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This Chicken-Sized Dinosaur Had Excellent Night Vision and Road-Runner Legs

The little dino has long been a mystery to palaeontologists.
Shuvuuia deserti artist's reconstruction
An artist's reconstruction of Shuvuuia deserti. Image: Viktor Radermaker

Dinosaur fossils found around the world have piqued curiosity and more questions about their lives. To understand these iconic extinct animals, scientists have done everything from microdosing alligators with ketamine to understand dinosaur hearing better to reconstructing a dinosaur’s butthole.
Now, in a new study led by the University of Witwatersrand in South Africa, palaeontologist Jonah Choiniere has found that the Shuvuuia deserti - a dino that looked like a bird, was the size of a chicken and pronounced as shu-VOO-ee-ah - had extraordinary hearing and night vision. The study was published in the journal Science


Shuvuuia was a small dinosaur, about the size of a chicken, and was first discovered in 1998. It lived in the deserts of what is now Mongolia. Thanks to its unique appearance, the Shuvuuia has always bamboozled scientists. It had a fragile, bird-like skull, brawny, weightlifter arms with a single claw on each hand, and long, roadrunner-like legs. 

The Shuvuuia wasn’t the only dinosaur being researched in this study. Scientists used CT scans and detailed measurements to collect information about the relative size of the eyes and inner ears of nearly 100 living bird and extinct dinosaur species. The Shuvuuia was a theropod - the clade of dinosaurs that walked on two legs. All modern birds are the direct descendants of theropod dinosaurs, such as velociraptors and the mighty T-rex.

In order to assess the Shuvuuia’s hearing levels, the team measured the length of the lagena. The lagena is the organ that processes incoming sound information; this organ is known as the cochlea in mammals.

An artistic recreation of what the shuvuuia dinosaur might have looked like

An artistic recreation of what the shuvuuia might have looked like. Credit: Viktor Radermaker

Then, the team then assessed its vision. They examined the scleral ring, a series of bones surrounding the pupil. Just like a camera lens, the larger the pupil can open, the more light can get in, enabling better vision at night. By measuring the diameter of the ring, scientists could tell how much light the eye can gather.

Carnivorous dinosaurs such as Tyrannosaurus and Dromaeosaurus had vision optimised for the daytime, and better-than-average hearing presumably to help them hunt. However, the Shuvuuia had both, extraordinary hearing and night vision. The dino, referred to as “diminutive” by scientists, is a part of a group of small size dinos known as alvarezsaurus. Scientists have drawn comparisons to the barn owl since their lagena sizes are similar. The barn owl can hunt in complete darkness using hearing alone. This helped scientists understand that the Shuvuuia probably hunted at night too.  


But no one was really expecting the Shuvuuia to have extraordinary hearing. James Neenan, the joint lead author of the study said in a press statement, “As I was digitally reconstructing the Shuvuuia skull, I couldn't believe the lagena size.” He then called Choiniere to have a look. “We both thought it might be a mistake, so I processed the other ear - only then did we realise what a cool discovery we had on our hands!” 

Choiniere was equally stunned, “I couldn't believe what I was seeing when I got there - dinosaur ears weren't supposed to look like that!” he exclaimed.

Prof. Jonah Choiniere holding a 3D printed model of the lagena of Shuvuuia deserti

Prof. Jonah Choiniere holding a 3D printed model of the lagena of Shuvuuia deserti. Photo via Wits University

The team reported that the eyes of Shuvuuia had some of the proportionally largest pupils yet measured in birds or dinosaurs, suggesting that it could likely see very well at night.

With this data, scientists believe that like many desert animals, the Shuvuuia would have foraged at night, using its extraordinary sense of hearing and vision to find prey. The chicken-looking dino would prey on small mammals and insects and use its long legs to run that prey down. “Shuvuuia might have run across the desert floor under cover of night, using its incredible hearing and night vision to track small prey such as nocturnal mammals, lizards and insects,” said Choiniere.

The Shuvuuia’s characteristics live on in today’s species too. “Nocturnal activity, digging ability, and long hind limbs are all features of animals that live in deserts today,” said Choiniere, “but it's surprising to see them all combined in a single dinosaur species that lived more than 65 million years ago.”

The study of dinosaurs continues to evolve, but the Shuvuuia certainly had an active nightlife. “This really shows that dinosaurs had a wide range of skills and adaptations that are only just coming to light now,” Roger Benson, one of the authors in the study told Reuters. “We find evidence that there was a thriving ‘nightlife’ during the time of dinosaurs.”

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