Giant predatory shark fossil unearthed in Kansas





By Matt Walker
Editor, Earth News





A nurse shark may be similar in shape but not size to the prehistoric fossil


The fossilised remains of a gigantic 10m-long predatory shark have been unearthed in Kansas, US.
Scientists dug up a gigantic jawbone, teeth and scales belonging to the shark which lived 89 million years ago.
The bottom-dwelling predator had huge tooth plates, which it likely used to crush large shelled animals such as giant clams.
Palaeontologists already knew about the shark, but the new specimen suggests it was far bigger than previously thought.
The scientists who made the discovery, published in the journal Cretaceous Research, last week also released details of other newly discovered giant plankton-eating fish that swam in prehistoric seas for more than 100 million years.




The size of the jaw fragment in fact supports the contention that P. mortoni was a gigantic animal


Dr Kenshu Shimada, DePaul University



But this new fish, called Ptychodus mortoni, is both bigger and more fierce, having a taste for flesh rather than plankton.
It may even have been the largest shellfish-eating animal ever to have roamed the Earth.
Dr Kenshu Shimada of DePaul university in Chicago, Illinois, US found the fossilized remains of the shark in rocks known as the Fort Hays Limestone in Kansas.
"Kansas back then was smack in the middle of an inland sea known as the Western Interior Seaway that extended in a north-south direction across North America," says Dr Shimada.



The jawbone fragment came from a huge fish (diagram courtesy of Dr Shimada)



Along with a piece of jaw, Dr Shimada and colleagues uncovered a piece of jaw, teeth and scales.
"Although it represents a fraction of the entire body of the shark, the jaw fragment is gigantic. The estimated jaw length was almost 1m long, and that would suggest that the shark was likely at least 10m in length," says Dr Shimada.
Due to the lack of a complete skeleton, it is difficult to gauge the physical appearance of the shark.
But Dr Shimada suspects it had a body shaped much like that of a modern nurse shark (Ginglymostoma cirratum), with a broad rounded head and stout body.



MARINE PREDATORS: FIND OUT MORE




A colossal sea monster, a 16m-long pliosaur, was recently discovered along the coast of Dorset, UK
One of the rarest giants of the ocean, the smalleye stingray, was only caught on film for the first time last year: watch it here
Great white sharks of South Africa select a particular anchor point, and search for their next victim close to this location
The odd-shaped head of the hammerhead shark gives it outstanding binocular vision and an ability to see through 360 degrees
The modern whale shark is the largest fish in the world, the longest ever recorded being 13.5m in length: watch video of it here



However, its teeth and lifestyle would have been very different.
Hundreds of robust teeth line the upper and lower parts of the shark's mouth, forming large slab-like plates capable of crushing shellfish.
"This in turn suggests that P. mortoni was probably a sluggish bottom-dwelling shark, rather than an actively fast swimmer," says Dr Shimada.
Fossils of this and other closely-related species have long been known.
"While there have been many teeth and a few incomplete skeletal remains of P. mortoni in museum collections, the significance of this new specimen is that it contains one of the largest teeth of this species that were found with a gigantic jaw fragment.
"The size of the jaw fragment in fact supports the contention that P. mortoni was likely a gigantic animal," says Dr Shimada.
The scientists have dated the fossil at 88.7 million years old.
At that time, a variety of animals, such as giant clams, other sharks, bony fishes, and predatory marine reptiles called mosasaurs and plesiosaurs inhabited the same water.
Some, including certain mosasaurs would also have grown to gigantic proportions, reaching lengths of 10m or more.



Dr Shimada excavates the jawbone



Why P. mortoni became so huge is still a mystery.
"The emergence of large ptychodontids roughly coincides with the timing of when many other kinds of organisms, including clams as well as sharks and bony fishes, became bigger," explains Dr Shimada.
"Clearly, the food resources must have been abundant enough in the marine ecosystem to support such large organisms.
"Becoming big does have advantages such as deterring predators and being able to travel faster, but it does come with disadvantages as well, most notably needing more food for energy."



Ptychodus mortoni's tooth, close up



Another specimen of P. mortoni has been found alongside another type of meat-eating shark called Squalicorax, with some scientists suggesting that the meat-eating shark may have been scavenging on the body of its larger relative.
Last week, Dr Shimada and colleagues published details in the journal Science of how a dynasty of large plankton-eating fish roamed the oceans between 66 and 172 million years ago.
These fish died out with the dinosaurs.
Once they had vanished from the ecosystem, mammals and cartilaginous fish such as manta rays, basking sharks and whale sharks began to adapt to fill a similar ecological role.

