Thursday, April 22, 2010
McGill researchers uncover first evidence that warm and moderate climate allowed dinosaurs to expand into one massive homogenous community across North America.
Researchers at McGill University are unlocking the mysteries of the little-known habits of dinosaurs in discovering that the entire western interior of North America was likely once populated by a single community of dinosaurs. According to a statistical analysis of the fossil record, dinosaurs were adept at coping with all sorts of environments, and not as restricted in their geographic ranges as previously thought.
The discovery was made by McGill Professor Hans Larsson and Matthew Vavrek, a PhD student at the University. Using data from the Paleobiology Database (http://www.paleodb.org/), they found that the difference in species between regions over North America was relatively low - low enough to consider it a single homogeneous fauna. The finding is significant as it confirms that dinosaur ecosystems may have been as large as continents. The paper is to be published in the April 19 issue of the journal Proceedings of the National Academy of Sciences.
The McGill team zeroed in on alpha diversity, the number of species in an immediate area, versus beta diversity, which are the differences in species between two different areas. Their research shows low beta biodiversity among these dinosaurs with values comparable to species living in homogeneous climates today, but on smaller geographic scales. "This is significant because we lack living analogues of a complete terrestrial megafauna living in those kinds of stable climates. The findings give us an insight into what kind of ranges these types of communities may have had," Larsson, a Canada Research Chair in Macroevolution, explained. "We also demonstrate that after more than a century of collecting dinosaurs in North America, we should expect to find about 16 types, on average, in any one region of western North America just before their mass extinction."
The long extinct dinosaurs are not just long dead fossils, but they offer a unique insight into a complex megafauna that responded to their environment. But even though they are extinct, they can tell us about the ecology of the animals we see today. "Despite their appearance, dinosaurs are ecologically very similar to mammals of today," Vavrek said. "They were able to colonize and dominate the landscape over very large distances, and were not nearly as constrained as we might have once thought."
By examining a single time slice, the Maastrichtian stage (71-65 million years ago) and all known specimens of dinosaurs from the Western Interior region of North America, the duo concluded that multiple dinosaur faunal regions did not exist. "Our results show low beta diversity and support a single dinosaur community within the entire Western Interior region. This widespread ecosystem was likely due to the homogenous climate present in this region at the time." said Larsson. "What is exciting about this result is that now we can begin to ask many more questions about how such a large homogeneous community of dinosaurs lived. Did they migrate, or have adequate amounts of gene flow between regional populations, or a mixture of both? How did this widespread dinosaur megafaunal community affect other animals and plants on the regional and continental scale? We're just beginning to scratch the surface of dinosaur ecology."
See a nice response from Utah Museum of Natural History's Scott Sampson.
Image: Dinosaur stamp, art by James Gurney
Tuesday, April 20, 2010
New Haven, Conn. — Paleontologists have discovered a new species of dinosaur with a softball-sized lump of solid bone on top of its skull, according to a paper published in the April issue of the journal Cretaceous Research.
The species was a plant-eating dinosaur about as big as a medium-sized dog that lived 70 to 80 million years ago, said Nicholas Longrich of Yale University, lead author of the paper. The team discovered two skull fragments in Big Bend National Park in southwest Texas in 2008. They compared them to dozens of fossils from related species found in Canada and Montana before confirming that the fossils represented a new genus of pachycephalosaur, a group of bipedal, thick-skulled dinosaurs.
The researchers named the new species Texacephale langstoni. (“Texacephale” means “Texas head” and “langstoni” is in honor of Wann Langston, a fellow paleontologist.) The new species is one of about a dozen known to have solid lumps of bone on top of their skulls, which Longrich speculates was probably used to ram one another head-on in a manner similar to modern-day musk oxen and cape buffalo.
The discovery of the new species lends further weight to the idea, which has gained popularity in recent years, that dinosaurs found in Canada and the northern United States were distinct from their southern neighbors.
“Instead of roaming across the North American continent, we see pockets of different dinosaurs that are pretty isolated from one another,” Longrich said. “Every time we get good fossils from Texas, they end up looking very different from those to the north.”
Because fossils from the Big Bend region are rare and tend to be poorly preserved, scientists do not have a complete picture of the different species that once inhabited the area, Longrich said.
But the team may have uncovered an important piece of the puzzle with their discovery. They found that this particular group of dinosaurs, which was previously thought to have originated in Asia, likely evolved in North America.
Longrich expects more related species to be discovered in the future as fossils from the Texas site and elsewhere continue to be examined.
“I think we underestimate how many different species there were,” he says.
Other authors of the paper include Julia Sankey (California State University, Stanislaus), who led the fieldwork, and Darren Tanke (Royal Tyrrell Museum), who discovered the more complete specimen on which the naming of the new species was based.
FOUND IN: Science & Engineering Yale Bulletin
Photo: Dracorex hogwartsia, a pachycephalosaur
Tuesday, March 23, 2010
Which weighs more -- the skeleton of a two-ounce songbird or that of a two-ounce rodent?
For centuries biologists have known that bird bones are hollow, and even elementary school children know that bird skeletons are lightweight to offset the high energy cost of flying.
Nevertheless, the songbird skeleton would, in fact, tip the scale at about the same weight as that of the rodent.
Bird biologists have known this for a long time, but it took a modern bat researcher, Elizabeth Dumont of the Department of Biology, to explain how bird skeletons can look so delicate and still be heavy. The answer is that bird bones are denser than mammal bones, which makes them heavy even though they are thin and sometimes even hollow.
Her findings, supported by bone density measurements, are published in the March 17 issue of Proceedings of the Royal Society B. As Dumont explains, “The fact that bird bones are denser than bones in mammals not only makes them heavier for their size, but it may also make them stiffer and stronger. This is a new way to think about how bird skeletons are specialized for flying and solves the riddle of why bird skeletons appear so lightweight and are still relatively heavy. This has never been explained fully and so has never gotten into the textbooks. I’d like to see that change.”
