GERMANIA: TROVATO UN FLAUTO PREISTORICO DI 35. 000 ANNI
(AGI) – Parigi, 24 giu. – La Germania si sta rivelando una miniera di reperti preistorici. Un flauto risalente a 35.000 anni fa e’ stato ritrovato vicino Ulm nella valle di Ach, nel Sud del Paese nello stesso sito dove e’ stata rinvenuta la cosiddetta ‘Venere di Hohle Fels’ una statuina di avorio raffigurante una donna appena abbozzata. La scoperta’ e’ frutto del lavoro di un’equipe di archeologi guidati da Nicholas Conard. Secondo quanto riferisce Nature il flauto, realizzato con un osso di avvoltoio ha cinque buchi, e’ lungo 22 centimetri e si puo’ suonare come uno strumento attuale.
Prehistoric flute in Germany is oldest known
June 24th, 2009
The flute. Foto: H. Jensen. Copyright: Universität Tübingen.
Excavations in the summer of 2008 at the sites of Hohle Fels and Vogelherd produced new evidence for Paleolithic music in the form of the remains of one nearly complete bone flute and isolated small fragments of three ivory flutes.
The most significant of these finds, a nearly complete bone flute, was recovered in the basal Aurignacian deposits at Hohle Fels Cave in the Ach Valley, 20 km west of Ulm. The flute was found in 12 pieces. The fragments were distributed over a vertical distance of 3 cm over a horizontal area of about 10 x 20 cm. This flute is by far the most complete of all of the musical instruments thus far recovered from the caves of Swabia.
The preserved portion of the bone flute from Hohle Fels has a length of 21.8 cm and a diameter of about 8 mm. The flute preserves five finger holes. The surfaces of the flute and the structure of the bone are in excellent condition and reveal many details about the manufacture of the flute. The maker carved two deep, V-shaped notches into one end of the instrument, presumably to form the proximal end of the flute into which the musician blew. The find density in this stratum is moderately high with much flint knapping debris, worked bone and ivory, bones of horse, reindeer, mammoth, cave bear, ibex, as well as burnt bone. No diagnostic human bones have been found in deposits of the Swabian Aurignacian, but we assume that modern humans produced the artifacts from the basal Aurignacian deposits shortly after their arrival in the region following a migration up the Danube Corridor.
The maker of the flute carved the instrument from the radius of a griffon vulture (Gyps fulvus). This species has a wingspan between 230 and 265 cm and provides bones ideal for large flutes. Griffon vultures and other vultures are documented in the Upper Paleolithic sediments of the Swabian caves.
The 2008 excavations at Hohle Fels also recovered two small fragments of what are almost certainly two ivory flutes from the basal Aurignacian. The different dimensions of the fragments indicate that the two finds are not from the same instrument. Excavators at Vogelherd in the Lone Valley 25 km northwest of Ulm recovered another isolated fragment of another ivory flute.
The technology for making an ivory flute is much more complicated than making a flute from a bird bone. This process requires forming the rough shape along the long axis of a naturally curved piece of ivory, splitting it open along one of the bedding plains in the ivory, carefully hollowing out the halves, carving the holes, and then rejoining the halves of the flute with an air-tight seal. Given the tendency of delicate ivory artifacts to break into many pieces, it is not unusual to find isolated pieces of such artifacts.
The 10 radiocarbon dates from the basal Aurignacian fall between 31 and 40 ka BP. Available calibrations and independent controls using other methods indicate that the flutes from Hohle Fels predate 35,000 calendar years ago. Apart from the caves of the Swabian Jura there is no convincing evidence for musical instruments predating 30 ka BP.
These finds demonstrate that music played an important role in Aurignacian life in the Ach and Lone valleys of southwestern Germany. Most of these flutes are from archaeological contexts containing an abundance of organic and lithic artifacts, hunted fauna, and burnt bone. This evidence suggests that the inhabitants of the sites played musical instruments in diverse social and cultural contexts and that flutes were discarded with many other forms of occupational debris. In the case of Hohle Fels, the location of the bone flute in a thin archaeological horizon only 70 cm away from a female figurine of similar age suggests that a possible contextual link exists between these two finds.