Gulp! Long-Necked Dinosaurs Didn't Bother Chewing
By Jeanna Bryner, LiveScience Managing Editor
posted: 23 February 2010 04:00 pm ET









Sauropod dinosaurs like this newly discovered Abydosaurus had heads that were just one two-hundredth of the total body volume. That small size might explain why they didn't chew their food, the researchers say. Credit: Michael Skrepnick.

A team of paleontologists discovered four skulls of a newly identified sauropod dinosaur called Abydosaurus. The skulls all measured about 1.6 feet (0.5 meters) in length and about half as tall. Credit: Mark Philbrick/BYU..

A mom's wise words about chewing your food likely got lost on a giant, long-necked dinosaur that lived about 105 million years ago in North America. That's according to analyses of four skulls from a newly identified dinosaur species.
"They didn't chew their food; they just grabbed it and swallowed it," said study team member Brooks Britt, a paleontologist at Brigham Young University.
Paleontologists discovered the four skulls, two of which whose bones were fully intact, from a quarry in Dinosaur National Monument in eastern Utah.. Now called Abydosaurus mcintoshi, the dinosaur species is a type of sauropod (long-necked plant-eaters) and is most closely related to Brachiosaurus that lived 45 million years earlier.
No time for chewing



While scientists have suggested sauropods didn't chew their foods, there hasn't been much hard evidence to examine this premise. Just about 10 percent of the 120-plus sauropod species have been found with complete skulls.. And so most of what scientists know about these herbivores comes from the neck down.
With the skulls from Abydosaurus, the research team suspects sauropods' small heads, which are just about one two-hundredth the volume of their bodies, might explain why they skipped chewing.
"If you have a tiny skull and you're trying to feed a big body, you're wasting time if you're trying to process the food in your mouth," said Jeffrey Wilson of the Museum of Paleontology and Department of Geological Sciences at the University of Michigan.
That's especially true for sauropods, which are the largest animals to ever plod the earth. Abydosaurus was likely a bit smaller than Brachiosaurus, which stretched more than 65 feet (20 meters) and weighed nearly 20 tons.
During the Late Jurassic Period about 150 million years ago, sauropod fossils suggest the beasts sported both broad-crowned and narrow-crowned teeth.. That changed by the end of the dinosaur age, when all sauropods likely had narrow, pencil-like teeth.
Abydosaurus had teeth that seemed to be in transition from the broad shape to the narrowest ones. And while its teeth were narrower than those of Brachiosaurus, its skull looked pretty much the same.
Tooth replacement
Sauropods also replaced their teeth continuously. The narrower the teeth, the more can be packed into the jaws and the faster they were replaced, Wilson said. Abydosaurus had teeth that were as broad as those that replaced every two months or so, though the researchers haven't looked at this replacement rate yet.
To explain the rapid tooth replacement, Wilson says Abydosaurus may have been snagging abrasive foods. In addition, the dinosaurs may have been low browsers, where they would pick up sediment and other silica-containing material that can wear down teeth quickly.
Like Brachiosaurus and other sauropods, Abydosaurus didn't have any of the bells and whistles present in savvy plant-eating dinosaurs.
"For some reason sauropods don't develop any of the tricks that other dinosaurs developed for eating plants," Wilson told LiveScience. For instance, Triceratops and some duck-billed dinosaurs have pointed beaks to help cut vegetation. They also had cheeks, like us, where they could store food while they were processing it in their mouths before swallowing, and they developed batteries of teeth to process food.
"So sauropods could have evolved this machinery but didn't. Our explanation [is that] these adapatations are not good evolutionary investments for an animal whose skull is so small compared to rest of its body," Wilson said. "The sauropod strategy is to bite the food, maybe bite it once more, and then swallow it and let it digest in your gut."
The discovery is detailed in the most recent issue of the journal Naturwissenshaften.
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Human Culture, an Evolutionary Force


Per-Anders Pettersson/Getty Images
Genes enabling lactose tolerance, which probably resulted in more surviving offspring, were detected in cultures like this Kenyan shepherd’s..

By NICHOLAS WADE
Published: March 1, 2010, NY Times

As with any other species, human populations are shaped by the usual forces of natural selection, like famine, disease or climate. A new force is now coming into focus. It is one with a surprising implication â€" that for the last 20,000 years or so, people have inadvertently been shaping their own evolution.



Radu Sigheti/Reuters
Maasai tribesman are among a culture with adult lactose tolerance.