Dumont measured the density of the cranium, the upper arm bone or humerus and the thigh or femur bones in song birds, rodents and bats by measuring bone mass and volume. “I found that, on average, these bones are densest in birds, followed closely by bats. Many other studies have shown that as bone density increases, so do bone stiffness and strength. Maximizing stiffness and strength relative to weight are optimization strategies that are used in the design of strong and stiff but lightweight man-made airframes,” she points out. Density is a measure of mass per unit of volume; dense bones are both heavier and stronger, much as a titanium toothpick would be stronger than a wooden one.
Over time bird bones have evolved specializations that maximize stiffness and strength, Dumont says. These specializations include high bone density, a reduction in the total number of bones, fusion of some bones, and changes in bone shape. For example, a long history of studies have shown that the main bone in the bird wing, the humerus, is quite round in cross-section. This makes it stiffer in the same way that a round toothpick is harder to snap than a flat one.
Galileo described bird bones as lightweight in 1683, Dumont says. Her new data help to dispel the common misconception that bird skeletons are lightweight relative to body mass. Instead, bird and bat skeletons only appear to be slender and delicate—because they are dense, they are also heavy. Being dense, strong and stiff is one more way that birds’ and bats’ bones are specialized for flight.
Source: University of Massachusetts Amherst
Photos: upper right=Chicken skeleton; lower left=Northern Parula skull
Monday, March 22, 2010
COLUMBUS, Ga. - Ancient bite marks and fossilized feces discovered in Georgia are providing new details about a giant crocodile that roamed the Southeast United States about 79 million years ago.
The giant reptile, called Deinosuchus, reached at least 29 feet long in Georgia and preferred living in a shallow water environment and could take down dinosaurs its own size, as new findings show.
“We’re sure (Deinosuchus) ate a lot of sea turtles, but it’s evident it sometimes preyed on dinosaurs too,” said Columbus State paleontologist, Professor David Schwimmer who recently completed two studies on the giant croc with one of his students, Samantha Harrell.
Schwimmer and Harrell gave a combined presentation on the bite marks and the fossilized dung, called coprolites, at the March 13-16 Geological Society of America Northeastern-Southeastern annual meeting in Baltimore. Additionally, the coprolite study is being published as “Coprolites of Deinosuchus and other Crocodylians from the Upper Cretaceous of Western Georgia, USA” in a special symposium volume of the New Mexico Museum of Natural History and Science Bulletin, a publication of international interest.
The studies detail how bite marks on dinosaur bones discovered in various locations around the country, and large fossilized dung droppings discovered near Columbus, Ga., have been linked to the Deinosuchus.
The dung fossils are the first such documented samples from the Deinosuchus and help confirm the giant, ancient croc preferred living in the marine shallows. Meanwhile, the separate bite mark findings reveal aspect of the creature’s eating habits.
“In some cases we’re talking about a 29-foot Deinosuchus taking down a 29-foot dinosaur,” Schwimmer said.
A likely victim, Appalachiosaurus montgomeriensis — a relative of Tyrannosaurus rex — was discovered near Montgomery, Ala., and named in 2005 by Schwimmer and a pair of colleagues.
Schwimmer is regarded an expert on both the Deinosuchus and the Late Cretaceous paleontology of the southeastern United States. The status was affirmed with his 2002 book, King of the Crocodylians: The Paleobiology of Deinosuchus.
In spring 2009 Schwimmer asked Harrell to take command of a project as an independent study course to gather and analyze fossilized feces he had started to recover from a fossil hot spot along the banks of the Hannahatchee Creek in Stewart County, a major tributary of the Chattahoochee River, south of where the Piedmont meets the Coastal Plain.
Harrell, a senior geology major from Girdler, Ky., worked with 20 samples of fossil crocodylian dung. She attributed six of the large spindle shaped masses, 8-13 centimeters long, to Deinosuchus.
Harrell explained coprolites are studied in order to convey information about the lifestyles of the dead and buried. She discovered sand and lots of shell fragments, signifying the crocs lived in a shallow, brackish, warm-water environment — likely near the mouth of a river where it opened to a sea with sandy shoreline and an abundance of sea turtles for its diet.
The unusual nature of Harrell’s project drew the attention of Georgia Public Broadcasting, which highlighted Harrell’s research as part of its Dinosaur Week series last September. The series also featured Schwimmer in a pair of separate stories.
Harrell plans to pursue graduate study in paleontology. Schwimmer said Harrell is already off to a fast start in her field. “It’s a rare and outstanding accomplishment for an undergraduate to be the lead author of a study in an international journal.”
Harrell also will present her coprolite research as part of the March 27 Georgia Academy of Sciences annual meeting hosted by Columbus State University.
Photo above: American Crocodile
Friday, March 19, 2010
Near Complete Skeleton Will Help Further Describe Pre-Historic Relatives
WASHINGTON – A new species of raptor dinosaur being named "Linheraptor exquisitus" has been discovered by George Washington University doctoral candidate Jonah Choiniere and Michael D. Pittman, a graduate student at University College London (UCL). The exceptionally well-preserved, nearly complete skeleton is a relative of the well-known species "Velociraptor," and will help scientists further describe the physical appearance of other closely-related dinosaurs within the Dromaeosauridae family. The research, led by Xu Xing of the Chinese Academy of Sciences’ Institute of Vertebrate Paleontology and Paleoanthropology, will be published in the March 19, 2010, issue of "Zootaxa."
