Lo studio al microscopio elettronico delle tracce sui denti di alcuni Adrosauri ne rivelano la complessa tipologia di masticazione.
Dino tooth sheds new light on ancient riddle
Scientists discover major group of dinosaurs had unique way of eating unlike anything alive today
|| IMAGE: These are teeth from the lower jaw of a hadrosaur, Edmontosaurus, showing its multiple rows of leaf-shaped teeth. The worn, chewing surface of the teeth is towards the top.Click here for more information.
Microscopic analysis of scratches on dinosaur teeth has helped scientists unravel an ancient riddle of what a major group of dinosaurs ate- and exactly how they did it!
Now for the first time, a study led by the University of Leicester, has found evidence that the duck-billed dinosaurs- the Hadrosaurs- in fact had a unique way of eating, unlike any living creature today.
Working with researchers from the Natural History Museum, the study uses a new approach to analyse the feeding mechanisms of dinosaurs and understand their place in the ecosystems of tens of millions of years ago. The results are published today in the Proceedings of the National Academy of Sciences.
Palaeontologist Mark Purnell of the University of Leicester Department of Geology, who led the research, said: “For millions of years, until their extinction at the end of the Cretaceous, duck-billed dinosaurs – or hadrosaurs – were the World’s dominant herbivores. They must have been able to break down their food somehow, but without the complex jaw joint of mammals they would not have been able to chew in the same way, and it is difficult to work out how they ate. It is also unclear what they ate: they might have been grazers, cropping vegetation close to the ground – like today’s cows and sheep – or browsers, eating leaves and twigs – more like deer or giraffes. Not knowing the answers to these questions makes it difficult to understand Late Cretaceous ecosystems and how they were affected during the major extinction event 65 million years ago.
|| IMAGE: These are teeth from the upper jaw of a hadrosaur, Edmontosaurus. The specimen was molded and coated with gold for examination using a Scanning Electron Microscope to give high power…Click here for more information.
“Our study uses a new approach based on analysis of the microscopic scratches that formed on hadrosaur’s teeth as they fed, tens of millions of years ago. The scratches have been preserved intact since the animals died. They can tell us precisely how hadrosaur jaws moved, and the kind of food these huge herbivores ate, but nobody has tried to analyse them before.”
The researchers say that the scratches reveal that the movements of hadrosaur teeth were complex and involved up and down, sideways and front to back motion. According to Paul Barrett palaeontologist at the Natural History Museum “this shows that hadrosaurs did chew, but in a completely different way to anything alive today. Rather than a flexible lower jaw joint, they had a hinge between the upper jaws and the rest of the skull. As they bit down on their food the upper jaws were forced outwards, flexing along this hinge so that the tooth surfaces slid sideways across each other, grinding and shredding food in the process”.
The scratch patterns provide confirmation of a theory of hadrosaur chewing first proposed 25 years ago, and provides new insights into their ecology, say the researchers.
The research also sheds light on what the dinosaurs ate. Vince Williams of the University of Leicester said: “Although the first grasses had evolved by the Late Cretaceous they were not common and it is most unlikely that grasses formed a major component of hadrosaur diets. We can tell from the scratches that the hadrosaur’s food either contained small particles of grit, normal for vegetation cropped close to the ground, or, like grass, contained microscopic granules of silica. We know that horsetails were a common plant at the time and have this characteristic; they may well have been an important food for hadrosaurs”.
|| IMAGE: This is a highly magnified Scanning Electron Microscope view of the surface of one of the hadrosaur teeth, showing the scratches created about 67 million years ago by tooth movements…Click here for more information.
One of the big surprises of this study is that so much information about such large animals can be gleaned from such a tiny patch of tooth. “By looking at the pattern of scratches in an area that is only about as wide as a couple of human hairs we can work out how and what these huge herbivores were eating” notes Williams. “And because we can analyse single teeth, rather than whole skeletons, the technique has the potential to tell us a lot more about dinosaur feeding and the ecosystems in which they lived.”
For interviews contact:
Dr Mark A. Purnell
Reader in Geology
Department of Geology
University of Leicester
Leicester LE1 7RH
Tel +44 116 252 3645
Fax +44 116 252 3918
1. The erroneous idea that all dinosaurs could chew is so widely accepted that the memorable ‘Chewits’ advertising campaigns of the 1980s were based on the idea. Note that the dinosaur shown in the adverts is not a hadrosaur:
2. The paper “Quantitative analysis of dental microwear in hadrosaurid dinosaurs, and the implications for hypotheses of jaw mechanics and feeding” by Vincent S. Williams, Paul M. Barrett and Mark A. Purnell is published in the Proceedings of the National Academy of Sciences (online Early Edition).
