The National Science Foundation (NSF):Scientists discover fossil tumor in 255 million-year-old mammal forerunner .- Los científicos descubren un tumor fósil en un precursor de mamíferos de 255 millones de años

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Ancient tumor was hidden inside fossil from Tanzania

A thin-section image zooms in on the fossil odontomas. Each looks like a miniature tooth. Credit and Larger Version

December 8, 2016

When paleontologists cut into the fossilized jaw of an ancient creature, they got more than they bargained for: a toothy tumor.

As the scientists report in a paper published today in the Journal of the American Medical Association Oncology, they discovered evidence that the specimen harbored a benign tumor made up of miniature, tooth-like structures. This type of tumor, known as a "compound odontoma," is common to mammals today. But this animal lived 255 million years ago -- before mammals existed.

"We think this is by far the oldest known instance of a compound odontoma," said paper author Christian Sidor, a vertebrate paleontologist at the University of Washington. "It would indicate that this is an ancient type of tumor."

Before this discovery, the earliest evidence of odontomas came from ice age-era fossils.

"Until now, the oldest known occurrence of this tumor was about 1 million years ago in fossil mammals," said Judy Skog, program director in the National Science Foundation (NSF) Division of Earth Sciences, which funded the research. "These researchers have found an example in the ancestors of mammals that lived 255 million years ago. The discovery suggests that the suspected cause of an odontoma isn't tied solely to traits in modern species, as had been thought."

Skog added that the research demonstrates that paleontology can contribute to medical research. "This finding shows that the fossil record can play an important role in understanding how diseases evolve."

Mass of small "toothlets"

In humans and other mammals, a compound odontoma is a mass of small "toothlets" combined with tooth tissues like dentin and enamel. This type of tumor grows in the gums or other soft tissues of the jaw. It can cause pain and swelling and disrupt the positions of teeth.

Doctors consider odontomas benign tumors because they do not metastasize and spread throughout the body. But given the disruptions they cause, surgeons often opt to remove them.

The creature studied by the team didn't have the option of surgery. It was a gorgonopsian, a distant relative of mammals and the apex predator during its pre-dinosaur era, about 255 million years ago. Gorgonopsians are part of a larger group of animals called synapsids, which includes modern mammals as its only living member.

Some synapsids are called "mammal-like reptiles" because they possess some, but not all, the features of mammals. The first mammals evolved more than 100 million years ago.

"Most synapsids are extinct, and we -- that is, mammals -- are their only living descendants," said paper author Megan Whitney of the University of Washington. "To understand when and how our mammalian features evolved, we have to study fossils of synapsids like the gorgonopsians."

Slicing into a fossil

Paleontologists have categorized many "mammal-like" features of gorgonopsians. For example, like us, they have teeth differentiated for specialized purposes. But the researchers started studying gorgonopsian teeth to see if they had a different mammalian feature.

"Most reptiles alive today fuse their teeth directly to the jawbone," said Whitney. "But mammals do not. We use tough, but flexible, string-like tissues to hold teeth in their sockets. We wanted to know if the same was true for gorgonopsians."

A purely external examination of gorgonopsian fossils wouldn't answer that question. The scientists had to take the risky approach of slicing into a fossilized gorgonopsian jaw. By looking at thin sections of jaw and tooth under a microscope, they could see how a tooth was nestled within its socket.

Since this technique would damage the fossil, Whitney and Larry Mose, also of the University of Washington, used an "orphan" gorgonopsian lower jaw -- one that wasn't matched to a more complete fossil -- that Sidor had collected in southern Tanzania.

Mose prepared multiple thin slices from the gorgonopsian jaw, each only about as thick as a sheet of notebook paper, and mounted them onto slides. He and Whitney immediately noticed something unexpected within the jaw. Embedded next to the root of the canine were irregular clusters of up to eight tiny, round objects.

At higher magnification under a microscope, Whitney discovered that the objects in each cluster resembled small, poorly differentiated teeth, or toothlets. The toothlets harbored distinct layers of dentin and enamel.

"At first we didn't know what to make of it," said Whitney. "But after some investigation we realized that this gorgonopsian had what looked like a textbook compound odontoma."

Oldest odontoma

This is by far the oldest reported evidence for an odontoma, the scientists say, and possibly the first case in a non-mammal.

According to Sidor, odontomas have been reported in archaeological specimens, as well as in fossilized mammoths and deer. But those cases all date to within the last million years or so.