The force is human culture, broadly defined as any learned behavior, including technology. The evidence of its activity is the more surprising because culture has long seemed to play just the opposite role. Biologists have seen it as a shield that protects people from the full force of other selective pressures, since clothes and shelter dull the bite of cold and farming helps build surpluses to ride out famine.
Because of this buffering action, culture was thought to have blunted the rate of human evolution, or even brought it to a halt, in the distant past. Many biologists are now seeing the role of culture in a quite different light.
Although it does shield people from other forces, culture itself seems to be a powerful force of natural selection. People adapt genetically to sustained cultural changes, like new diets. And this interaction works more quickly than other selective forces, “leading some practitioners to argue that gene-culture co-evolution could be the dominant mode of human evolution,” Kevin N. Laland and colleagues wrote in the February issue of Nature Reviews Genetics. Dr. Laland is an evolutionary biologist at the University of St. Andrews in Scotland.
The idea that genes and culture co-evolve has been around for several decades but has started to win converts only recently. Two leading proponents, Robert Boyd of the University of California, Los Angeles, and Peter J. Richerson of the University of California, Davis, have argued for years that genes and culture were intertwined in shaping human evolution. “It wasn’t like we were despised, just kind of ignored,” Dr. Boyd said. But in the last few years, references by other scientists to their writings have “gone up hugely,” he said.
The best evidence available to Dr. Boyd and Dr. Richerson for culture being a selective force was the lactose tolerance found in many northern Europeans. Most people switch off the gene that digests the lactose in milk shortly after they are weaned, but in northern Europeans â€" the descendants of an ancient cattle-rearing culture that emerged in the region some 6,000 years ago â€" the gene is kept switched on in adulthood.
Lactose tolerance is now well recognized as a case in which a cultural practice â€" drinking raw milk â€" has caused an evolutionary change in the human genome. Presumably the extra nutrition was of such great advantage that adults able to digest milk left more surviving offspring, and the genetic change swept through the population.
This instance of gene-culture interaction turns out to be far from unique. In the last few years, biologists have been able to scan the whole human genome for the signatures of genes undergoing selection. Such a signature is formed when one version of a gene becomes more common than other versions because its owners are leaving more surviving offspring. From the evidence of the scans, up to 10 percent of the genome â€" some 2,000 genes â€" shows signs of being under selective pressure.
These pressures are all recent, in evolutionary terms â€" most probably dating from around 10,000 to 20,000 years ago, in the view of Mark Stoneking, a geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Biologists can infer the reason for these selective forces from the kinds of genes that are tagged by the genome scans. The roles of most of the 20,000 or so genes in the human genome are still poorly understood, but all can be assigned to broad categories of likely function depending on the physical structure of the protein they specify.
By this criterion, many of the genes under selection seem to be responding to conventional pressures. Some are involved in the immune system, and presumably became more common because of the protection they provided against disease. Genes that cause paler skin in Europeans or Asians are probably a response to geography and climate.
But other genes seem to have been favored because of cultural changes. These include many genes involved in diet and metabolism and presumably reflect the major shift in diet that occurred in the transition from foraging to agriculture that started about 10,000 years ago.
Amylase is an enzyme in the saliva that breaks down starch. People who live in agrarian societies eat more starch and have extra copies of the amylase gene compared with people who live in societies that depend on hunting or fishing. Genetic changes that enable lactose tolerance have been detected not just in Europeans but also in three African pastoral societies. In each of the four cases, a different mutation is involved, but all have the same result â€" that of preventing the lactose-digesting gene from being switched off after weaning.
Many genes for taste and smell show signs of selective pressure, perhaps reflecting the change in foodstuffs as people moved from nomadic to sedentary existence. Another group under pressure is that of genes that affect the growth of bone. These could reflect the declining weight of the human skeleton that seems to have accompanied the switch to settled life, which started some 15,000 years ago.


A third group of selected genes affects brain function. The role of these genes is unknown, but they could have changed in response to the social transition as people moved from small hunter-gatherer groups a hundred strong to villages and towns inhabited by several thousand, Dr. Laland said. “It’s highly plausible that some of these changes are a response to aggregation, to living in larger communities,” he said.

