Con un po` di ritardo ecco il post su una notizia “eccezonale”.
Un osso ritrovato in sedimenti di origine marina nel Cenomaniano della Sicilia e stato identificato come appartenente a un dinosauro (il quarto ritovato in Italia).
Per info piu` dettagliate: Blog – Teropoda
Garilli, V, et al. “First dinosaur bone from Sicily identified by histology and its palaeobiogeographical implications.” Neues Jahrbuch für Geologie und Paläontologie 252.2 (2009):207-216.
Proteins, soft tissue from 80-million-year-old dino support theory that molecules preserve over time
A North Carolina State University paleontologist has more evidence that soft tissues and original proteins can be preserved over time – even in fossilized remains – in the form of new protein sequence data from an 80 million-year-old hadrosaur, or duck-billed dinosaur.
Dr. Mary Schweitzer, associate professor of marine, earth and atmospheric sciences at NC State with a joint appointment at the N.C. Museum of Natural History, along with colleague Dr. John Asara from the Beth Israel Deaconess Medical Center (BIDMC) and Harvard Medical School, Dr. Chris Organ from Harvard University, and a team of researchers from Montana State University, the Dana Farber Cancer Institute, and Matrix Science Ltd. analyzed the hadrosaur samples.
The researchers’ findings appear in the May 1 edition of Science.
Schweitzer and Asara had previously used multiple methods to analyze soft tissue recovered from a 68 million-year-old Tyrannosaurus Rex. Mass spectrometry conducted on extracts of T. rex bone supported their theory that the materials were original proteins from the dinosaur.
These papers were controversial, and the team wanted to demonstrate that molecular preservation of this sort in dinosaurs was not an isolated event. Based upon other studies, they made predictions of the type of environment most likely to favor this preservation, so Schweitzer and students, working with Jack Horner’s Museum of the Rockies field crews, went looking for a dinosaur preserved under a lot of sandstone. Using specially designed field methodology, with the aim of avoiding environmental exposure until the fossil was inside the lab, they set aside the femur from a Brachylophosaurus canadensis – a hadrosaurid dinosaur–buried deeply in sandstone in the Judith River formation.
“This particular sample was chosen for study because it met our criteria for burial conditions of rapid burial in deep sandstones,” Schweitzer says. “We know the moment the fossil is removed from chemical equilibrium, any organic remains immediately become susceptible to degradation. The more quickly we can get it from the ground to a test tube, the better chance we have of recovering original tissues and molecules.”
Preliminary results seemed to confirm their methodology, as Schweitzer found evidence of the same fibrous matrix, transparent, flexible vessels and preserved microstructures she had seen in the T. rex sample in the much older hadrosaur bone. Because of the rapidity of analyses after the bones were removed, the preservation of these dinosaurian components was even better. The samples were examined microscopically via both transmitted light and electron microscopes to confirm that they were consistent in appearance with collagen. They were also tested against antibodies that are known to react with collagen and other proteins.
Next, Schweitzer sent the samples to Asara’s lab to be analyzed by a new mass spectrometer, capable of producing sequences with much greater resolution than the one used previously. Mass spectrometry identifies molecules by measuring the mass of the protein fragments, or peptides, that result from breaking apart molecules with specific enzymes. The masses are measured with very high mass accuracy, and then compared with existing databases of proteins to achieve a best fit. In this way, Asara was able to identify eight collagen peptides from the hadrosaur, then confirm the identity of the sequences by comparing them both to synthesized fragments and to modern proteins analyzed under the same conditions. Once sequence data were validated, they were evaluated by Organ who determined that, like T.rex, this dinosaur’s protein family tree is closer to that of modern birds than that of alligators.
All results were independently verified by researchers at BIDMC, Montana State University, Harvard University, the Dana Farber Cancer Institute, and Matrix Science of London.
The data were consistent with that of the earlier T. rex analysis, confirming that molecular preservation in fossilized remains is not an isolated event. “We used improved methodology with better instrumentation, did more experiments and had the results verified by other independent labs,” Schweitzer says. “These data not only build upon what we got from the T. rex, they take the research even further.”
Schweitzer hopes that this finding will lead to more work by other scientists on these ancient molecules.
“I’m hoping in the future we can use this work as a jumping off point to look for other proteins that are more species-specific than collagen. It will give us much clearer insight into all sorts of evolutionary questions.”
