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Ancient Cheetah Fossil Points to Old World Roots?
Writer:Rebecca Carroll

The most primitive known cheetahs roamed present-day China more than two million years ago, according to new research. The study supports the theory that the big cats originated in the Old World, not North America.

Researchers examined and named a new species of prehistoric cheetah. A nearly complete fossil cranium of the new species, found in China's Gansu Province, is similar in size and shape to modern cheetah skulls, researchers found.

But some of its teeth are extremely primitive, said study co-author Ji H. Mazák of the Shanghai Science and Technology Museum. This "mosaic of anatomical features" suggests the Chinese cheetah, called Acinonyx kurteni, represents an early stage in cheetah evolution, he said.

The varied traits also indicate skull and dental characteristics considered unique to cheetahs evolved gradually, according to the study published today in Proceedings of the National Academy of Sciences.

Throwing a potential wrench in the new discovery, other scientists say they had already identified the species and given it another name.

All American?

The cheetah, the fastest land animal, is a highly threatened species with an estimated adult population of only 7,500, according to the International Union for Conservation of Nature (IUCN).

The only known wild cheetah population outside of Africa today is a critically endangered group of fewer than a hundred in Iran. But fossils of cheetah-like animals have been found throughout Africa, Europe, Asia, the Indian subcontinent, and even North America that date to between 3.2 million and 2,000 years old, Mazák said.

The newly studied fossils were dated to the late Pliocene, between 2.15 and 2.55 million years ago.

Two prehistoric cheetah-like species of North America are believed by some scientists to be distant cousins of giant cheetahs of ancient Europe.

This possible relationship has led some researchers to speculate that the earliest cheetahs may have originated in North America and traveled across the Bering Strait from Alaska to Siberia.

Intercontinental Travel?

Mazák said the new finds challenge this theory, suggesting instead a Eurasian-African origin of the cheetah lineage.

For instance, the primitive dental features would have been more developed in the Chinese fossil if cheetahs had come from North America.

This leaves the question of whether cheetahs traveled across the Bering Strait the other way—from Siberia to Alaska—or if the American cheetah-like cat evolved separately, as some scientists argue.

By Any Other Name?

Deng Tao, a professor at the Chinese Academy of Sciences in Beijing, was "astonished" reading the new study.

The newly identified skull is not from a new species, he said in an email.

Deng said his team had already described this species as Sivapanthera linxiaensis. Deng said Sivapanthera is the fossil genus of the ancient cheetah—today's cheetahs belong to the Acinonyx genus.

Mazák responded that his team and Deng's team had studied different species. He argued that Deng's fossils more closely resembled the genus Panthera—which includes the tiger, leopard, jaguar and lion—than Acinonyx.

Deng's fossils were also too big to belong to a cheetah species, Mazák said, adding that Sivapanthera is not a universally accepted species.

Deng also said that the skull in the new study was not an intact original, but rather a compilation from bones of various individuals and possibly even various species.

The difference between an intact skull and a compilation is apparent from comparisons of the photos of the skull in the current study and the skulls his team studied, Deng said.
Mazák denied this charge, saying his team had carefully examined their cranium and determined that all of its parts—including teeth—belonged to the same individual.

Dinosaur-Bird Link: Ancient Proteins Preserved In Soft Tissue From 80 Million-Year-Old Hadrosaur
ScienceDaily (May 1, 2009) — Ancient protein dating back 80 million years to the Cretaceous geologic period has been preserved in bone fragments and soft tissues of a hadrosaur, or duck-billed dinosaur, according to a study in the May 1 issue of Science.
Led by scientists at Beth Israel Deaconess Medical Center (BIDMC) and North Carolina State University (NCSU), the research support earlier results from analyses suggesting that collagen protein survived in the bones of a well preserved Tyrannosaurus rex, and offer robust new evidence supporting previous conclusions that birds and dinosaurs are evolutionarily related.

In April 2007 John Asara, PhD, Director of the Mass Spectrometry Core at BIDMC, together with NCSU paleontologist Mary Schweitzer, PhD, published two papers in Science describing their discovery that collagen extracted from bone fragments of a 68-million-year-old T. rex closely matched the amino acid sequences of modern day chickens. Not surprisingly, the widely publicized findings created a great deal of controversy.

"With this new paper, we hoped to show that our T. rex discovery was not a unique occurrence," notes Asara, who is also an Instructor in Pathology at Harvard Medical School. "This is the second dinosaur species we've examined and helps verify that our first discovery was not just a one-hit wonder. Our current study was the collaborative effort of a number of independent laboratories, whose findings collectively add up to a robust conclusion."

