Shuvuuia deserti: Desert-Living Dinosaur Had Extraordinary Vision and Hearing
Shuvuuia deserti, a species of alvarezsauroid dinosaur that lived during the Late Cretaceous period in what is now Mongolia, had extreme low-light vision and specialized hearing acuity, rivaling that of today’s barn owl.
“Owls and nightbirds are nocturnal hunters of active prey that combine visual and hearing adaptations to overcome limits on sensory performance in low light,” said Professor Jonah Choiniere from the Evolutionary Studies Institute at the University of the Witwatersrand and colleagues.
“Such sensory innovations are unknown in non-avian theropod dinosaurs and are poorly characterized on the line that leads to birds.”
In the new study, the researchers used CT scanning and detailed measurements to collect information on the relative size of the eyes and inner ears of nearly 100 living bird and extinct dinosaur species.
To measure hearing, they looked at the lagena, the organ that processes incoming sound information.
The barn owl, which can hunt in complete darkness using hearing alone, has the proportionally longest lagena of any bird.
To assess vision, the scientists looked at the scleral ring, a series of bones surrounding the pupil, of each species.
However, a diminutive theropod dinosaur species called Shuvuuia deserti had both extraordinary hearing and night vision.
The extremely large lagena of the species is almost identical in relative size to today’s barn owl, suggesting that Shuvuuia deserti could have hunted in complete darkness.
Its eyes had some of the proportionally largest pupils yet measured in birds or dinosaurs, suggesting that they could likely see very well at night.
The authors hypothesize that, like many desert animals, Shuvuuia deserti would have foraged at night, using its hearing and vision to find prey like small mammals and insects, using its long legs to rapidly run that prey down, and using its strong forelimbs to pry the prey out of burrows or shrubby vegetation.
“Nocturnal activity, digging ability, and long hind limbs are all features of animals that live in deserts today,” Professor Choiniere said.
“But it’s surprising to see them all combined in a single dinosaur species that lived more than 65 million years ago.”
The findings appear in the journal Science.
Jonah N. Choiniere et al. 2021. Evolution of vision and hearing modalities in theropod dinosaurs. Science 372 (6542): 610-613; doi: 10.1126/science.abe7941