Contact: Tracey Peake – email@example.com - 919-515-6142 – North Carolina State University###
An abstract of the paper follows.
“Biomolecular Characterization and Protein Sequences of the Campanian Hadrosaur Brachylophosaurus canadensis“
Authors: Mary H. Schweitzer, North Carolina State University and the N.C. Museum of Natural Sciences; John M. Asara, Beth Israel Deaconess Medical Center and Harvard Medical School, et al.
Published: May 1, 2009 in Science
Abstract: Molecular preservation in non-avian dinosaurs is controversial. We present multiple lines of evidence that endogenous proteinaceous material is preserved in bone fragments and soft tissues from an 80 million year old Campanian hadrosaur, Brachylophosaurus canadensis (MOR 2598). Microstructural and immunological data are consistent with preservation of multiple bone matrix and vessel proteins, and phylogenetic analyses of Brachylophosaur collagen sequenced by mass spectrometry robustly support the bird-dinosaur clade, consistent with an endogenous source for these collagen peptides. These data complement earlier results from Tyrannosaurus rex (MOR 1125) and confirm that molecular preservation in Cretaceous dinosaurs is not a unique event.
Chiaramente ogni commento e` superfluo, spero soltanto con tutto il cuore che tutte le persone che ho conosciuto durante la mia attivita` di geologo a l`Aquila (in prmis ovviamente le persone care alla Prof. Emma Ruggiero Taddei) e i loro familiari siano in salvo …
News: by Google news
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).
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Scoperto fossile di dinosauro nano
Viveva nell’America del nord 75 milioni di anni fa
(ANSA)- ROMA, 17 MAR – Dei mini-dinosauri carnivori vivevano nell’America del nord, 75 milioni di anni fa. Lo conferma un fossile scoperto da paleontologi canadesi. Il fossile, scoperto da Nick Longrich e Philip Currie delle universita’ di Calgary e Alberta, viveva nell’odierno Canada. Era piu’ piccolo di un gatto e correva su due zampe fornite di artigli. Probabilmente cacciava insetti e piccoli mammiferi. Resti fossili di questo dinosauro furono gia’ trovati circa 25 anni fa.
Alberta researchers discover mini meat-eating
It had razor sharp claws and its teeth may have been the terror of Alberta 75 million years ago — among animals smaller than a squirrel, that is.
University of Calgary researcher Nicholas Longrich sits with a model of tiny dinosaur, which likely weighed less than two kilograms. (University of Calgary)
The kitten-sized predator identified by paleontologists at the University of Calgary and the University of Alberta is the smallest carnivorous dinosaur ever found in North America. The next smallest meat-eating dinosaur ever found on the continent was about the size of a wolf.
“Until we found this animal, basically we had no evidence for any small carnivores being present in North America,” said University of Calgary researcher Nicholas Longrich, in a video released by the university on Monday.
Longrich and the University of Alberta’s Philip Currie have written an article describing the velociraptor-like dinosaur, published Monday in the Proceedings of the National Academy of Science.
The tiny, bird-like predator ran on two legs and was about half the size of a housecat, weighing less than two kilograms, and standing about as tall as an average wastebasket. It likely hunted near the ground in marshes and forests for insects, small mammals, amphibians and “maybe even baby dinosaurs,” Longrich said.
The researchers have given the dinosaur the scientific name Hesperonychus Elizabethae.
Hesperonychus means “western claw” and Elizabethae is a tribute to the late Elizabeth (Betsy) Nicholls, the well-known Alberta paleontologist and former curator at the Royal Tyrrell Museum in Drumheller who originally unearthed the bones.
Found 20 km from Dinosaur Provincial Park
Nicholls found the fossilized claws and a well-preserved pelvis in 1982 at the Dinosaur Park Formation, about 20 kilometres east of Dinosaur Provincial Park, or about 140 kilometres east of Calgary. Longrich said he was going through the collections at the University of Alberta when he stumbled across the bones less than two years ago.
Previously, paleontologists believed they belonged to a juvenile dinosaur of some sort.
Longrich noticed that one of the bones looked like the hip bones of some velociraptor-like dinosaurs excavated in China. Those Chinese dinosaurs were a little less than a metre long.