At the heart of the controversy is the idea that ancient protein can exist at all. When an animal dies, protein immediately begins to degrade and, in the case of fossils, is slowly replaced by mineral, a substitution process assumed to be complete by 1 million years. But with this latest evidence, it appears that some proteins do indeed have real staying power.

"We wound up identifying nearly double the number of amino acids we recovered in the T. rex study," says Asara. "The sequences displayed high spectral quality and the interpretations were of high confidence."

The two scientists had decided to collaborate again after Schweitzer and paleontologist Jack Horner of Montana State University's Museum of the Rockies recovered the 80-million-year-old Brachylophosaurus canadensis femur bone in the summer of 2007 and observed that it appeared to be even better preserved than the original T. rex fossil.

Schweitzer's initial laboratory analyses confirmed this observation: After being subjected to demineralization, the B. canadensis bone fragments showed marked preservation of original tissues and molecules, with microstructures resembling soft, transparent vessels, cells and fibrous matrix – even though the fossil was much older than the T. rex sample.

"Deep burial in sandstone seems to favor exceptional preservation," notes Schweitzer, explaining that this fossil was found under approximately seven meters of sandstone in the Judith River Formation, in parts of what is now Eastern Montana.

Chemical extractions of bone and vessel were subsequently sent to the laboratories of BIDMC scientists Lewis Cantley, PhD, and Raghu Kalluri, PhD, where immunoblots and immunochemistry analyses were conducted to determine the presence of collagen protein in the samples.

"Having been a part of the T. rex study, I was curious to be part of this investigation as well," explains Cantley, Chief of the Division of Signal Transduction at BIDMC. "In view of the skepticism about the original findings, it was important to demonstrate that our findings in T. rex could be verified in another dinosaur and in other laboratories."

The results confirmed the existence of protein. "Because I am a collagen biochemist, our lab was contacted to perform an independent analysis of this new bone find," explains Kalluri, who is Chief of the Division of Matrix Biology at BIDMC. "We isolated the proteins – collagen, laminin and elastin – from the bone, and also extracted bone cells and blood vessels from this sample. Our findings demonstrated that it did contain basement membrane matrix."

In addition, In situ mass spectrometry studies conducted at Montana State University by Recep Avci and Zhiyong Suo independently verified amino acids in dinosaur tissues, including the collagen signature amino acid, hydroxylated proline.

From there, using a combination of two mass spectrometry technologies – linear ion trap and hybrid linear ion trap/orbitrap – Asara was able to improve upon the techniques he had used in analyzing both the T. rex specimen and specimens from bones of other prehistoric animals including a 300,000-year-old mammoth and mastodon.

At the beginning of the study, Asara explains, his lab used an ion trap mass spectrometer, which captures and holds peptides through time so that after the collected peptides are measured for mass they are isolated and fragmented to reveal their amino acid sequence. Then, while the study was in progress, his lab acquired a high-resolution and highly mass-accurate Orbitrap XL mass spectrometer, which was used during the second half of the analysis.

"Because it is capable of sub 2 ppm mass accuracy, the Orbitrap allowed us to make more confident sequence calls than we did in the T. rex study," Asara explains. "For example, the mass difference between a hydroxyproline amino acid residue [which is plentiful in collagen] and a leucine or isoleucine residue is only 0.0364 Da. Although this very small measurement proved to be an obstacle for the ion trap, it was not a problem for the Orbitrap." Material for mass spectrometry sequence analysis was also sent to the lab of William Lane at Harvard University and mass spectrometry sequence data were independently verified by John Cottrell, PhD, at Matrix Science in London, UK.

The end result was a total of eight collagen peptides and 149 amino acids from four different samples, sequences that held up when multiple validation steps were performed, including comparisons with synthetic peptides using a spectral comparison algorithm and statistical evaluation.

In the final portion of the study, coauthor Chris Organ, PhD, a Postdoctoral Fellow in the Department of Organismic and Evolutionary Biology at Harvard University, conducted a rigorous phylogenetic analysis of the identified sequences to determine B. canadensis' place within the evolutionary tree of animals. The B. canadensis collagen sequence data were compared to a database of collagen sequence data from 21 species of living animals and sequences from two other fossils, mastodon and T. rex. The results placed B. canadensis on the same family-tree branch with T. rex, in the same group as chicken and ostrich, and more distantly, to alligator and lizard.

"The phylogenetic analysis yielded clear results, but the placement of the extinct dinosaurs still rests on a limited amount of sequence data," notes Organ. "There is not enough sequence data to correctly parse out the relationships within Dinosauria [the group containing B. canadensis, T. rex and the two birds] but the group as a whole is well supported by the analysis, which is consistent with studies based on morphology."