“I only saw the tip of the claw sticking out of a cliff face, and it was a total surprise that the whole skeleton was buried deeper in the rock,” said Mr. Choiniere. “This fossil is going to tell us a lot about the evolution of the skeleton in the group that includes 'Velociraptor'.”
At approximately eight feet long and 50 pounds, the researchers believe "Linheraptor" would have been a fast, agile predator that preyed on small horned dinosaurs related to "Triceratops." Like other dromaeosaurids, it possessed a large, highly curved claw on the foot, which may have been used to capture prey. Within the Dromaeosauridae family, "Linheraptor" is most closely related to another recently discovered species "Tsaagan mangas." The head and neck of the "Tsaagan" skeleton was discovered in Mongolia in 1993 by James Clark, the Ronald B. Weintraub Professor of Biology at The George Washington University's Columbian College of Arts and Sciences. "Tsaagan’s" skull indicates that it is more primitive than "Velociraptor," and the skeleton of the new species should help reconstruct the series of evolutionary changes within the Dromaeosauridae.
“This is a really beautiful fossil and it documents a transitional stage in dromaeosaurid evolution,” said Dr. Xu.
"Linheraptor" was found by the researchers in approximately 75 million year-old red sandstone rocks during a 2008 field expedition in Inner Mongolia, China. It is the fifth dromaeosaurid discovered in these rocks, which are famous for their preservation of uncrushed, complete skeletons. These red sandstones are best known from the Flaming Cliffs field site in outer Mongolia, the location where "Velociraptor" was discovered and dinosaur eggs and nests were first found.
“The original 'Tsaagan' find was very intriguing, and this discovery should really help us flesh out what these animals looked like,” said Dr. Clark.
Dromaeosauridae is a family of bird-like theropod dinosaurs that lived during the Cretaceous Period. In addition to "Linheraptor" and "Velociraptor," theropod dinosaurs include charismatic meat-eaters like "Tyrannosaurus rex" and modern birds.
This research was funded by the U.S. National Science Foundation and the Chinese National Science Foundation, the Jurassic Foundation, the Geological Society of London and The George Washington University.
Mr. Choiniere is a doctoral student of Dr. Clark’s and first accompanied Dr. Clark on his excavations in China in 2005. Though this discovery is Mr. Choiniere’s first significant fossil find, he was the lead author of the recent "Science" article, “A Basal Alvarezsauroid Theropod from the Early Late Jurassic of Xinjiang, China.” Mr. Pittman is a doctoral student of Dr. Paul Upchurch and Dr. John R. Hutchinson and has worked with Chinese scientists since 2006.
The article, “A new dromaeosaurid (Dinosauria: Theropoda) from the Upper Cretaceous Wulansuhai Formation of Inner Mongolia, China,” appears in the March 19, 2010, issue of "Zootaxa." "Zootaxa" is an international journal for animal taxonomists.
Photo above: Velociraptor model
Wednesday, March 10, 2010
University Park, Pa. — A team of scientists has discovered that the drastic decline in Arctic musk ox populations that began roughly 12,000 years ago was due to a warming climate rather than to human hunting.
"This is the first study to use ancient musk ox DNA collected from across the animal's former geographic range to test for human impacts on musk ox populations," said Beth Shapiro, the Shaffer Career Development assistant professor of biology at Penn State and one of the team's leaders. "We found that, although human and musk ox populations overlapped in many regions across the globe, humans probably were not responsible for the decline and eventual extinction of musk oxen across much of their former range."
The team's findings will be published in the early on-line edition of the journal Proceedings of the National Academy of Sciences during the week ending Friday, March 12.
Musk oxen once were plentiful across the entire Northern Hemisphere, but they now exist almost solely in Greenland and number only about 80,000 to 125,000. According to the researchers, musk oxen are not the only animals to suffer during the late Pleistocene Epoch.
"The late Pleistocene was marked by rapid environmental change as well as the beginning of the spread of humans across the Northern Hemisphere," said Shapiro. "During that time several animals became extinct, including mammoths and woolly rhinoceroses, while others, including horses, caribou and bison, survived into the present. The reasons for these drastically different survival patterns have been debated widely, with some scientists claiming that the extinctions were due largely to human hunting. Musk oxen provide a unique opportunity to study this question because they suffered from a decline in their population that coincided with the Pleistocene extinctions, yet they still exist today, which allows us to compare the genetic diversity of today’s individuals with those individuals that lived up to 60,000 years ago."
To conduct their research, the team collected musk ox bones and other remains from animals that lived during different times -- up to 60,000 years ago -- and from animals that lived across the species' former range. From these remains, the scientists isolated and analyzed the mitochondrial DNA, which is useful for studying ancient population dynamics due to its rapid rate of evolutionary change. The scientists also isolated and analyzed the mitochondrial DNA of musk oxen that are alive today. They then used a Bayesian statistical approach to estimate how the amount of genetic diversity of the musk oxen populations changed through time.
"Over the past decade, ancient DNA studies have matured, moving away from simply identifying animals to actually giving us insights into the population size and dynamics of animals, stretching back over the last 100,000 years," said Tom Gilbert, an associate professor at the University of Copenhagen in Denmark and another of the team's leaders. "Thanks to significant computational developments made by colleagues of ours, we have the fantastic opportunity to watch what happened to the ancient populations. When did they increase, or decrease, and at what rate?"
Scientists believe that a reduction in genetic diversity of an animal's population can reflect a decrease in the size of the population. By estimating when the genetic diversity of musk oxen began to decline, the team was able to test whether the decline was due to the arrival of humans in a particular region or to some other effect. The scientists found that the genetic diversity of the musk ox was much higher during the Pleistocene than it is today. They also found that the genetic diversity of the species increased and decreased frequently over the past 65,000 years.
