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 Scientists announced on Tuesday the discovery of the skull as well
as neck bones of a newly identified dinosaur called Sarmientosaurus
that roamed Patagonia 95 million years ago. CT scans of the skull
revealed its brain structure and provided close understanding of its
hearing, sight and feeding behavior.
Sarmientosaurus, about 40-50 feet long (12-15 meters) and 8-12 tons,
belonged to a group called titanosaurs, plant-eating dinosaurs known
for long necks, long tails and huge bodies.
Sarmientosaurus was a medium-sized titanosaur. The largest species
exceeded 100 feet (30 meters) and 50 tons. Of the 60 known
titanosaur species, only four, including Sarmientosaurus, have been
found with complete skulls.
 "The head is key to understanding an animal's biology. It's home to
the brain, sense organs, jaws and teeth - food-gathering mechanisms
- and more," said paleontologist Matt Lamanna of the Carnegie Museum
of Natural History in Pittsburgh.
Titanosaurs were part of a larger group of similar dinosaurs called
sauropods.
"As for its brain, Sarmientosaurus, bless its heart, was not the
sharpest tooth in the jaw," Ohio University anatomist Lawrence
Witmer said.
"Sauropod dinosaurs in general are famous for having the smallest
brain size relative to body size, and Sarmientosaurus was no
exception. Its brain was about the size of a lime yet its body
weighed as much as two or three elephants."
Its skull provided the best information on brain structure for any
sauropod, Witmer said.
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Its hearing organ, the cochlear duct, was long, indicating good
hearing of low-frequency sounds transmitted over long distances,
perhaps to keep track of other members of the herd when they were
out of sight, Witmer said.
Its eye sockets and eyeballs were relatively large, suggesting
vision was particularly important for Sarmientosaurus, Witmer added.
Its inner ear orientation on the skull indicates Sarmientosaurus had
a nose-down head posture and that it fed mostly on ground plants
rather than cropping leaves from tall trees, Witmer said.
"It makes sense to envision Sarmientosaurus standing with its feet
planted and moving that long neck around like the wand of a vacuum
cleaner while the head vacuums up all the low-growing plants in the
area," Witmer said.
The research was published in the journal PLOS ONE.
(Reporting by Will Dunham; Editing by Frances Kerry)
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