Tuesday, April 12, 2011

Sniffing out history

ATHENS, Ohio (April 13, 2011) – 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 dinosaurs to birds, the sense of smell 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 Proceedings of the Royal Society B, 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.”

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 Paleontology 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 oldest known bird, Archaeopteryx, inherited its sense of smell from small meat-eating dinosaurs about 150 million years ago,” said Fran├žois 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.

“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 birds, suggesting that their enhanced smarts may have decreased the need for a strong sniffer, he said.

Other authors on the article include Amanda McGee, a graduate student at the University of Calgary, and Ryan Ridgely, a research associate in the WitmerLab at Ohio University. The research was funded by grants to Zelenitsky from the Natural Sciences and Engineering Research Council of Canada and to Witmer and Ridgely from the U.S. National Science Foundation.

Contacts:

1. USA (Eastern time zone): Lawrence Witmer, (740) 593-9489 and (740) 591-7712, witmerL@ohio.edu.

2. Canada (Mountain time zone): Darla Zelenitsky, (403) 804-4998, and (403) 220-8016; dkzeleni@ucalgary.ca; Fran├žois Therrien, (587) 777-4548, francois.therrien@gov.ab.ca.

Photo: Bambiraptor skull, Children's Museum of Indianapolis, by Casey Tucker/Wild Auk Photography

Friday, April 8, 2011

The Vulnerability of Museum Collections

Unfortunately, museum specimens are occasionally misplaced or accidentally destroyed, which means the loss of valuable information. All too often, however, specimens are stolen by people who have gained access to museum collections.

In his book, Curse of the Labrador Duck, Glen Chilton details how at least one specimen of a Labrador Duck was stolen from a diorama at the American Museum of Natural History. Additionally, many other museum specimens were lost or destroyed in Europe during WWII.

This recent news story illustrates how susceptible museum collections can be for individuals with unscrupulous intentions. On the positive side, the culprit behind this crime was caught and sentenced. On the down side, his actions has resulted in the loss and destruction of many valuable specimens and information that can never be regained.

Museums have to be cautious about who they allow access to their collections, but as the story above illustrates, even with certain security protocols museum specimens can still be vulnerable.

Photo: Stachyris speciosa, Cincinnati Museum of Natural History, photo by Casey Tucker/Wild Auk Photography

Wednesday, April 6, 2011

Parrot Pigments Preserve Plumage!

Colourful parrot feathers resist bacterial degradation

Biology Letters. 23 April 2011 vol. 7 no. 2 214-216

Edward H. Burtt Jr, Max R. Schroeder, Lauren A. Smith, Jenna E. Sroka and Kevin J. McGraw

Abstract

The brilliant red, orange and yellow colours of parrot feathers are the product of psittacofulvins, which are synthetic pigments known only from parrots. Recent evidence suggests that some pigments in bird feathers function not just as colour generators, but also preserve plumage integrity by increasing the resistance of feather keratin to bacterial degradation. We exposed a variety of colourful parrot feathers to feather-degrading Bacillus licheniformis and found that feathers with red psittacofulvins degraded at about the same rate as those with melanin and more slowly than white feathers, which lack pigments. Blue feathers, in which colour is based on the microstructural arrangement of keratin, air and melanin granules, and green feathers, which combine structural blue with yellow psittacofulvins, degraded at a rate similar to that of red and black feathers. These differences in resistance to bacterial degradation of differently coloured feathers suggest that colour patterns within the Psittaciformes may have evolved to resist bacterial degradation, in addition to their role in communication and camouflage.

Photo: Rainbow Lorikeet by Casey Tucker/Wild Auk Photography

Monday, April 4, 2011

Update on TV Dinosaurs

So it appears that Steven Spielberg's new TV series, "Terra Nova," has pushed the premier back from summer to fall. One rumor suggests that the delay may be due to the fact that animators need more time to work on animating the dinosaurs in the show.

On a positive note, Angie Rodrigues, of Art by Angie, provides us with a link to view a preview of the Discovery Channel's anxiously awaited new documentary series, "Reign of the Dinosaurs." Rodrigues was one of the artists working on the series. You have to watch the demo-reel clip to see several short clips from the series, but it is well worth it. Following the "Reign of the Dinosaurs" clips are several short clips from a previous Discovery Channel series, titled "Monsters Resurrected."


Hopefully both "Terra Nova" and "Reign of the Dinosaurs" will be on track to view later this year. If they're on TV during the same time period we might have quite a bit of mainstream dinosaur overload like we haven't seen since Jurassic Park first appeared in theaters.

Lost Art of the Museum Diorama

I've recently begun reading a relatively new book, by author Jay Kirk, titled "Kingdom Under Glass."

The book details the life and work of taxidermist and artist Carl Akeley who created some of the most memorable habitat dioramas in museums like the American Museum of Natural History and the Chicago Field Museum.

Reading about Akeley's life and work reminded me of my visits to the old Cincinnati Museum of Natural History and how much I enjoyed their dioramas.

The art of the classic diorama, featuring taxidermied animals, is somewhat of a lost artform.


Many museums (or science centers) are moving, or have already moved, away from static displays to more "interactive" exhibits, which often involve levers and buttons and lights and sounds. While these newer exhibits push agendas and encourage museum-goers (mostly children) to explore and to make learning "fun", they don't allow for the quiet study, curiosity, and introspection that the classic dioramas encouraged. Good dioramas often stimulated your imagination so that you could almost see the animals moving.


Some museums still utilize dioramas, but rarely with taxidermied animals. Often newer dioramas utilize animal sculptures, which are less realistic and convincing then their taxidermied predecessors.


The taxidermied specimen in a good diorama was only part of the overall art of the exhibit. Another major component was the background or habitat depicted in the diorama. These components skillfully and realistically reconstructed the habitat that a specimen was found in when it was alive. Some artists, like John Agnew and Sean Murtha, have successfully kept the art of the museum diorama background alive. In John's case his works have even appeared in the habitat exhibits of zoos.

If you want to check out some of Carl Akeley's dioramas, without having to travel to Chicago or New York, check out the book, "Windows on Nature" or check out the website of the American Museum of Natural History.


Mountain goat diorama at the Cleveland Museum of Natural History. Photo by Casey Tucker/Wild Auk Photography.