Paleontology news

The mode of reproduction seen in modern sharks is nearly 400 million years old. That is the conclusion drawn by Professor Per Erik Ahlberg, Uppsala University, from his discovery of a so-called "clasper" in a primitive fossil fish earlier this year. The research results are published today in Nature. In February this year, a paper published in Nature by a team of Australian and British researchers showed that placoderms, a group of ancient fishes that died out more than 350 million years ago, gave birth to live young. Beautifully preserved fossil embryos in the body cavity of the placoderm Incisoscutum showed that these fishes, close to the common origin of all jawed vertebrates, had a mode of reproduction similar to modern sharks. Live birth requires internal fertilisation; sharks achieve this by using a "clasper", an extension of the pelvic fin that functions like a penis. The authors looked for a clasper in their placoderm fossils but couldn't find one, so they were forced to argue that it had been made of soft cartilage and had not been preserved.

Shortly afterwards, Per Erik Ahlberg from Uppsala University visited one of the Australian researchers and spotted a perfectly preserved bony clasper in one of their Incisoscutum fossils.

"It was lying in plain view but had been misinterpreted as part of the pelvis and overlooked," he says.

Together with the original authors he is publishing a short paper in this week's Nature that presents this missing piece of the puzzle and completes the picture of placoderm reproduction from mating to birth.

"It provides a pedigree of nearly 400 million years for the "advanced" and seemingly specialised reproductive biology of modern sharks," says Per Ahlberg.

credited to esciencenews.com

Prehistoric communities in one part of Peru’s Andes Mountains may have gone from maize to amazingly complex. Bioarchaeologist Brian Finucane’s analyses of human skeletons excavated in this region indicate that people living there 2,800 years ago regularly ate maize. This is the earliest evidence for maize as a staple food in the rugged terrain of highland Peru, he says.

Maize agriculture stimulated ancient population growth in the Andes and allowed a complex society, the Wari, to develop, Finucane contends in the August Current Anthropology. Wari society included a central government and other elements of modern states. It lasted from around 1,300 to 950 years ago and predated other Andes civilizations, including the Inca.

Scientists disagree about when and how civilizations formed in the Andes. One theory holds that complex societies, which perhaps fell short of states with centralized bureaucracies, first appeared at least 3,600 years ago in fishing villages along Peru’s coast and then spread inland. Based on remains of various wild and domesticated plants found at inland sites, other researchers suspect that agriculture had an especially big impact on the establishment of highland societies, beginning roughly 2,500 years ago. Questions also remain about whether prehistoric Andean civilizations depended primarily on maize or on a suite of crops including potatoes and beans.

Previous work has shown that prehistoric societies in the lowland areas of Central and North America depended on maize to grow large enough in numbers to develop state institutions, a pattern that Finucane sees paralleled in the Andes Mountains.

“These new findings indicate that intensive maize agriculture was the economic foundation for the development of the Wari state,” says Finucane, currently a law student at Yale University.

The new data convincingly demonstrate that highland residents relied on maize shortly before the rise of the Wari state, comments archaeologist Daniel Sandweiss of the University of Maine in Orono. A warmer, wetter climate during the Wari period and the spread of terraced cultivation areas may also have spurred maize farming, he suggests.

Not directly addressed by Finucane’s findings is whether ancient fishing villages provided the basis for later Andean civilizations, such as the Wari, says Sandweiss, a proponent of that hypothesis.

Finucane analyzed the chemical composition of bones from 103 individuals excavated by other researchers at six prehistoric sites in Peru’s Ayacucho Valley, one of several Andean regions where early civilizations arose. Ratios of certain chemical isotopes that collect in bone reflect the types of foods that an individual consistently consumed over at least the last decade of life.

Radiocarbon measurements of human bones at each site yielded age estimates that ranged from 2,800 years to 900 years. This time span encompasses three eras of Ayacucho prehistory: the Formative period of small farming villages, the Huarpa period of expanded settlements and irrigated fields, and the Wari period of centralized bureaucracy and state government.

Chemical signatures of substantial maize consumption appeared in the bones of individuals from every Ayacucho site, including three from Formative period sites, Finucane says.

Only a relatively small part of the Andean valley contains soil suitable for maize cultivation. Competition for cropland, he speculates, may account for evidence of considerable warfare during the Huarpa and Wari periods.

Finucane “makes a strong case” for maize as a key food in the Ayacucho Valley by about 1,800 years ago, but not 2,800 years ago as argued in his new paper, remarks Yale University anthropologist Richard Burger, who was not involved in the study. Only one skeleton in Finucane’s sample can be definitively dated to the Formative period, and signs of maize consumption in that specimen remain preliminary, in Burger’s view.

Finucane’s proposal is not out of the question, though. Another recent study of bone isotopes suggests that maize was regularly eaten at highland Andes sites in Argentina beginning around 4,000 years ago, says anthropologist Robert Tykot of the University of South Florida in Tampa. Tykot co-authored that investigation.

Chemical analyses are needed of other human skeletons that have been found at Formative period sites, Burger adds. Investigations of prehistoric diets in Andes valleys located at higher altitudes than Ayacucho will offer additional insights.

credited to sciencenews.org

It has been 400 years since English explorer Henry Hudson mapped the northeast coast of North America, leaving a wake of rivers and towns named in his honor, yet what happened to the famed explorer remains a mystery.

Hudson was never heard from again after a mutiny by his crew during a later voyage through northern Canada. That he died in the area in 1611 is a certainty, and he may have even been killed in cold blood, according to new research.

Australian palaeontologists say they have discovered three new dinosaur species after examining fossils dug up in Queensland.