Though the genome scans certainly suggest that many human genes have been shaped by cultural forces, the tests for selection are purely statistical, being based on measures of whether a gene has become more common. To verify that a gene has indeed been under selection, biologists need to perform other tests, like comparing the selected and unselected forms of the gene to see how they differ.
Dr. Stoneking and his colleagues have done this with three genes that score high in statistical tests of selection. One of the genes they looked at, called the EDAR gene, is known to be involved in controlling the growth of hair. A variant form of the EDAR gene is very common in East Asians and Native Americans, and is probably the reason that these populations have thicker hair than Europeans or Africans.
Still, it is not obvious why this variant of the EDAR gene was favored. Possibly thicker hair was in itself an advantage, retaining heat in Siberian climates. Or the trait could have become common through sexual selection, because people found it attractive in their partners.
A third possibility comes from the fact that the gene works by activating a gene regulator that controls the immune system as well as hair growth. So the gene could have been favored because it conferred protection against some disease, with thicker hair being swept along as a side effect. Or all three factors could have been at work. “It’s one of the cases we know most about, and yet there’s a lot we don’t know,” Dr. Stoneking said.
The case of the EDAR gene shows how cautious biologists have to be in interpreting the signals of selection seen in the genome scans. But it also points to the potential of the selective signals for bringing to light salient events in human prehistory as modern humans dispersed from the ancestral homeland in northeast Africa and adapted to novel environments. “That’s the ultimate goal,” Dr. Stoneking said. “I come from the anthropological perspective, and we want to know what the story is.”
With archaic humans, culture changed very slowly. The style of stone tools called the Oldowan appeared 2.5 million years ago and stayed unchanged for more than a million years. The Acheulean stone tool kit that succeeded it lasted for 1.5 million years. But among behaviorally modern humans, those of the last 50,000 years, the tempo of cultural change has been far brisker. This raises the possibility that human evolution has been accelerating in the recent past under the impact of rapid shifts in culture.
Some biologists think this is a possibility, though one that awaits proof. The genome scans that test for selection have severe limitations. They cannot see the signatures of ancient selection, which get washed out by new mutations, so there is no base line by which to judge whether recent natural selection has been greater than in earlier times. There are also likely to be many false positives among the genes that seem favored.
But the scans also find it hard to detect weakly selected genes, so they may be picking up just a small fraction of the recent stresses on the genome. Mathematical models of gene-culture interaction suggest that this form of natural selection can be particularly rapid. Culture has become a force of natural selection, and if it should prove to be a major one, then human evolution may be accelerating as people adapt to pressures of their own creation.
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Chameleon tongues snappy even when cold

Elastic collagen tissue provides an edge over other cold-blooded hunters
By Sid Perkins
Web edition : 4:32 pm
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Quick trickA chameleon doesn’t depend on muscle power to flick its tongue, so it can nab prey in cool temperatures that stymie other cold-blooded predators.C.V. Anderson

Cool weather typically weakens muscle power in cold-blooded creatures, but new data show that chameleons can nab prey even at near-freezing temperatures thanks to an elastic, energy-storing sheath of collagen inside their tongues.
Although most chameleons live in warm climates, some live in alpine ecosystems and can feed when their body temperatures are as low as 3.5° Celsius â€" a trick that scientists haven’t been able to explain, says Christopher V. Anderson, a biologist at the University of South Florida in Tampa.
Now, data suggest that the chameleon’s trick lies in a clump of rubbery tissue at the base of its tongue. Using elastic collagen instead of muscle power to shoot its tongue at prey lets chameleons catch breakfast even when their muscles are stiff from the cold, Anderson and University of South Florida colleague Stephen M. Deban contend online March 8 in Proceedings of the National Academy of Sciences.
At a temperature of 35° C, the veiled chameleon Chamaeleo calyptratus can flick its tongue toward prey at an average of 4.4 meters per second, the team’s tests show. That amounts to an acceleration 44 times Earth’s gravity, or almost five times that of a fighter jet in a high-speed turn. Drop the temp to a chillier 15° C, and the chameleon’s tongue-shooting speed falls to about 3.4 m/s.
That’s a decline of about 23 percent. But the speed at which the chameleon pulls its tongue back in falls off by around 58 percent over the same temperature range.
The dramatic difference, Anderson and Deban contend, is that a chameleon’s tongue retraction is powered by muscles, which are slow to contract in cool temperatures. The tongue-extending action, however, is driven by energy stored in a rubber bandâ€"like collagen sheath that surrounds the bone in the base of the tongue. That biophysical modification, a trait common to all chameleons, lets the creatures forage in conditions too cool for other lizards in the same ecosystem, the researchers note.
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"Snowball Earth" Confirmed: Ice Covered Equator

But volcanoes would've made Earth more mud ball than snowball, scientists say.