The flutes from Hohle Fels, Vogelherd and previous finds from nearby Geißenklösterle Cave demonstrate that a musical tradition existed in the cultural repertoire of the Aurignacian around the time modern humans settled in the Upper Danube region. The development of a musical tradition in the Aurignacian accompanied the development of the early figurative art and numerous innovations, including a wide array of new forms of personal ornaments, as well as new lithic and organic technologies. The presence of music in the lives of Upper Paleolithic peoples did not directly produce a more effective subsistence economy and greater reproductive success, but music seems to have contributed to improved social cohesion and new forms of communication, which indirectly contributed to demographic expansion of modern humans relative to the culturally more conservative Neanderthal populations.
The flutes from the caves of the Swabian Jura constitute a key part a major exhibit in Stuttgart entitled Ice Age Art and Culture, which will run from September 18, 2009 – January 10, 2010.
More information: The authors of the paper “New flutes document the earliest musical tradition in southwestern Germany” are Nicholas J. Conard Maria Malina and Susanne C. Münzel. The paper will be published as Advance online publication in Nature, June 25, 2009.
Provided by Universitaet Tuebingen
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
Rare prehistoric pregnant turtle found in Utah
At least three eggs are visible from the outside of the fossil, and Montana State University researchers this week have been studying images taken from a CT scan in search of others inside.
Montana State graduate student Michael Knell says the turtle was probably about a week from laying her eggs when she died and became entombed for millions of years in sandstone.
The fossil was found in 2006 in a remote part of Grand Staircase-Escalante National Monument. The eggs weren’t discovered until after it sat in storage for two years and was being re-examined by a volunteer.
This image provided Montana State University shows CT technician, Tanya Spence preparing to run a 75 million-year-old turtle fossil through a CT scanner at Deaconess Hospital in Bozeman, Mont. (AP Photo/Montana State University, Kelly Gorham)
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 …
Fossil Corals Show Catastrophic Sea-Level Rise?
April 15, 2009
Fossil coral reefs at a Mexican theme park “confirm” that sea levels rose rapidly about 121,000 years ago, according to a controversial new study.
Previous research on fossil reefs had shown that sea levels surged by 13 to 19 feet (4 to 6 meters) near the end of the last time period between ice ages, known as an interglacial period. But researchers have been unsure whether this sea-level rise happened quickly or gradually.
By mapping the ages and locations of ancient corals at Xcaret, an eco-park in the Yucatán Peninsula, Paul Blanchon of the National Autonomous University of Mexico, and colleagues, were able to chart when the reefs died and were replaced by others on higher ground.
Their data suggest that sea levels rose by about 10 feet (3 meters) in 50 years—much faster than the current annual rate of 0.08 to 0.1 inch (2 to 3 millimeters).
Because this event happened during an interglacial period—similar to the one we’re in currently—the find boosts the chances that today’s melting ice sheets could trigger rapid sea-level rise, the study authors say.
But not all experts on corals and climate are convinced by the new study.
Tad Pfeffer, of the University of Colorado at Boulder, noted that Blanchon’s team couldn’t directly measure the rate of sea level change around the Mexican corals, because the age estimates aren’t accurate enough.
Instead the study authors compared changes seen in Xcaret to those seen in reefs with well-established ages in the Bahamas.
“It’s an interesting idea, but one that for me is only suggestive and not compelling,” Pfeffer said.
“I’d want to see something more solid than this if I’m going to buy the idea of such rapid sea level rise at the time [of the last interglacial].”
Even if the new study is confirmed, Pfeffer added, more research would be needed to determine if rapid sea-level rise 121,000 years ago provides evidence that similar changes can happen now.
“And of course, when would ‘now’ be?” he asked.
“‘In the next few decades’ vs. ‘the next few thousand years’ are both ‘now’ on the time scales at which glacial and interglacial periods are defined, but are very different situations in terms of how we determine responses.”
Mike Kearney, of the University of Maryland, said it’s “within the realm of possibility” that global warming will trigger a sudden collapse of the West Antarctic ice sheet, which could lead to a rapid increase in sea levels like that predicted by the new study.
(Related: “PHOTOS: Jamaica-Size Ice Shelf Breaks Free”)
“But the big unknown is whether any of the things we think we know about the Antarctic ice sheet prove to be true,” Kearney cautioned.
“One camp says [rapid sea-level rise] could happen, another camp says it would take thousands of years. I’m not sure what the conventional wisdom is right now. It depends on who you talk to.”
Findings appear in this week’s issue of the journal Nature.
CBC.ca – 20 ore fa
The last time the Earth grew warmer than it is today, melting ice caused the oceans to rise very suddenly, a new study of fossil corals has found.
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: email@example.com).
