Giant Clawed Dinosaur Unearthed in Utah Desert
Jennifer Viegas, Discovery News
July 14, 2009 — A multi-institutional team of scientists this week reports the discovery of a giant new dinosaur in Utah, Nothronychus graffami, which stood 13 feet tall and had nine-inch-long hand claws that looked like scythes.
SLIDE SHOW: Therizinosaur: A Dino With Nine-Inch Nails
Its skeleton, described in the current issue of Proceedings of the Royal Society B, represents the most complete remains ever excavated of a therizinosaur, meaning “reaper lizard.” It is one of only three such dinosaurs ever found in North America.
Lead author Lindsay Zanno told Discovery News that therizinosaurs, including the new Utah species, “are unusual in that they have small heads with a keratinous beak at the front of the mouth — the same material as the beak of modern birds — and small leaf-shaped teeth.”
“Their bellies are proportionally enormous, supporting large guts,” added Zanno, who is a researcher in the Department of Geology at The Field Museum. “They have greatly enlarged claws on their hands, short legs and tails, and four-toed feet.”
Therizinosaurs are theropod predatory dinosaurs, a group that includes the legendary Tyrannosaurus rex. The newly discovered 92.5-million-year-old Utah dinosaur was no lightweight either. As Zanno said, “You wouldn’t want to run into this guy in a dark alley.” But its teeth, beak, gut and other anatomical characteristics suggest it was an omnivore that mostly feasted on plants.
Co-author David Gillette, curator of paleontology at the Museum of Northern Arizona, told Discovery News the formidable-looking claws on Nothronychus graffami probably weren’t used to kill other large animals, but instead might have tackled “digging into termite mounds, mucking on the bottom of a lake or pond like a goose or moose, and raking leaves into its mouth from a mangrove forest like a ground sloth.”
To better understand the dietary evolution of theropods, the researchers studied information on 75 other species within this group. They determined therizinosaurs experienced an early evolutionary split from the Maniraptora, which includes modern birds and their closest extinct relatives. One such relative was Velociraptor, a carnivore that probably kicked prey to death with its large hind foot claws.
The new Utah dinosaur therefore suggests that “iconic predators like Velociraptor, one of the dinosaurian villains in the movie Jurassic Park — may have evolved from less fearsome plant-eating ancestors,” according to the scientists.
Since the very meat-loving Velociraptor emerged some 20 million years after plant-chomping Nothronychus graffami, it’s now thought that some dinosaurs might have first been carnivores that evolved into omnivores or herbivores, which re-evolved back into meat-eaters.
Paleontologists aren’t sure why some dinosaur lineages may have see-sawed back and forth with their diets.
“Our current thoughts are that in gaining the ability to eat more than just meat, maniraptorans may have been able to invade new niches in the ecosystem that were unavailable to them before,” Zanno said. “In other words, they may have been able to find a new way of living in the ecosystem and new resources to exploit that gave them an advantage and allowed them to diversify into new forms.”
Aside from what it reveals about dinosaur diets, the new Utah species is significant because of where it was found: in marine sediments that would have been between 60 and 100 miles away from the closest shoreline. The ancient sea is now part of a desert. Merle Graffam, a member of the excavation team, found the dinosaur while searching for sea-dwelling animals. The dinosaur was named after him.
“A big mystery is how this animal — either alive or as a carcass — could get so far out to sea without being torn apart by predators and scavengers,” Gillette said. “This ecosystem had at least five species of plesiosaurs and many sharks and predatory, scavenging fish.”
He added, “Maybe (the dinosaur) was stranded at sea and struggled for a few days before drowning and sinking to the bottom.”
Paul Heinrich, a research associate at the Louisiana Geological Survey, offers another explanation. He thinks such complete dinosaur skeletons recovered in seaways may have rafted out to open water on “floating islands” after storms.
The recovered Utah dinosaur’s remains are now on public display at the Museum of Northern Arizona. The exhibit, Therizinosaur: Mystery of the Sickle-Claw Dinosaur, will close in September before moving to the Arizona Museum of Natural History in Mesa.