On closer examination, Longrich noticed that the pelvic bones had fused together — something that happens after the animal stops growing, indicating that it was an adult.
Because quite a number of bones were found, the researchers suggest that Hesperonychus was an important part of the ecosystem in the late Cretaceous period, as small predators such as cats and foxes are an important part of the ecosystem today.
The results also show for the first time that tiny velociraptor-like dinosaurs lived not just in China, but also in North America, and that such dinosaurs continued to roam the Earth about 45 million years longer than previous records suggested.
Reuters - 13 ore fa
By Scott Haggett CALGARY, Alberta (Reuters) – Canadian researchers said on Monday they have discovered North America’s smallest known dinosaur, a pint-sized …
AFP - 18 minuti fa
WASHINGTON (AFP) – Meat-eating dinosaurs the size of a small chicken roamed areas of North America 75 million years ago, according to research by Canadian …
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
L’acidificazione degli oceani dovuta al crescente aumento di CO2 nell’atmosfera, ha comportato una riduzione del 35% nello spessore della conchiglia nel foraminifero Globigerina bulloides dal periodo pre-industiale ad oggi.
Ciò oltre ad alterare l’equilibrio della vita marina è una brutta notizia anche per noi esseri umani in quanto una riduzione di spessore nelle conchiglie significa una maggior quantità di CO2 che non viene fissato dagli organismi nelle loro conchiglie e che quindi rimane ad intossicare l’aria che respiriamo.
Proof on the Half Shell: A More Acid Ocean Corrodes Sea Life
Ocean acidification is taking a toll on tiny shell-building animals
By David Biello
SHELL GAME: Foramnifera, like Globigerina bulloides pictured here, are having a harder time building big shells in a more caustic Southern Ocean. COURTESY OF ANDREW MOY
The shells of tiny ocean animals known as foraminifera—specifically Globigerina bulloides—are shrinking as a result of the slowly acidifying waters of the Southern Ocean near Antarctica. The reason behind the rising acidity: Higher carbon dioxide (CO2) levels in the atmosphere, making these shells more proof that climate change is making life tougher for the seas’ shell-builders.
Marine scientist Andrew Moy at the Antarctic Climate & Ecosystems Cooperative Research Center (ACE) in Hobart, Tasmania, and his Australian colleagues report in Nature Geoscience this week that they made this finding after comparing G. bulloides shells in ocean cores collected along the South Tasman Rise in 1995 with samples from traps collected between 1997 and 2004. The cores provide records that stretch back 50,000 years.
“We knew there were changes in carbonate chemistry of the surface ocean associated with the large-scale glacial-interglacial cycles in CO2 [levels], and that these past changes were of similar magnitude to the anthropogenic changes we are seeing now,” says study co-author William Howard, a marine geologist at ACE. “The Southern [Ocean] works well [to study this issue] as it is a region where anthropogenic CO2 uptake, and thus acidification, has progressed more than in other regions. Other variables, such as temperature, have changed, but not as much.”
The researchers found that modern G. bulloides could not build shells as large as the ones their ancestors formed as recently as century ago. In fact, modern shells were 35 percent smaller than in the relatively recent past—an average of 17.4 micrograms compared with 26.8 micrograms before industrialization. (One microgram is one millionth of a gram; there are 28.3 grams in an ounce.)
“We don’t yet know what impact this will have on the organisms’ health or survival,” Howard says, but one thing seems clear: the tiny animals won’t be storing as much CO2 in their shells in the form of carbonate. “If the shell-making is reduced, the storage of carbon in the ocean might be, as well.”
That’s bad news for the climate, because the ocean is responsible for absorbing at least one quarter of the CO2 that humans load into the air through fossil fuel burning and other activities—and it is the action of foraminifera and other tiny shell-building animals, along with plants like algae that lock it away safely for millennia.
It will be harder to get such a clear sign in a shell from other ocean regions—as variables like temperature and the amount of minerals available can significantly change the chemistry of a given ocean region. As Howard noted, the Southern Ocean has absorbed lots of manmade CO2 while temperatures and nutrients have not changed as much, making it more ideal for studying ocean acidification than other areas. Scientists examining foraminifera in the Arabian Sea, however, have found similar results, and Howard speculates the situation may be similar in the North Atlantic region, because it also absorbs a significant chunk of manmade CO2.