3. Vince Williams and Mark Purnell are at the University of Leicester, UK; Paul Barrett is at the Natural History Museum, London, UK. A pdf of the paper is available from Mark Purnell: firstname.lastname@example.org
4. Winner of Visit London’s 2008 Kids Love London Best Family Fun Award, the Natural History Museum is also a world-leading science research centre. Through its collections and scientific expertise, the Museum is helping to conserve the extraordinary richness and diversity of the natural world with groundbreaking projects in 68 countries
5. To arrange an interview with Paul Barrett please contact: Claire Gilby, Senior Press Officer, Natural History Museum, Tel: 020 7942 5106 Email: email@example.com (not for publication)
6. Following images can be obtained from University of Leicester firstname.lastname@example.org
- Teeth from the lower jaw of a hadrosaur, Edmontosaurus, showing its multiple rows of leaf-shaped teeth. The worn, chewing surface of the teeth is towards the top. Credit: Vince Williams, University of Leicester.
- Teeth from the upper jaw of a hadrosaur, Edmontosaurus. The specimen was moulded and coated with gold for examination using a Scanning Electron Microscope to give high power magnification of the microscopic scratches. Credit: Vince Williams, University of Leicester.
- Highly magnified Scanning Electron Microscope view of the surface of one of the hadrosaur teeth, showing the scratches created about 67 million years ago by tooth movements and feeding. The small black boxes show the areas, each less than half a millimetre wide, in which scratches were analysed. Credit: Vince Williams, University of Leicester.
- Artists reconstruction of a hadrosaur eating; analysis of tooth wear indicates grazing low growing silica rich plants, like horsetails, was more likely than browsing on bushes. Contact email@example.com for image.
Hadrosaur fact file
This study is based on Edmontosaurus: Lived USA and Canada 65-68 million years ago; Length up to 13 m, weight up to 3 tonnes; One of the most abundant dinosaurs of its time; Known from many complete skeletons, including several mummies with skin impressions and gut contents preserved.
Notes for editors:
http://nature.ca/puijila/index_e.cfm (Official home page)
http://www.eurekalert.org/pub_releases/2009-04/cmon-feo042009.php (good scientific description of the discovery)
Fossil of a walking seal found
Remains of a previously unknown mammal could represent a missing link in pinniped evolution
: Wednesday, April 22nd, 2009
- Researchers discovered remains of a previously unknown pinniped in the Canadian Arctic. (Inset shows bones that were found.) The fossilized skeleton was about 65 percent complete. (Illustration fills in the missing pieces.)
A fossilized skeleton of what researchers are calling a walking seal has been uncovered in the Canadian Arctic. The remains of this previously unknown mammal could shed light on the evolution of pinnipeds, the group that includes seals, sea lions and walruses, researchers report in the April 23 Nature.
The animal, named Puijila darwini, had a long tail and an otterlike body with webbed feet and legs like a terrestrial animal, the researchers report. But P. darwini also had a pinniped-like skull.
“We realized there was no way this was an otter,” says study coauthor Natalia Rybczynski of the Canadian Museum of Nature in Ottawa. The walking seal probably lived about 20 million years ago and was adept at moving both on land and in water, the team reports.
Researchers describe Puijila darwini (illustration shown) as a walking seal, with the legs of a terrestrial animal, a seal-like skull and webbed feet.
Scientists had theorized that pinnipeds evolved from land-dwelling ancestors but had little fossil evidence to support that claim. The new finding could be the missing link in pinniped evolution, the researchers report.
“This is a fantastic discovery,” comments evolutionary biologist Annalisa Berta of San Diego State University.
The finding may also indicate that the Arctic was a geographic center for pinniped evolution, the researchers speculate.
But, Berta notes, other early pinnipeds have been discovered in the North Pacific and Eurasia. “We can’t yet conclude the Arctic was the area of origin for pinnipeds,” Berta says.
The Associated Press – 22-apr-2009
One expert called it “a fantastic discovery” that fills a crucial gap in the fossil record. The 23 million-year-old creature was not a direct ancestor of …
Paleontologia/Bimbi di Neanderthal nascevano come quelli di oggi
Anche se, scoperte differenze in alcuni meccanismi del parto
Roma, 20 apr. (Apcom) – Come nasceva l’uomo di Neanderthal? Esattamente come fanno oggi tutti i bambini del mondo, anche se c’erano differenze tra il canale del parto delle nostre progenitrici e quello delle donne moderne. A scoprirlo Tim Weaver e Jean Jacques Hublin, Department of Anthropology, University of California, Davis, CA, che, come riferiscono in una ricerca pubblicata su Proceedings of National Academy of Sciences, hanno ricostruito la dimensione e la forma del condotto della nascita (che comprende utero, vagina e vulva), utilizzando una pelvi fossile trovata a Tabun in Israele e confrontata con il canale del parto delle donne moderne. La ricostruzione virtuale, realizzata dai paleontologi, ha mostrato che le donne di Neanderthal possedevano un maggior numero di meccanismi primitivi che facilitavano il parto e che non permettevano la rotazione del corpo del feto quando transitava attraverso il condotto per nascere. Nelle donne moderne questo passaggio di forma ovale cambia, durante il parto, le sue dimensioni e orientamento dal punto di entrata a quello di uscita, costringendo il bambino a ruotare. La rotazione è uno di quei meccanismi che aiuta la madre durante il travaglio e il bambino a venire al mondo. Secondo ricerche precedenti i meccanismi della nascita degli uomini sarebbero il risultato della pressione evolutiva della postura eretta, della deambulazione sulle due estremità degli arti e del dare alla luce bambini con un cervello più grande. Ma, malgrado le differenze anatomiche , il canale del parto del Neanderthal e quello delle donne moderne è sostanzialmente molto simile soprattutto nelle dimensioni, a testimoniare che anche i bambini che nascevano allora erano, più o meno, grandi quanto quelli che nascono oggi e che le difficoltà del parto non sono cambiante in centinaia di migliaia di anni.
