Science | Tiny dinosaur had extraordinary hearing and night vision, study finds

TO tiny dinosaur called theropod Shuvuuia, part of a group known as alvarezsaurs, had extraordinary hearing and night vision.

The extremely large lagena – the organ that processes information from incoming sound (called the cochlea in mammals) – is nearly identical in relative size to today’s Barn Owl, suggesting that Shuvuuia it could have hunted in complete darkness.

The finding, featured in Science, was the result of a new study led by University of the Witwatersrand scientist Professor Jonah Choiniere, who sought to investigate how the visual and auditory abilities of dinosaurs and birds compare. The international team of researchers used CT scans and detailed measurements to gather information on the relative size of the eyes and inner ears of nearly 100 species of live birds and dinosaurs Extinct.

To measure hearing, the team measured the length of the lagena. The barn owl, which can hunt in complete darkness just by hearing, has the proportionally longest lagena of all birds.

To assess vision, the team looked at the scleral ring, a series of bones that surround the pupil, of each species. Like a camera lens, the larger the pupil can be opened, the more light can enter, allowing for better vision at night. By measuring the diameter of the ring, the scientists were able to determine how much light the eye can capture.

Optimized vision

The team found that many carnivorous theropods such as Tyrannosaurus and Dromaeosaurus had optimized daytime vision and better-than-average hearing, presumably to help them hunt.

The great lagena of Shuvuuia It was a surprise discovery for Dr. James Neenan, Choiniere’s former postdoc at Wits. “While digitally reconstructing the skull of Shuvuuia, I couldn’t believe the size of lagena … I called Professor Choiniere to take a look. We both thought it could be a mistake, so I processed the other ear, only then did I realize the great discovery we had in our hands. I couldn’t believe what I was seeing when I got there, the ears of dinosaur They weren’t supposed to look like that, “Choiniere said.

The eyes of Shuvuuia They were also notable in that they had some of the proportionally largest pupils ever measured in birds or dinosaurs, suggesting that they could probably see very well at night.

Shuvuuia it was a little dinosaur, the size of a chicken, and lived in the deserts of what is now Mongolia. The skeleton of Shuvuuia It is one of the strangest dinosaurs: it has a fragile, bird-like skull, muscular powerlifter arms with a single claw on each hand, and long legs like roadrunners. This strange combination of characteristics has puzzled scientists since its discovery in the 1990s.

With the new data on the senses of Shuvuuia, the scientific team hypothesizes that, like many desert animals, Shuvuuia It would have foraged for food at night, using its hearing and vision to find prey such as small mammals and insects, using its long legs to quickly run down, and using its strong front legs to pull prey out of burrows or shrubby vegetation.

“Nocturnal activity, digging ability, and long hind legs are characteristic of animals that live in deserts today,” said Choiniere, “but it is surprising to see them all combined into a single species of dinosaur that lived more than 65 million years ago. “

(With information from Europa Press)

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