Fossili di 3 grandi dinosauri scoperti in Australia
SYDNEY (Reuters) – Fossili di tre nuove specie di dinosauri sono stati scoperti in Australia, di cui quello di un carnivoro più grande del Velociraptor dei film di Jurassic Park, lasciando intendere che l’Australia potrebbe avere un passato preistorico più complesso di quanto si pensi.
I tre fossili, due di erbivori e uno di un carnivoro — i primi resti di grandi dinosauri rinvenuti dal 1981 — sono stati trovati nel Queensland e risalgono al Cretaceo, 98 milioni di anni fa.
“Questa scoperta ci fa conoscere non solo due affascinanti giganti dal collo lungo del continente australiano antico, ma anche il nostro primo grande predatore” ha detto oggi il paleontologo John Long, del Museo Victoria.
Il paleontologo Ben Kear dell’Università La Trobe di Melbourne ha detto che la scoperta apre la strada a nuovi studi sui dinosauri australiani e il loro habitat.
“L’Australia è una delle grandi risorse poco sfruttate per la comprensione della vita nel periodo dei dinosauri”, ha detto Kear. “Questo … farà sicuramente crescere l’interesse nelle finora incomplete ma rilevanti scoperte in questo continente”.
Triple Fossil Find Puts Australia Back On The Dinosaur Map
ScienceDaily (July 3, 2009) — Scientists have discovered three new species of Australian dinosaur discovered in a prehistoric billabong in Western Queensland.
Artistic representations of the three new Australian dinosaur taxa: Australovenator (top); Wintonotitan (middle); Diamantinasaurus (bottom). (Credit: Artwork by: T. Tischler, Australian Age of Dinosaurs Museum of Natural History / Scott A. Hocknull, Matt A. White, Travis R. Tischler, Alex G. Cook, Naomi D. Calleja, Trish Sloan, David A. Elliott. New Mid-Cretaceous (Latest Albian) Dinosaurs from Winton, Queensland, Australia. PLoS ONE, 2009; 4 (7): e6190 DOI: 10.1371/journal.pone.0006190)
Reporting on July 3 in the open-access, peer-reviewed journal, PLoS ONE, Scott Hocknull and colleagues at the Queensland Museum and the Australian Age of Dinosaurs Museum of Natural History describe the fossils of three new mid-Cretaceous dinosaurs from the Winton Formation in eastern Australia: two giant, herbivorous sauropods and one carnivorous theropod, all of which are to be unveiled in Queensland on July 3. The three fossils add to our knowledge of the Australian dinosaurian record, which is crucial for the understanding of the global paleobiogeography of dinosaurian groups.
Australia’s dinosaurian fossil record is extremely poor, compared with that of other similar-sized continents, such as South America and Africa. However, the mid-Cretaceous Winton Formation in central western Queensland has, in recent years, yielded numerous fossil sites with huge potential for the discovery of new dinosaurian taxa. Between 2006 and 2009, extensive excavations have yielded many well-preserved dinosaur fossils, as well as the remains of other contemporaneous fauna.
In a single, comprehensive, publication, Hocknull and colleagues describe the remains of three individual dinosaur skeletons, found during joint Australian Age of Dinosaurs Museum and Queensland Museum digs in two different sites in the Winton Formation. They represent three new genera and species of dinosaur: two giant herbivorous sauropods and a carnivorous theropod.
The carnivore, named by the authors on the paper Australovenator wintonensis (nicknamed “Banjo”) is the most complete meat-eating dinosaur found in Australia, to date and sheds light on the ancestry of the largest-ever meat-eating dinosaurs, the carcharodontosaurs, a group of dinosaurs that became gigantic, like Giganotosaurus.
“The cheetah of his time, Banjo was light and agile,” said lead author Scott Hocknull. “He could run down most prey with ease over open ground. His most distinguishing feature was three large slashing claws on each hand. Unlike some theropods that have small arms (think T. rex), Banjo was different; his arms were a primary weapon.