"The periods of growth and decline observed in the musk ox populations in this study are considerably different from those that have been reconstructed previously for musk oxen or for other species, such as bison and mammoths," said Shapiro. "While musk oxen experienced a significant population decline nearly 65,000 years ago, mammoths first began to decline only around 48,000 years ago. Bison populations remained stable until around 35,000 years ago -- a period during which musk ox populations actually were growing. As we get a better idea of the overall picture of megafaunal dynamics in the Arctic, it is becoming clear that each species is following its own population trajectory. This is a strong argument that it is changes in habitat that are driving these population dynamics, and not a single factor such as the introduction of human hunters."
"We know from historical data that musk oxen are sensitive to changes in the Arctic environment," Shapiro continued. "While we cannot confirm exactly what climate factors are driving the changes we observe in musk oxen over the last 65,000 years, we can say with confidence that humans are not causing local extinctions. In Greenland, for example, humans and musk oxen arrived and began their expansion at the same time."
According to Gilbert, "We wonder how the current climatic instability will effect the survival of musk oxen in the near future. There's a lot in the news about the plight of polar bears, but musk ox may be similarly at risk."
This research was funded, in part, by Forsknings-og Innovationsstyrelsen and the Marie Curie Actions "GeneTime."
For more information, contact Shapiro at firstname.lastname@example.org or 814-863-9178, or Barbara Kennedy, Penn State press officer, at email@example.com or 814-863-4682. For high-resolution images associated with this story, visit http://www.science.psu.edu/news-and-events/2010-news/Shapiro3-2010 online.
Tuesday, March 9, 2010
By Pallab Ghosh Science correspondent, BBC News
Researchers have found that eggshells of extinct bird species are a rich source of preserved DNA.
An international team isolated the delicate DNA molecules of species including the massive "elephant birds" of the genus Aepyorni.
The Proceedings of the Royal Society B research demonstrated the approach also on emu, ducks and the extinct moa.
The team says that the technique will enable researchers to learn more about ancient birds and why they died out.
"Researchers have tried unsuccessfully to isolate DNA from a fossil eggshell for years," said Charlotte Oskam at Murdoch University in Western Australia, who authored the research.
"It just turned out that they were using a method designed for bone that was not suitable for a fossil eggshell."
The team has obtained DNA from the shells of a variety of species, most notably the elephant bird Aepyornis, which at half a tonne was heaviest bird to have ever existed.
Aepyornis looked like an outsized ostrich, standing three metres tall; most of them died out 1,000 years ago.
Archaeologist Mike Parker Pearson at the University of Sheffield hopes that an analysis of the bird's DNA will shed more light on why the bird went extinct.
The extinction coincided with humans arriving at Aepyornis's natural habitat in Madagascar.
The mystery, according to Professor Parker Pearson, is that there's no evidence that the bird was hunted by humans.
"There's not even evidence that they ate the eggs - even though each one could make omelettes for 30 people," he told BBC News.
The elephant bird may be at the root of legends about giant birds. Marco Polo claimed erroneously that these giant birds could fly. There are also tales of birds that could pick up elephants in 1001 Arabian Nights.
There are complete skeletons of the elephant bird, but by analysing its DNA researchers hope to build up a more detailed picture of the creature and discover why it went extinct.
above photo: Great Auk egg
Friday, March 5, 2010
(left--Skunk Cabbage (Symplocarpus foetidus) from Englewood, Ohio; right--Chocolate Lily (Fritillaria camschatcensis ) from Anchorage, AK)
To learn more about how plants mimic corpses to attract insects as food, check out this great article in National Geographic magazine.
Wednesday, March 3, 2010
Tuesday, March 2, 2010
A life-sized flesh reconstruction of the scene immediately before burial was designed and executed by University of Chicago paleoartist Tyler Keillor. The team will donate the first cast to the Geological Survey of India at a formal function to be held in Mumbai, India, on March 12, 2010.
Wednesday, February 24, 2010
A University of Iowa researcher and his colleagues have found evidence in existing fossil collections that horned crocodiles lived in the Olduvai Gorge region of Tanzania, Africa, about two million years ago.
"Olduvai Gorge is the location of many key discoveries of early human ancestors, and these crocodiles appear to have dined on them," said Chris Brochu, associate professor of geoscience in the UI College of Liberal Arts and Sciences. Brochu is the co-author of an article published in the Feb. 24 issue of the journal PLoS ONE (Public Library of Science) that describes a new species of crocodile.
"So, what I've got is a horned, man-eating crocodile," said Brochu. "In fact, its name is Crocodylus anthropophagus, and 'anthropophagus' literally means 'eater of people.'"
Crocodylus anthropophagus would have been about as large as its living cousin, the Nile crocodile, which can reach lengths of almost 20 feet and weigh up to a ton. The early humans walking along the lake and stream margins that used to exist at Olduvai Gorge were smaller than people of today and would have been in grave danger if they got too close to the water, according to Brochu.
"The bones of early humans have been found in rocks of the same age in Olduvai Gorge showing bite marks made by crocodiles," he said.
A crocodile that ate humans would have been frightening enough, but this variety also had horns.
"Not antlers or anything, but the back of the skull was somewhat fancier than in most living crocs," he said. "Two living crocodiles -- the Cuban and Siamese crocodiles -- also have horns, but those of the Olduvai crocodile were more prominent." Of course, horns probably would have given the crocodile a devilish appearance, as if that were needed on a man-eating crocodile.
Brochu and his colleagues based their conclusions on fossils collected over many decades. Some were collected in 2007 by a team led by Robert Blumenschine of Rutgers University and Jackson Njau, then of the National Natural History Museum of Tanzania. But others were collected as long ago as the 1930's and kept in museums in Kenya and the United Kingdom. Most of these fossils, by themselves, are fragmentary and not very impressive, but together, they reveal a crocodile different from any of its living relatives.
