New study reveals how metamorphosis has shaped the evolution of salamanders

JUNE 23, 2020

by Natural History Museum

A team of scientists, led by Natural History Museum postdoctoral researcher Dr. Anne-Claire Fabre, have conducted the first study on how metamorphosis has influenced the evolution of salamanders.

Using micro-CT scanning to study the skulls of this group of animals, the team were able to build a huge dataset of 148 species of salamanders and used cutting-edge methods to describe the shape of the skull with nearly 1000 reference points, known as landmarks.

Dr. Fabre said, "Most studies of this kind are limited to just a few dozen landmarks. Our study is the first large-scale investigation of this incredibly diverse group. We have captured the shape of the skull in such great detail that it has allowed us to learn more than ever before about how these creatures evolved."

The results showed that the ancestor of all salamanders was metamorphic but that different life cycles have evolved at least 11 times across the group. Even more interesting, when different life cycles evolve, salamanders show a burst of rapid evolution, showing that shifts in life cycle promoted the evolution of new forms and increased their diversity.

Prof. Anjali Goswami, a research leader at the Natural History Museum, who is the senior author of the study, said, "We can see that metamorphosis has profoundly influenced salamander evolution, allowing for more independent evolution of the parts of the skull related to feeding and ultimately resulting in a greater diversity of skull shapes. This means that metamorphosis, and repeated changes from metamorphosis to other life cycles like live birth or losing the larval or adult stage entirely, have been key drivers of the diversity of salamanders over the past 180 million years."

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Palaeontologists Identify New Prehistoric Amphibian: A Salamander Named Egoria - via Herp Digest

TOPICS:Amphibians Evolution Paleontology By ST. PETERSBURG STATE UNIVERSITY FEBRUARY 21, 2020

A group of Russian and German paleontologists have described a previously unknown genus and species of prehistoric salamanders. The new amphibian is named Egoria malashichevi — in honor of Yegor Malashichev a talented scientist and associate professor of the Department of Vertebrate Zoology at St Petersburg University, who passed away at the end of 2018. Credit: Vadim Glinskiy 

They lived on the Earth about 166-168 million years ago, in the Middle Jurassic. The paleontologists found the remains of the ancient amphibian at the Berezovsky quarry, a fossil locality in the Krasnoyarsk Krai near the town of Sharypovo. Fossils of ancient fish, various reptiles, mammals, herbivorous and predatory dinosaurs have been previously found there. The research materials were collected on field expeditions in the mid-2010s. In these expeditions the scientists from St Petersburg University worked alongside experts from the University of Bonn (Germany), the Tomsk State University, the Zoological Institute of the Russian Academy of Sciences, and the Sharypovo Museum of Local History and Nature. 

Four vertebrate fossils enabled the scientists to declare the finding of a new genus and species. These were: three trunk vertebrae and the atlas — the first and, in the case of the salamander, the only cervical vertebra. Since the atlas is a highly specialized vertebra, providing for attachment and rotation movements of the skull, it has a rather complex structure, the scientists explain. It is therefore most suitable for describing a new species as it provides much information for analysis. The amphibian proved to have belonged to the geologically oldest stem salamanders. 

It was not the first time that remains of ancient salamanders had been found at the Berezovsky quarry. One of them — a basal stem salamander Urupia monstrosa, named after the nearby Uryup River — was about 50-60 centimeters long. Another one — Kiyatriton krasnolutskii — was named after a local historian Sergei Krasnolutskii, the discoverer of the fossil locality Berezovsky quarry. By contrast, this one was quite small in size (about 10-15 centimeters) and looked more like modern Hynobiidae. The newly discovered salamander, judging by the size of the vertebrae, was of medium length (about 20 centimeters). 

‘Salamanders first appear in the fossil records in the Middle Jurassic, including representatives of both the present-day salamander families and the most primitive ones,’ said Pavel Skutschas, associate professor of St Petersburg University, doctor of biology, expert in Mesozoic vertebrates. ‘When they had just appeared, salamanders made efforts to occupy different ecological niches. Thus, the stem salamanders filled the niche of large water bodies; while those close to the present-day salamanders found their niche in small water bodies. As for the newly discovered salamander, it occupied a middle position, although morphologically, it is closer to the primitive.’ 