“He’s Australia’s answer to Velociraptor, but many times bigger and more terrifying.”
The skeleton of Australovenator solves a 28-year-old mystery surrounding an ankle bone found in Victoria, which was originally classified as a dwarf Allosaurus, although this classification remained controversial until the discovery of Australovenator—the researchers are now able to confirm that the ankle bone belonged to the lineage that led to Australovenator.
The two plant-eating theropods, named Witonotitan wattsi (“Clancy”) and Diamantinasaurus matildae (“Matilda”), are different kinds of titanosaur (the largest type of dinosaur ever to have lived). While Witonotitan represents a tall, gracile animal, which might have fitted into a giraffe-like niche, the stocky, solid Diamantinasaurus represents a more hippo-like species.
All three dinosaurs are nicknamed after characters from a world-famous, Australian poet. Banjo Patterson composed Waltzing Matilda in 1885 in Winton, where the song was also first performed (and where the fossils were discovered). Waltzing Matilda is now considered to be Australia’s national song.
In a quirky twist of fate, the song Waltzing Matilda describes the unfortunate demise of a swag-man, who steals a jumbuck (sheep) but is driven to leap into a billabong (an Australian word for a small oxbow lake) to avoid being captured by the police. He ends up drowning in the billabong alongside the stolen sheep.
Banjo and Matilda were found buried together in what turns out to be a 98-million-year-old billabong. Whether they died together or got stuck in the mud together remains a mystery; however, echoing the song, both predator and possible prey met their end at the bottom of a billabong, 98 million years ago. This shows that processes that were working in the area over the last 98 million years are still there today. “Billabongs are a built-in part of the Australian mind,” said Hocknull, “because we associate them with mystery, ghosts and monsters.”
The finding and documentation of the fossils was a 100% Australian effort. Both Matilda and Banjo were prepared by Australian Age of Dinosaurs Museum thanks to thousands of hours of volunteer work and philanthropy.
“This is the only place in Australia where you can come off the street and be taught to be a palaeontologist and find, excavate and prepare your own part of Australian natural history,” said Hocknull. The dinosaurs will now be part of a museum collection and this effort will enable future generations of scientists to be involved in a new wave of dinosaur discoveries and to bring the general public in touch with their own natural heritage.”
This collaborative effort links closely with PLoS ONE’s philosophy of making science freely accessible to the general public. “One of my major motivations for submitting to PLoS ONE was the fact that my research will reach a much wider community, including the hundreds of volunteers and public who gave their time and money to the development of natural history collections,” said Hocknull. “They are the backbone of our work (excuse the pun) and they usually never get to see their final product because they rarely subscribe to scientific journals.”
All three new taxa, along with some fragmentary remains from other taxa, indicate a diverse Early Cretaceous sauropod and theropod fauna in Australia, and the finds will help provide a better understanding of the Australian dinosaurian record, which is, in turn, crucial for the understanding of the global palaeobiogeography of dinosaurian groups.
The authors agree that even though hundreds of bones have already been found at the site, these fossils are just the tip of the iceberg. “Many hundreds more fossils from this dig await preparation and there is much more material left to excavate,” they said. Australian Age of Dinosaurs Museum and Queensland Museum staff and volunteers will continue to dig at this and other sites in 2010.
The fossils will be unveiled at the Australian Age of Dinosaurs Museum of Natural History in Queensland, Australia, July 3 by Anna Bligh, the Premier of Queensland. Stage 1 of the museum, a non-profit, volunteer-driven, science initiative that aims to bring Australian dinosaurs to the world, will also be opened by Ms Bligh on July 3.
- Scott A. Hocknull, Matt A. White, Travis R. Tischler, Alex G. Cook, Naomi D. Calleja, Trish Sloan, David A. Elliott. New Mid-Cretaceous (Latest Albian) Dinosaurs from Winton, Queensland, Australia. PLoS ONE, 2009; 4 (7): e6190 DOI: 10.1371/journal.pone.0006190
per informazioni in italiano vedi:
BLOG THEROPODA – Limusaurus inextricabilis Xu et al. (2009) – Prima Parte: Un Ceratosauria senza denti dal Giurassico Superiore della Cina!