· abstract and links
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· Supplementary info
Virgilio Notizie – 16 ore fa
(Apcom) – Una nuova analisi fatta sulle ossa fossili dell’Homo erectus di Zhoukoudian, meglio noto come l’uomo di Pechino, rivela che questo reperto …
‘Peking Man’ older than thought
Nature.com (subscription) – 3 ore fa
The age of Homo erectus, known familiarly as Peking Man, has been hotly debated. This week Shen et al. use a recently developed dating technique that …
Nature.com (subscription) – 3 ore fa
Re-evaluation of the age of Zhoukoudian, a prominent site of Homo erectus occupation in China, prompts a rethink of the species’ distribution in both the …
Nature.com (subscription) – 3 ore fa
The age of Zhoukoudian Homo erectus, commonly known as ‘Peking Man’, has long been pursued, but has remained problematic owing to the lack of suitable …
MSNBC – 2 ore fa
After the first fossil was found, anthropologists eventually turned up skulls and bones representing at least 40 H. erectus individuals, other mammal …
By Paul Rincon
Science reporter, BBC News
The Zhoukoudian caves have yielded many fossils of Homo erectus
Iconic ancient human fossils from China are 200,000 years older than had previously been thought, a study shows.
The new dating analysis suggests the “Peking Man” fossils, unearthed in the caves of Zhoukoudian are some 750,000 years old.
The discovery should help define a more accurate timeline for early humans arriving in North-East Asia.
A US-Chinese team of researchers has published its findings in the prestigious journal Nature.
The cave system of Zhoukoudian, near Beijing, is one of the most important Palaeolithic sites in the world.
Between 1921 and 1966, archaeologists working at the site unearthed tens of thousands of stone tools and hundreds of fragmentary remains from about 40 early humans.
Palaeontologists later assigned these members of the human lineage to the species Homo erectus.
The pre-war Peking Man fossils vanished in 1941 whilst being transported to the US for safekeeping. Luckily, the palaeontologist Franz Weidenreich had made casts for researchers to study.
Experts have tried various methods over the years to determine the age of the remains. But they have been hampered by the lack of suitable techniques for dating cave deposits such as those at Zhoukoudian.
Now, Guanjun Shen, from Nanjing Normal University in China, and colleagues have applied a relatively new method to the problem.
This method is based on the radioactive decay of unstable forms, or isotopes, of the elements aluminium and beryllium in quartz grains. This enabled them to get a more precise age for the fossils.
The results show the Peking Man fossils came from ground layers that were 680,000-780,000 years old, making them about 200,000 years older than had previously been believed.
Comparisons with other sites show that Homo erectus survived successive warm and cold periods in northern Asia.
Researchers Russell Ciochon and E Arthur Bettis III, from the University of Iowa, US, believe these climatic cycles may have caused the expansion of open habitats, such as grasslands and steppe. These environments would have been rich in mammals that could have been hunted or scavenged by early humans.
Recent revised dates for other hominid occupation sites in North-East Asia show that human habitation of the region began about 1.3 million years ago. The Nature study forms an important addition to this work.
The Peking Man fossils are a vital component of the Out of Africa 1 migration theory, which proposes that Homo erectus first appeared in Africa around two million years ago before spreading north and east (modern humans, Homo sapiens, would follow much later and supplant all other Homo species).
Evidence of the first dispersal comes from the site of Dmanisi in Georgia, where numerous hominid fossils dating to 1.75 million years ago have been unearthed. Finds from Java suggest early humans reached South-East Asia by 1.6 million years ago.
The northern populations represented at Zhoukoudian were probably separated from southern populations represented on the island of Java by a zone of sub-tropical forest inhabited by the giant panda, orangutans, gibbons and a giant ape called Gigantopithecus.
These early humans may have survived in island South-East Asia until 50,000 years ago.
Recent discoveries suggest that on the Indonesian island of Flores, Homo erectus, or another early human species, became isolated and evolved into a dwarf species called Homo floresiensis, nicknamed “The Hobbit”.
It is not clear whether H. erectus ever reached Europe; the earliest European fossils have been assigned to the species Homo antecessor. But this classification is disputed, and some researchers believe the Spanish antecessor fossils do indeed belong with H. erectus.
