Tuesday, June 23, 2009

Indonesian elephant fossil opens window to past


Scientists arrange the bones of an estimated 200,000 year-old giant elephant at Geology Museum in Bandung, West Java, Indonesia, Thursday, June 18, 2009. Indonesian scientists are reconstructing the largest, most complete skeleton of an ancient elephant ever found in the tropics, a finding that may offer new clues into the largely mysterious origins of its modern Asian cousin. Based on the fossil, the ancient elephant stood four meters (13-feet) tall, was five meters (16-feet) long and weighed more than 10 tons, considerably larger than the great Asian mammals now on Earth. (AP Photo/Dita Alangkara)
(AP) -- Indonesian scientists are reconstructing the largest, most complete skeleton of a prehistoric giant elephant ever found in the tropics, a finding that may offer new clues into the largely mysterious origins of its modern Asian cousin.
The prehistoric elephant is believed to have been submerged in quicksand shortly after dying on a riverbed in Java around 200,000 years ago. Its bones - almost perfectly preserved - were discovered by chance in March when an old sand quarry collapsed during monsoon rains.
The animal stood four meters (13-feet) tall, five meters (16-feet) long and weighed more than 10 tons - closer in size to the woolly mammoth of the same period than to the great Asian mammals now on Earth.
Animal fossils are rare in the humid, hot climate of the equator because decomposition occurs extremely quickly.
Following a monthlong excavation, a team of seven paleontologists from the Museum in Bandung, West Java, set the bones in plaster for the trip back to their office where they will be laboriously pieced back together.
"We believe from the shape of its teeth that it was a very primitive elephant," but little else has been verified, said paleontologist Fachroel Aziz, who is heading a 12-strong skeletal reconstruction team.
Scientists agree it is the first time an entire prehistoric elephant has been unearthed since vertebrate findings began to be recorded in Indonesia in 1863.
"It is very uncommon to discover a fossil like this in a tropical region like Indonesia," said Edi Sunardi, an independent expert at Indonesia's Pajajaran University in Bandung, West Java. "It apparently was covered by volcanic sediment that protected it from high temperatures, erosion and decay."
The next challenge will be removing the delicate bones from their molds and joining them into a stable, upright structure, a process that experts said is already being hampered by a lack of funding, inadequate tools and poor expertise.
Indonesia, an emerging and impoverished democracy of 235 million people, cannot afford to allocate more than a token sum to its aging museums, even for projects that have the potential to advance knowledge about the origin of key native species.
Gert van den Berg, a researcher at Australia's Wollongong University who helped dig up the skeleton, said tests are under way to determine its precise age and species, and that they will help provide details "about when the modern evolved into what they are now."
About 2,000 old elephant remains have been found across the island nation over the past 150 years, but never in such good condition, Aziz said.
"We want to exhibit it publicly because this is a spectacular discovery," he said.

Cold Case Techniques Bring Mummy’s Face To 'Life'


ScienceDaily (June 23, 2009) — Thanks to the skills of artists who work on cold case investigations, people have a chance to see what the University of Chicago’s mummy Meresamun may have looked like in real life.
A Chicago forensic artist and a police artist in Maryland prepared the images, which depict an engaging woman in her late 20s as she would have looked in 800 B.C. Both artists, though working independently, produced strikingly similar images.*
Dr. Michael Vannier, Professor of Radiology, began the process of restoring the mummy’s facial features with two exhaustive CT examinations of Meresamun in 2008 at the University of Chicago Medical Center.
“A huge number of CT scans of the skull were used to create a 3-D digital model of Meresamun’s skull,” said Emily Teeter, Research Associate at the Oriental Institute an curator of a museum exhibition about the mummy. “Those files were given to forensic artists who use methods employed in cold case investigations where skeletal remains need to be identified.”
The Oriental Institute wanted to compare multiple reconstructions, in order to obtain a trustworthy image of Meresamun’s face. Both a digital version of the traditional forensic reconstruction and a missing person-type sketch were submitted.
In the traditional forensic method, layers of fat, muscle and flesh are built up upon the skull. Starting with a three-dimensional image of the skull created from multiple CT scans, Chicago artist Joshua Harker used a technique known as the Gatliff-Snow American Tissue Depth Marker Method to calculate the contours of the face to digitally recreate Meresamun’s appearance.
“The skull is the driving architecture of the face—all the proportions and placements are there, if know how to read it,” Harker explained. “Even the shapes of the lips, nose and eyebrows can be determined if you know what to look for,” The American Tissue Depth Marker method has been shown to be effective in accurately reconstructing a face, both in identifying victims and as admissible evidence in court.
“I try not to make any assumptions without expert direction, whether that be from an anthropologist regarding the race, gender or age, or from and expert like Emily Teeter who can give me an accurate description about details based on historical evidence,” Harker said. “I am ecstatic that my reconstruction of Meresamun has been so well received by the community who knows the most about her.”
Michael Brassell, who works with the Department of Justice/Maryland State Police Missing Persons Unit, used his skills as a trained sketch artist to produce a second, more traditional reconstruction.
“The project was no different then any of the postmortems drawings I have worked on for cold case homicides. The CT scans were very clear, making my job easy,” he said. “If this was a homicide case, I would almost go as far to guarantee a hit on the profile drawing.”
Meresamun lived in Thebes (ancient Luxor) about 800 B.C. and died of undetermined causes about age 29-30. An exhibit, “The Life of Meresamun: A Temple Singer in Ancient Egypt,” features her mummy and coffin and will be featured through Dec. 6 at the Oriental Institute Museum. A video display allows visitors to view features of Meresamun’s physical state and perform a “virtual unwrapping” of the mummy, enabling them to see how it was prepared. Advanced digital techniques have made it possible to recreate Meresamun’s appearance.
She was tall by ancient standards—5-and-a-half feet—her features were regular with wide-spaced eyes and she had an overbite. “Meresamun was, until the time of her death at about 30, a very healthy woman,” Vannier said. “The lack of arrest lines on her bones indicates good nutrition through her lifetime and her well-mineralized bones suggest that she lived an active lifestyle.”
*The drawings are on display at the Oriental Institute Museum, and have been placed on the institute’s Web site (http://oi.uchicago.edu/museum/special/meresamun/), on Meresamun’s Facebook page, her Wikipedia listing and on YouTube.
Adapted from materials provided by University of Chicago.

54-million-year-old Skull Reveals Early Evolution Of Primate Brains


ScienceDaily (June 23, 2009) — Researchers at the University of Florida and the University of Winnipeg have developed the first detailed images of a primitive primate brain, unexpectedly revealing that cousins of our earliest ancestors relied on smell more than sight.
The analysis of a well-preserved skull from 54 million years ago contradicts some common assumptions about brain structure and evolution in the first primates. The study also narrows the possibilities for what caused primates to evolve larger brain sizes. The study is scheduled to appear online the week of June 22 in the Proceedings of the National Academy of Sciences.
The skull belongs to a group of primitive primates known as Plesiadapiforms, which evolved in the 10 million years between the extinction of the dinosaurs and the first traceable ancestors of modern primates. The 1.5-inch-long skull was found fully intact, allowing researchers to make the first virtual mold of a primitive primate brain.
"Most explanations on the evolution of primate brains are based on data from living primates," said lead author Mary Silcox, an anthropologist at the University of Winnipeg and research associate at UF's Florida Museum of Natural History. "There have been all these inferences about what the brains of the earliest primates would look like, and it turns out that most of those inferences are wrong."
Researchers used CT scans to take more than 1,200 cross-sectional X-ray images of the skull, which were combined into a 3-D model of the brain.
"A large and complex brain has long been regarded as one of the major steps that sets primates apart from the rest of mammals," said Florida Museum vertebrate paleontologist and study co-author Jonathan Bloch. "At our very humble beginnings, we weren't so special. That happened over tens of millions of years."
The animal, Ignacius graybullianus, represents a side branch on the primate tree of life, Bloch said. "You can think of it as a cousin of the main line lineage that would have given rise ultimately to us."
In previous research, Bloch and Silcox established that Plesiadapiforms were transitional species. Ignacius was similar to modern primates in terms of its diet and tree-dwelling but did not leap from tree to tree like modern fast-moving primates.
In many ways, the early primate behaved like living primates but with a brain that was one-half to two-thirds the size of the smallest modern primates. This means that factors such as tree-dwelling and fruit-eating can be eliminated as potential causes for primates evolving larger brain sizes, Silcox said, because "the smaller brained Ignacius was already doing those things."
The mold suggests a "startling combination" of features in the early primate that requires a rethinking of primate brain evolution, said Florida State University anthropologist Dean Falk, who was not involved in the study.
"Hypotheses about early primate brain evolution often link keen smell with nocturnal insect-eating, and a more recently evolved increase in visual processing with fruit-eating in arboreal habitats," Falk said.
The move to larger brain size occurred during an evolutionary burst that happened 10 million years after the extinction of the dinosaurs. At that point, visual features in the brain became much more prominent while the olfactory bulbs became proportionately smaller.
More than likely, Bloch said, this change in brain structure and size was related to primates living in closed canopy forests that brought trees closer together and allowed for more leaping. But answering that will require the discovery and analysis of new fossils.
Changes in brain size and brain structure in the early stages of primate evolution have generated enormous debates for decades. But until now, fossil evidence has been lacking.
Many models of the ancestral primate brain are based on tree shrews, which come from southeast Asia and are distantly related to humans. But with some 70 million years of evolution between them and humans, "it turns out tree shrew brains are not a good model," Silcox said.
Adapted from materials provided by University of Florida.