The scientists not only described the external characteristics of the specimens, but were able to look inside the fossils. In this, they were assisted by the experts from the ‘Centre of X-ray diffraction studies’ at the Research Park of St Petersburg University, where the specimens were scanned on up-to-date microtomography scanners. Based on the obtained data, the paleontologists created 3D reconstructions of the vertebrae and described their internal structure. As expected, it proved to be very similar to that of the large stem salamanders. The ancient amphibian received the name Egoria malashichevi — in honor of Yegor Malashichev, associate professor of the Department of Vertebrate Zoology at St Petersburg University, who, among other things, studied the morphology of caudate amphibians. ‘Yegor Malashichev was a wonderful person and a very talented scientist. 

He supported aspiring palaeontologists and did everything to help them to stay in scientific research,’ remarked Pavel Skutschas. Additionally, Malashichev studied the phenomenon of lateralization (body asymmetries associated with the functioning of the nervous system), as well as other asymmetries in motor performance and visual perception. Yegor Malashichev’s professional career was almost exclusively connected with St Petersburg University. In 1996, he graduated from the Faculty of Biology and Soil Science. In 2000, he began to teach there, and in 2003, he defended his dissertation and was awarded a PhD in biology. Sadly, in late 2018, he passed away unexpectedly. The next step for the paleontologists is to compare the bones of the ‘Berezovsky’ salamanders with the fossils from Great Britain: the ‘Kirtlington’ salamanders which were found at the Kirtlington quarry in Oxfordshire. The Siberian and British faunas of the mid-Jurassic time were very similar. Besides, the paleontologists are aware of similar amphibians that lived in the territory of present-day England. 

‘They may be representatives of the same genera. However, to ascertain this, a detailed comparison of the palaeontological collections is required. In the coming spring, our colleagues from England will come to St Petersburg to study our research materials. We may discover that Urupia and Egoria used to have a very wide habitat, extending across Europe and Asia,’ mused Pavel Skutschas. 

Reference: “A new small-sized stem salamander from the Middle Jurassic of Western Siberia, Russia” by Pavel Skutschas, Veniamin Kolchanov, Sergey Krasnolutskii, Alexander Averianov, Rico Schellhorn, Julia Schultz and Thomas Martin, 19 February 2020, PLOS ONE. DOI: 10.1371/journal.pone.0228610A

Perfectly preserved fossil salamander even has last meal in gut-A Frog – via Herp Digest

By Richa Malhotra, New Scientist, 10/12/17 

The fossil of an extinct salamander is so exquisitely preserved that the remains of its last meal – a frog – can be seen in its gut.

The fossil comes from the site of the Quercy phosphorites in south-west France, which has thrown up many vertebrate fossils over the years. This is despite a large number of specimens probably being destroyed by phosphate mining in the 19th and 20th centuries.

The salamander fossil had remained largely forgotten in the French National Museum of Natural History for decades, until Jérémy Tissier of the JURASSICA Museum in Porrentruy, Switzerland, and his colleagues took a closer look.

They scanned the fossil using advanced imaging techniques, and named it Phosphotriton sigei after the phosphorus-rich sediments of Quercy. It is the only known fossil of this species, with a search in museums and sediment deposits coming up empty.

The salamander died 34 to 40 million years ago, yet aside from its skeleton, many of its soft tissues are preserved: an initial examination identified skin and a lung. These were protected by a process called permineralisation, sometimes loosely known as “mummification”. Under this mechanism, minerals from groundwater seep into a buried animal and fill any empty pockets, or even individual cells.

This type of soft tissue preservation is rare, says Dean Lomax at the University of Manchester, UK.

When Tissier and his colleagues revisited the scan, they spotted other tissues, including digestive tract, nerves, muscles and an unidentified organ. But the “big surprise” came when they examined the digestive tract and found frog bones inside.

Those bones comprised four vertebrae and a 5-millimetre-long limb bone. “It was clear that they didn’t belong to the salamander, because they were in the wrong position and too small,” Tissier says. He isn’t sure whether the frog bones all belong to the same individual, but they do not come from any fully developed adults.

Regardless, the finding makes P. sigei the only extinct salamander known to have consumed frogs. “We definitely didn’t expect frog bones,” says Tissier, because modern salamanders rarely eat those animals.

