Metro

  • Written by Lars Schmitz, Associate Professor of Biology, Scripps College

Today, barn owls, bats, leopards and many other animals rely on their keen senses to live and hunt under the dim light of stars. These nighttime specialists avoid the competition of daylight hours[1], hunting their prey under the cloak of darkness, often using a combination of night vision and acute hearing.

But was there nightlife 100 million years ago? In a world without owls or leopards, were dinosaurs working the night shift? If so, what senses did they use to find food and avoid predators in the darkness? To better understand the senses of the dinosaur ancestors of birds, our team[2] of paleontologists[3] and paleobiologists[4] scoured research papers and museum collections looking for fossils that preserved delicate eye and ear structures. And we found some.

Using scans of fossilized dinosaur skulls, in a paper published in the journal Science on May 6, 2021[5], we describe the most convincing evidence to date for nocturnal dinosaurs. Two fossil species – Haplocheirus sollers and Shuvuuia deserti – likely had extremely good night vision. But our work also shows that S. deserti also had incredibly sensitive hearing similar to modern-day owls. This is the first time these two traits have been found in the same fossil, suggesting that this small, desert-dwelling dinosaur that lived in ancient Mongolia was probably a specialized night-hunter of insects and small mammals.

Nocturnal dinosaurs: Night vision and superb hearing in a small theropod suggest it was a moonlight predator Shuvuuia deserti had acute hearing and low-light vision that would have allowed it to hunt at night. Viktor Radermaker, CC BY-ND[6]

Looking to theropods

By studying fossilized eye bones, one of us, Lars Schmitz, had previously found that some small predatory dinosaurs may have hunted at night[7]. Most of these potentially nocturnal hunters were theropods, the group of three-toed dinosaurs that includes Tyrannosaurus rex and modern birds. But to date, fossils for only 12 theropod species included the eye structures[8] that can tell paleontologists about night vision.

Our team identified four more species of theropods with clues for their sense of vision – for a total of 16. We then looked for fossils that preserve the structures of the inner ear and found 17 species. Excitingly, for four species, we were able to get measurements for both eyes and ears.

A close up photo of the skull of _S. deserti_ showing a large eye socket. The eye socket – and specifically the sclerical ring – of S. deserti shows an eye with a very large pupil capable of letting in large amounts of light. Mick Ellison/American Museum of Natural History, CC BY-ND[9]

Eye bones built for night vision

Scleral ossicles are thin, rectangular bone plates that form a ring-like structure surrounding the pupils[10] of lizards as well as birds and their ancestors – dinosaurs. Scleral rings define the largest possible size of an animal’s pupil and can tell you how well that animal can see at night[11]. The larger the pupil compared to the size of the eye, the better a dinosaur could see in the dark.

An owl skull with a cone like ring attached to the eye socket. This owl skull clearly shows the large scleral ring that helps animals see in darkness. David J. Stang/WikimediaCommons, CC BY-SA[12][13]

Since the individual bony ossicles of these rings fell apart after these animals died more than 60 million years ago, our team made scans of the fossils and then digitally reconstructed the eyes. Of all the theropods we examined, H. sollers and S. deserti had some of the proportionally largest pupils.

S. deserti‘s pupil made up more than half of its eye, very similar to night-vision specialists that live today like geckos and nightjars. Our team then compared the fossils to 55 living species of lizards and 367 species of birds with known day or night activity patterns. According to the statistical analyses our team performed, there is a very high chance – higher than 90% – that H. sollers and S. deserti were nocturnal.

But those were not the only two theropods our team looked at. Our analysis also found a few other likely nighttime specialists – such as Megapnosaurus kayentakatae – as well as daylight specialists like Almas ukhaa. But we also found some species – like Velociraptor mongoliensis – with eyesight seemingly adapted for medium light levels. This might suggest that they hunted around dawn or dusk.

Nocturnal dinosaurs: Night vision and superb hearing in a small theropod suggest it was a moonlight predator Molds of the inner ear canal from a barn owl (left) and S. deserti (right) are almost identical, suggesting that the small dinosaur had incredible hearing. Jonah Choiniere/Wits University, CC BY-ND[14]

Incredible ears of a dinosaur

In today’s nocturnal animals, hearing can be as important as keen eyesight[15]. To figure out how well these extinct dinosaurs could hear, we scanned the skulls of 17 fossil theropods to decipher the structure of their inner ears and then compared our scans to the ears of modern animals.

All vertebrates have a tube-like canal called the cochlea deep in their inner ear. Studies of living mammals and birds show that the longer this canal, the wider the range of frequencies an animal can hear[16] and the better they can hear very faint sounds[17].

Our scans showed that S. deserti had an extremely elongated inner ear canal for its size – also similar to that of the living barn owl and proportionally much longer than all of the other 88 living bird species we analyzed for comparison. Based on our measurements, among dinosaurs, we found that predators had generally better hearing than herbivores. Several predators – including V. mongoliensis – also had moderately elongated inner ears, but none rivaled S. deserti’s.

The life of a nocturnal dinosaur

By studying the sensory abilities of dinosaurs, paleontologists like us not only are learning what species roamed the night, but can also begin to infer how these dinosaurs lived and shared resources.

S. deserti had extreme night vision and sensitive hearing[18], and this little dinosaur probably used its incredible senses to hunt prey at night. It could likely hear and follow rustling from a distance before visually detecting its prey and digging it up from the ground with its short single-clawed arms. In the dry, desert-like habitats of millions of years ago, it might have been an evolutionary advantage to be active in the cooler temperatures of the night.