New dinosaur gives bird wing clue
The Limusaurus fossil sits among small crocodile fossils
A new dinosaur unearthed in western China has shed light on the evolution from dinosaur hands to the wing bones in today’s birds.
The fossil, from about 160 million years ago, has been named Limusaurus inextricabilis.
The find contributes to a debate over how an ancestral hand with five digits evolved to one with three in birds.
The work, published in Nature, suggests that the middle three digits, rather than the “thumb” and first two, remain.
Theropods – the group of dinosaurs ancestral to modern birds and which include the fearsome Tyrannosaurus rex – are known for having hands and feet with just three digits.
It has been a matter of debate how the three-fingered hand developed from its five-fingered ancestor. Each digit among the five was composed of a specific number of bones, or phalanges.
Palaeontologists have long argued that it is the first (corresponding to the thumb), second, and third fingers from that ancestral hand that survived through to modern birds, on grounds that the three fingers in later animals exhibit the correct number of phalanges.
However, developmental biologists have shown that bird embryos show growth of all five digits, but it is the first and fifth that later stop growing and are reabsorbed.
The remaining three bones fuse and form a vestigial “hand” hidden in the middle of a bird’s wing.
James Clark of George Washington University in Washington DC and Xing Xu from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing hit an palaeontologist’s gold mine in the Junggar Basin of northwestern China.
Previous digs have unearthed the oldest known fossil belonging to the tyrannosaur group and the oldest horned dinosaur among several others.
The dinosaurs had beaks and may have had feathers
This time, the ancient mire has yielded a primitive ceratosaur, a theropod that often had horns or crests, many of whom had knobbly fingers without claws.
“It’s a really weird animal – it’s got no teeth, had a beak and a very long neck, and very wimpy forelimbs,” Professor Clark told BBC News.
“Then when we looked closely at the hand, we noticed it was relevant to a very big question in palaeontology.”
The fossil has a first finger which is barely present, made up of just one small bone near the wrist. The fifth finger is gone altogether.
It is a fossil that appears to offer a snapshot of evolution, proving that the more modern three-fingered hand is made up of the middle digits of the ancestral hand, with the outer two being shed.
The third finger is made up of the four phalange bones that the second should have, and it is presumed that the second would lose one bone to become like the first finger that was missing in the fossil.
This process of shifting patterns of gene expression from one limb or digit to another is known as an “identity shift”, and was again caught in the act – making the conflicting theories of bird hand origin suddenly align.
“This is amazing – it’s the first time we’ve seen this thing actually starting to disappear,” Jack Conrad, a palaeontologist at the American Museum of Natural History, told BBC News.
“There’s been this fundamental rift – there was no way to make peace between the good data we were seeing from the developmental biologists and the palaeontological evidence that showed with every fossil we found we were seeing [fingers] one, two and three.”
FOXNews – 17/giu/2009
World’s largest ornithomimosauris to be exhibited in China
LANZHOU, May 8 (Xinhua) — The world’s largest ornithomimosauris, a dinosaur named Beishanlong Grandis discovered in northwest China’s Gansu Province, will get its first public show in July, experts told Xinhua Friday. The Beishanlong Grandis found about three years ago was recognized in April as the largest of the world’s ornithomimosauris in terms of size by Chinese and American palaeontologists and it will be seen by the public for the first time in July at a dinosaur exhibition in Lanzhou Stadium in Gansu, said Li Daqing, director of the Palaeontological Center, with Gansu Geology Bureau.
The Beishanlong Grandis was both longer and heavier than the previous largest ornithomimosauris named Gallinimus found in Mongolia, Li said.
The dinosaur is at least 100 million years old and was discovered in June 2006 at Beishan in Yujingzi Basin in Gansu, Li said.