Monday, June 22, 2009

Obsidian 'trail' provides clues to how humans settled, interacted in Kuril Islands


Tiny obsidian flakes such as this found in the Kuril Islands have been traced to their source on Japan's Hokkaido Island and Russia's Kamchatka Peninsula.
(PhysOrg.com) -- Archaeologists have used stone tools to answer many questions about human ancestors in both the distant and near past and now they are analyzing the origin of obsidian flakes to better understand how people settled and interacted in the inhospitable Kuril Islands.
Using X-ray fluorescence spectrometers, archaeologists from the University of Washington and the Smithsonian Institution have found the origin of 131 flakes of obsidian, a volcanic glass. These small flakes were discarded after stone tools were made from obsidian and were found at 18 sites on eight islands in the Kurils. The flakes were found with other artifacts that were dated over a time period spanning about 1,750 years, from 2500 to 750 years before the present.
The Kuril Archipelago stretches for nearly 800 miles between the northern-most Japanese island of Hokkaido and the Kamchatka Peninsula in Russia. Despite the islands' volcanic origin, there are no known local sources of obsidian.
"A key quality of obsidian is you can create very sharp edge. Obsidian flakes easily and fractures in a way that is predictable. When it was available have used it," said Colby Phillips, lead author of the new study and an anthropology doctoral student at the University of Washington. His co-author is Robert Speakman of the Smithsonian's Museum Conservation Institute.
Obsidian is formed when magma is extruded from a volcano and can be geochemically identified Phillips said. That's because the obsidian from each volcano has a unique based on the amount of elements such as rubidium, zirconium and strontium in the glass. Archaeologists gather obsidian samples from volcanoes to create a data base of chemical signatures and compare archaeological samples collected in the field to the data base.
Phillips and Speakman pinpointed the Kuril flakes they analyzed to four locations on Hokkaido and five sources on Kamchatka. The majority of the flakes, slightly more than 60 percent, originated in Kamchatka.
Human occupation of the Kurils began about 4,000 years ago at the southern end of the island chain near Hokkaido and gradually spread northward. And where humans went they carried obsidian with them.
"Obsidian only makes up about 8 percent of the stone tools and the waste left from their manufacture, but it shows up at all sites and over all time periods," said Phillips. "Obsidian may have played a role in maintaining social and trade networks as people migrated across the Kurils. Our work suggests social relationships can be important in local and regional areas. Here we have people living in an isolated area that is covered by fog and clouds and subject to tsunamis, volcanic eruptions and earthquakes. So it would be advantageous to have connections with other people. The fact that we have a material such as obsidian throughout the islands shows people were proactive in maintaining ties in the prehistoric era."
The researchers found a basic pattern of obsidian distribution in the islands. Obsidian from Hokkaido was primarily found in the Southern Kurils with a few samples discovered in the Central Kurils. Kamchatka obsidian was only found in the Central and Northern Kurils.
The Southern Kurils are separated from the other islands in the chain by the 70-mile-wide Bussol Strait. Phillips believes that at some time it became too costly to make the dangerous ocean crossing, and people in the central and northern began trading for Kamchatka obsidian.
Since the research was accepted for publication, Phillips and Speakman have analyzed the sources of an additional 700 obsidian flakes and their results mirror the newly published data.
Source: University of Washington (news : web)

Dinosaurs May Have Been Smaller Than Previously Thought


ScienceDaily (June 22, 2009) — The largest animals ever to have walked the face of the earth may not have been as big as previously thought, reveals a paper published June 21 in the Zoological Society of London’s Journal of Zoology.
Scientists have discovered that the original statistical model used to calculate dinosaur mass is flawed, suggesting dinosaurs have been oversized.
Widely cited estimates for the mass of Apatosaurus louisae, one of the largest of the dinosaurs, may be double that of its actual mass (38 tonnes vs. 18 tonnes).
"Paleontologists have for 25 years used a published statistical model to estimate body weight of giant dinosaurs and other extraordinarily large animals in extinct lineages. By re-examining data in the original reference sample, we show that the statistical model is seriously flawed and that the giant dinosaurs probably were only about half as heavy as is generally believed" says Gary Packard from Colorado State University.
The new predictions have implications for numerous theories about the biology of dinosaurs, ranging from their energy metabolism to their food requirements and to their modes of locomotion.
Journal reference:
. Allometric equations for predicting body mass of dinosaurs. Journal of Zoology, June 21, 2009 DOI: 10.1111/j.1469-7998.2009.00594.x
Adapted from materials provided by Wiley - Blackwell, via AlphaGalileo.

Ice Sheets Can Retreat 'In A Geologic Instant,' Study Of Prehistoric Glacier Shows


ScienceDaily (June 22, 2009) — Modern glaciers, such as those making up the Greenland and Antarctic ice sheets, are capable of undergoing periods of rapid shrinkage or retreat, according to new findings by paleoclimatologists at the University at Buffalo.
The paper, published on June 21 in Nature Geoscience, describes fieldwork demonstrating that a prehistoric glacier in the Canadian Arctic rapidly retreated in just a few hundred years.
The proof of such rapid retreat of ice sheets provides one of the few explicit confirmations that this phenomenon occurs.
Should the same conditions recur today, which the UB scientists say is very possible, they would result in sharply rising global sea levels, which would threaten coastal populations.
"A lot of glaciers in Antarctica and Greenland are characteristic of the one we studied in the Canadian Arctic," said Jason Briner, Ph.D., assistant professor of geology in the UB College of Arts and Sciences and lead author on the paper. "Based on our findings, they, too, could retreat in a geologic instant."
The new findings will allow scientists to more accurately predict how global warming will affect ice sheets and the potential for rising sea levels in the future, by developing more robust climate and ice sheet models.
Briner said the findings are especially relevant to the Jakobshavn Isbrae, Greenland's largest and fastest moving tidewater glacier, which is retreating under conditions similar to those he studied in the Canadian Arctic.
Acting like glacial conveyor belts, tidewater glaciers are the primary mechanism for draining ice sheet interiors by delivering icebergs to the ocean.
"These 'iceberg factories' exhibit rapid fluctuations in speed and position, but predicting how quickly they will retreat as a result of global warming is very challenging," said Briner.
That uncertainty prompted the UB team to study the rates of retreat of a prehistoric tidewater glacier, of similar size and geometry to contemporary ones, as way to get a longer-term view of how fast these glaciers can literally disappear.
The researchers used a special dating tool at UB to study rock samples they extracted from a large fjord that drained the ice sheet that covered the North American Arctic during the past Ice Age.
The samples provided the researchers with climate data over a period from 20,000 years ago to about 5,000 years ago, a period when significant warming occurred.
"Even though the ice sheet retreat was ongoing throughout that whole period, the lion's share of the retreat occurred in a geologic instant -- probably within as little as a few hundred years," said Briner.
The UB research reveals that the period of rapid retreat was triggered once the glacier entered deep ocean waters, nearly a kilometer deep, Briner said.
"The deeper water makes the glacier more buoyant," he explained.
"Because the rates of retreat were so much higher in the deep fjord, versus earlier when it terminated in more shallow waters or on land, the findings suggest that contemporary tidewater glaciers in Greenland and Antarctica that are retreating into deep waters may begin to experience even faster rates of retreat than are currently being observed," said Briner.
Right now, Jakobshavn Isbrae is draining into waters that are nearly a kilometer deep, he said, which means that its current rates of retreat -- as fast as 10 kilometers in the past decade -- could continue for the next hundred years.
"If modern glaciers do this for several decades, this would rapidly raise global sea level, intercepting coastal populations and requiring vast re-engineering of levees and other mitigation systems," said Briner.
Co-authors on the paper were Aaron C. Bini, formerly a master's of science candidate in the UB Department of Geology, and Robert S. Anderson, Ph.D., in the Department of Geological Sciences at the University of Colorado, Boulder.
Briner's research was funded by the National Science Foundation.
Adapted from materials provided by University at Buffalo.