Maroon glacial-deposit layers helped prove this Canadian rock was ice covered and at the Equator during the "snowball Earth" period.
Photograph courtesy Francis A. Macdonald


Christine Dell'Amore
National Geographic News
Published March 4, 2010

Earth's now steamy Equator was covered with ice 716 million years ago, according to a new study.
The finding appears to add solid evidence to the theory of an ancient "snowball Earth."
The discovery hinged on proving that the right rocks had been covered by glaciers in the right place at the right time.
Study leader Francis Macdonald, an Earth scientist at Harvard University, and colleagues worked with volcanic rocks in Canada that were found sandwiched between glacial deposits. Such deposits are recognizable by the presence of debris left behind by melting glaciers and sediments deformed by glacial movement.
Using extremely precise uranium-lead mass spectrometry, the researchers determined that both the volcanic rocks and glacial sediments were deposited about 716.5 million years agoâ€"during the purported snowball-Earth period.
The team then matched their findings to previous magnetic studies that had found these rocks had formed when Canada was situated near the Equator.
Over time the movement of Earth's tectonic plates had pushed the rocks north to Canada's Yukon and Northwest Territories.
Snowball Earth or Mud-ball Earth?
There's still plenty of mystery surrounding snowball Earthâ€"aka the Sturtian glaciationâ€"Macdonald said.
For example, an icy Equator alone can't tell scientists the extent of ice cover around the world. The continents may have been in a total deep freeze, or the planet may have simply been subjected to a patchwork of constantly moving glaciers or icebergsâ€"or something in between.
And even the "snowball Earth" name might need rethinking.
Earth probably wasn't "just a white ball, but more of a mud ball," Macdonald said. Regular eruptions of ash-spewing volcanoes likely made the continents "dusty messes."
Since plants had not yet evolved 700 million years ago, the dirty ice could have been the only dark spots on Earth's surface to absorb the sun's rays. As a result, these regions may have been more likely to melt, creating water bodies where primitive life-forms, such as algae and fungi, could thrive.
That some organisms survivedâ€"and even branched off into new speciesâ€"during the Sturtian glaciation adds credence to the idea that snowball Earth harbored open-water refuges, or at least cracks in the ice, Macdonald said.
For instance, modern-day ice cracks off Antarctica are "chockablock" with single-celled life-forms, he said.
(Also see "Did Plants Cool the Earth and Spark Explosion of Life?")
Global Warming Insights

Learning about Earth's past extremes may also give scientists new perspectives on modern climate change.
For instance, scientists know that over the millennia our planet has yo-yoed between pervasive ice cover and hothouse conditions such as those during the ice-free, dinosaur-packed Cretaceous period, said Macdonald, whose study appears tomorrow in the journal Science (prehistoric time line).
"This is just all to say that Earth is sensitive, and we can get perturbations that can lead to a different world," he said.
For instance, eruptions during the snowball-Earth period are thought to have added sulfur particles to the atmosphere, blocking sunlight and cooling the planet. Some experts have suggested doing the same thing artificially as a modern cure for global warming.
That means investigating such "natural experiments" in Earth's history is crucial, Macdonald said. "That's going to tell us a lot more than any little [computer] model can say."

Program Investigating If And How Past Climate Influenced Human Evolution



By altering the landscape, past changes in climate may have exerted pressures that led to genetic selection and innovation in humans.

by Staff Writers
Washington DC (SPX) Mar 08, 2010
Understanding how past climate may have influenced human evolution could be dramatically enhanced by an international cross-disciplinary research program to improve the sparse human fossil and incomplete climate records and examine the link between the two, says a new report from the National Research Council.
Climate and fossil records suggest that some events in human evolution - such as the evolution of new species or movements out of Africa - coincided with substantial changes in African and Eurasian climate. This raises the intriguing possibility that environmental factors affected or controlled our species' evolution.
By altering the landscape, past changes in climate may have exerted pressures that led to genetic selection and innovation in humans. But because the human fossil record and our understanding of past climate conditions are incomplete, the details of how climates influenced human evolution remain unclear.
The report recommends several research initiatives over the next 10 to 20 years:
+ a major effort to locate new fossil sites using modern remote-sensing tools and traditional ground examination. In addition, many existing sites should be further analyzed to better determine when species first appeared and then disappeared, along with noting specific adaptations and behaviors. Currently, efforts to understand links between climate and evolution are limited by gaps in the human fossil record.
+ a comprehensive program to drill on land and in lakes and ocean basins in the regions where humans evolved. An integrated drilling program should be part of a larger effort to collect more data to reconstruct past environments - including temperatures, precipitation, and vegetation - near human fossil sites. Describing the plants and animals that lived with our human ancestors is a key component for understanding past environments.
+ a major investment in climate modeling experiments for the key time intervals and regions that are critical for understanding human evolution. The objective would be to characterize regional and local climates in the areas where humans evolved and to integrate these modeling experiments with records of the past ecology and environment.
+ an enhanced public outreach effort, including teaching curricula and traveling exhibitions, that takes advantage of broad public interest in human evolution and climate change.
A public briefing to discuss the report's findings and recommendations will be held on March 31 at the Smithsonian Institution's National Museum of Natural History
in Washington, D.C. Several members of the committee that wrote the report will present and answer audience questions. For more information, please call or e-mail the Office of News and Public Information (contacts listed above).