Researchers from the University of California at Davis and the Max Planck Institute for Evolutionary Anthropology in Leipzig digitally reconstructed the pelvis of a Neanderthal female found in the Tabun Cave in Israel. The virtual model provides valuable insight into how early humans gave birth.
From the announcement issued by Max Planck Institute:
The size of Tabun’s reconstructed birth canal shows that Neanderthal childbirth was about as difficult as in present-day humans. However, its shape indicates that Neanderthals retained a more primitive birth mechanism than modern humans, without rotation of the baby’s body.A significant shift in childbirth apparently happened quite late in human evolution, during the last 400,000 – 300,000 years. Such a late shift underscores the uniqueness of human childbirth and the divergent evolutionary trajectories of Neanderthals and the lineage leading to present-day humans.
The virtual reconstruction of the pelvis from Tabun is going to be the first of its kind to be available for download on the internet for everyone interested in human evolution. The computer files will be available from the websites of University of California at Davis and the Max Planck Institute for Evolutionary Anthropology.
Press release: “You will give birth in pain”: Neanderthals too …
Image: Virtual reconstruction of the pelvis of a female Neanderthal from Tabun (Israel). The colours indicate the individual bone fragments that were fit together. The gray wedge shows the estimated configuration of the sacrum (lower part of the spinal column). Credit: Tim Weaver, University of California
FOXNews – 21 ore fa
By Clara Moskowitz Neanderthal women had different birth canals than humans today. But childbirth was probably just as difficult, a new study finds. …
Uno studio di un iologo evoluzionista australiano pubblicato Biology letter supporta la teoria dei Sauropodi aspiravolvere. Secondo tale studio i sauropodi non potevano sollevare la testa (la pressione sanguigna da sopportare per inviare sangue al cerevello), tuttavia la loro stazza gli permetteva comunque di arrivare a raccogliere foglie da rami inaccessibili ad altri erbivori mentre il lungo collo gli permetteva di sostare in luogo e di agire appunto come un aspirapolvere agendo tutto intorno
Sauropod dinos kept a level head
Long-necked sauropod dinosaurs would had to have used far too much energy to hold their neck upright and browse tall trees, says an Australian evolutionary biologist.
Dr Roger Seymour of the University of Adelaide reports his findings in the Royal Society journal Biology Letters.
Sauropods were about as heavy as a whale and had necks nearly five times the length of a giraffe’s.
The animals have generally been reconstructed with upright necks and it was assumed they grazed on tall trees.
But Seymour has calculated that to do this the dinosaurs would have needed to use 50% of the energy they consumed just to support their long necks.
“I think most people would agree that if you spent half of your energy pumping the blood around the body it would be an enormous cost,” says Seymour, who studies blood pressure in animals.
Seymour says the longer an animal’s neck, the higher the blood pressure it requires to pump blood to the brain.
“The giraffe’s blood pressure is twice that of other mammals,” he says.
While a human has a blood pressure of around 100 millimetres of mercury, a giraffe has a blood pressure of 200, says Seymour.
He says a sauropod with an upright 9-metre neck would have had to have a blood pressure of 700.
“That is exceptionally high,” says Seymour.
Seymour says to produce such a high pressure, the sauropod would need a heart with a 2-tonne left ventricle, which would be a challenge to fit in the animal.
And his most recent research has calculated that 50% of the energy it consumed would be used just to circulate the sauropod’s blood.
“Even though they may have had access to a larger amount of food, it would have cost more than the gain, basically,” says Seymour.
He says a giraffe with a 2-metre neck uses around 20% of its energy to circulate blood and humans use about 10%.
The ‘vacuum cleaner principle’
Previously, it was thought that sauropods must have been semi-aquatic or amphibious to support their enormous bulk.
When palaeontologists decided the animals were terrestrial, they assumed the neck was used like a giraffe’s, says Seymour.
But, he says, the sauropod’s enormous size meant the animal would have had many options for feeding even without having to lift their long neck vertically.
“Even without raising the head, these animals could browse higher than a giraffe,” says Seymour.
Seymour says feeding with a horizontal neck meant the animal could keep the bulk of its body in one place while using its long neck to graze in numerous places.
“It’s the vacuum cleaner principle,” he says.