Ultimately, notes Asara, "We were able to achieve these results, in part, because the mass spectrometry systems that our lab has set up for cancer research are capable of a similar concentration range – low to sub femtomole -- needed for ancient fossil protein sequencing. We hope to meet with similar success when it comes to identifying novel signaling proteins from cancerous tissues."

This study was funded, in part, through grants from the National Science Foundation, the David and Lucile Packard Foundation, the Merck Postdoctoral Science Research Fellowship, the National Institutes of Health and the Taplin Funds for Discovery, Harvard Medical School.

In addition to Asara and Schweitzer, coauthors include BIDMC investigators Lewis Cantley, Raghu Kalluri, Lisa Freimark, Valerie Lebleu, and Michael Duncan II; Wenxia Zheng of North Carolina State University; Chris Organ, John Neveu and William Lane of Harvard University; Recep Avci, and Zhiyong Suo of Montana State University; John Horner of the Museum of the Rockies (MT); Matthew Vander Heiden of the Dana-Farber Cancer Institute; and John Cottrell of Matrix Science, London, UK.

Samples of ancient protein dating back 80 million years preserved in bone fragments and soft tissues of a hadrosaur. (Credit: Courtesy of NCSU)

Brachylophosaurus canadensis

Young Dinosaurs Roamed Together, Died Together
A herd of young birdlike dinosaurs met their death on the muddy margins of a lake some 90 million years ago, according to a team of Chinese and American paleontologists that excavated the site in the Gobi Desert in western Inner Mongolia.
The sudden death of the herd in a mud trap provides a rare snapshot of social behavior. Composed entirely of juveniles of a single species of ornithomimid dinosaur (Sinornithomimus dongi), the herd suggests that immature individuals were left to fend for themselves when adults were preoccupied with nesting or brooding.

"There were no adults or hatchlings," said Paul Sereno, professor at the University of Chicago and National Geographic Explorer-in-Residence. "These youngsters were roaming around on their own," remarked Tan Lin, from the Department of Land and Resources of Inner Mongolia.

Within an exquisite pair of the skeletons, prepared for display in Sereno's lab and airlifted back to China in late February, stomach stones and the animal's' last meals are preserved.

Sereno, Tan and Zhao Xijin, professor in the Chinese Academy of Sciences, led the 2001 expedition that found the fossils. Team members also included David Varricchio of Montana State University (MSU), Jeffrey Wilson of the University of Michigan and Gabrielle Lyon of Project Exploration.

"Finding a mired herd is exceedingly rare among living animals," said Varricchio, an assistant professor of paleontology at MSU. "The best examples are from hoofed mammals," such as water buffalo in Australia or feral horses in the American West, he said.

The first bones from the dinosaur herd were spotted by a Chinese geologist in 1978 at the base of a small hill in a desolate, windswept region of the Gobi Desert. Some 20 years later, a Sino-Japanese team excavated the first skeletons, naming the dinosaur Sinornithomimus ("Chinese bird mimic").

Sereno and associates then opened an expansive quarry, following one skeleton after another deep into the base of the hill. In sum, more than 25 individuals were excavated from the site. They range in age from one to seven years, as determined by the annual growth rings in their bones.

The team meticulously recorded the position of all of the bones and the details of the rock layers to try to understand how so many animals of the same species perished in one place. The skeletons showed similar exquisite preservation and were mostly facing the same direction, suggesting that they died together and over a short interval.

The details provided key evidence of an ancient tragedy. Two of the skeletons fell one right over the other. Although most of their skeletons lay on a flat horizontal plane, their hind legs were stuck deeply in the mud below. Only their hip bones were missing, which was likely the handiwork of a scavenger working over the meatiest part of the body bodies shortly after the animals died.

"These animals died a slow death in a mud trap, their flailing only serving to attract a nearby scavenger or predator," Sereno said. Usually, weathering, scavenging or transport of bone have long erased all direct evidence of the cause of death. The site provides some of the best evidence to date of the cause of death of a dinosaur.

Plunging marks in mud surrounding the skeletons recorded their failed attempts to escape. Varricchio said he was both excited and saddened by what the excavation revealed. "I was saddened because I knew how the animals had perished. It was a strange sensation and the only time I had felt that way at a dig," he said.

In addition to herd composition and behavior, the site also provides encyclopedic knowledge of even the tiniest bones in the skull and skeleton. "We even know the size of its eyeball," Sereno said. "Sinornithomimus is destined to become one of the best- understood dinosaurs in the world."

The work was funded by the National Geographic Society and the David and Lucile Packard Foundation.

