inside its head! That’s what a group of researchers from the U.K. and U.S. did when they recreated the brain of a therizinosaur called Erlikosaurus andrewsi — a 10-foot-long feathered theropod that lived in what is now Mongolia during the Cretaceous period, about 90 million years ago.
Erlikosaurus is a member of the bird-like “predatory” dinosaur lineage that includes fearsome hunters like Velociraptor, but scientists believe that Erlikosaurus was a peaceful plant-eater. Did the change from predator to prey affect the brain of animals like Erlikosaurus? To test the hypothesis, a team of paleontologists decided to create 3-D models of an Erlikosaurus brain and inner ear and study the areas that corresponded to senses like sight, smell and hearing.
The paleontologists, Stephan Lautenschlager and Emily Rayfield of the University of Bristol, Perle Altangerel of the National University of Ulaanbaatar, Lindsay Zanno of the North Carolina Museum of Natural Sciences and North Carolina State University, and Lawrence Witmer of Ohio University, used high-resolution CT scanning and 3-D computer visualization to look at how the brain of Erlikosaurus andrewsi fit inside its skull, and which regions of the brain were well-developed.
They found that Erlikosaurus most likely had excellent senses of smell, hearing and balance, and that it was also quite smart, compared to other dinosaurs. If Erlikosaurus was a plant-eater, it still had the sensory powers of a predator. The findings raise questions about how senses evolve and whether it ever makes sense to go backward on the sensory scale. In this case, Erlikosaurus may have just inherited its good sense from its predatory ancestors.
In Erlikosaurus’ case, the researchers theorize that a good sense of smell may have come in handy in sniffing out edible varieties of plants, while hearing and speed would aid in evading predators. “Once you’ve evolved a good sensory toolkit it’s probably worth hanging on to, whether you’re hunting or being hunted,” Zanno says.
The findings appear online in PLOS One.
—Tracey Peake, NC State University News Services
PLOS One paper link: http://dx.plos.org/10.1371/journal.pone.0052289 
Video link: http://www.oucom.ohiou.edu/dbms-witmer/Erlikosaurus_brain.htm 
Blog post: Did Plants Make Feathered Dinosaurs Dumb?  by Lindsay Zanno
Reconstructed soft tissues in the head of Erlikosaurus: brain (blue), cranial nerves (yellow), and inner ear (pink).