"It would have looked more or less like a Nile crocodile except for a deeper snout and, of course, the horns," Brochu said.
Apart from the very scary image projected by the beast, Brochu said that the discovery of Crocodylus anthropophagus teaches us something new about the variety of crocodiles to be found in pre-historic Africa.
"The fossil evidence is geologically fairly young, at just under two million years. We knew crocodiles were more diverse in the geological past, but we assumed their diversity was much lower as recently as 2 million years ago. Crocodile diversity in Africa remained higher than at present for longer than we had thought," he said.
Brochu's co-authors are Njau, Blumenschine and Llewellyn Densmore of Texas Tech University.
STORY SOURCE: University of Iowa News Services, 300 Plaza Centre One, Iowa City, Iowa 52242-2500
In a rare twist, they recovered four heads – two still fully intact – from a quarry in Dinosaur National Monument in eastern Utah. Complete skulls have been recovered for only eight of more than 120 known varieties of sauropod.
Britt is a co-author on the discovery paper scheduled to appear in the journal Naturwissenshaften. The lead author is Daniel Chure, a paleontologist at Dinosaur National Monument, who has no trouble boiling down the significance of the discovery.
Thursday, February 18, 2010
Scientists mapped five types of light receptors in the chicken's eye. They discovered the receptors were laid out in interwoven mosaics that maximized the chicken's ability to see many colors in any given part of the retina, the light-sensing structure at the back of the eye.
"Based on this analysis, birds have clearly one-upped us in several ways in terms of color vision," says Joseph C. Corbo, M.D., Ph.D., senior author and assistant professor of pathology and immunology and of genetics. "Color receptor organization in the chicken retina greatly exceeds that seen in most other retinas and certainly that in most mammalian retinas."
Corbo plans follow-up studies of how this organization is established. He says such insights could eventually help scientists seeking to use stem cells and other new techniques to treat the nearly 200 genetic disorders that can cause various forms of blindness.
Scientists published their results in the journal PLoS One.
Birds likely owe their superior color vision to not having spent a period of evolutionary history in the dark, according to Corbo. Birds, reptiles and mammals are all descended from a common ancestor, but during the age of the dinosaurs, most mammals became nocturnal for millions of years.
Vision comes from light-sensitive photoreceptor cells in the retina. Night-vision relies on receptors called rods, which flourished in the mammalian eye during the time of the dinosaurs. Daytime vision relies on different receptors, known as cones, that are less advantageous when an organism is most active at night.
Birds, now widely believed to be descendants of dinosaurs, never spent a similar period living mostly in darkness. As a result, birds have more types of cones than mammals.
"The human retina has cones sensitive to red, blue and green wavelengths," Corbo explains. "Avian retinas also have a cone that can detect violet wavelengths, including some ultraviolet, and a specialized receptor called a double cone that we believe helps them detect motion."
In addition, most avian cones have a specialized structure that Corbo compares to "cellular sunglasses": a lens-like drop of oil within the cone that is pigmented to filter out all but a particular range of light. Researchers used these drops to map the location of the different types of cones on the chicken retina. They found that the different types of cones were evenly distributed throughout the retina, but two cones of the same type were never located next to each other.
"This is the ideal way to uniformly sample the color space of your field of vision," Corbo says. "It appears to be a global pattern created from a simple localized rule: you can be next to other cones, but not next to the same kind of cone."
Corbo speculates that extra sensitivity to color may help birds in finding mates, which often involves colorful plumage, or when feeding on berries or other colorful fruit.
"Many of the inherited conditions that cause blindness in humans affect cones and rods, and it will be interesting to see if what we learn of the organization of the chicken's retina will help us better understand and repair such problems in the human eye," Corbo says.
Funding from the National Eye Institute supported this research.
Tuesday, February 16, 2010
Dinosaurs Resurrected will be a genuinely 360° brand encompassing a prime-time television series (based on a returning format) for delivery in 2011 and a feature-length narrative 3D movie for theatrical release. The movie will be the first major dinosaur experience using the latest immersive 3D technology in the world, for both cinemas and IMAX. The project will include accompanying books, DVD, tie-in consumer products and educational resources as well as gaming spin-offs and live events.
Dinosaurs Resurrected brings together the specialist expertise of four companies. FME is one of the world’s leading licensing, distribution and home entertainment companies responsible for launching some of the best-known entertainment brands including recent global phenomenon The Adventures of Merlin, a Shine Production for the BBC. Selling to over 180 countries, FME has co-invested in the series, with the programme featuring spectacular CGI from Oscar-winning effects house The Mill. Additional entertainment franchises include Idols, now entering its ninth season, with brand extensions including The American Idol Experience at Walt Disney World Resort. FME has had tremendous success with other prestigious television projects such as the CGI family series Prehistoric Park produced by Impossible Pictures which has sold to over 150 countries, and will be distributing the CGI 90-minute special, March of The Dinosaurs which will be produced by Wide-Eyed Entertainment.
Atlantic Productions has a seventeen-year track record in producing high-end, award-winning and acclaimed programming for global audiences such as recent hits The Link, Predator X and Egypt Unwrapped, the latter of which is distributed internationally by FME. All titles feature high-end CGI in their story-telling which further underscores the strong partnership between companies in bringing this next dinosaur experience to a global audience.
Rounding out the producing partners, ZOO brings their talent as a specialist digital effects company, previously working with the best visual effects artists and animators from the around the world - members of the ZOO team have worked on award-winning features including Harry Potter, The Chronicles of Narnia, Lord of the Rings, King Kong and 10,000 BC. And Geffen-Medavoy Pictures bring their established gravitas in creating feature documentaries for theatrical release, chaired by Mike Medavoy, the Hollywood producer who has been behind seven Best Picture Academy Award winning movies.