“The frog was really small, which may have made it easier for the salamander to catch it,” he adds. The prey was just 18-20 millimetres long, whereas the salamander may have been 150 mm – although the fossil is only about 60mm long because it is missing its head and parts of its tail and neck.

Most present-day salamanders feed on invertebrates, with their mouths too small to consume large vertebrates, says herpetologist Sara Viernum. “But if they can fit a vertebrate prey in their mouths, they typically will eat it.” The frog’s small relative size may have doomed it.

Journal reference: PeerJ, DOI: 10.7717/peerj.3861

Int’l team identifies smallest salamander species - via Herp Digest

SAN FRANCISCO, Nov. 16 (Xinhua) -- 11/17/2016 An international team of researchers has identified three new species of the world's smallest salamander and warned that the rare creatures are in danger of dying out.

The species, from the enigmatic genus Thorius, the adults of which are smaller than a matchstick, are the smallest four-legged tailed organism on Earth, and their miniaturized bodies are highly unusual for vertebrates.

Once extremely abundant and now rarely found in nature, populations of Thorius have declined precipitously over the last 30 to 35 years. The latest findings were made in remote mountains of Oaxaca, Mexico, and published on Tuesday in the journal PeerJ.

"Salamanders of the highlands of Mexico are closer to extinction than any other on Earth," said David Wake, a University of California, Berkeley, professor in the Department of Integrative Biology and a co-author of the paper. "The main factors are habitat conversion and new infectious diseases." 

First discovered in the 19th century, Thorius were believed to be a single species for the next 75 years. Nine additional species were discovered between 1940 and 1960, but the adults are so small that the species were hard to tell apart.

A breakthrough came in the 1970s, when biologists discovered that many species, while anatomically similar, could be told apart by using molecular techniques. Since then, more species have been discovered and the three newly found species bring the current total to 29.

The new species were discovered in southern Mexico by the team of researchers from the United States, Mexico and Spain through decades of fieldwork and using a combination of sophisticated molecular analyses, including deoxyribonucleic acid (DNA) sequencing; digital imaging, such as X-ray computed tomography; and statistical analysis of external and internal anatomy.

"We have known about the salamanders we have described for decades, at a time when they were exceedingly common, but only recently have we obtained evidence that they are indeed new species, though now critically endangered," Wake was quoted as saying in a news release from UC Berkeley.

"This is a common experience with other high-altitude species in Mexico, and a biological disaster is facing us.”

For at least the last 30 years, the number of valid named amphibian species worldwide has increased at a rate of about 3 percent per year. Whereas in 1985, biologists thought there were around 4,000 species of amphibians, today they recognize more than 7,700. More new ones are being discovered almost daily.

However, the discovery and documentation of amphibian diversity coincides with the precipitous decline of amphibians globally.

Many once-abundant species have gone extinct in the last 50 years, and others are likely doomed to a similar fate barring effective steps to save them.

Of the nearly 30 species of Thorius now recognized, almost all are regarded as endangered or critically endangered by the International Union for the Conservation of Nature. Indeed, the researchers said, Thorius may be the world's most endangered genus of amphibians.

Giant 200-year-old salamander found hiding in China cave

DECEMBER 17, 2015
by Brett Smith

Giant salamanders are both comically bizarre and fascinating natural specimens with amazingly long lifetimes. In fact, a giant salamander was recently discovered in southwestern China that experts say is around 200 years old!

This pre-American Civil War creature found in a cave near Chongqing, China measures more than four-and-a-half feet long and weighs almost 115 pounds, according to Chinese state media and reported by Gizmodo. Considered critically endangered, giant salamanders are currently under threat from hunting, pollution, and climate change. This particular big guy was transferred to a research facility for care and study.

One recent study on the strange amphibian revealed that it's capable of striking at prey in front of it and at either side. The study team used three-dimensional modeling to explain the unusual quick-strike feeding mechanism.

The team also found that once the amphibian has its prey caught, it draws it to the back of the jaw to perform an even more robust bite, stopping its would-be victim from getting away. The authors suspect that this skill may be associated with the structure of the creature’s skull. Unlike that of most other salamanders, the giant salamander’s skull does not have a connection linking its upper jaw with its side-jaw area.