Friday, June 19, 2009

Sudden Collapse In Ancient Biodiversity: Was Global Warming The Culprit?

ScienceDaily (June 19, 2009) — Scientists have unearthed striking evidence for a sudden ancient collapse in plant biodiversity. A trove of 200 million-year-old fossil leaves collected in East Greenland tells the story, carrying its message across time to us today.
Results of the research appear in the journal Science.
The researchers were surprised to find that a likely candidate responsible for the loss of plant life was a small rise in the greenhouse gas carbon dioxide, which caused Earth's temperature to rise.
Global warming has long been considered as the culprit for extinctions--the surprise is that much less carbon dioxide gas in the atmosphere may be needed to drive an ecosystem beyond its tipping point than previously thought.
"Earth's deep time climate history reveals startling discoveries that shake the foundations of our knowledge and understanding of climate change in modern times," says H. Richard Lane, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which partially funded the research.
Jennifer McElwain of University College Dublin, the paper's lead author, cautions that sulfur dioxide from extensive volcanic emissions may also have played a role in driving the plant extinctions.
"We have no current way of detecting changes in sulfur dioxide in the past, so it's difficult to evaluate whether sulfur dioxide, in addition to a rise in carbon dioxide, influenced this pattern of extinction," says McElwain.
The time interval under study, at the boundary of the Triassic and Jurassic periods, has long been known for its plant and animal extinctions.
Until this research, the pace of the extinctions was thought to have been gradual, taking place over millions of years.
It has been notoriously difficult to tease out details about the pace of extinction using fossils, scientists say, because fossils can provide only snap-shots or glimpses of organisms that once lived.
Using a technique developed by scientist Peter Wagner of the Smithsonian Institution National Museum of Natural History in Washington, D.C., the researchers were able to detect, for the first time, very early signs that these ancient ecosystems were already deteriorating--before plants started going extinct.
The method reveals early warning signs that an ecosystem is in trouble in terms of extinction risk.
"The differences in species abundances for the first 20 meters of the cliffs [in East Greenland] from which the fossils were collected," says Wagner, "are of the sort you expect. "But the final 10 meters show dramatic loses of diversity that far exceed what we can attribute to sampling error: the ecosystems were supporting fewer and fewer species."
By the year 2100, it's expected that the level of carbon dioxide in the modern atmosphere may reach as high as two and a half times today's level.
"This is of course a 'worst case scenario,'" says McElwain. "But it's at exactly this level [900 parts per million] at which we detected the ancient biodiversity crash.
"We must take heed of the early warning signs of deterioration in modern ecosystems. We've learned from the past that high levels of species extinctions--as high as 80 percent--can occur very suddenly, but they are preceded by long interval of ecological change."
The majority of modern ecosystems have not yet reached their tipping point in response to climate change, the scientists say, but many have already entered a period of prolonged ecological change.
"The early warning signs of deterioration are blindingly obvious," says McElwain. "The biggest threats to maintaining current levels of biodiversity are land use change such as deforestation. "But even relatively small changes in carbon dioxide and global temperature can have unexpectedly severe consequences for the health of ecosystems."
The paper was co-authored by McElwain, Wagner and Stephen Hesselbo of the University of Oxford in the U.K.
Journal reference:
. Fossil Plant Relative Abundances Indicate Sudden Loss of Late Triassic Biodiversity in East Greenland. Science, June 18, 2009
Adapted from materials provided by National Science Foundation.

Size Did Matter: Evidence Of Giant Sperm Found In Microfossils


ScienceDaily (June 19, 2009) — The mystery of giant sperm present in some living animal groups today has now taken on a new dimension -- in one group of micro-crustaceans new evidence shows that it is a feature at least 100 million years old.
In the competition for a partner, males typically have to vie with each other – be it with a colorful plumage, a large set of antlers or a seductive courtship dance. The females of some species, however, copulate with several males, so that rivals even after mating are still not defeated. So their sperm become rivals. Because greater size can increase the chance of fertilization, in some species truly giant sperm cells have evolved – some grow to be even larger than the male that produced them.
Now, an international group of researchers led by Dr. Renate Matzke-Karasz, Ludwig-Maximilians-Universität (LMU) in Munich, has indirectly detected signs of giant sperm in fossilized ostracods. Using synchrotron X-ray holotomography, a highly complex imaging technique developed at the European Synchrotron Radiation Facility, the researchers were able to look non-invasively deep inside these tiny crustaceans, which measure only one millimeter in length. "In these microfossils, we detected organs that are required for transferring giant spermatozoa," reports Matzke-Karasz. "Since recent ostracods still produce giant sperm, and maneuver them with the same organs as 100 million years ago, it's safe to say that this distinctive feature evolved only once in this group. It seems to be an evolutionary successful reproduction strategy, even though it comes at an exceedingly high price for both genders."
A human sperm would have to be over 17 meters long in order to measure up against one group of modern ostracods, whose sperm are up to ten times as big as the animals themselves. Roughly 34,000 of the 50 micron-long human sperm would have to line up to match the body length of a man (of 1,70m).
If a female allows more than one male to mate with her, then the males' rivalry has to continue after mating. This situation seems to result in enough pressure to uproot even the most valid theory of sexual selection: According to that, males who produce a large number of tiny spermatozoa quickly and cheaply better their chances for reproduction, while females invest in only a few, yet larger ova. But if the sperm have to compete inside the female's body, quality sometimes seems to trump quantity. In these cases chances of fertilizing an ovum can increase with the size of the sperm cell. This applies as much to the sperm of a single individual as it does to rival sperm of different males. So much so, that the animals invest a lot of energy in producing and carrying such enormous sperm.
This has led to some true giants evolving along the way. A human sperm would have to be 40 meters long in order to measure up against Drosophila bifurca, for example: the males of this fruit-fly are only a few millimeters in size, but produce giant sperm around six centimeters long. Also other insects, as well as some primates, birds and worms are known for the production of giant sperm. Another example is one group of ostracods, whose sperm are up to ten times as big as the animals themselves. These aquatic crustaceans typically grow to only a few millimeters, and are – much like mussels – surrounded by a bivalve-like calcareous shell.
This protective armor fossilizes particularly well, so ostracods are some of the most common fossils found, some dating back to 450 million years ago. "They are an important group in that their remains store information about the environment they lived in," Matzke-Karasz says. "The fossilized shells of ostracods are therefore a kind of archive of earth's history, storing information on climate, ecology and geology thousands, even millions of years ago." Only in rare cases, however, remains of the soft parts of the body and its appendages are preserved along with the calcareous valves. Because these fossils are particularly interesting to evolutionary biologists, the group working with Matzke-Karasz investigated fossils of the Cretaceous Harbinia micropapillosa that still had intact remains of the soft body. Fortunately, these exceptionally rare fossils belong to the same group of ostracods that produces giant sperm today, providing an excellent opportunity to look for fossil evidence of giant sperm.
The highly complex, high-tech investigation was performed at the "European Synchrotron Radiation Facility (ESRF, Grenoble, France)", which also financed the project: "Holotomography is a non-destructive imaging technique like computer tomography, where powerful and coherent synchrotron X-rays are used," explains Dr. Paul Tafforeau of ESRF. "With this method, a three-dimensional image of the inner structures even of microscopically small objects can be reproduced without doing any damage, with contrast and precision levels not reachable with any other techniques." Holotomography has been only very recently applied to imaging of fossils, but the recent results demonstrate that such technique will surely lead to many important discoveries on fossils. "We obtained an excellent image of the reproductive apparatus of the fossil ostracods and were in for a real surprise," reports Dr. Giles Miller of the Natural History Museum in London. "Our results show that these 100 million year old Cretaceous ostracods were already reproducing with giant sperm."
Recent relatives of these crustaceans have a complex reproductive apparatus that makes up about a third of their bodies in volume. In both sexes, the reproductive organs exist as two separately functioning units, one on each side of the body. In the males, these include two large sperm pumps called Zenker organs. Matching these, the female ostracods possess two long passages leading to two vaginal openings. These characteristic structures are a perfect adaptation to the transport of giant sperm. The X-ray investigation of the fossilized ostracods revealed pairs of hollow tubes in the males that correspond to Zenker organs.
"In the females, on the other hand, we found two elongated hollow cavities in the abdomen, which we also see in recent species," says Radka Symonova of Charles University in Prague. "These cavities are sperm storage receptacles. They only occur in ostracods whose females retain giant spermatozoa within their bodies until the moment of oviposition, when each ovum is fertilized by one sperm. From recent species we know that the seminal vesicles only obtain their typical shape when they are filled with giant sperm." Accordingly, the fossilized females must have mated shortly before their entombment in the sediment. "Our holotomographies actually revealed a fossil insemination," Symonova resumes.
"So, reproduction with giant sperm had already developed around 100 million years ago in this group of ostracods," Dr. Robin James Smith of Lake Biwa Museum in Shiga, Japan ponders. "Until now, it had been unknown whether giant sperm ostracod sperm arose multiple times over the course of evolution, like those of Drosophila, or whether they have been a persistent feature in certain groups for millions of years," Matzke-Karasz continues. "This question can now be answered once and for all: giant sperm have been produced in at least some species over long periods of time, even though they come at an extremely high price for both, males and females. The next stage of our research is to try to understand why and how it has persisted for so long."
The project led by the LMU Munich paleontologist was funded by ESRF (Grenoble), the European Union in the scope of the Marie Curie RT Network "SEXASEX" and the Lake Biwa Museum.
Journal reference:
R. Matzke-Karasz, R. J. Smith, R. Symonova, C. G. Miller, and P. Tafforeau. Sexual intercourse involving giant sperm in Cretaceous ostracods. Science, 2009; DOI: 10.1126/science.1173898
Adapted from materials provided by Ludwig-Maximilians-Universität München, via EurekAlert!, a service of AAAS.