Since this synapsid had an odontoma, it would indicate that this condition existed well before the first mammals evolved.

"This discovery demonstrates that the fossil record can tell us a lot about our present-day lives, even the diseases or pathologies that are part of our mammalian heritage," Sidor said. "From the outside, you could never tell that this creature had this."

A University of Washington Mary Gates Research Fellowship also funded the study.

-NSF-

Media Contacts Cheryl Dybas, NSF, (703) 292-7734, cdybas@nsf.gov
James Urton, University of Washington, (206) 543-2580, jurton@uw.edu

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2016, its budget is $7.5 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives more than 48,000 competitive proposals for funding and makes about 12,000 new funding awards. NSF also awards about $626 million in professional and service contracts yearly.

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Discovery of oldest known fossil tumor
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A gorgonopsian lower jaw. This specimen is representative of gorgonopsian fossils in general.
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A CT scan of the front half of a gorgonopsid lower jaw. Bone is in blue, teeth are in red.
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Thin-section of the gorgonopsian jaw. The small circles form a compound odontoma.
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Thin-section of the gorgonopsian jaw, from halfway along the length of the canine root.
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The odontomas have eaten away at the root of the canine, a key characteristic of odontomas.
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The National Science Foundation (NSF)
Guillermo Gonzalo Sánchez Achutegui
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nsf.gov - National Science Foundation - Paleontologists discover new species of titanosaurian dinosaur in Tanzania

Rare find of sauropod dinosaur skeleton from Africa

Where did Rukwatitan live? This artist's rendition shows the dinosaur's likely paleoenvironment. Credit and Larger Version

September 8, 2014

For video b-roll associated with this discovery, please contact Dena Headlee at dheadlee@nsf.gov.

Paleontologists have identified a new species of titanosaurian, a member of the large-bodied sauropods that thrived during the final period of the dinosaur age, in Tanzania.

Although many fossils of titanosaurians have been discovered around the globe, especially in South America, few have been recovered from the continent of Africa.

The new species, named Rukwatitan bisepultus, was first spotted embedded in a cliff wall in the Rukwa Rift Basin of southwestern Tanzania.

With the help of professional excavators and coal miners, the scientists unearthed vertebrae, ribs, limbs and pelvic bones over the course of several months.

CT scans of the fossils, combined with detailed comparisons with other sauropods, revealed unique features that suggested an animal that was different from previous finds--including those from elsewhere in Africa, according to a paper published today in the Journal of Vertebrate Paleontology.

"This titanosaur finding is rare for Africa, and will help resolve questions about the distribution and regional characteristics of what would later become one of the largest land animals known," says Paul Filmer, a program director in the National Science Foundation's (NSF) Division of Earth Sciences, which funded the research.

"Titanosaurians make up the vast majority of known Cretaceous sauropods, and have been found on every continent, yet Africa has so far yielded only four formally recognized members."

Rukwatitan bisepultus lived approximately 100 million years ago during the middle of the Cretaceous Period.

Titanosaurian sauropods, the group that includes Rukwatitan, were herbivorous dinosaurs known for their iconic large body sizes, long necks and wide stance.

Although not among the largest of titanosaurians, Rukwatitan is estimated to have forelimbs reaching 2 meters and may have weighed as much as several elephants.

"Using traditional and new computational approaches, we were able to place the new species within the family tree of sauropod dinosaurs and determine its uniqueness as a species--and to delineate other species with which it is most closely related," says lead paper author Eric Gorscak, a biologist at Ohio University.

The dinosaur's bones exhibit similarities with another titanosaurian, Malawisaurus dixeyi, previously recovered in Malawi.

But the two dinosaurs are distinctly different from one another, and from titanosaurians known from northern Africa, says co-author Patrick O'Connor, an anatomist at Ohio University's Heritage College of Osteopathic Medicine.

The fossils of middle Cretaceous crocodile relatives from the Rukwa Rift Basin also exhibit distinctive features when compared to forms from elsewhere on the continent.

"There may have been certain environmental features, such as deserts, large waterways and/or mountain ranges, that would have limited the movement of animals and promoted the evolution of regionally distinct faunas," O'Connor says.

"Only additional data on faunas and paleoenvironments from around the continent will let us further test such hypotheses."

In addition to providing new data about species evolution in sub-Saharan Africa, the results contribute to fleshing out the portrait of titanosaurians, which lived in habitats across the globe through the end of the Cretaceous period.

