Birds inherited strong sense of smell from dinosaurs (w/ video)

Apr 13, 2011
Birds inherited strong sense of smell from dinosaurs
Evolution in birds of the olfactory bulb, the part of the brain where smell information is processed, passing from a dinosaur (Bambiraptor) through early birds (Lithornis, Presbyornis) to a modern-day bird (pigeon). Courtesy of WitmerLab at Ohio University.

(PhysOrg.com) -- Birds are known more for their senses of vision and hearing than smell, but new research suggests that millions of years ago, the winged critters also boasted a better sense for scents.

A study published today by scientists at the University of Calgary, the Royal Tyrrell Museum and the Ohio University College of Osteopathic Medicine tested the long-standing view that during the evolution from to birds, the declined as birds developed heightened senses of vision, hearing and balance for flight. The team compared the olfactory bulbs in the brains of 157 species of dinosaurs and ancient and modern-day birds.

The findings, published in the journal , dispute that theory. The scientists discovered that the sense of smell actually increased in early bird evolution, peaking millions of years ago during a time when the ancestors of modern-day birds competed with dinosaurs and more ancient branches of the bird family.

"It was previously believed that birds were so busy developing vision, balance and coordination for flight that their sense of smell was scaled way back," said Darla Zelenitsky, assistant professor of paleontology at the University of Calgary and lead author of the research. "Surprisingly, our research shows that the sense of smell actually improved during dinosaur-bird evolution, like vision and balance."

This video is not supported by your browser at this time.
Animation of the evolution in birds of the olfactory bulb, the part of the brain where smell information is processed, passing from a dinosaur (Bambiraptor) through early birds (Lithornis, Presbyornis) to a modern-day bird (pigeon). Movie by Ridgely & Witmer, Courtesy of WitmerLab at Ohio University.

In an effort to conduct the most detailed study to date on the evolution of sense of smell, the research team made CT scans of dinosaurs and extinct bird skulls to reconstruct their brains. The scientists used the scans to determine the size of the creatures' olfactory bulbs, a part of the brain involved in the sense of smell. Among modern-day birds and mammals, larger bulbs correspond to a heightened sense of smell.

"Of course the actual brain tissue is long gone from the fossil skulls," said study co-author Lawrence Witmer, Chang Professor of at the Ohio University College of Osteopathic Medicine, "but we can use CT scanning to visualize the cavity that the brain once occupied and then generate 3D computer renderings of the olfactory bulbs and other brain parts."

The study revealed details of how birds inherited their sense of smell from dinosaurs.

The dinosaur Bambiraptor in a turkey vulture's colours. Bambiraptor had a keen sniffer similar to that of a modern-day turkey vulture. Courtesy of Julius Csotonyi.

"The oldest known bird, Archaeopteryx, inherited its sense of smell from small meat-eating dinosaurs about 150 million years ago," said François Therrien, curator of dinosaur palaeoecology at the Royal Tyrrell Museum and co-author of the study. "Later, around 95 million years ago, the ancestor of all modern birds evolved even better olfactory capabilities."

How well did dinosaurs smell, especially compared to modern animals? Although scientists haven't been able to make an exhaustive comparison, Witmer noted that the ancient beasts most likely exhibited a range of olfactory abilities. T. rex had large olfactory bulbs, which probably aided the creature in tracking prey, finding carcasses and possibly even territorial behavior, while a sense of smell was probably less important to dinosaurs such as Triceratops, he said.

The team was able to make some direct comparisons between the ancient and modern-day animals under study. Archaeopteryx, for example, had a sense of smell similar to pigeons, which rely on odors for a number of behaviors.

Graph of olfactory bulb size and body size of individual bird (black symbols) and dinosaur (green symbols) species. Similarities in olfactory bulb size and body size between species, as illustrated by the dinosaur Bambiraptor, the turkey vulture, and the albatross, suggest a comparable sense of smell. Courtesy of Darla Zelenitsky

"Turkey vultures and albatrosses are birds well known for their keen sense of smell, which they use to search for food or navigate over large areas," says Zelenitsky. "Our discovery that small Velociraptor-like dinosaurs, like Bambiraptor, had a sense of smell as developed as turkey vultures and albatrosses suggests that smell may have played an important role while these dinosaurs hunted for food."

If early birds had such powerful sniffers, why do birds have a reputation for a poor sense of smell? Witmer explained that the new study confirms that the most common birds that humans encounter today—the backyard perching birds such as crows and finches, as well as pet parrots—indeed have smaller olfactory bulbs and weaker senses of smell. It may be no coincidence that the latter are also the cleverest , suggesting that their enhanced smarts may have decreased the need for a strong sniffer, he said.

Explore further: Unique entry complex discovered at Herodian Hilltop Palace

More information: Zelenitsky, D. K., F. Therrien, R. C. Ridgely, A. R. McGee, and L. M. Witmer. 2011. Evolution of olfaction in non-avian theropod dinosaurs and birds. Proceedings of the Royal Society B. 13 April 2011.

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User comments : 7

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kevinrtrs
1 / 5 (11) Apr 13, 2011
So now it's an established fact that birds have "evolved" from dinosaurs?

Sheer speculation, repeated often enough with more and more scientifically sounding jargon has turned a myth into a fact.

Just how did the heavy bones of dinosaurs turn into the small lightweight bones of birds?
And how did the lumbering cardiovascular system change into the specialized hollow-sack system in birds?
Where did the specifications for materials, shape and function for feathers come from?
How did the incredible power to mass ratios develop for the overall body?

It's all too easy to say it evolved without being able or required to show just how it actually occurred.

Right now, as things stand, one has to take it all on faith. Basically it's a religious belief that dinosaurs turned into birds.
kevinrtrs
1 / 5 (9) Apr 13, 2011
It may be no coincidence that the latter are also the cleverest birds, suggesting that their enhanced smarts may have decreased the need for a strong sniffer, he said.

Pure fishing. There's no established path for such a development. Dogs have extremely good sense of smell yet are also very intelligent. So how does this statement by the researcher line up to that FACT? Yes, I'm comparing dogs to birds to show that one cannot generalise and FISH as the researcher is doing just to fill in an unexplained gap.
kaasinees
4 / 5 (5) Apr 13, 2011
Trololololol.

kevin, how did the fish evolve to live in the radiation near the chernobyl disaster?
jmcanoy1860
5 / 5 (4) Apr 13, 2011
It may be no coincidence that the latter are also the cleverest birds, suggesting that their enhanced smarts may have decreased the need for a strong sniffer, he said.

Pure fishing. There's no established path for such a development. Dogs have extremely good sense of smell yet are also very intelligent. So how does this statement by the researcher line up to that FACT? Yes, I'm comparing dogs to birds to show that one cannot generalise and FISH as the researcher is doing just to fill in an unexplained gap.


All of your "questions" can be answered easily with a little research, Creationist.
FrankHerbert
2.3 / 5 (6) Apr 13, 2011
Your god must feel awfully cramped in those gaps. They're getting smaller all the time.
RobertKarlStonjek
3 / 5 (2) Apr 14, 2011
The Tyrannosaurus Rex is just a big canary with teeth...I'm sure if you put one into a (large) bird cage it would sing sweetly from its perch and crap into its water dish just like the modern (smaller) variety...
6_6
1 / 5 (3) Apr 15, 2011
I believe bird species were made with specific purposes, in addition to dinosaurs who also have their own designated purpose.

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