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
Multimedia and scientific article from Nature:
The mother fish
Ancient fish fossils shed light on the origins of sex.
see also previous post: 2009-02-28 – L’origine del sesso (sex origin)
Scientific publication, Info and Abstract:
Devonian arthrodire embryos and the origin of internal fertilization in vertebrates
John A. Long, Kate Trinajstic & Zerina Johanson
Nature 457, 1124-1127 (26 February 2009) | doi:10.1038/nature07732;
Evidence of reproductive biology is extremely rare in the fossil record. Recently the first known embryos were discovered within the Placodermi1, an extinct class of armoured fish, indicating a viviparous mode of reproduction in a vertebrate group outside the crown-group Gnathostomata (Chondrichthyes and Osteichthyes). These embryos were found in ptyctodontids, a small group of placoderms phylogenetically basal to the largest group, the Arthrodira2, 3. Here we report the discovery of embryos in the Arthrodira inside specimens of Incisoscutum ritchiei from the Upper Devonian Gogo Formation of Western Australia4 (approximately 380 million years ago), providing the first evidence, to our knowledge, for reproduction using internal fertilization in this diverse group. We show that Incisoscutum and some phyllolepid arthrodires possessed pelvic girdles with long basipterygia that articulated distally with an additional cartilaginous element or series, as in chondrichthyans, indicating that the pelvic fin was used in copulation. As homology between similar pelvic girdle skeletal structures in ptyctodontids, arthrodires and chondrichthyans is difficult to reconcile in the light of current phylogenies of lower gnathostomes2, 3, 5, we explain these similarities as being most likely due to convergence (homoplasy). These new finds confirm that reproduction by internal fertilization and viviparity was much more widespread in the earliest gnathostomes than had been previously appreciated.
Antichissime impronte rinvenute nel precambriano dell’arabia Saudita sono state riconosciute come impronte di spugne. La scoperta ha ovviamente importantissime implicazioni di carattere ia tassonomico che soprattutto paleobiologico ed evoluzionistico
Ancient sponges leave their mark
By Jonathan Amos
Science reporter, BBC News
The rocks date to a time of dramatic gaciation on Earth
Traces of animal life have been found in rocks dating back 635 million years.
The evidence takes the form of chemical markers that are highly distinctive of sponges when they die and their bodies break down in rock-forming sediments.
The discovery in Oman pushes back the earliest accepted date for animal life on Earth by tens of millions of years.
Scientists tell Nature magazine that the creatures’ existence will help them understand better what the planet looked like all that time ago.
“The fact that we can detect these signals shows that sponges were ecologically important on the seafloor at that time,” said lead author Gordon Love, from the University of California, Riverside.
“We’re not saying we captured the first animal; we’re saying they’re an early animal phylum and we’re capturing them when their biomass was significant.”
Researchers can usually determine the presence of ancient life in rock strata by looking for the fossilised remains of skeletons or the hardened record of the creatures’ movements, such as their footprints or crawl marks.
Sponges are among the simplest multi-celled organisms
But for organisms deep in geological history that were extremely small and soft bodied, scientists have had to develop novel techniques to uncover their existence.
One of these newer methods involves detecting breakdown products from the lipid molecules which act as important structural components in the cell membranes of animals.
Over time, these will transform to leave a molecule known as cholestrane; and for sponges, this exclusively takes the form known as 24-isopropylcholestane.
Dr Love’s team found high concentrations of this biomarker in rocks located at the south-eastern edge of the Arabian peninsula.
They were laid down in what would have been a shallow marine environment at least 635 million years ago.
“Even though there must have been sufficient oxygen in the water to maintain the metabolism of these primitive animals, I think their size would have been restricted by oxygen being nowhere near modern values,” the UC Riverside researcher said.
“We’re probably talking about small colonies of sponges with body dimensions of a few millimetres at most. They’d have been filtering organic detritus in the water column.”
The discovery is fascinating because it pre-dates the end of the Marinoan glaciation, a deep freeze in Earth history that some argue shrouded the entire planet in ice.
Scientists often refer to the term “snowball Earth” to describe conditions at this time.
So to find animal life apparently thriving during this glaciation seems remarkable, commented Jochen Brochs, from the Australian National University, Canberra.
“If there really was a snowball Earth, how did those sponges survive? The full snowball Earth hypothesis would predict that the oceans were frozen over by 2km, even at the equator,” he told BBC News.
“Only at hot springs could any organism survive but it is questionable that you would have sponges in a hot spring. I haven’t made my mind up about snowball Earth but perhaps these sponges are telling us something about this glaciation.”
Dr Love’s view is that the presence of these animals puts limits on the scale of the ice coverage.
“I believe there were areas of what we might call refugia – areas of open ocean where biology could go on. And in this case, it could be evidence that we had some sort of evolutionary stimulation of new grades of organisms as well.”