Sands Of Gobi Desert Yield New Species Of Nut-cracking Dinosaur


ScienceDaily (June 17, 2009) — Plants or meat: That's about all that fossils ever tell paleontologists about a dinosaur's diet. But the skull characteristics of a new species of parrot-beaked dinosaur and its associated gizzard stones indicate that the animal fed on nuts and/or seeds. These characteristics present the first solid evidence of nut-eating in any dinosaur.
"The parallels in the skull to that in parrots, the descendants of dinosaurs most famous for their nut-cracking habits, is remarkable," said Paul Sereno, a paleontologist at the University of Chicago and National Geographic Explorer-in-Residence. Sereno and two colleagues from the People's Republic of China announce their discovery June 17 in the Proceedings of the Royal Society B.
The paleontologists discovered the new dinosaur, which they've named Psittacosaurus gobiensis, in the Gobi Desert of Inner Mongolia in 2001, and spent years preparing and studying the specimen. The dinosaur is approximately 110 million years old, dating to the mid-Cretaceous Period.
The quantity and size of gizzard stones in birds correlates with dietary preference. Larger, more numerous gizzard stones point to a diet of harder food, such as nuts and seeds. "The psittacosaur at hand has a huge pile of stomach stones, more than 50, to grind away at whatever it eats, and this is totally out of proportion to its three-foot body length," Sereno explained.
Technically speaking, the dinosaur is also important because it displays a whole new way of chewing, which Sereno and co-authors have dubbed "inclined-angle" chewing. "The jaws are drawn backward and upward instead of just closing or moving fore and aft," Sereno said. "It remains to be seen whether some other plant-eating dinosaurs or other reptiles had the same mechanism."
The unusual chewing style has solved a major mystery regarding the wear patterns on psittacosaur teeth. Psittacosaurs sported rigid skulls, but their teeth show the same sliding wear patterns as plant-eating dinosaurs with flexible skulls.
Funding sources: National Geographic Society; David and Lucile Packard Foundation; Biological Sciences Division, University of Chicago; and the Long Hao Institute of Stratigraphic Paleontology
Journal reference:
Paul A. Sereno et al. A new psittacosaur from Inner Mongolia and the parrot-like structure and function of the psittacosaur skull. Proceedings of the Royal Society B, June 17, 2009
Adapted from materials provided by University of Chicago, via EurekAlert!, a service of AAAS.

Maya Intensively Cultivated Manioc 1,400 Years Ago


ScienceDaily (June 17, 2009) — A University of Colorado at Boulder team has uncovered an ancient and previously unknown Maya agricultural system -- a large manioc field intensively cultivated as a staple crop that was buried and exquisitely preserved under a blanket of ash by a volcanic eruption in present-day El Salvador 1,400 years ago.
Evidence shows the manioc field -- at least one-third the size of a football field -- was harvested just days before the eruption of the Loma Caldera volcano near San Salvador in roughly A.D. 600, said CU-Boulder anthropology Professor Payson Sheets, who is directing excavations at the ancient village of Ceren. The cultivated field of manioc was discovered adjacent to Ceren, which was buried under 17 feet of ash and is considered the best preserved ancient farming village in all of Latin America.
The ancient planting beds of the carbohydrate-rich tuber are the first and only evidence of an intensive manioc cultivation system at any New World archaeology site, said Sheets. While two isolated portions of the manioc field were discovered in 2007 following radar work and limited excavation, 18 large test pits dug in spring 2009 -- each measuring about 10 feet by 10 feet -- allowed the archaeologists to estimate the size of the field and assess the related agricultural activity that went on there.
Sheets said manioc pollen has been found at archaeological sites in Belize, Mexico and Panama, but it is not known whether it was cultivated as a major crop or was just remnants of a few garden plants. "This is the first time we have been able to see how ancient Maya grew and harvested manioc," said Sheets, who discovered Ceren in 1978.
Ash hollows in the manioc planting beds at Ceren left by decomposed plant material were cast in dental plaster by the team to preserve their shape and size, said Sheets. Evidence showed the field was harvested and then replanted with manioc stalk cuttings just a few days before the eruption of the volcano.
A few anthropologists have suspected that manioc tubers -- which can be more than three feet long and as thick as a man's arm -- were a dietary salvation for ancient, indigenous societies living in large cities in tropical Latin America. Corn, beans and squash have long been known to be staples of the ancient Maya, but they are sensitive to drought and require fertile soils, said Sheets.
"As 'high anxiety' crops, they received a lot of attention, including major roles in religious and cosmological activities of the Maya," said Sheets. "But manioc, which grows well in poor soils and is highly drought resistant did not. I like to think of manioc like an old Chevy gathering dust in the garage that doesn't get much attention, but it starts right up every time when the need arises."
Calculations by Sheets indicate the Ceren planting fields would have produced roughly 10 metric tons of manioc annually for the 100 to 200 villagers believed to have lived there. "The question now is what these people in the village were doing with all that manioc that was harvested all at once," he said. "Even if they were gorging themselves, they could not have consumed that much."
The CU-Boulder team also found the shapes and sizes of individual manioc planting ridges and walkways varied widely. "This indicates the individual farmers at Ceren had control over their families' fields and cultivated them they way they wanted, without an external higher authority telling them what to do and how to do it," he said.
The team also found that the manioc fields and adjacent cornfields at Ceren were oriented 30 degrees east of magnetic north -- the same orientation as the village buildings and the public town center, said Sheets. "The villagers laid out the agricultural fields and the town structures with the same orientation as the nearby river, showing the importance and reverence the Maya had for water," he said.
The volcano at Ceren shrouded adobe structures, thatched roofs, house beams, woven baskets, sleeping mats, garden tools and grain caches. The height of the corn stalks and other evidence indicate the eruption occurred early on an August evening, he said.
Because it is unlikely that the people of Ceren were alone in their intensive cultivation of manioc, Sheets and his colleagues are now investigating chemical and microscopic botanical evidence at other Maya archaeological sites that may be indicators of manioc cultivation and processing.
Sheets said Maya villagers living in the region today have a long tradition of cutting manioc roots into small chunks, drying them eight days, then grinding the chunks into a fine, flour-like powder known as almidón. Almidón can be stored almost indefinitely, and traditionally was used by indigenous people in the region for making tamales and tortillas and as a thickening agent for stews, he said.
Since indigenous peoples in tropical South America use manioc today to brew alcoholic beverages, including beer, the CU-Boulder team will be testing ceramic vessels recovered from various structures at Ceren for traces of manioc. To date, 12 structures have been excavated, and others detected by ground-penetrating radar remain buried, he said.
Sheets is particularly interested in vessels from a religious building at Ceren excavated in 1991. The structure contained such items as a deer headdress painted red, blue and white; a large, alligator-shaped painted pot; the bones of butchered deer; and evidence that large quantities of food items like meat, corn, beans and squash were prepared on-site and dispensed to villagers from the structure, said Sheets.
Ceren's residents apparently were participating in a spiritual ceremony in the building when the volcano erupted, and did not return to their adobe homes, which excavations showed were void of people and tied shut from the outside. "I think there may have been an emergency evacuation from the ceremonial building when the volcano erupted," he said. To date, no human remains have been found at Ceren.
The research team also included CU-Boulder doctoral student Christine Dixon, Professor David Letz and graduate student Angie Hood from the University of Cincinnati, University of Costa Rica graduate student George Maloof and University of Central Florida graduate student Andrew Tetlow. The research was funded by the National Science Foundation.
Adapted from materials provided by University of Colorado at Boulder.