The study, published in the journal PLOS One, said the find could explain how early tetrapods and amphibians fed.

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Salamanders living in the state (North Carolina) need better protection – via Herp Digest

The Daily Tar Heel - Op-Ed 11/2/15

North Carolina is home to over 56 different types of salamanders, giving the state one of the most diverse salamander populations in the world. Some of these species live in incredibly small habitats in remote parts of the western part of the state. Sadly, due to deforestation and other anthropogenic causes, populations are on the decline. Some of these species uniquely exist within this state and it is the job of all living within its borders, especially policymakers, to protect these super cool creatures. One such species is the green salamander, which lives in very small pockets in the western part of the state. This species is highly reclusive. The green salamander is about five inches long and can live up to 10 years. It also uses camouflage to blend into its surroundings. It is typically nocturnal, preferring to venture out during the cooler parts of each day to look for food.

Train derailment in 2008 leads to study of rare salamander in Mississippi River – via Herp Digest

Nov 9, 2015-  GURRENBERG (AP) | One fortunate byproduct of a 2008 train derailment is that scientists are gaining a better understanding of a rare salamander species that lives in the Mississippi River.

The U.S. Fish and Wildlife Service is working on a long-term survey of mudpuppies in the river near Guttenberg.

Herpetologist Jeff LeClere is helping with the study of the salamanders that can grow up to 16 inches long.

Little is known about the threatened species because the salamanders tend to hide in rocky areas and are most active in winter.

"These records are few and far between, and herpetologists seem to have a difficult time trying to capture mudpuppies," he said. "And the reason for that is we really didn't understand a whole lot of their natural history until recently."

In July 2008, a train derailed after a boulder dislodged by heavy rain tore up part of the track near Guttenberg. Four locomotives sank in the river and leaked oil for days.

Slower-moving aquatic life, such as the salamanders and mussels, were affected by the oil.

The train derailment led to a $625,000 settlement with the Dakota Minnesota and Eastern Railroad, a subsidiary of Canadian Pacific. That is helping pay for the mudpuppy study.

"In the cleanup operation, we did find one dead mudpuppy. We believe it was a juvenile," said Kevin Hanson with the Iowa Department of Natural Resources. "Because of that, we requested some of the funds to go toward research to find out more about their population in (Mississippi River) Pool 11 here."

Already, five mudpuppies have been captured as part of the survey, so the work is off to a good start.

Salamander fossil found in amber is all kinds of cool

AUGUST 19, 2015

by John Hopton

A fossil of a salamander found in the Caribbean and encased in amber is causing excitement for several reasons, Discovery News reported.

This discovery made scientists giggly 20-30 million years after its death, because 1) It is the first salamander ever to be found encased in amber, 2) It proves that salamanders once lived in the Caribbean, and 3) It is evidence of a species (now extinct) which was previously unknown.

Scientists from Oregon State University (OSU) and the University of California at Berkeley were working in an amber mine in a mountainous region between Puerto Plata and Santiago in Dominican Republic when they found the specimen.

"There are very few salamander fossils of any type, and no one has ever found a salamander preserved in amber," said George Poinar, Jr., a professor emeritus in the OSU College of Science. "And finding it in Dominican amber was especially unexpected, because today no salamanders, even living ones, have ever been found in that region."

The researchers, who published their findings in the journal Paleodiversity, have named the creature Palaeoplethodon hispaniolae.

Read more at

'Monster salamanders' found in fossilised mass grave

By Jonathan Webb

Science reporter, BBC News

24 March 2015 

Scientists have discovered a new species of massive, toothy amphibian dating from 220 million years ago.

Hundreds of the creatures probably died when a lake dried up, leaving a huge jumble of bones which is now being excavated in southern Portugal.

Although related to modern salamanders, the two-metre beast probably lived more like a crocodile, snapping up fish and scrapping with rivals on the shore.

The find is reported in the Journal of Vertebrate Paleontology.

Nobody's pet

"It's basically a salamander that's the size of a car," said Dr Steve Brusatte, a palaeontologist at the University of Edinburgh who led the research.

"It's one of those creatures from the distant past that looks like an alien - but it actually has quite a lot of relevance. These kind of big amphibians were the ancestral stock that modern frogs, salamanders and newts came from."