Telegraph.co.uk – 1-apr-2009
Long-necked dinosaurs kept their heads down and did not raise them to the trees to graze, according to a new study. By Kate Devlin, Medical Correspondent …
Un nuovo dinosauro con le piume
Il ritrovamento in Cina di un nuovo fossile di dinosauro dotato di piumaggio riapre il dibattito sulla diffusione di questi rettili preistorici. Questa volta gli scienziati hanno portato alla luce un piccolo esemplare che viveva nelle regioni nord-orientali del continente asiatico più di cento milioni di anni fa. L’animale aveva il corpo coperto da lunghi filamenti simili a piume, era piccolo, agile e scattante. Camminava su due zampe, aveva una lunga coda e si cibava probabilmente di piante, insetti e piccoli vertebrati.
PENNUTI PREISTORICI – È stato chiamato Tianyulong confuciusi, dalla somma del nome del museo dove è conservato e di quello del filosofo Confucio. Diversamente dai dinosauri «piumati» ritrovati fino ad oggi e appartenenti al sottordine dei teropodi (di cui fa parte anche il T-rex), questo pennuto preistorico è un eterodontosauride vissuto nel Cretaceo inferiore, circa 144 milioni di anni fa. Secondo gli scienziati le sue piume sono diverse sia da quelle degli uccelli che da quelle dei cugini teropodi: si tratta infatti di strutture meno flessibili e più compatte, e comunque non adatte al volo. Ma nonostante le differenze, sicuramente tutte le tipologie di proto-piume conosciute sono correlate tra loro.
L’ETÀ DELLE PIUME – Secondo alcuni paleontologi quindi le piume primitive sono una caratteristica ereditata dai due gruppi di dinosauri da un antenato comune e risalgono presumibilmente a 200 milioni di anni fa. Grazie alle particolari condizioni geologiche della provincia cinese del Liaoning, è sempre più frequente il ritrovamento di fossili di dinosauri provvisti di piume, e ciò fa pensare che fossero molto più diffusi di quanto si pensasse fino a pochi anni fa. Resta comunque ancora oscura la funzione (probabilmente ornamentale) di queste appendici che, come le piume degli uccelli attuali, erano molto colorate ma sicuramente alle origini non erano nate per volare
19 marzo 2009
Reconstruction of Tianyulong confuciusi, a feathered heterodontosaurid ornithischian dinosaur (Illustration: Li-Da Xing)
Approfondimento sui Blog
Earliest feathered dinosaur discovered
Primitive plumes probably used for display, scientists say.
A primitive form of feather may have evolved much earlier than was previously thought, according to an analysis of a dinosaur fossil that is more than 100 million years old. The specimen supports arguments that dinosaurs may have used feathers for display.
Finding feathers in dinosaurs is becoming a common occurrence. This is especially true in China’s Liaoning Province, where fine-grained sedimentary rocks often contain fossils with exquisite details still intact. But all of these feathered fossils have been of the bipedal, carnivorous theropod lineage, which includes Tyrannosaurus and Velociraptor.
Now, Xiao-Ting Zheng at the Shandong Tianyu Museum of Nature in China suggests that feathers were not limited to the theropods. He and his colleagues have discovered a dinosaur fossil in Liaoning that has long feather-like structures sticking up from its body. Based on the bones present, it looks like it was small, active, agile, and probably eating a mix of insects, small vertebrates and plants.
The team has identified the species as a heterodontosaurid from the Early Cretaceous period, which began about 144 million years ago. This in itself is remarkable as heterodontosaurids were most widespread during Late Triassic times, more than 65 million years earlier, and animal groups rarely survive for such long periods of geological time. “Heterodontosaurids are exceptionally rare, and previously unknown from Asia,” says Richard Butler at the Natural History Museum in London. This fossil “confirms that heterodontosaurids, one of the oldest groups of dinosaurs, survived into the Cretaceous”, Butler adds.
The skull of Tianyulong confuciusi. - X-T Zheng et al
Dinosaurs are divided into two main orders: saurischians, which have forward-pointing pubic bones, and ornithischians, which have backward-pointing pubic bones. All previous feathered theropods belong to the saurischian order, whereas the new fossil belongs to the ornithischian.
The find “pulls the origin of feathers down into the Triassic, when the saurischian and ornithischian lineages of dinosaurs split”, says Philip Currie at the University of Alberta in Canada. The fossil is described this week in Nature1.
Birds of a feather
The feathery structures found on this heterodontosaurid, dubbed Tianyulong confuciusi, are not like those found on modern birds or even on some of the smaller, more bird-like theropods. Whereas modern feathers are flexible and have a central shaft with vanes that run off either side at angles, the feathers on T. confuciusi are all relatively stiff and lack vanes.
To date, only one ornithischian fossil find has suggested the presence of anything that approximates feathers: Psittacosaurus has bristle-like structures on its tail that have been hotly debated. T. confuciusi will no doubt add fuel to the debate about whether feathers evolved once, twice or many times.
Hai-Lu You, one of the palaeontologists who identified T. confuciusi, believes that the fossil supports the idea of a single evolution of feathers. “We still have some missing data between T. confuciusi and feathered theropod dinosaurs, but I think further discovery will fill these gaps,” he says. If this proves to be true, then many dinosaurs may once have sported feather-like structures, with descendant species losing the characteristic later on.