American palaeontologists Peter J. Makovicky from the Field Museum of Natural History in Chicago and experts from New York’s Natural History Museum joined the research.
The Beishanlong Grandis was eight meters long and 626 kilograms while the Gallinimus was four meters long and 440 kilograms, Li said.
The experts had jointly published an article on the research in the Proceedings of the Royal Society, published in London, in April, Li said.
They found the dinosaur was only a 14-year-old when it died and experts believe an adult Beishanlong Grandis could be even larger, Li said.
The Beishanlong Grandis was a herbivorous dinosaur with 15-centimeter-long, strong forepaws which lived during the Cretaceous period in the warm and humid basin. It could dig and rake, searching for food, Li said.
The discovery of the Beishanlong Grandis has attracted the attention of the world’s experts and further research will be done on its living habits and evolution, Li said.
Sulla rivista “Acta Palaeontologica Polonica”
Trappola mortale per i piccoli dinosauri
I resti suggeriscono che gli individui ancora immaturi venissero lasciati badare a loro stessi mentre gli adulti erano occupati nella costruzione del nido o nella cova delle uova
Un branco di giovani dinosauri simili a uccelli hanno trovato la morte nei fangosi margini di un lago circa 90 milioni di anni fa, secondo quanto annunciato da un gruppo di paleontologi cinesi e statunitensi che hanno scavato in un sito del Deserto del Gobi, nella parte occidentale della Mongolia interna.
L’improvvisa morte degli animali in una trappola di fango fornisce una rara istantanea del loro comportamento sociale. Composto soltanto da esemplari giovani di una singola specie di dinosauri ornitomimidi (Sinornithomimus dongi), il branco suggerisce che gli individui ancora immaturi venissero lasciati badare a loro stessi mentre gli adulti erano occupati nella costruzione de nido o nella cova delle uova.
“Non c’erano adulti intorno, questi cuccioli scorrazzavano da soli”, ha spiegato Paul Sereno, professore dell’Università di Chicago ed esploratore del National Geographic e coautore dell’articolo apparso sulla rivista “Acta Palaeontologica Polonica”.
Le prime ossa vennero scoperte da un geologo cinese nel 1978 alla base di una piccola collina in una desola regione del Deserto del Gobi e circa 20 anni fa un gruppo sino-giapponese estrasse i primi scheletri, battezzando il dinosauro Sinornithomimus (“che somiglia a un uccello cinese”).
Sereno e colleghi hanno seguito lo scavo di uno scheletro dopo l’altro fino a penetrare in profondità nella base della collina. Complessivamente, sono stati estratti 25 individui di età compresa tra uno e sette anni, come determinato dagli anelli di crescita annuale delle loro ossa.
Il gruppo ha poi registrato in meticolosamente la posizione di tutte le ossa e i dettagli degli strati di roccia per cercare di comprendere in che modo cosi tanti individui di una stessa specie siano periti nello stesso luogo. Gli scheletri mostrano un ottimo stato di conservazione e il fatto che siano tutti nella stessa direzione fa supporre che siano morti anche entro un arco temporale molto breve.
I dettagli forniscono le prove di una piccola tragedia. “Gli animali hanno subito una morte lenta in una trappola di fango, e la loro agitazione è servita solo ad attrarre predatori o animali che si nutrivano di carogne”, ha concluso Sereno. Di solito gli eventi atmosferici, l’azione di altri animali o il trasporto di ossa cancellano qualunque prova diretta delle cause di morte. Perciò questo sito è unico per ricchezza di dettagli sugli animali e sulla loro morte.” (fc)
Photo: “Teen” Dinosaurs Roamed in Herds, Mass Grave Suggests
Young Sinornithomimus dinosaurs may have wandered in packs (illustrated at top), fending for themselves while adults were busy nesting, according to a recent report.
Two juvenile Sinornithomimus skeletons (photo at bottom) died when they were a little over one year old. In their rib cages are stomach stones and the carbonized remains of the last plants they consumed.