But according to our analysis, S. deserti wasn’t the only dinosaur active at night. Other dinosaurs like V. mongoliensis and the plant-eating Protoceratops mongoliensis both lived in the same habitat and had some level of night vision.

Paleontologists currently do not know the full suite of animals that shared S. deserti’s extreme nocturnal lifestyle in the ancient deserts of Mongolia – it is rare to find fossils with the right bones intact that allow paleontologists to investigate their senses. However, the presence of a specialized night forager highlights that much like today, some dinosaurs avoided the dangers and competition of daylight hours and roamed under the stars.

[Get the best of The Conversation, every weekend. Sign up for our weekly newsletter[19].]

References

  1. ^ nighttime specialists avoid the competition of daylight hours (doi.org)
  2. ^ our team (scholar.google.com)
  3. ^ paleontologists (scholar.google.com)
  4. ^ paleobiologists (scholar.google.com)
  5. ^ published in the journal Science on May 6, 2021 (science.sciencemag.org)
  6. ^ CC BY-ND (creativecommons.org)
  7. ^ may have hunted at night (doi.org)
  8. ^ 12 theropod species included the eye structures (doi.org)
  9. ^ CC BY-ND (creativecommons.org)
  10. ^ ring-like structure surrounding the pupils (doi.org)
  11. ^ can see at night (doi.org)
  12. ^ David J. Stang/WikimediaCommons (commons.wikimedia.org)
  13. ^ CC BY-SA (creativecommons.org)
  14. ^ CC BY-ND (creativecommons.org)
  15. ^ hearing can be as important as keen eyesight (doi.org)
  16. ^ wider the range of frequencies an animal can hear (doi.org)
  17. ^ very faint sounds (doi.org)
  18. ^ S. deserti had extreme night vision and sensitive hearing (doi.org)
  19. ^ Sign up for our weekly newsletter (theconversation.com)

Authors: Lars Schmitz, Associate Professor of Biology, Scripps College

Read more https://theconversation.com/nocturnal-dinosaurs-night-vision-and-superb-hearing-in-a-small-theropod-suggest-it-was-a-moonlight-predator-160152

Metropolitan republishes selected articles from The Conversation USA with permission

Visit The Conversation to see more

Entertainment News

Elijah Rock - My Musical Journey

I started my musical journey singing in the Lee Heights Community Church children’s choir. People often ask me how old I was when I first discovered I could sing and interestingly enough, an age doesn’t come to mind. I can’t remember a time when I ...

Elijah Rock - avatar Elijah Rock

What is a Musician?

As a band manager, when I think about what a musician truly is, I feel like I’m on the outside looking in – but I also think my role with Greye gives me a perspective that is unique and objective and probably different than they might see themselve...

Karen Wardle, Band Manager for Greye, Daytona Beach, Florida - avatar Karen Wardle, Band Manager for Greye, Daytona Beach, Florida

Krisanthi Pappas - My Musical Journey

The Joy Of Music Persisted My musical journey began with me singing as a child in my backyard. For the sheer joy  of singing. The journey has taken me through many peaks and valleys but always  focused on the joy, my latest success has been throu...

Krisanthi Pappas - avatar Krisanthi Pappas

MICHAEL MESEY - WHAT MUSIC MEANS TO ME

As Chuck Berry’s go-to special show drummer for many years, I had the honor of meeting and playing with a lot of rock and roll icons, including original members of Bill Haley & The Comets. A few years back in Branson, MO, I went to see them per...

Michael Mesey - avatar Michael Mesey

DORIAN PAUL - MY MUSICAL JOURNEY

It’s so wonderful to be back singing and recording again after a long layoff to raise my family as a single dad. Even though my latest track “Shake It Around” has my trademark grits and gravy funk vibe, major grooves and horn sizzle right out of Ca...

Dorian Paul - avatar Dorian Paul

Originality in Music: Innovators and Imitators

Someone once said to me, “Artists are either innovators or imitators.” Nowhere is this more true than in music.  First off, I want to make it clear that both of these paths have value. People are easily impressed with innovation. If something hasn’t...

Angela Predhomme - avatar Angela Predhomme

Metropolitan Business News

5 Major Advantages of Starting a Real Estate Business

Starting and operating a real estate business is a broad concept. This is because it may involve selling, buying, managing, and developing real estate properties. It can also be a challenging line...

NewsServices.com - avatar NewsServices.com

Should I refinance my home in 2021?

Since last year, we all have seen how mortgage rates have dropped to historical lows of 3% or even less. Because of this current real estate market many have been taking advantage of either buying...

Money.com - avatar Money.com

Importance of SEO services in digital marketing

SEO services are an indispensable part of digital marketing. It is your responsibility to increase the visibility of your website and keep it ahead of all competitors. Improve website visibility, user...

NewsCo - avatar NewsCo

4 Creative suggestions for your first business card

Almost all businesses nowadays have a business card. Business cards are important to easily showcase your brand, yourself, and your business. However, not all business cards are made the same. Som...

NewsCo - avatar NewsCo

WHEN WORLDWIDE BUSINESS BUILDING POWERHOUSE ASHLEY ANN SPEAKS, LIVES CHANGE

Ask any of her thousands of global followers - especially the 11,000-plus who’ve learned to monetize their social media, and the 700-plus who’ve created six figure incomes – and they’ll be happy to ...

NewsCo - avatar NewsCo

Why Creativity Is So Important In Digital Marketing

The Role of Creativity in Digital Marketing's Future  As marketers, one of the key tasks is to be creative and look for ways to generate demand and interest in our services and products. Creati...

NewsCo - avatar NewsCo

Writers Wanted


NewsServices.com

Content & Technology Connecting Global Audiences

More Information - Less Opinion