At present, no-one is sure of the function of the protofeathers. “If these are protofeathers, then they were not related in any way to flight,” explains Butler. “The fact that the filaments over the tail are so long and stiff suggests a possible display function.”
“Dinosaurs were clearly highly visual animals that not only modified their skeletons for show, but exaggerated their effect through external structures,” adds Currie. “It doesn’t take that much to imagine dinosaurs as colourful as their descendants — the birds.”
San Francisco Chronicle – 12 ore fa
Fossil hunters in China have discovered a strange little dinosaur that lived more than 100 million years ago and had tough skin with patches of spiky …
Xiao-Ting Zheng, Hai-Lu You, Xing Xu & Zhi-Ming Dong
Nature 458, 333-336 (19 March 2009) | doi:10.1038/nature07856
Ornithischia is one of the two major groups of dinosaurs, with heterodontosauridae as one of its major clades. Heterodontosauridae is characterized by small, gracile bodies and a problematic phylogenetic position1, 2. Recent phylogenetic work indicates that it represents the most basal group of all well-known ornithischians3. Previous heterodontosaurid records are mainly from the Early Jurassic period (205–190 million years ago) of Africa1, 3. Here we report a new heterodontosaurid, Tianyulong confuciusi gen. et sp. nov., from the Early Cretaceous period (144–99 million years ago) of western Liaoning Province, China. Tianyulong extends the geographical distribution of heterodontosaurids to Asia and confirms the clade’s previously questionable temporal range extension into the Early Cretaceous period. More surprisingly, Tianyulong bears long, singular and unbranched filamentous integumentary (outer skin) structures. This represents the first confirmed report, to our knowledge, of filamentous integumentary structures in an ornithischian dinosaur.
Correspondence to: Hai-Lu You: Email: firstname.lastname@example.org).
· abstract and links
· Figures and tables
· Supplementary info
Ancient meat-eating dinosaurs held their arms with palms facing inwards like their bird descendants, a rare set of 198-million-year-old fossilised handprints has revealed. An analysis of the prints, published this week in PLoS One, supports theories that even very early therapods [lit. ‘beast feet’] such as tyrannosaurs and velociraptors had bird-like forelimbs, and walked only on two legs, well before they evolved feathery wings.
The handprints came from a dinosaur that sat down on the edge of a lake in St George, Utah, and extended its arms far enough to leave sediment marks. Six other resting dinosaur traces have been reported before, but they all lack clear hand prints.
This means, reports the Chicago Tribune, that we must banish images of tyrannosaurs holding their forearms like monkeys, with palms facing downwards – a posture that palaeontologists apparently term the “bunny position” – as depicted in Jurassic Park. Instead, we must imagine that dinosaurs were extremely good at holding basketballs.
“What this seems to imply is that, even from fairly early in their history, dinosaurs were entirely bipedal and weren’t using their forearms to support themselves in any way,” paleontologist Tom Holtz of the University of Maryland, says. “Because of that, the hands could specialize as weapons, to grab on to a struggling animal or to fight with other dinosaurs.”
Image: Dilophosaurus wetherilli in bird-like resting pose/Heather Kyoht Luterman
Los Angeles Times – 3-mar-2009
At left, dinosaur tracks with hand prints show bird-like inward-facing palms at Johnson Farm, Utah. At right, an artist’s reconstruction shows the formation …
National Geographic —————————————————————————–
free access article on PlosOne
Bird-Like Anatomy, Posture, and Behavior Revealed by an Early Jurassic Theropod Dinosaur Resting Trace
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.”
Alcuni ricercatori cinesi hanno riconosciuto nelle piume apparteneti ad un Beipaosaurus (Dinosauria, Theropoda, Therizinosauridae) un morfotipo attualmente associato a piume utilizzate per “esibizionismo” (display) e non per il volo. Questa é la prima volta che viene riscontrata questa peculiarità in Teropodi non aviani.
Earliest Feathers for Show, Not Flight
Jennifer Viegas, Discovery News
Jan. 12, 2009 — The world’s first feathers probably had nothing to do with flight or staying warm but were instead for showy display purposes, according to a new study that documents the most primitive known version of feathers, which were found on a Chinese dinosaur.
The dinosaur, Beipiaosaurus, sported the likely colorful feathers on its limbs, trunk, tail, head and neck, with the neck feathers resembling a lion’s mane.
Paleontologists now believe feathers evolved very early in archosaurs, the group that included dinosaurs, pterosaurs and relatives of crocodiles, in addition to today’s modern birds, crocodiles and alligators.
“Our analysis suggests that feathers might have a much longer history than previously thought,” lead author Xing Xu told Discovery News.
“The first feathers might have appeared in the fossil record in the Middle Triassic about 235 million years ago,” said Xu, a paleontologist at the Chinese Academy of Sciences in Beijing.
Xu and colleagues Xiaoting Zheng and Hailu You studied the remains of the Chinese dinosaur, which was excavated at the Early Cretaceous Yixian Formation of Jianchang, western Liaoning. They noticed two types of feathers on the specimen: short, thread-like structures, and longer, stiff, broader ones that represent the rudimentary feathers, according to the study.