Read more ...

The case of the missing mudpuppies USD biologist trying to sleuth out salamander species not seen here for decades - via Herp Digest

By Lance Nixon Lance.Nixon@capjournal.com  June 11, 2014 11:42 pm

Call it a cold case for investigators trying to track down one cold-blooded individual.

Biologists know that one of South Dakota’s two known species of salamander was found here decades ago, but they’re not sure it’s here now. So this summer and probably next winter, University of South Dakota students will probe wetlands in northeastern South Dakota to try to sleuth out the missing amphibian.

“We have a crew right now looking for a particular salamander called the mudpuppy that has been seen since the 1920s. Our last museum sample was from 1927,” said USD associate professor Jake Kerby. Kerby is a herpetologist, or a scientist who studies reptiles and amphibians. “We are going to survey Day, Marshall and Roberts counties.”

Kerby is optimistic that the species might still be here after all, in part because in addition to those museum specimens from the 1920s and earlier, one of his USD students sorting through a collection up the road at South Dakota State University at Brookings found a mudpuppy that had been collected as recently as 1981.

“I feel pretty hopeful that they’re still out there, just that they’re in low numbers and nobody’s looking for them,” Kerby said.

Kerby said the only other salamander species in South Dakota, the tiger salamander, is more common. Since South Dakota is at the western edge of the eastern tiger salamander’s range and the western tiger salamander’s range begins somewhere in eastern South Dakota, there may be quite a lot of diversity within that tiger salamander’s population. To make matters more complicated, the tiger salamander and the mudpuppy look alike in the larval stages.

The only way to tell them apart at that stage is to count the toes on the back feet. Kerby said the mudpuppy has four toes on the back foot; the more common tiger salamander has five.

Kerby added that mudpuppies remain aquatic, so the only salamander South Dakotans will ever see on land is the more common tiger salamander.

Kerby and his colleagues have proposed a range for the mudpuppy that would include the northeastern corner of South Dakota, the eastern fringe of North Dakota, and western Minnesota. He added that colleagues in Minnesota who catch mudpuppies have told him it’s actually easier to find mudpuppies in winter, since the cold-blooded amphibians remain active under the ice. His students will probably drill through the ice this winter and use traps to try to capture mudpuppies in that same northeast part of the state; but they are already searching for mudpuppies this summer.

The mystery of the vanished mudpuppies also has an element of whodunit. If the salamanders have indeed vanished from the state, or simply if they’re less abundant, there are plenty of potential villains.

Kerby said introduced fish species sometimes leave native species of salamander unable to adapt to an aggressive new predator. Pollutants could be a factor. So could disease – especially one called chytrid fungus that preys on amphibians in cold climates, and another called ranavirus. And then there’s the biggest villain of all.

“The number one factor is just habitat loss,” Kerby said. “That can include drainage of wetlands or modification of lakes.”

There are an estimated 15 species of amphibians in South Dakota in all, Kerby said, though the count sometimes varies depending on how scientists count certain species.

A grant from the South Dakota Department of Game, Fish & Parks supports the project.

Kerby notes that anyone who has found a mudpuppy – remember to look for four toes instead of five on the back feet – should photograph it and contact Kerby directly Jacob.Kerby@usd.edu. Or contact Casey.Heimerl@state.sd.us.

Salamanders Give Clues to How We Might Regrow Human Limbs (Op-Ed)

By Max Yun, University College London | June 20, 2014 02:52am ET

This article was originally published at The Conversation. The publication contributed the article to Live Science's Expert Voices: Op-Ed & Insights.

Humans have some regenerative abilities but compared to creatures like the salamander, which has an amazing ability to regenerate after injury, we’re pretty limited. Not only are salamanders the only adult vertebrates able to regrow full limbs, they’re able to regenerate an impressive repertoire of complex structures including parts of their hearts, eyes, spinal cord and tails.

In recent years, researchers have been studying salamander regeneration in the hope that the knowledge gathered would contribute to understanding how can they regenerate, and how to promote human regeneration.

Continued

Two new species of Salamander discovered in Colombia as deadly fungus detected for first time

Chytridiomycosis detected for the first time in north-east Colombia

February 2013. A team of young researchers from Colombia have recently found two new species of salamander that were discovered during a project supported by the Conservation Leadership Programme and Save Our Species.