While approaching the edge of a lake in what is today the Gobi Desert of Inner Mongolia, a herd of young Sinornithomimus dinosaurs suddenly finds itself hopelessly trapped in mud some 90 million years ago. (Credit: Art by Todd Marshall, courtesy of Project Exploration)

Tyrannosaur 'Missing Link' Among New Dinosaurs From China
The new species are described in the Proceedings of the Royal Society B. The papers will appear in print later this year in a special volume entitled "Recent advances in Chinese palaeontology."

An early precursor to T. rex

One of the new animals is an early relative of T. rex, and is named Xiongguanlong baimoensis (shong-GWAN-long by-mo-EN-sis). The generic name derives from the ancient Chinese name Xiong Guan ("Grand Pass") for Jiayuguan and long for dragon. The specific name baimoensis comes from "bai-mo," for "white ghost," in reference to a dramatic landform in the field area known as the "white ghost castle."

Xiongguanlong would have stood about five feet tall at the hip and weighed close to 600 pounds. It had a skull over a foot and half in length and armed with over 70 teeth. "Although impressive by today's standards, Xiongguanlong was still a fly weight predator compared to its heavy-weight relatives such as T. rex," says Peter Makovicky, PhD, Curator of Dinosaurs at Chicago's Field Museum, and corresponding author on the study of this animal. The world's largest known T. rex specimen, housed at The Field Museum and popularly known as SUE, was nearly 14 feet tall at the hips and is estimated to have weighed between six and seven tons.

Xiongguanlong represents a "missing link" in the fossil record of tyrannosaur dinosaurs. Large tyrannosaurs that lived near the end of the age of dinosaurs like T. rex and Albertosaurus have been known to science for over a hundred years, and the last decade has witnessed the discovery of some of the earliest tyrannosaurs from China and England. However, until recently there has been a huge gap between these early and late chapters of tyrannosaur evolutionary history.

According to Mark Norell of the American Museum of Natural History in New York, another member of the team that worked on the two new dinosaurs, "Xiongguanlong sheds light on the missing 40 to 50 million years of tyrannosaur evolution." Xiongguanlong is unusual among tyrannosaurs in having a very long and narrow snout, rather than a wide, massive skull optimized for powerful biting as is seen in T. rex. Despite this difference, Xiongguanlong does mark the earliest appearance of several hallmark traits of larger, geologically younger tyrannosaurs, including a short, broad braincase, broad struts of bone near the temples, expanded areas for jaw muscle attachment on the skull roof, modified "nipping" teeth at the front of the mouth, and expanded vertebral structures to support a large head. Many of these features represent structural modifications for increasing bite forces and presage the specialized skulls of larger tyrannosaurs.

Norell notes that "Xiongguanlong underscores that tyrannosaurs started as small to mid-sized predators, but a number of the traits related to the enormous bite forces of T. rex were already evident at this relatively early stage of tyrannosaur evolution."

Adds Makovicky, "The proportions of Xiongguanlong's skull are similar to those of juveniles of large tyrannosaurs, confirming that massive skulls of T. rex and its closest relatives evolved from animlas with long slender snouts like Xiongguanlong."

Second find: A giant "ostrich-mimic"

The team also discovered three specimens of a remarkable, second theropod from the Yujingzi basin during the 2006 and 2007 field seasons. Beishanlong grandis (bay-SHAN-long gran-DIS) is a new species of ornithomimosaur, or ostrich-mimic dinosaur. Ornithomimosaurs are a lineage of theropods that evolved a toothless beak and were likely omnivorous or herbivorous, superficially resembling present day ostriches.

With an estimated body mass of almost 1400 lbs. (626 kg), Beishanlong is one of the largest ornithomimosaurs yet described, rivaling the Late Cretaceous ornithomimosaur Gallimimus in size. Bone microstructure analysis on a cross section of one of the lower leg bones of the principal specimen by co-author Gregory Erickson of Florida State University reveals that the holotype individual was not yet fully grown when it died. According to Dr. Erickson, "Growth line counts revealed that the animal perished during its 14th year of life. Although it is hard to fathom, this giant was still actively growing when it died. Growth line spacing in the bones of the teen-giant show only moderate decreases in width towards the periphery. Somewhere out there are even larger specimens awaiting discovery."

Beishanlong was equipped with hand claws up to six inches in length and relatively powerful forelimbs compared to most other ornithomimosaurs. "We know the forelimbs could not be brought far forward or elevated too much" says Makovicky, who is the lead author on the study, "but their range of motion and the shape of the claws suggest they may have been used for digging or raking the ground."