Both types are described in a paper published in this week’s Proceedings of the National Academy of Sciences.
Similar structures have been found on Psittacosaurus, or “Parrot Lizard,” as well as some pterosaurs. The researchers therefore suspect the common ancestor of these creatures — along with Beipiaosaurus, which lived 125 million years ago — had the early feathers too.
Previously documented feathers on dinosaurs were described as having multiple filaments, or many fluff-creating strands. The feathers on the recently documented Chinese dinosaur, however, are believed to represent a much more primitive stage, since the feathers consist of just a single broad filament, but have a different structure than hair.
The morphology and distribution of these early feathers rule out use for flight and helping to keep the dinosaur warm, but instead suggest they were flashed during displays, perhaps for mating, identification and competition purposes.
“Most previous studies suggest that insulation might have been the primary function for the first feathers, but our discovery supports that display represents one of the earliest functions for feathers,” Xu said, adding that “flight function appears very late in feather evolution.”
The discovery negates the prior theory that feathers and flight co-evolved. It instead indicates pterosaurs, birds and other fliers recruited already existing feathers for flight.
Xu and her colleagues aren’t certain how feathers came into being in the first place, but they suspect that at some point, an animal’s skin developed epidermal tissue that gave rise to the thin, tubular protrusions. Members of the opposite sex must have liked what they saw in displays, since the trait stuck and flourished. An average bird today has over 20,000 feathers.
Cheng-Ming Chuong and his team from the Keck School of Medicine at the University of Southern California foreshadowed the recent discovery. Their studies on chickens predicted what these first, more basic, feathers would’ve looked like.
“Just like Rome, feathers are not made in one process,” Chuong said, hinting that a long and colorful history for feathers would likely emerge as more findings, such as the new discovery on Beipiaosaurus, come to light.
He added, “While Darwin’s theory has explained the ‘why’ of evolution, much of the ‘how’ remains to be learned. Evo-Devo (evolution of development) research promises a new level of understanding.”
The remains of the flashy, primitive-feathered Chinese dinosaur are now housed at the Shandong Tianyu Museum of Nature in China.
source: Dicovery channel news
IN GERMAN: faz.net
A new feather type in a nonavian theropod and the early evolution of feathers (PNAS link)
Xing Xu, Xiaoting Zheng and Hailu You
All described feathers in nonavian theropods are composite structures formed by multiple filaments. They closely resemble relatively advanced stages predicted by developmental models of the origin of feathers, but not the earliest stage. Here, we report a feather type in two specimens of the basal therizinosaur Beipiaosaurus, in which each individual feather is represented by a single broad filament. This morphotype is congruent with the stage I morphology predicted by developmental models, and all major predicted morphotypes have now been documented in the fossil record. This congruence between the full range of paleontological and developmental data strongly supports the hypothesis that feathers evolved and initially diversified in nonavian theropods before the origin of birds and the evolution of flight.
Stanford scientists scan birdlike dinosaur for evolution clues
Posted: 12/11/2008 12:01:00 AM PST
Stanford scientists are using powerful X-ray beams on a rare feathered dinosaur that perished more than 150 million years ago in an effort to see its inner tissues and perhaps someday understand the anatomical split that sent birds and reptiles down different evolutionary paths.
The archaeopteryx fossil has come to SLAC Laboratory to undergo a revolutionary analysis. (Courtesy of SLAC)
At SLAC’s Stanford Synchrotron Radiation Lightsource in Menlo Park, the scientists are using the beams to scan one of the world’s most valuable fossils, delicately transported by pickup truck from its home in a Wyoming dinosaur museum.
The X-rays, generated by a particle accelerator, cause tiny amounts of a dozen chemicals to glow without harming the ancient fossil, believed to be the earliest representation of a bird.
Scientists hope the chemicals will correlate with organs, blood vessels and other interior parts of the creature, called archaeopteryx, or “ancient wing,” which has both reptilian and avian features. When compared with scans of other fossils, such anatomical information could help explain evolutionary changes.
“What we are hoping is that we will learn more information than just what you can see with your eyes,” said Uwe Bergmann, staff scientist at SSRL. “The body decays, but the chemical elements — silicon, calcium, potassium, iron, all the chemicals which make up living animals — some of them will be preserved.”
What is visible in stone is just a faint imprint of a physical feature, such as a feather, he said. But soft tissues have unique chemical characteristics that aid in their identification. For instance, calcium would suggest a bone; iron might mean blood. By measuring the distribution of these chemicals in a fossil, it may be possible to re-create anatomy — and hence, evolution.
The latest effort is not the first time the intensely bright X-rays, emitted by particles circulating near the speed of light, have been used to solve ancient mysteries. In 2005, they helped decipher a 10th century manuscript that contained rare copies of works by the mathematician Archimedes.
But the tool brings new possibilities to our understanding of archaeopteryx. Some of the 10 known specimens of the creature have previously undergone extensive visual analyses and even CT scans, but nothing as comprehensive as the X-ray imaging researchers are utilizing at SSRL.