The two new salamanders belong to the genus Bolitoglossa, otherwise known as tropical climbing or web-footed salamanders. One of the salamanders (B. leandrae) has been named after an 11-year old girl who became friends with the team whilst they conducted their fieldwork. "Leandra grew fascinated by the world of amphibians," explains team leader Aldemar Acevedo. "She was eager to learn about our work and became an excellent spokesperson for nature conservation among the community."

Bolitoglossa tamaense. 

Credit: Aldemar Acevedo.

Small salamander
Bolitoglossa leandrae is a relatively small salamander (its body measures roughly 2.5 cm in length, about the size of a 50 pence, 20 cent or US quarter coin) with a narrow head and long, slender tail. Males are dark brown with thin yellow stripes along the length of the body and females are reddish brown.

Bolitoglossa tamaense is slightly longer than B. leandrae (the body of the longest specimen measured approximately 5 cm, or the same as the height of a credit card) and has a broad head and relatively long body and legs. A number of different colourations and patterns were recorded, but the body is generally brown or dark red, and the tail and limbs can be dark brown, red, orange or yellow.

Read on:

http://www.wildlifeextra.com/go/news/salamander-colombia.html

In Mexico, the ajolote's fate lies in troubled waters – via Herp Digest

The salamander, long a metaphor for the Mexican soul, risks extinction unless its sole habitat, the canal system of Xochimilco, can be restored.

 By Richard Fausset, Los Angeles Times

October 1, 2012, 

Mexico City— Somewhere underneath the hull of Armando Tovar's boat, the aquatic manifestation of the great god Xolotl was slithering along the muddy canal bottom, digesting bugs, laying eggs and trying to avoid extinction.

Even though he could not see the creature, Tovar knew it would be confronting its troubled environment with that weird fixed smile, the one that makes it appear to be in on some cosmic joke.

As a 9-inch salamander, of course, the ajolote (pronounced ah-ho-LO-tay) couldn't know its own cultural significance in Mexico. It couldn't know its role in the Aztec creation myth. Or its freak-show star status among biology nerds for its ability to regenerate lost limbs, heart cells and bits of brain. Or its allure, in the world of arts and letters, as both a cryptic literary symbol and a metaphor for the Mexican soul.

It couldn't know, on this placid Tuesday morning, that Armando Tovar was in this long, flat wooden boat, with his colleagues and their water-quality monitoring devices, hoping to save it from oblivion.

Tovar, 33, a biologist at Mexico's National Autonomous University, or UNAM, is one of a group of scholars seeking to solve the ecological puzzle of the ajolote and its sole habitat, the canal system of Xochimilco, the last watery remnant of the Aztec society built on the lakes and wetlands of the Valley of Mexico.

Today, Xochimilco is a heavily visited oasis of crops and canals hemmed by the teeming, concrete presence that some here call la mancha urbana, the urban stain. Its 110 miles of waterways are a place where tourists and locals fritter away Sunday afternoons, floating on brightly colored gondolas, drinking beer and taking in the area's remaining chinampas, small agricultural islands that were invented by Aztec farmers.

The precious green space scrubs carbon dioxide from Mexico City's famously polluted air, serves as a rest stop for 84 species of migratory birds and helps recharge a perilously overtaxed aquifer.

But it also is dealing with pollution issues of its own, and that has consequences for the salamander whose strangely childish looks have made waves as far as Japan, where it was the inspiration for a Pokemon character.

In 1998, Xochimilco was home to tens of thousands of ajolotes. Today, Tovar said, the number might be as low as 100.

The forces aligned against the ajolote are formidable, some as old as Mexico itself.

Luis Zambrano, the director of UNAM's Ecological Restoration Laboratory and leader of the rescue effort, said the problems started with the 16th century conquistadors who, hailing from arid Spain, saw the lake system as a problem to be solved. So they drained it, making way for a modern metropolis in which, he said, natural water systems are still often viewed as a hindrance to progress.

The researchers, despite years of restoration efforts, have struggled to undo the harm. The ajolote habitat has been degraded by water extraction, industrial fertilizers, the pressures of tourism, and untreated wastewater discharged by rogue developments inside Xochimilco's protected area.