Illustration by Todd Marshall, courtesy Project Exploration; photograph by Mike Hettwer, courtesy Project Exploration
MSU paleontologist authors paper on social behavior among adolescent dinosaurs
March 16, 2009 — By Michael Becker, MSU News Service
BOZEMAN — A Montana State University researcher is the lead author of a recently published paper that sheds new light on the behaviors of dinosaur families and gives a rare glimpse into the social life — and death — of a herd of dinosaurs.
David Varricchio, an assistant professor and paleontologist in the Department of Earth Sciences, and colleagues from the University of Chicago and China wrote the paper after a 2001 expedition to the Gobi Desert. It was published in December in the journal Acta Palaeontologica Polonica.
The paper describes the team’s work at a 90-million-year-old dry lake bed in western Mongolia. Over the past decade, paleontologists have recovered more than two dozen fossilized skeletons of the dinosaur Sinornithomimus.
All of the skeletons belonged to animals between one and seven years old and were well-preserved. Most of skeletons were facing the same direction, suggesting that they died together in a short period of time, Varricchio said.
“Normally there are a lot of post-mortem effects that transpire between when a dinosaur died and when it was buried,” he said. “This site really provides, in my mind, better evidence than any other dinosaur locality of how the dinosaurs perished, and that’s pretty rare for any fossil vertebrate.”
Varricchio believes that the dinosaurs probably became mired in the mud around a partially dry lakebed during the Cretaceous Period. During times of drought, as were common in the region at the time, these oases likely attracted many animals, he said.
Many of those animals were probably weak from starvation and dehydration, which could explain why so many of them became trapped in the mud. It’s a phenomenon that’s still seen around dry desert lakes today, he said.
The fact that so many young dinosaurs of the same species died at roughly the same time and in the same place tells paleontologists something about the social behavior of the animals, Varricchio said. It may be that young dinosaurs — too old for the nest but not yet old enough to fend for themselves — roamed together in social herds, he said.
“We get a snapshot-like view of what a herd of these animals looked like back in the Cretaceous Period,” Varricchio said. “That snapshot gives us a glimpse into their biology and their behavior.”
Past studies have theorized that dinosaurs had strong and complicated parenting relationships with their young, Varricchio said. Female — and even male — dinosaurs were tied to a nesting spot for the breeding portions of the year while they took care of their eggs, he said.
The fact that the parent dinosaurs were busy with the eggs could explain why a group of adolescent dinosaurs was roaming together without adult supervision, Varricchio said. These and most dinosaurs would take several years, at least, to fully mature. Groups of juveniles would consist of those individuals too old to be cared for by parents, but too young to breed, he said.
“This site argues that this might be a general trend among dinosaurs,” and is further evidence of the theory that dinosaurs were dedicated parents, he said.
Varricchio’s collaborators include Paul Sereno from the University of Chicago, Tan Lin from he Department of Land and Resources of Inner Mongolia and Zhao Xijin from the Chinese Academy of Sciences. Also on the team were Jeffrey Wilson from the University of Michigan and Gabrielle Lyon from Project Exploration.
The work was funded by the National Geographic Society and the David and Lucile Packard Foundation.
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||MSU’s David Varricchio examines fossils in his laboratory in the basement of Traphagen Hall. (MSU photo by Kelly Gorham)
MSNBC – 17 ore fa
Like teenagers today, some juvenile dinosaurs used to hang out together, according to research announced today. Also like teens, the dinos sometimes hung …
ABC Online – 5 ore fa
In the rocky desert of Inner Mongolia, an international team of palaeontologists has unearthed a mass grave of young dinosaurs. The 25 birdlike dinosaurs …
Montana State University
Dinosaur Is First Patient at New Hospital
updated 2:15 p.m. ET Feb. 25, 2009
It was quite a debut for the Pomona Valley Health Center in Claremont. While its doors officially opened on Monday, it had already had its first patient. But the patient was nowhere near human.