Archaeopteryx holds a unique place in history. When the first specimen was discovered about a century and a half ago, just a year after Charles Darwin published “On the Origin of Species,” its shared reptile-avian features provided the strongest evidence yet for the theory of evolution.
The Jurassic-era fossil has a beaklike mouth, winglike forelimbs, long feathers and feet for perching. But it also has reptilelike teeth in its jaws, claws on its fingers and a long tail. A little over a foot long, it could probably fly — but without the grace of modern birds.
“If you want to find a single fossil which is a missing link in the evolution of dinosaurs into birds, this is it,” said University of Manchester paleontologist Phil Manning. “It’s a bird with sharp teeth, claws and a long bony tail. If you were to freeze-frame evolution, you would end up with archaeopteryx.”
Millions of years ago, the creature under study at SSRL sank to the bottom of a shallow lagoon and became entombed in limestone near Solnhofen, Germany. It is now owned by the Wyoming Dinosaur Center, located in Thermopolis, Wyo.
Last weekend, scientists packed the creature into a small wooden box, loaded it into the cab of a white Chevy Silverado truck and drove the 850 miles to SLAC. Upon its arrival Monday night, it was moved into a helium-filled tray for analysis.
The creature heads back home after the weekend. Then, for SLAC scientists, the real work begins.
“We could build up a library of samples,” Bergmann said. “We’d start out with parts of creatures that are still in existence — let’s say, a bird’s feather, or maybe the shells of turtles or skins of lizards. Then we could do more fossils. Once you have all that information together, it’s possible to compare.”
“I don’t see that one measure of archaeopteryx will provide all the answers,” he said. “But if we work hard and very broadly, studying lots of samples, I think we’ll be in for a surprise.”
Contact Lisa Krieger at email@example.com or (408) 920-5565.
Technology gets fossil to reveal its secrets
Saturday, December 13, 2008
(12-12) 19:19 PST — Physicists aimed Stanford’s mighty beam of high-energy X-rays on a stone fossil of a 150 million-year-old bird Friday in the first effort to discover what chemical mysteries of evolution lie inside the ancient creature.
The famed bird is an Archaeopteryx, the oldest known example of the flying dinosaurs that evolved long, long ago from more familiar creatures like Tyrannosaurus rex and the vicious Velociraptor.
It is, in fact, a major missing link between early dinosaurs and their descendants, the modern birds.
“This is one of the most important fossils on the planet,” said Phillip Manning, a paleontologist from England’s University of Manchester. “Any information about its elements and its chemical compounds that we can tease apart from its body with the X-ray beam from Stanford’s huge machine will let us compare it to the chemicals that changed during its evolution into modern birds.”
Those chemical changes over millions of years between flying dinosaurs and birds could reveal processes of evolution that Charles Darwin himself never dreamed of.
Inside the Stanford Synchrotron Radiation Lightsource at the SLAC National Accelerator Laboratory, the 16-inch square slab of stone holds a virtually complete but vague impression of the bird as it must have died in some ancient muddy lake bed. It reveals only outline sketches of its wings, legs, skull and twisted body.
Known as the “Thermopolis Fossil,” the bird has a mysterious past and a bit of the Maltese Falcon in it, too.
No one knows when it was actually discovered in Germany’s well known Solnhofen dinosaur quarry, but it later appeared somehow in the estate of an unnamed Swiss fossil collector who died 40 years ago.
It is one of only 10 Archaeopteryx fossils ever found – the first one was discovered only two years after Darwin published his “On the Origin of Species” in 1859. Like the others, this one is immensely valuable. At some point, an anonymous donor put up funds to buy it from the Swiss collector’s widow and ship it to the Wyoming Dinosaur Center, a museum in Thermopolis, Wyo., where it is on “permanent loan.”
The idea for X-raying the fossil first came from Robert Morton, an oil company chemist in Bartlesville, Okla., and its transport to Stanford was arranged by Peter Larson of the Black Hills Institute of Geological Research in South Dakota, which offers a wide variety of fossils for sale.
On Friday, SLAC’s synchrotron lightsource aimed its intensely bright X-ray beam at the fossil’s surface to reveal the structure of the Archaeopteryx’s interior bones and tiny teeth, and even hint at its soft tissues. Each individual chemical inside the fossil emitted a specific frequency of fluorescent light that identified it, Manning said.
Uwe Bergmann, a physicist at SLAC, runs the synchrotron lightsource, where X-ray beams are generated by magnets tapping a stream of electrons racing at 3 million electron volts inside a storage ring and accelerated to nearly the speed of light.
The stuff of ancient birds
In a short time, the beam has already identified an entire roster of the bird’s elements: sulfur, phosphorous, copper, zinc, manganese, calcium and more, Bergmann said, and the experiment will continue this weekend in a hunt for organic compounds, too.
“But we were puzzled when the X-rays revealed something we hadn’t expected,” he said. “Then we realized it was only varnish – a thin coat of varnish that someone had applied to part of the fossil some time after it was found in Germany.”