The canals are also teeming with nonnative carp and tilapia, introduced in a misguided '70s-era aquaculture project. These heartier foreign species feast on ajolote eggs and compete for scarce resources. "I call it, 'A society's defeat, caused by society,'" Tovar said.

Last month, the director of the National Water Commission, Jose Luis Luege, said Xochimilco was in danger of deteriorating so severely that it could lose its status as a UNESCO World Heritage Site. He recommended that the federal government immediately launch an ambitious, 20-year restoration plan, the newspaper Excelsior reported.

The city and federal governments already have spent millions over the years. But Zambrano said the funding for the ajolote project is wildly inconsistent from year to year, making it difficult to plan long term.

To Zambrano, Xochimilco's famous salamander is a slimy sentinel, a canary in Mexico City's ecological coal mine. Its disappearance from the wild, he argues, would be a warning that the megacity was no longer a sustainable proposition.

Protecting the ajolote, he wrote in a recent essay, "means protecting ourselves from ourselves."

***

The Aztecs believed that the creature formally known as the Ambystoma mexicanum was an iteration of Xolotl, the deformed god of lightning and Charon-like ferryman of the dead to the underworld. Xolotl, the legend goes, took the form of an ajolote to escape a death sentence imposed upon him as the current universe was being created. UCLA art history professor John Pohl notes that the Aztecs also saw in the amphibian's regenerative powers a metaphor for the bounty of the lake system that sustained them.

Until recent decades, when the creature began to disappear, ajolote-derived products were important components in local folk medicine. Its flesh also was valued as a particularly tasty tamale filling.

Over the centuries, naturalists worldwide have been fascinated not only with the ajolote's regenerative abilities, but also with its state of suspended pre-adolescence: Unlike most amphibians, which trade gills for lungs upon reaching adulthood, the ajolote keeps its external gills, which appear like a spiky collar behind its curiously smiling face.

The creature's biological anomalies, historic resonance and otherworldly appearance offered an inescapable appeal to a certain kind of Latin American thinker. The ajolote was the subject of a well-known Kafkaesque short story by the late Argentine writer Julio Cortazar and has featured prominently in poems by Mexican writers Octavio Paz ("Salamander/in the abstract city/between the vertiginous geometries") and Jose Emilio Pacheco ("The ajolote is our emblem/embodying the fear of being no one/and retreating/into the perpetual night, in which the gods/rot under the mud").

In 1987, the Mexican academic Roger Bartra, in his influential book "The Cage of Melancholy," embarked on an extended meditation on the ajolote, comparing it to the Mexican national character, a "strange amphibian" that is developmentally suspended, ajolote-like, between the primitive and the modern.

As Tovar and his colleagues toured a muddy, green chinampa, their boat docked, they said they didn't buy into Bartra's assertion that the animal bears "the terrible weight of symbolizing the Mexican national character."

But that didn't mean they weren't taking advantage of the ajolote's notoriety. To Tovar, the ajolote — cute, as far as salamanders go — serves as a kind of polar bear for the effort to save Xochimilco. It is their sympathetic critter. At a recent environmental fair, the biologists hawked copies of a children's book with a smiling cartoon ajolote on the cover, piloting one of Xochimilco's famous boats.

"In truth, the ajolote itself is not so important to me … or, rather, it's only important in the broader context of this threatened environment," Tovar said. "The ajolote is our flag."

***

But an intellectual pedigree and a cute face can help only so much.

Tovar's colleague Leonardo Sastre said the group contracts with local fishermen to haul an average of 100 tons of nonnative fish out of the canals each year. Yet their populations are still growing. At one point, on the prow of the little boat, he pointed as the normally still water began to shudder and quake.

"Look," he said. "Tilapia."

The rescue team is also working with an environmental group to encourage farmers on the chinampas to raise their crops without the fertilizers that harm the water. But less fertilizer means more work.

Carlos Sumano, a member of the environmental group, dreams of the day when hip Mexico City chefs who subscribe to the slow-food movement will buy regularly from the chinamperos. But , he said, fewer than a dozen of the hundreds of the farmers have changed their ways.