According to the San Gabriel Valley Tribune, the skull of Gryposaurus monumentensis, also known as the duck-billed dinosaur. It was the first to make use of the new center and its state-of-the-art, 64-slice CT scanner.
The fossil was discovered in 2002 during a paleontology trips conducted by Alf Museum of Paleontology on the grounds of the Webb Schools in Claremont.
The information gained through the scanning of the fossil will allow scientists in other parts of the world to study the dinosaur skull.
Un nuovo dinosauro piumato scoperto in Cina, l’Anchiornis, può aiutare a comprendere meglio la “transizione” da dinosauri ad ucccelli essendo “più basale di Archaeopteryx.
New Feathered Dinosaur Adds to Bird Evolution Theory
January 16, 2009
A fossil of a primitive feathered dinosaur uncovered in China is helping scientists create a better model of how dinosaurs evolved into modern birds.
The winged dinosaur is still in the process of being dated, and might have lived toward the end of the Jurassic period, which lasted from 208 to 144 million years ago.
Anchiornis - A fossil of a primitive feathered dinosaur uncovered in China (above) is helping create a better model of how dinosaurs evolved into modern birds, experts said in January 2009. - Photograph courtesy Xu Xing
In many ways, it is “more basal, or primitive, than Archaeopteryx,” said paleontologist Xu Xing at Beijing’s Institute of Vertebrate Paleontology and Paleoanthropology. Archaeopteryx, the earliest known bird, lived 150 million years ago.
The protobird is “very close to the point of divergence” at which a new branch of winged dinosaurs first took flight, said Xu.
The new species, called Anchiornis huxleyi, was discovered in the ashes of volcanoes that were active during the Jurassic and Cretaceous (144 to 65 million years ago) periods in what is now northeastern China.
(Read about the prehistoric world.)
Anchiornis, which is Greek for “close to bird,” measured just 13 inches (34 centimeters) from head to tail and weighed about 4 ounces (110 grams).
The dinosaur’s body and forelimbs were covered with feathers, and it “might have had some aerial capability,” Xu said.
“Anchiornis is one of the smallest theropod dinosaurs ever uncovered,” Xu explained. Theropods were a group of carnivorous dinosaurs that walked on two legs.
The fossil provides new clues about how feathers, wings, and flight progressively appeared among theropods, along with evidence that certain types of feathered dinosaurs decreased in stature even as their forelimbs became elongated.
The compact structure of Anchiornis “reinforces the deduction that small size evolved early in the history of birds,” Xu explained”[Anchiornis] exhibits some wrist features indicative of high mobility, presaging the wing-folding mechanisms seen in more derived birds,” he said.
“The wrist is a big part of the formation of wings, and pivotal to flight,” Xu added. “During flight, steering and flapping greatly depend on the wrist.”
Despite this protobird’s relatively advanced feathers and wrist, it is unclear if Anchiornis could actually engage in powered flight.
“Behavior and biomechanics are very difficult to determine solely from the fossil record, and perhaps flight is impossible to determine,” said Mark Norell, chairman and curator of the division of paleontology at the American Museum of Natural History in New York.
“Feathers have lots of functions, and probably evolved as thermoregulators,” said Norell, who closely examined the fossil during a trip to Beijing.
“Dinosaurs might have used feathers for sexual display or to make themselves appear bigger, or as camouflage to avoid predators,” he said.
Patterns of spots and bars evident on one species of feathered dinosaur from China might have functioned as a camouflage defense, Norell added.
(Related: “First Dinosaur Feathers for Show, Not Flight?” [October 22, 2008].)
Xu said that the region in northeastern China where most of the world’s feathered dinosaurs, including Anchiornis, have been discovered is a virtual paradise for dinosaur hunting.
“This area has three circles of volcanic activity,” with eruptions that intermittently covered and preserved entire biospheres starting from the early Jurassic.
“Volcanos periodically killed the animals and plants and preserved them perfectly in volcanic ash,” he said.
“Sometimes the volcanic ash even preserves soft tissues, leaving behind an exceptional 3-D fossil.”