Announcing the collaboration, David Ellender, Global CEO of FME, said, "This group of partners has at our collective fingertips the fantastic combination of the most up to date production technology and the latest from the science community which means we can create a groundbreaking and completely up to date dinosaur franchise across numerous platforms. It is a big undertaking for FME and one we wouldn't have taken on without the calibre of partners we'll be working with."
Anthony Geffen, CEO of Atlantic Productions, added, “We are delighted to be working with Fremantle on this exciting venture. In the same way that Jurassic Park and Walking With Dinosaurs revolutionised our experience of dinosaurs at the end of the 20th century, this project will bring dinosaurs into the 21st century – on HD and in 3D. We are looking forward to combining the very best of traditional storytelling techniques with all the opportunities new technologies and platforms offer.”
Mike Medavoy, chairman of Geffen-Medavoy Pictures, said “Ever since they were first discovered, dinosaurs have captured our imagination. This project is a fantastic opportunity to bring them back to life for movie audiences around the world in the most realistic, most complex and most terrifying way we’ve ever seen.”
Monday, February 15, 2010
Wednesday, February 10, 2010
Kirchman, J. J., New York State Museum, Albany, USA,
ABSTRACT: We obtained the first DNA sequences from the extinct Carolina Parakeet (Conuropsis carolinensis) and used these data to infer the phylogenetic relationships of this iconic North American parrot. We compared our sequences of the mitochondrial CO1 gene obtained from two C. carolinensis museum specimens to homologous sequences from individuals representing 44 species in 25 genera of Neotropical parrots (Tribe Arini), and four outgroups from Old World tribes of Psittacines. Maximum likelihood and Bayesian analyses place C. conuropsis on a long branch, sister to a wellsupported clade of Aratinga parakeets that includes the most northern extant species of Neotropical parrots and species endemic to Cuba, Hispaniola, and Socorro Island. Our data do not support a close relationship with the Monk Parakeet (Myiopsistta monachus) with which C. conuropsis shares fully feathered ceres, a putative adaptation for cold tolerance. Based on the high level of sequence divergence from all sampled species (uncorrected P > 5.6%), we recommend continued recognition of the monotypic genus Conuropsis. Taxonomic revision of the highly polyphyletic genus Aratinga is needed.
Thursday, February 4, 2010
Unlike recently published work from China that inferred the existence of two types of melanin pigments in various species of feathered dinosaurs, the Science study analyzed color-imparting structures called melanosomes from an entire fossil of a single animal, a feat which enabled researchers to reveal rich color patterns of the entire animal.
In fact, the analysis of melanosomes conducted by Yale team was so precise that the team was able to assign colors to individual feathers of Anchiornis huxleyi, a four-winged troodontid dinosaur that lived during the late Jurassic period in China. This dinosaur sported a generally gray body, a reddish-brown, Mohawk-like crest and facial speckles, and white feathers on its wings and legs, with bold black-spangled tips.
“This was no crow or sparrow, but a creature with a very notable plumage,” said Richard O. Prum, chair and the William Robertson Coe Professor of Ornithology, Ecology and Evolutionary Biology at Yale and a co-author of the study. “This would be a very striking animal if it was alive today.”
The color patterns of the limbs, which strongly resemble those sported by modern day Spangled Hamburg chickens, probably functioned in communication and may have helped the dinosaur to attract mates, suggested Prum.
The transformation of mankind’s view of dinosaurs from dull to flamboyant was made possible by a discovery by Yale graduate student Jakob Vinther in the Department of Geology and Geophysics. Vinther was studying the ink sac of an ancient squid and realized that microscopic granular-like features within the fossil were actually melanosomes – a cellular organelle that contains melanin, a light-absorbing pigment in animals, including birds.
While some scientists thought these granules were remnants of ancient bacteria, Vinther, Prum and Derek E.G. Briggs, the Frederick William Beinecke Professor of Geology and Geophysics and director of the Yale Peabody Museum of Natural History, disagreed. First, they tested Vinther’s theory on a 112 million year old feather from Brazil and later inferred the colors of an extinct 47 million-year-old bird.
The latest research team — which also included scientists from the University of Texas at Austin, University of Akron, Peking University and the Beijing Museum of Natural History — decided to use the same procedures to closely examine a fossil of Anchiornis huxleyi, recently described in Liaoning Province, People’s Republic of China. The area has been a gold mine for paleontologists and, among other things, provided abundant evidence confirming a once-controversial theory that modern birds are descendants of theropod dinosaurs.
The Yale team and Julia Clarke, an associate professor of paleontology at the University of Texas at Austin’s Jackson School of Geosciences, worked closely with Gao Keqin of Peking University and Li Quanguo and Meng Qingjin of the Beijing Museum of Natural History to select, sample and evaluate the anatomy and feathering of Anchiornis huxleyi, important in its own right as a new feathered dinosaur. The team's effort was funded by a special grant from the National Geographic Society and by the National Science Foundation.
The team closely examined 29 feather samples from the dinosaur and did an exhaustive measurement and location of melanosomes within the feathers. The team then did a statistical analysis of how those melanosomes compared to the types of melanosomes known to create particular colors in living birds, using data compiled by Matt Shawkey and colleagues at the University of Akron. The analysis allowed scientists to discern with 90 percent certainty the colors of individual feathers and, therefore, the colorful patterns of an extinct animal.
The research adds significant weight to the idea that dinosaurs first evolved feathers not for flight but for some other purposes.
"This means a color-patterning function — for example, camouflage or display — must have had a key role in the early evolution of feathers in dinosaurs, and was just as important as evolving flight or improved aerodynamic function,” Clarke said.