Beaked, Bird-like Dinosaur Tells Story Of Finger Evolution


ScienceDaily (June 18, 2009) — Scientists have discovered a unique beaked, plant-eating dinosaur in China. The finding, they say, demonstrates that theropod, or bird-footed, dinosaurs were more ecologically diverse in the Jurassic period than previously thought, and offers important evidence about how the three-fingered hand of birds evolved from the hand of dinosaurs.
The discovery is reported in a paper published in the June 18 edition of the journal Nature.
"This work on dinosaurs provides a whole new perspective on the evolution of bird manual digits," said H. Richard Lane, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research.
"This new animal is fascinating, and when placed into an evolutionary context it offers intriguing evidence about how the hand of birds evolved," said scientist James Clark of George Washington University.
Clark, along with Xu Xing of the Chinese Academy of Science's Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, made the discovery. Clark's graduate student, Jonah Choiniere, also was involved in analyzing the new animal.
"This finding is truly exciting, as it changes what we thought we knew about the dinosaur hand," said Xu. "It also brings conciliation between the data from million-year-old bones and molecules of living birds."
Limusaurus inextricabilis ("mire lizard who could not escape") was found in 159 million-year-old deposits located in the Junggar Basin of Xinjiang, northwestern China. The dinosaur earned its name from the way its skeletons were preserved, stacked on top of each other in fossilized mire pits.
A close examination of the fossil shows that its upper and lower jaws were toothless, demonstrating that the dinosaur possessed a fully developed beak. Its lack of teeth, short arms without sharp claws and possession of gizzard stones suggest that it was a plant-eater, though it is related to carnivorous dinosaurs.
The newly discovered dinosaur's hand is unusual and provides surprising new insights into a long-standing controversy over which fingers are present in living birds, which are theropod dinosaur descendants. The hands of theropod dinosaurs suggest that the outer two fingers were lost during the course of evolution and the inner three remained.
Conversely, embryos of living birds suggest that birds have lost one finger from the outside and one from the inside of the hand. Unlike all other theropods, the hand of Limusaurus strongly reduced the first finger and increased the size of the second. Clark and Xu argue that Limusaurus' hand represents a transitional condition in which the inner finger was lost and the other fingers took on the shape of the fingers next to them.
The three fingers of most advanced theropods are the second, third and fourth fingers-the same ones indicated by bird embryos-contrary to the traditional interpretation that they were the first, second and third.
Limusaurus is the first ceratosaur known from East Asia and one of the most primitive members of the group. Ceratosaurs are a diverse group of theropods that often bear crests or horns on their heads, and many have unusual, knobby fingers lacking sharp claws.
The fossil beds in China that produced Limusaurus have previously yielded skeletons of a variety of dinosaurs and contemporary animals described by Clark and Xu.
These include the oldest tyrannosaur, Guanlong wucaii; the oldest horned dinosaur, Yinlong downsi; a new stegosaur, Jiangjunosaurus junggarensis; and the running crocodile relative, Junggarsuchus sloani.
This research was also funded by the National Geographic Society, the Chinese National Natural Science Foundation, the Jurassic Foundation and the Hilmar Sallee bequest.
Adapted from materials provided by National Science Foundation.

Mammoths Survived In Britain Until 14,000 Years Ago, New Discovery Suggests

ScienceDaily (June 18, 2009) — Research which finally proves that bones found in Shropshire, England provide the most geologically recent evidence of woolly mammoths in North Western Europe publishes June 17 in the Geological Journal. Analysis of both the bones and the surrounding environment suggests that some mammoths remained part of British wildlife long after they are conventionally believed to have become extinct.
The mammoth bones, consisting of one largely complete adult male and at least four juveniles, were first excavated in 1986, but the carbon dating which took place at the time has since been considered inaccurate. Technological advances during the past two decades now allow a more exact reading, which complements the geological data needed to place the bones into their environmental context. This included a study of the bones' decay, analysis of fossilised insects which were also found on the site, and a geological analysis of the surrounding sediment.
The research was carried out by Professor Adrian Lister, based at the Natural History Museum in London, who has conducted numerous studies into 'extinction lag' where small pockets of a species have survived for thousands of years longer than conventionally thought.
"Mammoths are conventionally believed to have become extinct in North Western Europe about 21,000 years ago during the main ice advance, known as the 'Last Glacial Maximum'" said Lister. "Our new radiocarbon dating of the Condover mammoths changes that, by showing that mammoths returned to Britain and survived until around 14,000 years ago."
As the Shropshire bones are the latest record of mammoths in North Western Europe they not only prove that the species survived for much longer than traditionally believed it also provides strong evidence to settle the debate as to whether mammoth extinction was caused by climate change or human hunting.
"The new dates of the mammoths' last appearance correlate very closely in time to climate changes when the open grassy habitat of the Ice Age was taken over by advancing forests, which provides a likely explanation for their disappearance," said Lister. "There were humans around during the time of the Condover mammoths, but no evidence of significant mammoth hunting."
Dr Lister's findings feature in one of three papers on the Condover Mammoths which are all published in the Geological Journal. The other papers focus on the Palaeoenviromental context of the mammoths (Allen et al) and a geological study of the site in which the mammoths were discovered (Scourse et al).
Journal references:
Lister A. Late-glacial mammoth skeletons (Mammuthus primigenius) from Condover (Shropshire, UK): anatomy, pathology, taphonomy and chronological significance. Geological Journal, DOI: 10.1002/gj.1162
Allen.J.R.M, Scourse.JD, Hall,A.R, Coope G.R. Palaeoenviromental context of the Late-glacial woolly mammoth (Mammuthus primigenius) discoveries at Condover, Shropshire, UK(pn/a). Geological Journal, 2009 DOI: 10.1002/gj1161
Scourse, Coope et al. Late-glacial remains of woolly mammoth Mammuthus primigenius) from Shropshire UK: stratigraphy, sedimentology and geochronology of the Condover site (p n/a). Geological Journal, 2009 DOI: 10.1002/gj.1163
Adapted from materials provided by Wiley-Blackwell, via EurekAlert!, a service of AAAS.

Friday, June 12, 2009

Prehistoric Whale Discovered On The West Coast Of Sweden


ScienceDaily (June 8, 2009) — The skeleton of a whale that died around 10,000 years ago has been found in connection with the extension of the E6 motorway in Strömstad. The whale bones are now being examined by researchers at the University of Gothenburg who, among other things, want to ascertain whether the find is the mystical "Swedenborg whale".
Similar to the "Swedenborg whale"
There are currently four species of right whale. What is particularly interesting is that the size and shape of the whale bones resemble those of a fifth species: the mystical "Swedenborg whale", first described by the scientist Emmanuel Swedenborg in the 18th century.
"Bones from what is believed to be Swedenborg's right whale have previously been found in western Sweden. However, determining the species of whale bones found in earth is complicated and there is no definitive conclusion on whether the whale actually existed, it could equally well be a myth," says zoologist Thomas Dahlgren and his colleague Leif Jonsson.
DNA tests conducted
To determine the species of whale that has been found Thomas Dahlgren has conducted DNA tests that are to be analysed in conjunction with researchers at the Natural History Museum in London. The whale bones are interesting in several respects. The fragments of bone were collected in a clay deposit and remains of marine organisms that today are also endangered species were found around them.
"The hunt for the large whale species, which led to the extinction of the Atlantic grey whale and perhaps the Swedenborg whale, may also have caused the extinction of a large number of species that are dependent on whale carcasses for their survival," says Thomas Dahlgren.
Preserved in clay
The whale bones are thought to be around 10,000 years old and were found 75 metres above sea level, but in a site that at that time was located out on the coast. It is conjectured that the bones have been preserved for such a long time as they were surrounded by fine, oxygen-free clay. The largest whale bone, approximately 2.5 metres long, is part of a jawbone. Among the smaller bones is a vertebra. Discussions are underway on whether the bones can be put in order and potentially put on public display.
Facts about the Swedenborg whale (Balaena swedenbo´rgii)
The whale species is believed to have existed in the North Sea from the period when the inland ice melted until about 8,000 years ago, and subsequently to have died out. Ten collections of bones from the species have been found in the west of Sweden. However, there is speculation that the bones have been mistaken for other species, and that the Swedenborg whale never existed. Source: Swedish National Encyclopedia
Adapted from materials provided by University of Gothenburg.