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Reindeer body clock switched off




Reindeer have to survive the light polar summer and dark polar winter


Reindeer have no internal body clock, according to scientists.
Researchers found that the animals are missing a "circadian clock" that influences processes including the sleep-wake cycle and metabolism.
This enables them to better cope with the extreme Arctic seasons of polar day, when the sun stays up all day, and polar night, when it does not rise.
The team from the universities of Manchester and Tromso report their study in Current Biology journal.
The body clock, or circadian clock, is the internal mechanism that drives hormone release on a rhythmic 24-hour cycle.
Light also influences these hormonal rhythms, but in most mammals, this "circuit" also involves the circadian clock, which can influence the release of hormones without the influence of light.




This could be the case for a range of animals living at the poles of the earth or in the depths of the ocean


Professor Andrew Loudon, University of Manchester



Anyone who has experienced jet lag is familiar with the effect of the body clock.
But the research team from research institutes in the UK and Norway found that, in Arctic reindeer, this circadian clock was absent.
Professor Andrew Loudon from The University of Manchester took part in the study.
He said that the reindeer may have "abandoned use of the daily clock that drives biological rhythms" in order to survive the extreme conditions in the Arctic.
He and his colleagues studied reindeer living in Northern Norway, 500 km north of the Arctic circle. Here there are 15 weeks of continuous daylight in summer and eight weeks during the winter where the Sun does not appear over the horizon.
They investigated levels of the hormone called melatonin - which is important in the sleep-wake cycle - in the reindeer's blood
They found that there was no natural internal rhythm of melatonin release into the blood - the hormone simply responded to the cycle of light and dark.
Professor Loudon said he believed that evolution had "come up with a means of switching off the cellular clockwork" and that the result was "a lack of internal daily timekeeping in these animals".
He commented: "Such daily clocks may be positively a hindrance in environments where there is no reliable light dark cycle for much of the year.
Organisms use their circadian clocks to correspond with their living environment; but if their environment has a very different cycle, it may be better to follow that rather than use the internal clock.
"This could be the case for a range of animals living at the poles of the Earth or in the depths of the ocean."

Ancient Amphibian Skull Discovered at Airport
By Clara Moskowitz, LiveScience Senior Writer
posted: 15 March 2010 02:07 pm ET

The exquisitely preserved skull of Fedexia striegeli, an early terrestrial amphibian. Credit: Mark A. Klingler/Carnegie Museum of Natural History

An illustration of Fedexia striegeli in the environment of the Pennsylvanian Period (300 million years ago). Credit: Mark A. Klingler/Carnegie Museum of Natural History

A meat-eating amphibian that lived 300 million years ago may represent one of the earliest examples of land-based vertebrate life, scientists announced today.
Researchers discovered the fossilized head of the ancient creature in 2004, near the Pittsburgh International Airport in western Pennsylvania. The ancient amphibian has been dubbed Fedexia striegeli after FedEx, which owns the land on which the fossil was found, and for Adam Striegel, who discovered the specimen while on a field trip as an undergrad at the University of Pittsburgh.
Scientists think the species lived during an important turning point for Earth's vertebrate life (animals with backbones), which had mostly been water-based until that period. Our planet's climate was changing around that time, becoming warmer and drier as it began to come out of an ice age.
"This reduced the number of environments for highly-aquatic amphibians to live in, and forced the amphibians to become more terrestrial," said study co-author David Brezinski, a paleontologist at the Carnegie Museum of Natural History in Pittsburgh.

"At that time, we had a number of widely distributed rare instances of other highly terrestrial animals that make their appearance in the fossil record," said co-researcher David S. Berman, also of the Carnegie Museum.The creature lived during the Late Pennsylvanian Period, or about 100 million years before mammals first appeared, and about 70 million years before dinosaurs began to walk the Earth. Because of the shifting of Earth's plates, during this period Pennsylvania was actually located near the equator, with a climate close to what we find in the Amazon basin today.
But the fact that animals with features that had evolved for living on land were showing up at this time means they had probably begun to make the shift even earlier, he said.
"They're already so highly advanced for a terrestrial existence, they must have been around for a while," Berman told LiveScience.
The researchers think Fedexia striegeli lived primarily on land because of a few features found on its well-preserved skull, which was about five inches long (11.5 centimeters). First, its nasal opening was divided into two portions, and scientist think the back portion held a gland that might have increased its sense of smell, or rid the body of excess salt. Both functions would have been helpful for terrestrial creatures.
The amphibian also lacked a set of grooves in its skull called a lateral line â€" a feature left over in many species from their fish ancestors. The lateral line helped aquatic animals to sense vibrations in water, which aided in hunting for food or prey, but served no purpose on land.
And finally, Fedexia striegeli's bones were highly ossified, which means they were thick and well-developed â€" another sign that a creature was walking around bearing its weight on land.
The researchers described their findings in the March 15 issue of the Annals of Carnegie Museum.
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Scientists At UCSB Discover 600 Million-Year-Old Origins Of Vision