Profound implications for Asian dinosaur faunas

Other dinosaurs found together with Beishanlong and Xiongguanlong include the beaked and probably herbivorous therizinosauroid theropod Suzhousaurus, primitive relatives of duck-billed dinosaurs, the small horned dinosaur Auroraceratops, and both small and large sickle-clawed theropods. Most of the famous Cretaceous dinosaur faunas of China and Mongolia, like the ones that include Velociraptor and Protoceratops, comprise members of the same dinosaur lineages as those found in Gansu, but very few others. Interestingly, horned dinosaurs and sickle-clawed dinosaurs tend to dominate red rocks deposited under dry conditions across almost all Cretaceous localities in the Gobi Desert, whereas tyrannosaurs, ornithomimosaurs, and duck-billed dinosaurs tend to occur in rocks deposited in wetter environments. The fauna collected by the Chinese-American team in Gansu shows evidence of such environmental separations between different kinds.

The fauna collected by the Chinese-American team in Gansu shows evidence of such environmental separations between different kinds of dinosaurs, and represents one of the earliest instances of both the environmental sorting of animals and the very stable, but depauperate, lineage composition of Cretaceous Central Asian dinosaur faunas that reined for the next 50 million years. Professor Gao Ke-Qin of Peking University, who also took part in this research, notes, "The abundance of new dinosaurs from Chinese localities like the Yujingzi Basin, allows us to study the long history of dinosaur evolution in light of both geographic and environmental parameters in a way that is impossible elsewhere in the world."

The researchers were funded by the US National Science Foundation, the National Science Foundation of China, and a Grainger Foundation grant from The Field Museum, and were joined in the field by students and post-docs from their institutions.


Reconstructed body silhouettes of three tyrannosaurs, showing where Xiongguanlong falls in the spectrum of body sizes in this lineage. Dilong on the left is 125 million years old and the smallest known tyrannosaur. Xiongguanlong, shown in grey, is much larger, but is still dwarfed by T. rex, shown on the right. "Although impressive by today's standards, Xiongguanlong was still a fly weight predator compared to its heavy-weight relatives such as T. rex" says Peter Makovicky, Curator of Dinosaurs at The Field Museum, and corresponding author on the study of Xiongguanlong. (Credit: M. Donnelly/The Field Museum)

Dynamite Used To Reveal New Layer Of Dinosaur Fossils
ScienceDaily (May 1, 2009) — What do you do when you have a fossil quarry that has yielded some of the most important and rarest of dinosaur fossils in North America, but the fossil-bearing layer of rock is tilted at 70 degrees and there is so much rock that not even jackhammers can get you to the fossils any longer?

That was the problem facing Dinosaur National Monument at a Lower Cretaceous dinosaur quarry -- the one that has produced the only complete brontosaur skulls from the last 80 million years of the Age of Dinosaurs in North America. The site is so scientifically important that excavations cannot be stopped, yet there was no way to reach the bones.

Dave Larsen, Steve Bors, and Tim George, a blasting team from Rocky Mountain National Park, rode to the rescue in mid-April. Over several days these skilled employees, using their expertise with explosives, blew away the rock covering the fossils and exposed a significant amount of the fossil-bearing layer so that excavation can begin again this year. Without their talents, scientifically important fossils would have remained locked underground in their stony mausoleum.

Fossil excavation often uses small tools, either pneumatic or manual, to carefully remove rock from delicate fossils. However, in some instances, instruments that are more powerful are needed. Although explosives might seem extreme, in the right setting and in the right hands, they are the right tool for the job --- staff at Dinosaur National Monument can certainly testify to that.

Air-filled Bones Extended Lung Capacity And Helped Prehistoric Reptiles Take First Flight
ScienceDaily — In the Mesozoic Era, 70 million years before birds first conquered the skies, pterosaurs dominated the air with sparrow- to Cessna-sized wingspans. Researchers suspected that these extinct reptiles sustained flight through flapping, based on fossil evidence from the wings, but had little understanding of how pterosaurs met the energetic demands of active flight.

Balloon-like air sacs, which extended from the lungs to inside the skeleton of pterosaurs, provided an efficient breathing system for these ancient beasts.
A new study published February 17 in the journal PLoS One by researchers from Ohio University, College of the Holy Cross and the University of Leicester explains how balloon-like air sacs, which extended from the lungs to inside the skeleton of pterosaurs, provided an efficient breathing system for the ancient beasts. The system reduced the density of the body in pterosaurs, which in turn allowed for the evolution of the largest flying vertebrates.

"We offer a reconstruction of the breathing system in pterosaurs, one that proposes the existence of a mechanism with the same essential structure to that of modern birds — except 70 million years earlier," said study co-author Leon Claessens, an assistant professor of biology at the College of the Holy Cross.