Neolithic Age: Prehistoric Complex Including Two 6,000-year-old Tombs Discovered In Britain


ScienceDaily (June 9, 2009) — A prehistoric complex including two 6,000-year-old tombs representing some of the earliest monuments built in Britain has been discovered by a team led by a Kingston University archaeologist. Dr Helen Wickstead and her colleagues were stunned and delighted to find the previously undiscovered Neolithic tombs, also known as long barrows, at a site at Damerham, Hampshire.
Some artefacts, including fragments of pottery and flint and stone tools, have already been recovered and later in the summer a team of volunteers will make a systematic survey of the site, recovering and recording any artefacts that have been brought to the surface by ploughing.
Dr Wickstead said that further work would help to reveal more about the Neolithic era. “We hope that scientific methods will allow us to record these sites before they are completely eroded,” she said. “If we can excavate, we’ll be able to say a lot more about Neolithic people in that area and find out things like who was buried there, what kinds of lives they led, and what the environment was like six thousand years ago.”
She said the find was particularly rare because it was close to Cranborne Chase, one of the most thoroughly researched prehistoric areas in Europe. “I was really excited. It’s rare to find sites of this kind and the tombs are likely to be of national importance,” said Dr Wickstead. ”What’s really extraordinary is the location – it’s one of the most famous prehistoric landscapes, a mecca for prehistorians, and you would have thought the archaeological world would have gone over it with a fine tooth comb.”
Dr Wickstead, a visiting researcher in the Faculty of Science, is also project manager of Damerham Archaeology Project, an educational body set up last year to discover more about the archaeology of the area around Damerham village.
The importance of the site at Damerham first emerged in 2003 when English Heritage spotted crop marks – which can indicate buried archaeological sites - on aerial photographs of the area. Dr Wickstead volunteered to begin geophysical tests of the area and it was while her team was planning the work that Martyn Barber, a member of the Damerham Archaeology Project, looked at a Windows Live Map of the area to find the car park where he was due to meet his colleagues and was astonished to see another tomb a few hundred metres from the first. “To find any new monuments of this date still visible as humps on the ground is unusual,” said Dr Wickstead, “But to find two is fantastic – we were flabbergasted.”
Work on the site is in its early stages but Dr Wickstead said the tombs may contain human bones, while nearby there are cropmark traces of some larger circular enclosures which may have been built at the same time as the prehistoric monument at Stonehenge, which is 15 miles away.
In Neolithic times, a ritual burial involved leaving a body out so the flesh would decay. Some of the bones were later put in a tomb, or relatives may even have kept some bones as a special talisman. ”We don’t know whether these sites contained chambers with bones in them - some long barrows never contained bones at all, rather like cenotaphs today. We may also find that any chambers have been destroyed by ploughing – only by excavating could we find out for sure,” said Dr Wickstead.
She said her team were sensitive to the emotions stirred by discovering human remains. “The recovery of ancient human remains is always handled sensitively,” said Dr Wickstead. “We feel respect for the dead people we study, and we treat their remains,with care.”
Adapted from materials provided by Kingston University, via AlphaGalileo.

Archeological Evidence Of Human Activity Found Beneath Lake Huron

ScienceDaily (June 9, 2009) — More than 100 feet deep in Lake Huron, on a wide stoney ridge that 9,000 years ago was a land bridge, University of Michigan researchers have found the first archeological evidence of human activity preserved beneath the Great Lakes.
The researchers located what they believe to be caribou-hunting structures and camps used by the early hunters of the period.
"This is the first time we've identified structures like these on the lake bottom," said John O'Shea, curator of Great Lakes Archaeology in the Museum of Anthropology and professor in the Department of Anthropology. "Scientifically, it's important because the entire ancient landscape has been preserved and has not been modified by farming, or modern development. That has implications for ecology, archaeology and environmental modeling."
A paper about the findings is published in the Proceedings of the National Academy of Sciences. Co-authors are O'Shea and Guy Meadows, director of the Marine Hydrodynamics Laboratories and a professor in the departments of Naval Architecture and Marine Engineering, and Atmospheric, Oceanic and Space Sciences.
O'Shea and Meadows found features that they believe to be hunting pits, camps, caribou drive lanes and stone piles used to attract the caribou to the drive lanes. Drive lanes are long rows of rocks used to channel caribou into ambushes. The 1,148-foot structure they believe is a drive lane closely resembles one on Victoria Island in the Canadian subarctic.
The hunting formations are on the 10-mile-wide Alpena-Amberley ridge that stretches more than 100 miles from Point Clark, Ontario to Presque Isle, Michigan. The ridge was a bridge between 10,000 and 7,500 years ago when water levels were much lower. Its surface is relatively unspoiled, unlike coastal areas where scientists believe other archeological sites exist. These coastal sites would now be deeply covered in sediment, so they're often considered lost forever.
Scientists have hypothesized for some time that the ridge might hold signs of ancient occupations. But they didn't know what signs to look for. O'Shea and Meadows zeroed in on caribou-hunting structures after considering the region's climate at the time, which would have been similar to the subarctic. Subarctic hunters are known to utilize caribou drive lanes.
The U-M researchers then narrowed down where to look for these structures by modeling the lake ridge as it would have been when it was dry. They worked with a Robert Reynolds a professor of computer scientist at Wayne State University to reconstruct the ancient environment and then simulate caribou migrations across the corridor. Based on this, they picked three spots to examine.
O'Shea and Meadows used U-M's new, cutting-edge survey vessel Blue Traveler, sonar equipment and underwater remote-operated vehicles with video cameras to survey these areas.
"The combination of these state-of-the art tools have made these underwater archeological investigations possible," Meadows said. "Without any one of these advanced tools, this discovery would not have happened."
Archaeologist will begin examining these areas this summer.
The Paleo-Indian and early Archaic periods are poorly known in the Great Lakes region because most of their sites are thought to have been lost beneath the lakes. Yet they are also times of major shifts in culture and the environment.
The Paleo-Indians were nomadic and pursued big game, O'Shea said. With the Archaic period, communities were more settled, with larger populations, a broad spectrum economy, and new long distance trade and ceremonial connections.
"Without the archeological sites from this intermediate time period, you can't tell how they got from point A to point B, or Paleo-Indian to Archaic," O'Shea said. "This is why the discovery of sites preserved beneath the lakes is so significant."
Perhaps more exciting than the hunting structures themselves is the hope they bring that intact settlements are preserved on the lake bottom. These settlements could contain organic artifacts that deteriorate in drier, acidic soils on land.
The research is funded by the National Science Foundation.
Journal reference:
. Evidence for early hunters beneath the Great Lakes. Proceedings of the National Academy of Sciences, June 8, 2009
Adapted from materials provided by University of Michigan.

