Earliest salamanders discovered (BBC report)

Earliest salamanders discovered

By Jonathan Amos
BBC News Online science staff

Scientists have discovered the earliest examples of salamanders - specimens up to 165 million years old - in fossil beds in Mongolia and China.

Scientists say they have found literally thousands of the animals preserved in volcanic ash.

The researchers describe one juvenile in particular that reveals the amphibian's eye, folds in its tail and a stomach bulging with clams.

The discoveries are part of an ongoing excavation programme being conducted by staff from the University of Chicago, US, and Peking University in Beijing, China.

Before these extraordinary finds, the oldest known salamander fossils dated back only to the Tertiary Period, which began 65 million years ago.

"What excites us is that we're not only seeing the earliest known salamanders in the fossil record, but we've thousands of them," Professor Neil Shubin told BBC News Online.

"There are whole bodies, impressions of soft tissue preserved, and stomach contents. It's really unusual that you have such a view of the early evolution of a group of animals like this."

In the journal Nature this week, the scientists describe in detail an amphibian they call Chunerpeton tianyiensis.

It is said to resemble the North American hellbender, a common salamander currently found in Asia, as well as in the Allegheny Mountains near Pittsburgh in the US state of Pennsylvania.

The bones in the front of its skull, its fingers, toes and ribs are all somewhat different, however.

Other complete fossils, including some with those rare soft tissue impressions, offer a wealth of new information on the salamander's origin and life cycle.

"You have tiny guys who might be just a millimetre long right up to adults that might be 20 centimetres long. It's remarkable," said Shubin, who is professor and chairman of organismal biology and anatomy at the University of Chicago.

"Some of the adults look like big larvae; some of them have retained their larval features as adults. And we have some that have clearly metamorphosed.

In one small larval specimen, the contents of its last meal are still in the stomach

"The exquisite condition of these fossils offers clues to evolutionary strategies - larval details such as gills in adult animals, for example."

The finds confirm, in Shubin's and colleague Ke-Qin Gao's view, that salamanders originated in Asia.

"About 200 million years ago, the world had one supercontinent, [Pangea]. Then the continents began to split apart - the big split being between a northern landmass called Laurasia and a southern landmass called Gondwana.

"Gondwana has Africa, South America, Australia, Antarctica. Laurasia has North America, Europe and northern Asia. It seems salamanders evolved around this split so that today they are almost entirely Laurasian in distribution.

"The creatures we are finding in China are relatives of the salamanders in Asia and North America today

Chunerpeton tianyiensis, which resembles the North American hellbender, was caught in volcanic ash.



http://news.bbc.co.uk/2/hi/science/nature/2896407.stm

That's a March 28, 2003 report.

Here's another BBC report from March 30, 2001:

'Pompeii' salamanders fill fossil gap

A collection of petrified Chinese salamanders is giving scientists valuable new information about amphibian evolution.

The little animals were suffocated en masse 150 million years ago when their pond, near Fengshan in Hebei Province about 400 kilometres (250 miles) north of Beijing, was smothered in volcanic ash.

It was, say researchers, a salamander equivalent of the eruption of Vesuvius in AD 79, which had a similar petrifying effect on the residents of nearby Pompeii.

The detail in the specimens is astonishing. The preservation process was so good that in some instances even the soft internal organs have left their mark.

The salamanders, which were recovered from an area no bigger than 10 metres square, are described in the journal Nature by Neil Shubin, of the University of Chicago, and Ke-Qin Gao, of the American Museum of Natural History in New York, US.

The specimens, which record both laval and adult stages, are 85 million years older than any other salamanders pulled out of the fossil record. They hint at an Asian origin for the creatures and show clearly that the animals have changed very little since they were running under the feet of dinosaurs in the Jurassic Period.

"Whether you look at a salamander you find under a rock in the local forest preserve or in a rock in China dating back 150 million years, they look alike," Shubin said.

"In fact, they look alike in great detail - the bones in their wrists are the same, the way their skulls are formed - intricate details are the same."



http://news.bbc.co.uk/2/hi/science/nature/1251318.stm

BBC
September 17, 1999

The salamander's secret sexual scent

Scientists have identified the secret love potion a salamander uses to woo his mate.

It is a pheromone, or signalling chemical, that the male wipes onto the female's nares or nostrils during their courtship dance.

As soon as this happens, things get a little steamy.

The molecule is produced in a gland under the male's chin. It is unique and different from the few other animal pheromones that have ever been identified, said University of Chicago graduate student Stephanie Rollmann, who did the research.

"To our knowledge this is the first vertebrate pheromone to affect female receptivity".

Rollmann and colleagues, who report their findings in the journal Science, studied the species Plethodon jordani, which lives in the mountains of western North Carolina.

They found that the designer fragrance is applied at a particular stage in courtship known as the tail-straddling walk, where the female walks forward with the male, straddling his tail and resting her chin on the tail base.

The male has to turn around to deliver the chemical signal.

After purifying the pheromone and isolating its principal protein component, the researchers tested its potency in courtship situations where the males had their chin gland removed. Test pairs that had the purified pheromone applied by the researchers spent a shorter amount of time tail-straddling, indicating that the female became receptive to the male's advances more quickly than couples without the pheromone.

Pheromones are increasingly being studied by researchers for the key roles they play in species recognition, reproduction and other behaviours. Pheromones have commonly been identified for many insects, but less so for vertebrate animal species.

However, there is some clear evidence of their operation in humans, said Lynne Houck, an associate professor of zoology at Oregon State University. Research has shown that female humans who spend a great deal of time in one another's company often send out chemical signals that help them synchronise their menstrual cycles.

There is also evidence that a woman who spends much time around a single man develops a more regular menstrual cycle, which might be conducive to successful conception.

"The sexuality of humans is obviously pretty complicated and goes far beyond a single chemical cue," Houck said. "But that doesn't preclude the possibility that in fact there are some chemical cues at work which we don't yet fully understand."

http://news.bbc.co.uk/1/hi/sci/tech/450092.stm

other fossil-related links:

New species of earliest-known salamanders found in China
University of Chicago Medical Center
March 26, 2003

http://www.uchospitals.edu/news/2003/20030326-salamanders.html

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Salamander Origins Pegged To Asia
National Geographic News
March 28, 2001

http://news.nationalgeographic.com/news/2001/03/0328_salamander.html


If there are indeed "literally thousands of the animals preserved in volcanic ash" like the BBC article said, I'd sure like to get my hands on one of them! Anybody know any place that sells legally obtained sal fossils?