The system would have facilitated the necessary gas exchange to enable sustained activity, added co-author Patrick O'Connor, an assistant professor of biomedical sciences at the Ohio University College of Osteopathic Medicine.

Claessens and O'Connor were inspired to conduct the study after David Unwin of the University of Leicester, then curator at the Natural History Museum in Berlin, showed them an extraordinarily preserved pterosaur in 2003. The scientists thought the specimen might finally shed light on how the animals powered sustained flight.

"The shape and size of the rib segments that articulate with the sternum indicate that the ribcage was mobile, contrary to previous ideas," Claessens said.

Unique and previously unrecognized projections on the ribs provided important leverage for the muscles that power lung ventilation, he added.

Because fossils rarely preserve soft tissues, the research team conducted a comparative study that included pterosaurs, birds and crocodilians in order to get a better understanding of the relationships among air sacs, lung structure and the skeleton. By using X-ray movies and CT scans, the group characterized how the skeleton works to move air through the lungs in living animals, and also how to identify the signature traces left on bones that have been invaded by air sacs.

Not only do the extinct pterosaurs show evidence that their bones that were invaded by air sacs, but patterns of pneumaticity throughout the entire skeleton of different pterosaur species parallel trends identified in many living bird groups. For example, there is a direct relationship between the proportion of the skeleton invaded by air sacs and the absolute body size of an animal.

"Whereas small-bodied pterosaurs and birds typically pneumatize only a restricted part of the backbone, larger-bodied species routinely pneumatize most bones of the body, including the wing skeleton out to the ends of the fingers," O'Connor said.

Such modifications of the skeleton would have reduced bone density and resolved a major problem with sustaining flight in large-bodied pterosaurs: the energetic cost of keeping a heavy body up in the air. Density reduction of the skeleton in pterosaurs may have been beneficial, particularly so in the aerial giants—just as it appears to be in the largest flying birds today.

Air sacs in birds also serve other purposes, such as for visual displays and the production of sound, the researchers said. The existence of an analogous air-sac system in pterosaurs highlights new areas of research in which paleobiologists can explore aspects of pterosaurian biology.

The research was funded by the National Science Foundation, Harvard University, and the Ohio University College of Osteopathic Medicine and Office of Research.

High-tech Imaging Of Inner Ear Sheds Light On Hearing, Behavior Of Oldest Fossil Bird
ScienceDaily — The earliest known bird, the magpie-sized Archaeopteryx, had a similar hearing range to the modern emu, which suggests that the 145 million-year-old creature — despite its reptilian teeth and long tail — was more birdlike than reptilian, according to new research.
Using innovative modern technology, a team of paleontologists and biologists from London, Munich and Ohio have shown for the first time how the length of the inner ear of birds and reptiles can be used to accurately predict their hearing ability and even aspects of their behavior.

"In modern living reptiles and birds we found that the length of the bony canal containing the sensory tissue of the inner ear is strongly related to their hearing ability," said study co-author Paul Barrett, a palaeontologist at London's Natural History Museum. "We were then able to use these results to predict how extinct birds and reptiles may have heard and found that Archaeopteryx had an average hearing range of approximately 2000 Hz. This means it had similar hearing to modern emus, which have some of the most limited hearing ranges of modern birds."

Researchers previously have only been able to estimate how prehistoric animals heard by examining the skulls of damaged fossils and relating brain region size to hearing ability, based on comparisons to the animals' modern relatives. Computed tomography or CT imaging, however, allowed the team to accurately reconstruct the inner ear anatomy of various intact bird and reptile specimens. Fifty-nine species were studied, including turtles, crocodiles, snakes and birds.

"By examining the three dimensional CT scans we were able to see for the first time the real relationship between hearing ability and behavior in extinct reptiles and birds," said Stig Walsh, Natural History Museum palaeontologist and lead author on the study. "The size of the cochlea duct (the bony part of the inner ear housing the hearing organ) in living birds and reptiles accurately predicts the hearing ranges of these animals. This simple measurement can therefore provide a direct means for determining hearing capabilities, and possibly behavior, in their extinct relatives, including Archaeopteryx."

The study, published in the latest issue of the journal Proceedings of the Royal Society B, also adds more information about how bird-like Archaeopteryx was, said Angela Milner, also from the Natural History Museum. "Our previous research has shown that the part of the ear that controls balance was just like that of modern birds, and now we know that Archaeopteryx had bird-like hearing too," she said.