The new discoveries provide a wealth of insights into the compelling history of feather evolution in dinosaurs prior to the origin of modern birds. The study documents that color patterning within feathers and among feathers evolved earlier than previously believed. Further, these results indicate dinosaur feathers may have evolved for communication.
"Writing the first scientifically-based ‘field guide’ description of the appearance of an extinct dinosaur was a exciting and unforgettable experience — the ultimate dream of every kid who was ever obsessed with dinosaurs,” Prum said. “Now that dream is really possible."
Friday, January 29, 2010
By Tan Ee Lyn
HONG KONG (Reuters) - China has unearthed the fossil of a two-legged carnivorous dinosaur that lived 160 million years ago and which researchers have identified as the earliest known member of a long lineage that includes birds.
The "Haplocheirus sollers" had a long, narrow skull, many small teeth and powerful biceps and forelimbs, which enabled it to hunt primitive lizards, small mammals and reptiles.
The individual, believed to be a young adult when it died, had a long tail and a total body length of between 190 and 230 cm. (6 feet 2 inches to 7 feet 6 inches), the researchers wrote in a paper published in the journal Science.
It was found in orange mudstone beds in the Junggar Basin in China's far western Xinjiang region.
"It has unique features but it shares some features with birds. It moves its hands sideways, like how birds can fold their wings. Its head, vertebral column, hind limbs, hands are all bird like," said Professor Xu Xing at the Chinese Academy of Sciences' Institute of Vertebrate Paleontology & Paleonanthropology.
"Their legs have four digits like modern birds, with three digits pointing forwards. The first digit, unlike in birds which point backwards, this one points sideways," he said.
Xu, a member on a research team led by Jonah Choiniere at the George Washington University in Washington, said that while this species shared some features with birds, it was more like a "typical carnivorous dinosaur."
"The most salient feature of this group is their forelimbs, they are predators. They have three claws on their hands, used to catch other animals. They have very bizarre forelimbs, they are very short but very stout and very strong," said Xu.
"Primitive lizards, small mammals, mammal-like reptiles were all possible food items," he told Reuters by telephone.
"They represent the earlier stage in the evolution of birds, but they are not birds. You can say they are early ancestors of birds ... and very slowly, it (the lineage) turned into birds."
This species belongs to the family of Alvarezsauridae -- a bizarre group of bird-like dinosaurs -- and its discovery pushes the fossil record of this family back by 60 million years into the Late Jurassic period (145 million to 161 million years ago).
The Haplocheirus is about 60 million years older than the next oldest known Alvarezsauroid, which was discovered in Argentina in 1991 and lived 95 million years ago during the Cretaceous period (65 million to 145 million years ago).
"We know birds are derived from dinosaurs. But most of our original fossils are from the Cretaceous period. Now we hope to find more Jurassic fossils. This way we can find more direct evidence to prove that birds evolved from dinosaurs," said Xu.
(Reporting by Tan Ee Lyn; Editing by Ron Popeski)
The newly found toothy tyrannosaur featured a hole in its skull and was recovered from New Mexico.
By Jennifer Viegas Thu Jan 28, 2010 07:00 PM ET
A newly found 29-foot-long tyrannosaur flashed more teeth than the well-known Tyrannosaurus rex, with which it shared a common ancestor, according to a paper in the latest Journal of Vertebrate Paleontology.
Remains of the badlands dinosaur, Bistahieversor sealeyi, were collected in the first paleontological excavation from a federal wilderness area, the Bisti/De-na-zin Wilderness of New Mexico. The dino's remains were removed VIP-style, airlifted by a helicopter operated by the Air Wing of the New Mexico Army National Guard.
"Bistahieversor sealeyi is the first valid new genus and species of tyrannosaur to be named from western North America in over 30 years," said co-author Thomas Williamson, curator of paleontology at the New Mexico Museum of Natural History.
It lived 74-75 million years ago, close to 10 million years before T. rex emerged. The earliest known tyrannosaurs date to about 167 million years ago and came from the American West, according to Carr. It is now therefore believed that the rough and tumble Tyrannosauridae family was born in the U.S.A.
Several features distinguish the new dinosaur, according to Williamson's partner on the project, Thomas Carr, who is director of the Carthage Institute of Paleontology and an assistant professor of biology at Carthage College.
It had around 64 teeth, while adult T. rex, had just 54.
However, Carr added, "The teeth of B. sealeyi were smaller and narrower than those of T. rex, which had the largest teeth among the tyrannosauroids."
The new dinosaur also had an unusual hole in its head, just above the eyes. The hole has not been seen on any other tyrannosaur, and might have helped to lighten the load of its head.
"The opening above the eye was produced by an air sac within the skull that removed bone where it was not needed," said Carr. "The opening would not have been visible when the animal was alive (because) it would have been covered by skin."
The dinosaur also had a "complex joint at its forehead." Carr explained that usually these animals show three prongs of the snout extending into the forehead, but the New Mexico beast had seven.
This complex joint might have functioned to stabilize and prevent motion at the joint," he said.
B. sealeyi additionally possessed a keel, or prominent ridge, that extended from the bottom edge of its lower jaw. The scientists aren't sure of the ridge's purpose, but it is another unique feature.
The researchers now think the deep snout characteristic of many tyrannosaurs evolved in the common ancestor of these animals, which lived west of the Western Interior Seaway, a shallow sea that split North America into two subcontinents during the Late Cretaceous.
Tyrannosaurs to the west of the sea continued to evolve this striking head feature, according to Carr, while those to the east retained the more primitive shallow snout. He believes that "selective pressures necessary for producing a deep snout were simply not in action" on the eastern side of the sea.
The badlands dinosaur along with other fossils collected from the Bisti site and from the lands of the Navajo Nation are currently on display at the New Mexico Museum of Natural History.