Fossil Bone Bed Helps Reconstruct Life Along California's Ancient Coastline

ScienceDaily (June 10, 2009) — In the famed Sharktooth Hill Bone Bed near Bakersfield, Calif., shark teeth as big as a hand and weighing a pound each, intermixed with copious bones from extinct seals and whales, seem to tell of a 15-million-year-old killing ground.
Yet, new research by a team of paleontologists from the University of California, Berkeley, the University of British Columbia in Vancouver, Canada, and the University of Utah paints a less catastrophic picture. Instead of a sudden die-off, the researchers say that the bone bed is a 700,000-year record of normal life and death, kept free of sediment by unusual climatic conditions between 15 million and 16 million years ago.
The team's interpretation of the fossils and the geology to establish the origins of the bone bed, the richest and most extensive marine deposit of bones in the world, are presented in the June 2009 issue of the journal Geology.
The mix of shark bones and teeth, turtle shells three times the size of today's leatherbacks, and ancient whale, seal, dolphin and fish skeletons, comprise a unique six-to-20-inch-thick layer of fossil bones, 10 miles of it exposed, that covers nearly 50 square miles just outside and northeast of Bakersfield.
Since the bed's discovery in the 1850s, paleontologists have battled over an obvious question: How did the bones get there? Was this a killing ground for megalodon, a 40-foot version of today's great white shark? Was it a long-term breeding area for seals and other marine mammals, like Mexico's Scammon's lagoon is for the California gray whale? Did a widespread catastrophe, like a red tide or volcanic eruption, lead to a massive die-off?
The new and extensive study of the fossils and the geology of Sharktooth Hill tells a less dramatic story, but an important one, for understanding the origin of rich fossil accumulations, said Nicholas Pyenson, a former UC Berkeley graduate student who is now a post-doctoral fellow at the University of British Columbia.
"If you look at the geology of this fossil bed, it's not intuitive how it formed," Pyenson said. "We really put together all lines of evidence, with the fossil evidence being a big part of it, to obtain a snapshot of that period of time."
Pyenson and his colleagues, totaling five UC Berkeley Ph.D.s and UC Berkeley integrative biology professor Jere Lipps, hope that the study will draw renewed attention to the bone bed, which Lipps said needs protection even though a small portion of it was added to the National Natural Landmark registry in 1976.
"This deposit, if properly developed, would look just like Dinosaur National Monument," said Lipps, referring to a popular park in Colorado and Utah. "(Sharktooth Hill) is actually much more extensive, and the top of the bone bed has complete, articulated skeletons of seals and other marine mammals."
One 12-foot-long fossil seal skeleton that Lipps helped excavate during the 50 years he has visited the bone bed was mounted and displayed for decades at the Natural History Museum of Los Angeles County (NHM), which houses thousands of fossils excavated from the Sharktooth Hill deposits during expeditions in the 1960s and 1980s. Other collections are in the California Academy of Sciences, San Diego Natural History Museum, Buena Vista Museum of Natural History in Bakersfield, and UC Berkeley's Museum of Paleontology (UCMP), where students over the years have made studies of the bone bed's extinct sea turtles, sharks, marine mammals and seabirds. Lipps is a faculty curator in the UCMP.
The paper's other coauthors - all of whom obtained their Ph.D.s from UC Berkeley - are Randall B. Irmis, now an assistant professor of geology and geophysics at the University of Utah, and Lawrence G. Barnes, Edward D. Mitchell Jr. and Samuel A. McLeod of NHM's Department of Vertebrate Paleontology.
When the bone bed formed between 15,900,000 and 15,200,000 years ago, the climate was warming, sea level was at a peak, California's Central Valley was an inland sea dubbed the Temblor Sea and the emerging Sierra Nevada was shoreline. By closely studying the geology of the Sharktooth Hill area, the paleontologists determined that it was part of an underwater shelf in a large embayment, directly opposite a wide opening to the sea.
Pyenson and Irmis examined some 3,000 fossilized bone and teeth specimens in the collections of many museums, including the NHM and UCMP, and they and Lipps also cut out a meter-square section of the bone bed, complete with the rock layers above and below, and transported it to UC Berkeley for study.
Below the bone bed, they found several feet of mudstone interlaced with shrimp burrows, typical of ocean floor sediment several hundred to several thousand feet below the surface. The bone bed itself averaged 200 bones per square meter, most of them larger bones, with almost no sediment. Most were disarticulated, as if the animal carcasses had decayed and their bones had been scattered by currents.
"The bones look a bit rotten," Lipps said, "as if they lay on the seafloor for a long time and were abraded by water with sand in it." Many bones had manganese nodules and growths, which form on bones that sit for long periods in sea water before being covered by sediment.
Toward the top of the bone bed, some articulated skeletons of seals and whales were found, while in the layer above the bone bed, most skeletons were articulated and encased in sediment.
The team's conclusion is that the climatic conditions were such that currents carried sediment around the bone beds for 100,000 to 700,000 years, during which time bones remained exposed on the ocean floor and accumulated in a big and shifting pile.
Given the rarity of bones marked by shark bites, plus the occurrence of terrestrial animals such as tapirs and horses that must have washed out to sea, predation by sharks like Carcharocles megalodon seems unlikely to have been the major source of the bone bed, the authors wrote. Because of few young or juvenile specimens, the team also discounted the hypothesis that this was a breeding ground for early seals such as Allodesmus. The absence of volcanic ash makes a volcanic catastrophe unlikely, while the presence of land mammal fossils makes red tide an unlikely cause.
"These animals were dying over the whole area, but no sediment deposition was going on, possibly related to rising sea levels that snuffed out silt and sand deposition or restricted it to the very near-shore environment," Pyenson said. "Once sea level started going down, then more sediment began to erode from near shore."
Pyenson noted that, while bone beds around the world occur in diverse land and marine environments, the team's analysis of the Sharktooth Hill Bone Bed could have implications for other fossil-rich marine deposits.
The work was funded by UCMP and UC Berkeley's Department of Integrative Biology, as well as by grants from the Geological Society of America and the American Museum of Natural History, and graduate fellowships from the National Science Foundation.
Adapted from materials provided by University of California - Berkeley.

Friday, June 5, 2009

High Arctic Mammals Wintered In Darkness 53 Million Years Ago


ScienceDaily (June 1, 2009) — Ancestors of tapirs and ancient cousins of rhinos living above the Arctic Circle 53 million years ago endured six months of darkness each year in a far milder climate than today that featured lush, swampy forests, according to a new study led by the University of Colorado at Boulder.
CU-Boulder Assistant Professor Jaelyn Eberle said the study shows several varieties of prehistoric mammals as heavy as 1,000 pounds each lived on what is today Ellesmere Island near Greenland on a summer diet of flowering plants, deciduous leaves and aquatic vegetation. But in winter's twilight they apparently switched over to foods like twigs, leaf litter, evergreen needles and fungi, said Eberle, curator of fossil vertebrates at the University of Colorado Museum of Natural History and chief study author.
The study has implications for the dispersal of early mammals across polar land bridges into North America and for modern mammals that likely will begin moving north if Earth's climate continues to warm. A paper on the subject co-authored by Henry Fricke of Colorado College in Colorado Springs and John Humphrey of the Colorado School of Mines in Golden appears in the June issue of Geology.
The team used an analysis of carbon and oxygen isotopes extracted from the fossil teeth of three varieties of mammals from Ellesmere Island -- a hippo-like, semi-aquatic creature known as Coryphodon, a second, smaller ancestor of today's tapirs and a third rhino-like mammal known as brontothere. Animal teeth are among the most valuable fossils in the high Arctic because they are extremely hard and better able to survive the harsh freeze-thaw cycles that occur each year, Eberle said.
Telltale isotopic signatures of carbon from enamel layers that form sequentially during tooth eruption allowed the team to pinpoint the types of plant materials consumed by the mammals as they ate their way across the landscape through the seasons, Eberle said.
"We were able to use carbon signatures preserved in the tooth enamel to show that these mammals did not migrate or hibernate," said Eberle. "Instead, they lived in the high Arctic all year long, munching on some unusual things during the dark winter months." The study was funded by the National Science Foundation.
An analysis of oxygen isotopes from the fossil teeth helped determine seasonal changes in surface drinking water tied to precipitation and temperature, providing additional climate information, said Eberle. The results point to warm, humid summers and mild winters in the high Arctic 53 million years ago, where temperatures probably ranged from just above freezing to near 70 degrees Fahrenheit, Eberle said.
The environment on central Ellesmere Island, located at about 80 degrees north latitude, was part of a much larger circumpolar Arctic region at the time, she said. It probably was similar to swampy cypress forests in the southeast United States today and still contains fossil tree stumps as large as washing machines, Eberle said.
On central Ellesmere Island in today's high Arctic -- a polar desert that features tundra, permafrost, ice sheets, sparse vegetation and a few small mammals -- the temperature ranges from roughly minus 37 degrees F in winter to 48 degrees F in summer and is the coldest, driest environment on Earth. There is sunlight in the high Arctic between October and February, and the midnight sun is present from mid-April through the end of August.
The year-round presence of mammals such as the hippo-like Coryphodon, tapirs and brontotheres in the high Arctic was a "behavioral prerequisite" for their eventual dispersal across high-latitude land bridges that geologists believe linked Asia and Europe with North America, Eberle said. Their dietary chemical signatures, portly shapes and fossil evidence for babies and juveniles in the Arctic preclude the idea of long, seasonal migrations to escape the winter darkness, she said.
"In order for mammals to have covered the great distances across land bridges that once connected the continents, they would have required the ability to inhabit the High Arctic year-round in proximity to these land bridges," Eberle said.
Instead, the animals likely made their way south from the Arctic in minute increments over millions of years as the climate shifted. "This study may provide the behavioral smoking gun for how modern groups of mammals like ungulates -- ancestors of today's horses and cattle -- and true primates arrived in North America," said Eberle, also an assistant professor in CU-Boulder's geological sciences department.
The surprising menagerie of Arctic creatures during the early Eocene epoch, which lasted from roughly 50 million to 55 million years ago, first became evident in 1975 when a team led by Mary Dawson of the Carnegie Museum of Natural History in Pittsburg discovered fossil alligator jaw bones. Since then, fossils of aquatic turtles, giant tortoises, snakes and even flying lemurs -- one of the earliest forms of primates -- have been found on Ellesmere Island, said Eberle.
The new Geology study also foreshadows the impacts of continuing global warming on Arctic plants and animals, Eberle said. Temperatures in the Arctic are rising twice as fast as those at mid-latitudes as greenhouse gases build up in Earth's atmosphere from rising fossil-fuel burning, and air temperatures over Greenland have risen by more than 7 degrees F since 1991, according to climate scientists.
"We are hypothesizing that lower-latitude mammals will migrate north as the temperatures warm in the coming centuries and millennia," she said. If temperatures ever warm enough in the future to rival the Eocene, there is the possibility of new intercontinental migrations by mammals."
Because the oldest known tapir fossils are from the Arctic, there is the possibility that some prehistoric mammals could have evolved in the circumpolar Arctic and then dispersed through Asia, Europe and North America, said Eberle. "We may have to re-think the world of the early Eocene, when all of the Arctic land masses were connected in a supercontinent of sorts," she said.
Adapted from materials provided by University of Colorado at Boulder.