This is a hydra, an ancient sea creature that flourishes today. Credit: Todd Oakley, UCSB

by Staff Writers
Santa Barbara, CA (SPX) Mar 15, 2010
By studying the hydra, a member of an ancient group of sea creaturesthat is still flourishing, scientists at UC Santa Barbara have made a discovery in understanding the origins of human vision. The finding is published in this week's issue of the Proceedings of the Royal Society B, a British journal of biology.
Hydra are simple animals that, along with jellyfish, belong to the phylum cnidaria. Cnidarians first emerged 600 million years ago.
"We determined which genetic 'gateway,' or ion channel, in the hydra is involved in light sensitivity," said senior author Todd H. Oakley, assistant professor in UCSB's Department of Ecology, Evolution and Marine Biology. "This is the same gateway that is used in human vision."
Oakley explained that there are many genes involved in vision, and that there is an ion channel gene responsible for starting the neural impulse of vision. This gene controls the entrance and exit of ions; i.e., it acts as a gateway.
The gene, called opsin, is present in vision among vertebrate animals, and is responsible for a different way of seeing than that of animals like flies. The vision of insects emerged later than the visual machinery found in hydra and vertebrate animals.
"This work picks up on earlier studies of the hydra in my lab, and continues to challenge the misunderstanding that evolution represents a ladder-like march of progress, with humans at the pinnacle," said Oakley. "Instead, it illustrates how all organisms -- humans included -- are a complex mix of ancient and new characteristics."
David Plachetzki, who received his Ph.D. for work done in the Oakley lab, is the first author. Plachetzki is now a postdoctoral fellow at UC Davis. UCSB undergraduate Caitlin R. Fong is the second author of the paper.
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The cemetery lies in what is now China’s northwest autonomous region of Xinjiang, yet the people have European features, with brown hair and long noses. Their remains, though lying in one of the world’s largest deserts, are buried in upside-down boats. And where tombstones might stand, declaring pious hope for some god’s mercy in the afterlife, their cemetery sports instead a vigorous forest of phallic symbols, signaling an intense interest in the pleasures or utility of procreation.
The long-vanished people have no name, because their origin and identity are still unknown. But many clues are now emerging about their ancestry, their way of life and even the language they spoke.
Their graveyard, known as Small River Cemetery No. 5, lies near a dried-up riverbed in the Tarim Basin, a region encircled by forbidding mountain ranges. Most of the basin is occupied by the Taklimakan Desert, a wilderness so inhospitable that later travelers along the Silk Road would edge along its northern or southern borders.
In modern times the region has been occupied by Turkish-speaking Uighurs, joined in the last 50 years by Han settlers from China. Ethnic tensions have recently arisen between the two groups, with riots in Urumqi, the capital of Xinjiang. A large number of ancient mummies, really desiccated corpses, have emerged from the sands, only to become pawns between the Uighurs and the Han.
The 200 or so mummies have a distinctively Western appearance, and the Uighurs, even though they did not arrive in the region until the 10th century, have cited them to claim that the autonomous region was always theirs. Some of the mummies, including a well-preserved woman known as the Beauty of Loulan, were analyzed by Li Jin, a well-known geneticist at Fudan University, who said in 2007 that their DNA contained markers indicating an East Asian and even South Asian origin.
The mummies in the Small River Cemetery are, so far, the oldest discovered in the Tarim Basin. Carbon tests done at Beijing University show that the oldest part dates to 3,980 years ago. A team of Chinese geneticists has analyzed the mummies’ DNA.
Despite the political tensions over the mummies’ origin, the Chinese said in a report published last month in the journal BMC Biology that the people were of mixed ancestry, having both European and some Siberian genetic markers, and probably came from outside China. The team was led by Hui Zhou of Jilin University in Changchun, with Dr. Jin as a co-author..
All the men who were analyzed had a Y chromosome that is now mostly found in Eastern Europe, Central Asia and Siberia, but rarely in China. The mitochondrial DNA, which passes down the female line, consisted of a lineage from Siberia and two that are common in Europe. Since both the Y chromosome and the mitochondrial DNA lineages are ancient, Dr. Zhou and his team conclude the European and Siberian populations probably intermarried before entering the Tarim Basin some 4,000 years ago.
The Small River Cemetery was rediscovered in 1934 by the Swedish archaeologist Folke Bergman and then forgotten for 66 years until relocated through GPS navigation by a Chinese expedition. Archaeologists began excavating it from 2003 to 2005. Their reports have been translated and summarized by Victor H. Mair, a professor of Chinese at the University of Pennsylvania and an expert in the prehistory of the Tarim Basin.