Their rise in diversity came in the wake of the decline of another group of sauropods, the diplodocoids, which include the dinosaur Apatosaurus.

"Much of what we know about titanosaurian evolutionary history stems from numerous discoveries in South America--a continent that underwent a steady separation from Africa during the first half of the Cretaceous Period," Gorscak says.

"With the discovery of Rukwatitan and study of the material in nearby Malawi, we are beginning to fill a significant gap from a large part of the world."

Co-authors of the paper are Nancy Stevens of the Ohio University Heritage College of Osteopathic Medicine and Eric Roberts of James Cook University of Australia.

The study was also funded by the National Geographic Society, the Ohio University Heritage College of Osteopathic Medicine and the Ohio University Office of the Vice President for Research and Creative Activity.

-NSF-

Media Contacts Cheryl Dybas, NSF, (703) 292-7734,

cdybas@nsf.gov
Andrea Gibson, Ohio University, (740) 597-2166,

gibsona@ohio.edu

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2014, its budget is $7.2 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives about 50,000 competitive requests for funding, and makes about 11,500 new funding awards. NSF also awards about $593 million in professional and service contracts yearly.

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Useful NSF Web Sites:
NSF Home Page:

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NSF News:

 http://www.nsf.gov/news/
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Awards Searches:

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NSF-funded paleontologists discover new species of dinosaur in Tanzania.
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View of the Rukwatitan quarry shows the "vertical nature" of the scientists' working conditions.
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The humerus, or upper arm bone, and ribs of Rukwatitan in a cliff; the 2-inch brush is for scale.
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Researcher Eric Gorscak quarrying in the Rukwa Rift Basin in southwestern Tanzania.
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Paleontologists remove the remaining portions of Rukwatitan's skeleton from the quarry.
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Image showing two tail vertebrae of the newly discovered Rukwatitan.
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Guillermo Gonzalo Sánchez Achutegui

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Science:Large Ice-Age Mammal Extinctions: Humans and Climate the Culprits

Hi my Friends: A VUELO DE UN QUINDE EL BLOG., The histories of six large herbivores--the woolly rhinoceros, woolly mammoth, wild horse, reindeer, bison and musk ox--are linked with climate fluctuations and human activity, especially at the end of the last ice age, scientists find in a new report.Many, but not all, ice-age mammals went extinct due to climate change and human influences.