Standing on the bank of a canal, Tovar showed examples of plants that have been introduced to naturally clean the water of contaminants, including a free-floating, spongy specimen known in English as duckweed. The vegetation has been introduced in some small canals that are also outfitted with barriers to block nonnative fish.

These trench "refuges" for the ajolote have been somewhat successful; however, they cover only about 1,600 square yards of water, a tiny fraction of the canal system. Sastre said there wasn't enough financing to do more.

Two cages were submerged in the dark water of one trench, dusted with bright green duckweed. They contained 15 ajolotes hatched inside. Their parents were raised in a lab.

The biologists are not ready to release them into the wild. They worry that could introduce new diseases and genetic problems to the ecosystem. And for now, Tovar said, the water beyond the clean trench was too filthy for them to survive in.

Tiny Carboniferous Steps (Fossilized Salamander Footprints) - via Herp Digest

By Brian Switek 9/6/11, Wired Science Blogs

http://www.wired.com/wiredscience/2012/09/tiny-carboniferous-steps/ for illustration

The tiny Batrachichnus salamandroides trackway found in Nova Scotia. Image courtesy Justin Spielmann.

Fossil footprints are lovely vestiges of prehistoric life. Even though skeletons are wonderful things, and immense mounts of defleshed dinosaurs were what inspired my love of paleontology in the first place, the variety of fossil tracks paleontologists have collected and cataloged are intricate snapshots of life in motion. Imprints and trackways record movement and behavior – petrified outlines of prehistoric moments that we can’t observe directly. And it’s this variety of fossil that allowed paleontologists to follow a tiny 315 million year old tetrapod on a little jaunt.

Discovered by amateur paleontologist Gloria Melanson along Nova Scotia’s Joggins Cliffs, the tiny trackway contains what Melanson, Matt Stimson, and Spencer Lucas deem to be the smallest fossil vertebrate footprints yet found. The whole trackway, containing about 30 footprints, is just under two inches long, and the imprints themselves range from 0.09 to 0.06 of an inch long each. This was a tiny, tiny tetrapod that strutted along a floodplain during a time when insects were giants and our own ancestors were small, lizard-like creatures. Based on the details of the tracks, it seems that the vertebrate was walking at a normal pace before slightly speeding up toward the end of the slab. But just what sort of animal made the tracks?

Students of trace fossils – technically known as ichnologists – constantly face what paleontologist Martin Lockley has called the “Cinderella Syndrome.” Unless an organism literally dies in its tracks, paleontologists face the problem of matching the trace to the trace-maker. Indeed, the situations that preserved body fossils weren’t always amenable to setting trace fossils in stone, and vice versa. And even in places like the Joggins Cliffs, where body and trace fossils are both found, many of the body fossils are fragments preserved in different settings than the footprints. In this case, what we know about the skeletons of the Joggins Cliffs animals comes from bones found inside the fossilized trunks of tree-like lycopsids – vascular plants most closely related to today’s club mosses and quillworts.

A restoration of the kind of amphibian that may have made the Batrachichnus tracks, courtesy Justin Spielmann.

Stimson and co-authors attribute the tracks to the ichnospecies Batrachichnus salamandroides. This is the name for the particular track type, but not the animal itself. (Just like body fossils, trace fossils are organized according to a binomial system which refers to specific trace fossil forms.) But the paleontologists also narrow down the list of possible creatures that could have made the Batrachichnus salamandroides footprints. Their prime candidate is a juvenile Dendrerpeton– a roughly salamanderish amphibian known from an articulated skeleton and other fossils found in the ancient lycopsid stumps. The crawler’s proportions, when shrunk down to scale, seem to match the proportions of the trackmaker.

Then again, Dendrerpeton isn’t the only suitable candidate. A different variety of amphibian, called a microsaur, could have made similar tracks. As Stimson and colleagues conclude, “multiple biotaxa of varying sizes could produce Batrachichnus salamandroides tracks.” We may never know for sure who left the tracks. The trail of itty bitty footprints can only take us so far into the past.

Reference:

Matt Stimson, Spencer G. Lucas & Gloria Melanson (2012): The Smallest Known Tetrapod Footprints: Batrachichnus salamandroides from the Carboniferous of Joggins, Nova Scotia, Canada, Ichnos: An International Journal for Plant and Animal Traces, 19:3, 127-140