As the Chinese archaeologists dug through the five layers of burials, Dr. Mair recounted, they came across almost 200 poles, each 13 feet tall. Many had flat blades, painted black and red, like the oars from some great galley that had foundered beneath the waves of sand.
At the foot of each pole there were indeed boats, laid upside down and covered with cowhide. The bodies inside the boats were still wearing the clothes they had been buried in. They had felt caps with feathers tucked in the brim, uncannily resembling Tyrolean mountain hats. They wore large woolen capes with tassels and leather boots. A Bronze Age salesclerk from Victoria’s Secret seems to have supplied the clothes beneath â€" barely adequate woolen loin cloths for the men, and skirts made of string strands for the women.
Within each boat coffin were grave goods, including beautifully woven grass baskets, skillfully carved masks and bundles of ephedra, an herb that may have been used in rituals or as a medicine.
In the women’s coffins, the Chinese archaeologists encountered one or more life-size wooden phalluses laid on the body or by its side. Looking again at the shaping of the 13-foot poles that rise from the prow of each woman’s boat, the archaeologists concluded that the poles were in fact gigantic phallic symbols.
The men’s boats, on the other hand, all lay beneath the poles with bladelike tops. These were not the oars they had seemed at first sight, the Chinese archaeologists concluded, but rather symbolic vulvas that matched the opposite sex symbols above the women’s boats. “The whole of the cemetery was blanketed with blatant sexual symbolism,” Dr. Mair wrote. In his view, the “obsession with procreation” reflected the importance the community attached to fertility.
Arthur Wolf, an anthropologist at Stanford University and an expert on fertility in East Asia, said that the poles perhaps mark social status, a common theme of tombs and grave goods. “It seems that what most people want to take with them is their status, if it is anything to brag about,” he said.
Dr. Mair said the Chinese archaeologists’ interpretation of the poles as phallic symbols was “a believable analysis.” The buried people’s evident veneration of procreation could mean they were interested in both the pleasure of sex and its utility, given that it is difficult to separate the two. But they seem to have had particular respect for fertility, Dr. Mair said, because several women were buried in double-layered coffins with special grave goods.
Living in harsh surroundings, “infant mortality must have been high, so the need for procreation, particularly in light of their isolated situation, would have been great,” Dr. Mair said. Another possible risk to fertility could have arisen if the population had become in-bred. “Those women who were able to produce and rear children to adulthood would have been particularly revered,” Dr. Mair said.
Several items in the Small River Cemetery burials resemble artifacts or customs familiar in Europe, Dr. Mair noted. Boat burials were common among the Vikings. String skirts and phallic symbols have been found in Bronze Age burials of Northern Europe.
There are no known settlements near the cemetery, so the people probably lived elsewhere and reached the cemetery by boat. No woodworking tools have been found at the site, supporting the idea that the poles were carved off site.
The Tarim Basin was already quite dry when the Small River people entered it 4,000 years ago. They probably lived at the edge of survival until the lakes and rivers on which they depended finally dried up around A.D. 400. Burials with felt hats and woven baskets were common in the region until some 2,000 years ago.
The language spoken by the people of the Small River Cemetery is unknown, but Dr. Mair believes it could have been Tokharian, an ancient member of the Indo-European family of languages. Manuscripts written in Tokharian have been discovered in the Tarim Basin, where the language was spoken from about A.D. 500 to 900. Despite its presence in the east, Tokharian seems more closely related to the “centum” languages of Europe than to the “satem” languages of India and Iran. The division is based on the words for hundred in Latin (centum) and in Sanskrit (satam).
The Small River Cemetery people lived more than 2,000 years before the earliest evidence for Tokharian, but there is “a clear continuity of culture,” Dr. Mair said, in the form of people being buried with felt hats, a tradition that continued until the first few centuries A.D.
An exhibition of the Tarim Basin mummies opens March 27 at the Bowers Museum in Santa Ana, Calif. â€" the first time that the mummies will be seen outside Asia.




An earlier version of this article incorrectly described Xinjiang as a province rather than an autonomous region.






A version of this article appeared in print on March 16, 2010, on page D1 of the New York edition.