Although he’s a physicist, Bergmann’s interests are wide: More than three years ago, he and his SLAC team aimed their super-X-ray beam at a layer of goatskin parchment many centuries old bearing a copy of writing by Archimedes, the Greek scientist, on mathematics. The document has become famed as the “Archimedes Palimpsest” – a palimpsest being a segment of writing on which someone has written something else on top of it. Some of Archimedes’ words had been covered by later writings.
The synchrotron’s X-ray beam revealed the very words in the Archimedes parchment that had been hidden from human eyes for many centuries.
Now Stanford’s X-ray beam – an essential tool for physicists and material scientists – is lending a hand to biologists, too, helping to reveal the inner secrets of a 72 million-year-old duck-billed dinosaur and an ancient jellyfish.
This article appeared on page A – 1 of the San Francisco Chronicle
Dinosaur “ghost” fossil revealed
USA Today – 21 ore fa
Scientist started working late last week on a stone fossil originally discovered in Germany and now owned by the Wyoming Dinosaur Center.
Scientists scan birdlike dinosaur for evolution clues St. Louis Post-Dispatch
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La scoperta di un cranio di un giovane esemplare di Heterodontosaurus favorisce nuove considerazioni sulla dieta e sul percorso evolutivo di questo dinosauro.
Prima della scoperta, la presenza di una dentatura eteromorfa (e in particolare la presenza dei canini) aveva dato luogo a due considerazioni contrastanti; alcuni ritenevano che tale dentatura costituisse una prova di un alimentazione onnivora, altri invece che la presenza dei canini fosse propria soltanto dei maschi e rappresentasse quindi solo un carattere sessuale secondario (vedi l’esempio attuale dei Trichechi)
Ora la scoperta di un esemplare giovane con canini già ben sviluppati avvalora la tesi dell’onnivoria e pone il genere Hterodontosaurus coma una delle fasi di passaggio tra un antenato carnivoro e i successori ornitischi (triceratopi, adrosauri, anchilosauri) erbivori.
One of world’s smallest dinosaurs ever discovered ate meat AND plants
By Daily Mail Reporter
Last updated at 10:33 AM on 24th October 2008
[Photo: Laura Porro with her amazing find. The skull of a Heterodontosaurus had lain in a drawer since the 1960s]
One of the world’s smallest dinosaur skulls has been discovered, which could help explain how plant eaters branched off from their carnivorous cousins.
The tiny skull belongs to a young Heterodontosaurus, which lived 190million years ago, according to British and U.S researchers.
The mini dinosaur, which weighed around the same as an MP3 players, had fang-like canine teeth at the front for biting and tearing and flat grinding teeth typical of herbivores at the back.
‘Since Heterodontosaurs are among the earliest dinosaurs adapted to eating plants, they may represent a transition phase between meat-eating ancestors and more sophisticated, fully herbivorous descendants,’ Laura Porro from the University of Chicago said.
‘This juvenile skull indicates that these dinosaurs were still in the midst of that transition.’
Porro came across the skull in a drawer in the Iziko South African Museum in Cape Town, while researching the eating habits of the Heterodontosaurs. ‘
‘I didn’t recognise it as a dinosaur at first,’ she said.
‘But when I turned it over and saw the eye looking straight at me, I knew exactly what it was.’
Although dug up in the 1960s it was never identified. The dinosaur lived during the Early Jurassic period of South Africa. Porro’s find was reported in the Journal of Vertebrate Paleontology.
[Photo: The adult creatures were the size of turkeys but youngsters were half the size and only weighed half a pound, say researchers]
The first dinosaurs appeared about 230 million years ago, and the earliest known ones were meat eaters.
There were other plant-eating dinosaurs at the time of Heterodontosaurus including the long-necked sauropods. But this little creature was one of the earliest of the ornithischians that soon become very important in the Age of Dinosaurs.
Later ornithischians included the duck-billed dinosaurs, horned dinosaurs such as Triceratops and tank-like dinosaurs such as Ankylosaurus.
While adult Heterodontosaurus were turkey-sized creatures that reached just over three feet in length and weighed about five pounds (2.5 kg), the juvenile likely weighed less than half a pound and would have been just about a foot and a half long.
[Photo: The rare juvenile skull of a 190 million-year-old dinosaur may help explain when an important group of plant eaters branched off from their carnivorous cousins]
The find also offers a rare chance to compare a young dinosaur to adults in the species. Porro said the eyes in the juvenile skull are much bigger, and the nose is much shorter.
‘It’s the same things that makes puppies and kittens appealing,” she said. “I think it’s adorable.’
|Tiny dinosaur on verge of swearing off meat
Reuters UK – 10 ore fa
By Julie Steenhuysen CHICAGO (Reuters) – A rare juvenile skull of a 190 million-year-old dinosaur may help explain when an important group of plant eaters …
|Dinosaur ‘was turning vegetarian’
The Press Association – 10 ore fa
One of the smallest dinosaur skulls ever discovered belonged to a creature in the process of turning vegetarian, say scientists. …
Journal of Vertebrate Paleontology (the link will be inserted when available) (Bioone)