Howard says that CO2 emissions must be cut or captured and stored permanently in some fashion to halt this gradual acidification of the world’s oceans. In the meantime, he adds, it’s likely that many of the other shell-building oceanic animals are suffering similar fates as G. bulloides.
ABC Science Online - 12 ore fa
“The ocean is currently taking up somewhere in the neighbourhood of a third of our fossil fuel emissions,” says Howard, a palaeo-climatologist.
Reduced calcification in modern Southern Ocean planktonic foraminifera
Andrew D. Moy, William R. Howard, Stephen G. Bray & Thomas W. Trull
Abstract: Anthropogenic carbon dioxide has been accumulating in the oceans, lowering both the concentration of carbonate ions and the pH (ref. 1), resulting in the acidification of sea water. Previous laboratory experiments have shown that decreased carbonate ion concentrations cause many marine calcareous organisms to show reduced calcification rates2, 3, 4, 5. If these results are widely applicable to ocean settings, ocean acidification could lead to ecosystem shifts. Planktonic foraminifera are single-celled calcite-secreting organisms that represent between 25 and 50% of the total open-ocean marine carbonate flux6 and influence the transport of organic carbon to the ocean interior7. Here we compare the shell weights of the modern foraminifer Globigerina bulloides collected from sediment traps in the Southern Ocean with the weights of shells preserved in the underlying Holocene-aged sediments. We find that modern shell weights are 30–35% lower than those from the sediments, consistent with reduced calcification today induced by ocean acidification. We also find a link between higher atmospheric carbon dioxide and low shell weights in a 50,000-year-long record obtained from a Southern Ocean marine sediment core. It is unclear whether reduced calcification will affect the survival of this and other species, but a decline in the abundance of foraminifera caused by acidification could affect both marine ecosystems and the oceanic uptake of atmospheric carbon dioxide.
Correspondence to: William R. Howard1 e-mail: Will.Howard@utas.edu.au
Link: nature.com - supplementary information
Nature Geoscience - Published online: 8 March 2009 | doi:10.1038/ngeo460
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
Oldest fossilized brain ever is uncovered in Kansas
By Katherine Harmon in 60-Second Science Blog
A 300 million-year-old fossilized fish brain was discovered during a routine computed tomography (CT) scan, according to a study published today in the Proceedings of the National Academy of Sciences. Until now, scientists assumed that brains rarely—if ever—turned into fossils. Other soft tissue fossils, such as muscles and kidneys, have been found that date back longer than 350 million years ago, but because the brain is delicate and consists mostly of water, it’s much less likely to be preserved in fossil form, says study co-author John Maisey, a curator in the paleontology division of the American Museum of Natural History in New York. But “It’s more than just a curiosity,” he says. “Modern technology has revealed a fossil that we really didn’t know about before.” High-powered scans using x-ray synchrotron microtomography (which, like a CT, uses x-rays to image cross-sections of an object) allowed scientists to peer into the rock-solid skull to see the 0.06-by-0.28-inch (1.5 by 7 mm) brain.
Image of fossilized brain courtesy of A. Pradel
The fossil was from an iniopterygian, an ancient extinct fish that is a relative of sharks, rays and ratfish. What surprised researchers even further is that it showed a brain similar to that of modern-day shark.
In the fossilization process, the brain itself was replaced with hard minerals, which preserved the shape of the original organ, and the rest of the cavity was filled with sediment, Maisey says. He notes that researchers found several fossilized craniums, each resembling a little “broken bowl of rock,” in rock from the Upper Carboniferous period in Kansas and Oklahoma. But only one has yielded a preserved brain structure.
“It’s quite possible that brain fossils are actually more common, and we simply haven’t been able to find them,” says Maisey, who noted that researchers may now try to check out other fossilized skulls with the high-tech scanners to see if they contain mineralized brains. Of course, this finding also means that paleontologists may have to stretch their own brains a bit to include things other than bones. “Now we have to learn new things about brains,” Maisey joked, “that we didn’t have to bother with [before].”
National Geographic - 3-mar-2009
The fossil was found in an iniopterygian, an extinct ancestor of modern ratfishes (see albino ratfish picture), which are distant relatives of sharks and …
AFP - 2-mar-2009
The imaging achievement, reported in the US journal Proceedings of the National Academy of Sciences, is important because soft tissue in fossils is very …