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Research led by evolutionary biologist Eske Willerslev of the Centre for GeoGenetics at the University of Copenhagen along with an international team of paleontologists, geologists, geneticists and climate modelers suggests early humans and changing climate were responsible for the extinction of some cold-adapted animals, and the near-extinction of others.
The journal Nature published the results of the study this week. It was the first to use genetic, archaeological and climate data to infer the population history of large-bodied ice age mammals.
"The combination of approaches in this study--including the most modern molecular tools and painstaking fieldwork--sheds a powerful light on the complex interactions of humans, ecosystems and climate," said Hedy Edmonds, arctic natural sciences program director in the National Science Foundation's (NSF) Office of Polar Programs, Division of Arctic Sciences.
The results carry a message about the possible fates of living mammals as Earth continues to heat up.
"Our findings put a final end to single-cause theories of these extinctions," said Willerslev.
"Our data suggest care should be taken in making generalizations regarding past and present species extinctions," he said. "The relative impacts of climate change and human encroachment on species extinctions really depend on which species we're looking at."
"We couldn't pinpoint what patterns characterize extinct species, despite the large and varying amount of data analyzed," said scientist Eline Lorenzen of the University of Copenhagen, the first author of the paper.
"This suggests that it will be challenging for experts to predict how existing mammals will respond to future global climate change--to predict which species will go extinct and which will survive."
Beth Shapiro, a biologist at Penn State University whose research for the project was funded by NSF, explained that all six of the studied species flourished during the Pleistocene Epoch--the period of geologic time that lasted from about two million to 12,000 years ago.
"During this time, there were lots of climate ups and downs--oscillations between long, warm intervals called interglacial periods, during which the climate was similar to what we have today, followed by long, cold intervals called glacial periods, or ice ages.
"Although cold-adapted animals fared better during the colder glacial periods, they still managed to find places where the climate was just right--refugia--to survive during warmer interglacial periods.
"Then after the peak of the last ice age around 20,000 years ago, their luck started to run out."
What changed?
To find answers, Shapiro and colleagues tested hypotheses about how, when and why the woolly rhinoceros, woolly mammoth and wild horse went extinct after the last ice age and why the reindeer, bison and musk ox were able to survive--albeit in more restricted ranges than during the ice ages.
"One source of information we used was DNA from the animals themselves," Shapiro said. "With genetic data, it's possible to estimate when and how much populations were able to grow and shrink as the climate changed and their habitat started to disappear."
The scientists also collected climate data--temperature and precipitation patterns--from both glacial and interglacial periods, as well as archaeological data, which they used to study the extent to which early humans may have influenced the survival of these species.
"For example, in locations where animal bones had been cooked or converted into spears, we know that humans lived there and were using these mammals as a resource," Shapiro said.
"Even where we didn't find evidence that humans were using the animals, if they lived in the same place and at the same time, humans could have had some influence on whether the animals survived or not."
In the case of the now-extinct woolly rhinoceros, the scientists found that in Europe the ranges of humans and woolly rhinoceros never overlapped.
"These data suggest that climate change, and not humans, was the main reason why this particular species went extinct in present-day Europe," Shapiro said.
"We expect, though, that humans might have played a role in other regions of the world where they did overlap with woolly rhinos."
Much clearer was the evidence that humans influenced, and not always negatively, the population sizes of the five other species in the study--the woolly mammoth, wild horse, reindeer, bison and musk ox.
Population fluctuations for all six species continued until around 14,000 years ago when many of the species simply disappeared at the end of the last ice age.
"The take-home message is that during the most recent warming event, when the last ice age faded into the warm interval we have today, something kept these animals from doing what they had always done, from finding alternative refugia--less-than-ideal, but good-enough chunks of land on which to keep their populations at a critical mass," Shapiro said.
"That 'something' was probably us."
During the time when the animals were declining, the human population was beginning its boom, and was spreading out across not only the large-bodied mammals' cold-climate habitats, but across their warm-climate refuges, changing the landscape with agriculture and other activities.
Many large-bodied, cold-adapted mammals, including the horse--which is considered extinct in the wild and now survives only as a domesticated animal--suddenly had no alternative living spaces, and, as such, no means to maintain their populations.
"The results of our study suggest that although past warm periods caused these animal species to go through periodic bottlenecks--evolutionary events during which the size of a population diminishes substantially and stays small for a long time--they always seemed to bounce back, and to return to their previous habitats as soon as Earth became cooler again," Shapiro said.
"Then, during the most-recent warming cycle, the trend changed."
As the climate became warmer after the last ice age, the woolly rhinoceros, woolly mammoth and wild horse went extinct, but the reindeer, bison and musk ox survived.
Reindeer managed to find safe habitat in high arctic regions where today they have few predators or competitors for limited resources.
Bison are extinct in Asia, where their populations were extensive during the ice ages, and now are found only in North America, although a related species survives in small numbers in Europe.
Cold-adapted musk oxen live only in the arctic regions of North America and Greenland, with small introduced populations in Norway, Siberia and Sweden.
Interestingly, if humans had any impact on musk ox populations, it may have been to help sustain them. Musk ox populations first became established in Greenland around 5,000 years ago, after which they expanded rapidly, despite having been a major food resource for the Paleo-Eskimo population.
Today, the species survives in large numbers.
These findings could help predict the fate of mammal populations threatened by present-day climate change and habitat alteration.
"The results provide direct evidence that something changed between the most-recent glacial cycle, when many of these species went extinct, and previous glacial cycles, through which they all managed to survive," said Shapiro.
"Although it's clear that climate change drives the dynamics of these species, we, as humans, have to take some of the blame for what happened during this most recent cycle."
Our ancestors, it seems, were able to change the landscape so dramatically, said Shapiro, that these animals were effectively cut off from what they needed to survive, even when the human population was small.
"There are many more humans today," she said, "and we have changed, and are continuing to change, the planet in even more important ways."
In addition to Shapiro, Willerslev and Lorenzen, many other scientists contributed to the research. They are from Denmark, Australia, Sweden, Spain, the United Kingdom, the Netherlands, Germany, Norway, Russia, China, Canada and the United States. U.S. co-authors are from institutions in Utah, California, Texas, Missouri, Maryland, Colorado, Massachusetts, Oregon and Kansas.
The Leverhulme Trust, the Awards Fund, the Danish National Research Foundation, the Lundbeck Foundation and the Danish Council for Independent Research also funded the research.
-NSF-
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com
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