New Hominid 12 Million Years Old Found In Spain, With 'Modern' Facial Features

ScienceDaily (June 2, 2009) — Researchers have discovered a fossilized face and jaw from a previously unknown hominoid primate genus in Spain dating to the Middle Miocene era, roughly 12 million years ago. Nicknamed "Lluc," the male bears a strikingly "modern" facial appearance with a flat face, rather than a protruding one. The finding sheds important new light on the evolutionary development of hominids, including orangutans, chimpanzees, bonobos, gorillas and humans.
In a study appearing in the Proceedings of the National Academy of Sciences, Salvador Moyà-Solà, director of the Institut Català de Paleontologia (ICP) at the Universitat Autònoma de Barcelona, and colleagues present evidence for the new genus and species, dubbed Anoiapithecus brevirostris. The scientific name is derived from the region where the fossil was found (l’Anoia) and also from its "modern" facial morphology, characterized by a very short face.
The research team at the ICP also includes collaborator David M. Alba, predoctoral researcher Sergio Almécija, postdoctoral researcher Isaac Casanovas, researcher Meike Köhler, postdoctoral researcher Soledad De Esteban, collaborator Josep M. Robles, curator Jordi Galindo, and predoctoral researcher Josep Fortuny.
Their findings are based on a partial cranium that preserves most of the face and the associated mandible. The cranium was unearthed in 2004 in the fossil-rich area of Abocador de Can Mata (els Hostalets de Pierola, l’Anoia, Barcelona), where remains of other fossilized hominid species have been found. Preparing the fossil for study was a complicated process, due to the fragility of the remains. But once the material was available for analysis, the results were surprising: The specimen (IPS43000) combined a set of features that, until now, had never been found in the fossil record.
Anoiapithecus displays a very modern facial morphology, with a muzzle prognathism (i.e., protrusion of the jaw) so reduced that, within the family Hominidae, scientists can only find comparable values within the genus Homo, whereas the remaining great apes are notoriously more prognathic (i.e., having jaws that project forward markedly). The extraordinary resemblance does not indicate that Anoiapithecus has any relationship with Homo, the researchers note. However, the similarity might be a case of evolutionary convergence, where two species evolving separately share common features.
Lluc's discovery may also hold an important clue to the geographical origin of the hominid family. Some scientists have suspected that a group of primitive hominoids known as kenyapithecines (recorded from the Middle Miocene of Africa and Eurasia) might have been the ancestral group that all hominids came from. The detailed morphological study of the cranial remains of Lluc showed that, together with the modern anatomical features of hominids (e.g., nasal aperture wide at the base, high zygomatic rood, deep palate), it displays a set of primitive features, such as thick dental enamel, teeth with globulous cusps, very robust mandible and very procumbent premaxilla. These features characterize a group of primitive hominoids from the African Middle Miocene, known as afropithecids.
Interestingly, in addition to having a mixture of hominid and primitive afropithecid features, Lluc displays other characteristics, such as a very anterior position of the zygomatic, a very strong mandibular torus and, especially, a very reduced maxillary sinus. These are features shared with kenyapithecines believed to have dispersed outside the African continent and colonized the Mediterranean region, by about 15 million years ago.
In other words, the researchers speculate, hominids might have originally radiated in Eurasia from kenyapithecine ancestors of African origin. Later on, the ancestors of African great apes and humans would have dispersed again into Africa -- the so-called "into Africa" theory, which remains controversial. However, the authors do not completely rule out the possibility that pongines (orangutans and related forms) and hominines (African apes and humans) separately evolved in Eurasia and Africa, respectively, from different kenyapithecine ancestors.
The project at els Hostalets de Pierola is continuing and, the researchers anticipate, more fossil remains will be found in the future that will provide key information to test their hypotheses.
Journal reference:
Salvador Moyà-Solà, David M. Alba, Sergio Almécija, Isaac Casanovas-Vilar, Meike Köhler, Soledad De Esteban-Trivigno, Josep M. Robles, Jordi Galindo, and Josep Fortuny. A unique Middle Miocene European hominoid and the origins of the great ape and human clade. Proceedings of the National Academy of Sciences, 2009; DOI: 10.1073/pnas.0811730106
Adapted from materials provided by Barcelona, Universitat Autònoma de.

Ancient Mammals Shifted Diets As Climate Changed


ScienceDaily (June 3, 2009) — A new University of Florida study shows mammals change their dietary niches based on climate-driven environmental changes, contradicting a common assumption that species maintain their niches despite global warming.
Led by Florida Museum of Natural History vertebrate paleontologist Larisa DeSantis, researchers examined fossil teeth from mammals at two sites representing different climates in Florida: a glacial period about 1.9 million years ago and a warmer, interglacial period about 1.3 million years ago. The researchers found that interglacial warming resulted in dramatic changes to the diets of animal groups at both sites.
"When people are modeling future mammal distributions, they're assuming that the niches of mammals today are going to be the same in the future," DeSantis said. "That's a huge assumption."
Co-author Robert Feranec, curator of vertebrate paleontology at the New York State Museum, said scientists cannot predict what species will do based on their current ecology.
"The study definitively shows that climate change has an effect on ecosystems and mammals, and that the responses are much more complex than we might think," Feranec said.
The two sites in the study, both on Florida's Gulf Coast, have been excavated quite extensively, DeSantis said. During glacial periods, lower sea levels nearly doubled Florida's width, compared with interglacial periods. But because of Florida's low latitude, no ice sheets were present during the glacial period. Despite the lack of glaciers in Florida, the two sites show dramatic ecological changes occurred between the two periods.
Both sites include some of the same animal groups, allowing DeSantis, Feranec and Bruce MacFadden, Florida Museum curator of vertebrate paleontology, to clarify how mammals and their environments responded to interglacial warming.
The research examined carbon and oxygen isotopes within tooth enamel to understand the diets of medium to large mammals, including pronghorn, deer, llamas, peccaries, tapirs, horses, mastodons, mammoths and gomphotheres, a group of extinct elephant-like animals.
Differences in how plants photosynthesize give them distinct carbon isotope ratios. For example, trees and shrubs process carbon dioxide differently than warm-season grasses, resulting in different carbon isotope ratios. These differences are incorporated in mammalian tooth enamel, allowing scientists to determine the diets of fossil mammals. Lower ratio values suggest a browsing diet (trees and shrubs) while a higher ratio suggests a grazing diet (grasses).
Animals at the glacial site were predominantly browsing on trees and shrubs, while some of those same animals at the warmer interglacial site became mixed feeders that also grazed on grasses. Increased consumption of grasses by mixed feeders and elephant-like mammals indicates Florida's grasslands likely expanded during interglacial periods.
Tooth enamel locks in the chemical signatures of the plants and water an animal consumes, allowing paleontologists to understand the diets and associated climate of fossil specimens that are millions of years old. To find these signatures, researchers run samples of tooth enamel through a mass spectrometer.
DeSantis and her collaborators analyzed enamel samples from 115 fossil teeth. For two of the specimens she took serial samples, small samples that run perpendicular to the growth axis and give insight into how the diet and climate changed over a specific period of time.
"That's one of the cool things about using mammal teeth," she said. "We can actually look at how variable the climate was within a year, millions of years ago."
The study highlights the importance of the fossil record in understanding long-term ecological responses to changes over time, DeSantis said. While ecological studies of modern impacts can cover only limited spans of time, "this study emphasizes the importance of using the fossil record to look at how mammals and other animals responded to climate change in the past, also helping us gain a better understanding of how they might respond in the future."
Journal reference:
DeSantis LRG, Feranec RS, MacFadden BJ. Effects of Global Warming on Ancient Mammalian Communities and Their Environments. PLoS ONE, 4(6): e5750 DOI: 10.1371/journal.pone.0005750
Adapted from materials provided by University of Florida.