Study Peers Into Dinosaur Heads
December 20, 2012

Brain Study Helps Unravel Characteristics Of ‘Black Sheep’ Dinosaur

Lee Rannals for — Your Universe Online

Scientists found one dinosaur species had particularly well developed senses of smell, hearing and balance, which could be attributed to the extinct animal's big forehead.

Scientists reported in PLOS ONE the well-developed senses in therizinosaurs might have affected or benefited from an enlarged forebrain.

Researchers were surprised by the findings, because exceptional sensory abilities would be expected from predatory creatures, but not plant-eating animals such as therizinosaurs.

This species of dinosaurs are part of the theropod dinosaurs, which lived between 145 and 66 million years ago. Members of the group evolved up to 23 feet, with more than 20 inch long claws on their forelimbs, elongated necks, and a coat of down-like feathers along their bodies.

The dinosaurs were closely related to the infamous Tyrannosaurus rex and Velociraptor, but were very different in that they were peaceful herbivores. One could say they were more of the black sheep of the family.

A group of palaeontologists decided to take a peak into the heads of these enigmatic dinosaurs because of their peculiar distinct characteristics from their relatives.

They studied the brain and inner ear anatomy of therizinosaurs using high-resolution CT scanning and 3D computer visualization to find out more about their sensory and cognitive capabilities. The team also set out to understand how these characteristics evolved with the transition from meat to plant eating.

The team's focus of the study was the skull of Erlikosaurus andrewsi, a 10- to 13-foot therizinosaur that lived more than 90 million years ago in Mongolia.

Stephan Lautenschlager of Bristol University's School of Earth Sciences, who was the lead author of the paper, said they found this creature would've used its skill set to its advantage.

"Our results suggest that therizinosaurs would have used their well-developed sensory repertoire to their advantage which, for herbivorous animals, must have played an important role in foraging, in the evasion of predators or in social complexity," Lautenschlager said in a statement.

"This study sheds a new light on the evolution of dinosaur senses and shows it is more complex than we thought."

Professor Lindsay Zanno of the North Carolina Museum of Natural History and North Carolina State University, co-author of the study, agreed with Lautenschlager.

"Once you've evolved a good sensory toolkit, it's probably worth hanging on to, whether you're hunting or being hunted," Zanno said in the statement.

The brain tissue is long gone from the fossil skulls, but the researchers can use CT scanning to visualize the cavity the brain once occupied, and then generate 3D computer renderings of the olfactory bulbs and other brain parts, according to co-author Lawrence Witmer, Chang Professor of Paleontology at the Ohio University Heritage College of Osteopathic Medicine.

The study has important ramifications for understanding how sensory function evolved in different dinosaur groups and whether it was developed as a response to their environment or inherited by their ancestors.