Other team members included Geoff Manley from the Technical University of Munich, who is a leading scientist in the study of hearing in modern animals, and Lawrence Witmer of Ohio University's College of Osteopathic Medicine in Athens, Ohio. Witmer has studied the structure of the brain and inner ear in dozens of species of dinosaurs and modern and extinct birds, including Archaeopteryx.

"This delicate little inner ear has only recently become a player for those of us trying to interpret the past, because it's buried deep within the skull," said Witmer, whose research is funded by the National Science Foundation. "Thanks to CT scanning, we can now get a clear picture of its structure. It's turned out to be a pretty useful organ for deciphering the lives of extinct animals. My previous research has shown that inner ear structure also can tell us about eye movements, head posture, agility, and the relative importance of hearing, and this new study now shows that this sensory Swiss-army knife can tell us about sociality, vocal complexity and maybe even habitat preference."

Animals with a long cochlear duct tended to have the best hearing and vocal ability. Modern living bird species are known to possess relatively longer cochlear ducts than living reptiles. A long cochlear duct is also an indicator of an individual's complex vocal communication, living in groups and even habitat choice. This is true for both mammals and birds.

"Species that form large social groups have more complicated vocal communication, which is understandably influenced by an individual's ability to hear. Species living in a closed environment where visual communication is ineffective often posses more complex vocal abilities, so now we can more accurately predict the habitat types that extinct animals lived in by examining their ability to hear and communicate," Barrett said.

The research received funding from the Natural Environment Research Council and the National Science Foundation.

Four, Three, Two, One . . . Pterosaurs Have Lift Off
ScienceDaily — Pterosaurs have long suffered an identity crisis. Pop culture heedlessly — and wrongly — lumps these extinct flying lizards in with dinosaurs. Even paleontologists assumed that because the creatures flew, they were birdlike in many ways, such as using only two legs to take flight.

Launching some 500 pounds of reptilian heft into flight required pterosaurs to use four limbs: two were ultra-strong wings which, when folded and balanced on a knuckle, served as front “legs” that helped the creature to walk — and leap. (Credit: Image courtesy of Johns Hopkins Medical Institutions)
Now comes what is believed to be first-time evidence that launching some 500 pounds of reptilian heft into flight required pterosaurs to use four limbs: two were ultra-strong wings which, when folded and balanced on a knuckle, served as front “legs” that helped the creature to walk — and leap.

Publishing in Zitteliana, Michael B. Habib, M.S., of the Center for Functional Anatomy and Evolution at the Johns Hopkins University School of Medicine, reports his comparison of bone strength in the limbs of pterosaurs to that of birds and concludes that pterosaurs had much stronger “arms” than legs. The reverse is true of birds.

“We’ve all seen birds take off, so that’s what’s most familiar,” says Habib. “But with pterosaurs, extinct 65 million years and with a fossil history that goes back 250 million years, what’s familiar isn’t relevant.”

A supersized glitch is inherent in the traditional bipedal launch model, Habib notes: “If a creature takes off like a bird, it should only be able to get as big as the biggest bird.”

Birds use legs to launch, wings to flap. They don’t get launch power from wings or flight power from legs. In fact, when a bird is aloft, its legs become payload, or cargo. The muscle on the two back limbs that provides the power to launch must be carried and therefore limits size. Released of that handicap by employing all four legs to launch, giant pterosaurs could fly despite the fact that they were roughly the same size and shape as modern-day giraffes.

“The difference between pterosaurs and birds with regard to critical mechanical properties is very, very large,” Habib says, especially when you’re talking about the big pterosaurs; as the size gets bigger, the difference gets bigger too.”

For example, the wings of these fantastic hairy reptiles, most notably those of Quetzalcoatlus northropi, which spanned to an impressive 35 feet when the creatures were aloft, propelled the creatures into the air during take-offs that Habib describes as leap-frogging long-jumps: “Pterosaurs had long, huge front limbs, so no partner was required. Then, with wings snapping out, off they’d fly.”

Using computer scans to obtain cross-sectional images and geometric data for 155 bird specimens representing 20 species, Habib calculated the strengths of bones in bird limbs and compared these to three species of pterosaurs, the bones strengths of which he calculated using measurements from previously published sources. Structural strength, taking into account length and diameter, among other things, is a measure of how much force a bone can take before it fractures.

Habib also spent time crunching the numbers using the old, bipedal launch model and simply couldn’t find a mathematical solution that would enable the largest of the pterosaurs — using hind legs alone — to launch at all.

“But using all four legs, it takes less than a second to get off of flat ground, no wind, no cliffs,” he said. “This was a good thing to be able to do if you lived in the late Cretaceous period and there were hungry tyrannosaurs wandering around.”