Wednesday, January 27, 2010
2. Department of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK
3. UCD School of Geological Sciences, University College Dublin, Belfield, Dublin 4, Ireland
4. Planetary and Space Sciences Research Institute, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
Spectacular fossils from the Early Cretaceous Jehol Group of northeastern China have greatly expanded our knowledge of the diversity and palaeobiology of dinosaurs and early birds, and contributed to our understanding of the origin of birds, of flight, and of feathers. Pennaceous (vaned) feathers and integumentary filaments are preserved in birds and non-avian theropod dinosaurs, but little is known of their microstructure. Here we report that melanosomes (colour-bearing organelles) are not only preserved in the pennaceous feathers of early birds, but also in an identical manner in integumentary filaments of non-avian dinosaurs, thus refuting recent claims that the filaments are partially decayed dermal collagen fibres. Examples of both eumelanosomes and phaeomelanosomes have been identified, and they are often preserved in life position within the structure of partially degraded feathers and filaments. Furthermore, the data here provide empirical evidence for reconstructing the colours and colour patterning of these extinct birds and theropod dinosaurs: for example, the dark-coloured stripes on the tail of the theropod dinosaur Sinosauropteryx can reasonably be inferred to have exhibited chestnut to reddish-brown tones.
Monday, January 25, 2010
By Dennis Normile--ScienceNOW Daily News 25 January 2010
How did birds learn to fly? The first flight tests of a foam model of a four-winged, feathered dinosaur suggest that early birds may have started their aviation careers by gliding down from trees.
The fight over bird flight evolution is one of the longest-running and most heated debates in paleontology. Were the first flyers arboreal creatures that initially glided from tree tops to the ground? Or were they bipedal ground runners whose evolving wings allowed them to take progressively longer jumps? There is still no complete consensus.
In recent years, researchers have tried to determine the flight capabilities of early birds with mathematical analyses and computer simulations. And at least one group has built a physical model based on fossils and put it in a wind tunnel. Taking a different tack, biomechanics specialist David Alexander of the University of Kansas, Lawrence, along with colleagues there and at Northeastern University in Shenyang, China, reconstructed a specimen of Microraptor, a dinosaur notable for having four wings. Microraptor is a type of dromeosaur, a genus of birdlike dinosaurs.
The team made a skeleton, covered the "bones" with a clay "body," and added plumage made from modern pheasant feathers trimmed to match impressions preserved in fossils. The researchers used this feathered reconstruction to make urethane foam models that they launched from various heights, recording the distance, velocity, and angle of each glide. "Microraptor was an adept glider and would have had little difficulty gliding from tree trunk to tree trunk," the authors report today online in the Proceedings of the National Academy of Sciences.
Alexander, who says he was added to the team of paleontologists because of his knowledge of flying airplane models, says he doesn't know of any other groups that have tried to fly models of dinosaurs. This new approach is "probably one of the most effective" ways of determining the flight capabilities of extinct animals, says Zhonghe Zhou, a paleontologist at the Chinese Academy of Sciences' Institute of Vertebrate Paleontology and Paleoanthropology in Beijing. He expects similar experiments based on fossils of other animals could help clarify how avian flight originated.
Julia Clarke, a paleontologist at the University of Texas, Austin, agrees that models could be useful, but they have to be constrained by an understanding of anatomy. In the case of Microraptor, "I'm not convinced that in life the animal could have gotten into some of the postures that they are exploring," she says. She also thinks the community has moved beyond the dichotomy of trees-down or ground-up hypotheses, focusing on a more nuanced set of questions such as what anatomical evolutions enabled powered flight.
Sunday, January 17, 2010
Birds, crocodiles and dinosaurs have much in common – including, it turns out, their breath. The hyper-efficient breathing system of birds is shared with alligators, and probably evolved in archosaurs, the common ancestor of crocodilians, birds and dinosaurs.
The researchers who have discovered the system in alligators believe it may have given dinosaurs the competitive edge over the ancestors of mammals following the mass extinction at the end of the Permian period, 250 million years ago.
Thanks to one-way airflow, birds are far more efficient breathers than mammals. When they breathe in, air does not go directly into the lungs. Instead, it enters the air sacs, where it is stored briefly before passing into the lungs at the next inhalation. In this way, air enters and exits a bird's lungs at different points – in via the air sacs, out via the windpipe – allowing them to maintain near-constant, one-way airflow through their lungs and extract up to two-and-a-half times as much oxygen per breath as a mammal.Previous research has suggested that one-way air flow is unique to birds and evolved specifically to allow them to make oxygen-demanding flights. It was also thought that the bellows-like air sacs were critical for pumping air one way.
Those conclusions have been toppled by the new study, in which devices to measure airflow were surgically implanted into the lungs of live alligators.
Gators flayedColleen Farmer of the University of Utah in Salt Lake City also placed the flow meters into the dissected lungs of four dead alligators, which the team then filled with air using a giant syringe. What they found was that alligator lungs function very much like birds'.
Alligators don't have air sacs like birds, but the researchers think an unusual airway that sits on either side of the alligator trachea may do the same job.
Per Ahlberg of Uppsala University in Sweden agrees that the efficient breathing system probably evolved in a common archosaur ancestor of crocodilians, birds and dinosaurs. "Swift, long-legged animals that might have relied on the rich oxygen supply provided by a one-way airflow were abundant in the early lineages of these groups," he says.
Farmer goes one step further and argues that the system would have allowed archosaurs to outcompete synapsids – the ancestors of mammals – following the end-Permian mass extinction."Oxygen levels were really low during the early Triassic [after the Permian], so the evolution of unidirectional airflow, which boosts oxygen delivery to muscles, may have made archosaurs more capable of vigorous exercise than synapsids," she says
Journal reference: Science, DOI: 10.1126/science.1180219