It stands to reason that a large-bodied animal needing to produce lots of power at take-off would use four legs instead of two, Habib says: “We put V8 engines in our biggest, heaviest cars, not V-4s, like the one in my Camry.”

Assumption and convention — rather than reason or data — held sway for centuries, ever since the classical bipedal model of pterosaur take-off was first championed, he notes.

The research was funded by the Jurassic Foundation. Habib, of Johns Hopkins, is the sole author of the paper.

Ancient Airways: Flying Drone Design Based On Prehistoric Flying Reptile
ScienceDaily — Texas Tech University paleontologist Sankar Chaterjee and Rick Lind, an aeronautical engineer from the University of Florida, have developed a 30-inch robotic spy plane modeled after a 225 million-year-old pterodactyl

The earliest known flying dinosaurs flew like the biplanes of early aviation. (Credit: Image courtesy of Texas Tech University)
The drone, featuring a strange design of a rudder at the nose of the craft instead of the tail, would gather data from sights, sounds and smells in urban combat zones and transmit information back to a command center.

According to Chatterjee and Lind, this project will demonstrate a next-generation capability of sensor emplacement using a pterodactyl as the model animal.

The unmanned, sensor-packed craft in development could soon be demonstrated using existing materials and actuators, the researchers said. Pterodrone, the military’s next generation of airborne drones, won’t just be small and silent – they will alter their wing shapes using morphing techniques to squeeze through confined spaces, dive between buildings, zoom under overpasses, land on apartment balconies or sail along the coastline for surveillance.

Born to Fly

Pterodactyls lived 228 to 65 million years ago from the late Triassic Period to the end of the Cretaceous Period, Chatterjee said. They dominated the Mesozoic sky, swooping over the heads of dinosaurs. Their sizes ranged from a sparrow to a Cessna plane with a wingspan of 35 feet. Their bodies featured lightweight bones and an intricate system of collagen fibers that added strength and agility to their membranous wings.

“These animals take the best parts of bats and birds,” Chatterjee said. “They had the maneuverability of a bat, but could glide like an albatross. Nothing alive today compares to the performance and agility of these animals. They lived for 160 million years, so they were not stupid animals. The skies were darkened by flocks of them. They were the dominant flying animals of their time.”

Tapejara wellnhoferi, a pterodactyl from Brazil, featured a large, thin rudder-like sail on its head that functioned as a sensory organ. Though as big as a Canada goose, its strange design made it stand out from the Cretaceous crowd when it came to flying. This design showed promise as a model to develop into an unmanned aerospace vehicle called Pterodrone, which has superior agility to perform missions requiring aerial, terrestrial and aquatic locomotion.

Divine Design

Putting the tail at the nose of an airplane would seem like a failed design. However, Chatterjee’s research into Tapejara’s flight showed that the rudder acted similarly to a flight computer in a modern-day aircraft and also helped with the animal’s turning agility.

“Since the discovery of a complete Tapejara in Brazil about 10 years ago, we’ve found they could actually sail on the wind for very long periods as they flew over the oceans,” he said. “They spent most of their time hunting for fish. By raising their wings like sails on a boat, they could use the slightest breeze in the same way a catamaran moves across water. They could take off quickly and fly long distances with little effort.”

Similarly, the drone will sail in the same manner.

Initially, Lind said he had his doubts about creating a drone built with a tail at the nose of the aircraft.

“A vertical tail on the head is a destabilizing influence, so we immediately questioned how Tapejara could survive in that configuration,” Lind said. “The issue of flight control becomes quite relevant as the animal, and thus aircraft, must alter its flight properties to take advantage of the turning capabilities presented by this vertical tail and yet remain stable.”

Chatterjee and Lind used computer simulation models and, based off the complete skeleton of the Tapejara, were able to unlock the secrets of flight from this strangely shaped flying animal.

“Sankar actually contacted me about three years ago after seeing a story on the Discovery Channel on our bird-inspired aircraft to inquire if a pterodactyl-inspired aircraft could also be feasible,” Lind said. “We shared some discussions for a while and then finally got serious this year once we had a common concept and could build upon that foundation.”

Bio-inspiration has led surprisingly to a wide variety of robotic design, especially small Unmanned Aerial Vehicles (UAVs) for urban environment that have taken cues from birds, bats and insects. Compared with a fixed-wing aircraft, a pterodactyl wing is a complicated structure of skin, hair, muscles, tendons, blood vessels and nerve tissue.

A team of students from the University of Florida will begin building the aircraft this fall. Chatterjee and Lind have submitted a joint proposal to The Defense Advanced Research Projects Agency at the Department of Defense, which is currently under review.