Writing in the journal PLOS One, they describe one of the creatures as a fearsome predator with three large slashing claws on each hand.

The other two were herbivores: one a tall giraffe-like creature, the other of stocky build like a hippopotamus.

The fossils date back nearly 100m years to the middle of the Cretaceous period.

They were found in rocks known as the Winton Formation.

Beyond velociraptor

Queensland Museum palaeontologist, Scott Hucknell, said the carnivore, Australovenator wintonensis, was even bigger and more terrifying than velociraptor made famous in the Jurassic Park movies.

"The cheetah of his time, Banjo was light and agile. He could run down most prey with ease over open ground," he told reporters.

The dinosaurs have been named after characters in Australia's famous song, Waltzing Matilda.

The carnivore has been named named after Banjo Patterson, who composed Waltzing Matilda in Winton in 1885, the Sydney Morning Herald newspaper explained.

Clancy, Witonotitan wattsi, was a tall slender animal, while Matilda, Diamantinasaurus matildae, was more stocky and hippo-like.

These two plant-eating, four-legged sauropod species are new types of titanosaurs - the largest animals ever to walk the earth.

Banjo and Matilda - possibly predator and his prey - were found buried together in a 98m year old billabong, or stagnant pond.

Breakthrough

The find was published in the public access journal Public Library of Science One, and was announced by Queensland Premier Anna Bligh at the Australian Age of Dinosaurs Museum of Natural History in Winton.

She said the discoveries were a major breakthrough in the scientific understanding of prehistoric life in Australia.

Museum Victoria palaeontologist, John Long, said the finds were "amazing".

The newspaper quoted him saying that the finds put Australia back on the international map of big dinosaur discoveries for the first time since 1981, when the discovery of Muttaburrasaurus, a large four-legged herbivore that could rear up on two legs, was announced.

The new species will be part of the Australian Age of Dinosaurs Museum of Natural History under construction in Winton. This aims to house the world's largest collection of Australian dinosaur fossils when it is completed in 2015.

New Zealand's best known palaeontologist, self-taught Havelock North fossil hunter Joan Wiffen, has died aged 87.

Mrs Wiffen, who became known as the Dinosaur Lady, died suddenly in Hastings Hospital on Tuesday.

Her dig at Maungahouanga in Hawke's Bay was the first known site where dinosaurs lived in New Zealand.

Mrs Wiffen was the author and co-author of more than a dozen scientific papers and wrote of her achievements in her book Valley of the Dragons.

Born in 1922 and brought up in the King Country and Hawke's Bay during the 1930s Depression, Mrs Wiffen later recalled marvelling at the presence of sea shells high in the hills.

But she had only a brief secondary education – her father believed higher education was wasted on girls and she was expected to get married and have a family.

She served in the Women's Auxiliary Air Force during World War 2 and worked for six years as a clerk before marrying Pont Wiffen in 1953.

The couple raised their two children at Haumoana near Hastings, and the family hobby was rock collecting – they gathered minerals and fossils from throughout New Zealand and Australia.

Her husband enrolled in night classes in geology, and when he was ill, she went in his place and recalled being "green with envy" when someone found a fossil shell in mudstone.

"I knew what I wanted – to collect fossils," she said later.

Following an old geological map indicating reptilian bones in the Te Hoe Valley, she found the tail bone of a theropod dinosaur in the Maungahouanga valley in northern Hawke's Bay in 1975.

Mrs Wiffen went on to find bones from half a dozen other dinosaurs, including an armoured ankylosaur, a hypsilophodont, as well as a pterosaur flying reptile, and marine reptiles, such as mosasaurs and plesiosaurs.

In 1999, she found bone from one of the largest known dinosaurs, a titanosaurid: "I saw a partly exposed concretion (sedimentary rock) about the size of a rugby ball in the stream bank. I dug it out and asked a colleague to break it open with a hammer," she said afterwards.

"I immediately saw a bone structure inside that looked different from the bone of a marine reptile."

Friends and family helped her recover heavy sandstone rock from which she extracted the fossils with painstaking cutting and grinding and use of acid baths.

In 1994, she received an honorary doctorate from Massey University and the following year a CBE.

In 2004, she accepted the Morris Skinner Award from the United States-based Society of Vertebrate Palaeontology for outstanding and sustained contributions to scientific knowledge.

Her fossil finds are held in the palaeontology collection of GNS Science, with some on loan to Te Papa.

A spokesman at GNS said her scientific endeavours spanned arduous field work, painstaking fossil preparation, taxonomic description and palaeontological interpretation.

"Her contributions were extremely important nationally and give New Zealand geographic position, internationally," the institute said.

She also promoted palaeontology through contributions to popular books and articles, public lectures and school presentations.

Mrs Wiffen is survived by her son and daughter and a stepson and their families.

credited to stuff.co.nz

A Princeton University geoscientist who has stirred controversy with her studies challenging a popular theory that an asteroid wiped out the dinosaurs has compiled powerful new evidence asserting her position. Gerta Keller, whose studies of rock formations at many sites in the United States, Mexico and India have led her to conclude that volcanoes, not a vast meteorite, were the more likely culprits in the demise of the Earth's giant reptiles, is producing new data supporting her claim.

Keller, a Princeton professor of geosciences, and several co-authors lay out the case in a paper published April 27 in the Journal of the Geological Society of London. Examinations at several new sites have produced "biotic evidence" -- the fossilized traces of plants and animals tied to the period in question -- indicating that a massive die-off did not occur directly after the strike but much later.

In addition, Keller and other researchers have found "aftermath" sediments that remained undisturbed and showed signs of active life, with burrows formed by creatures colonizing the ocean floor. This would quash a theory advanced by some that a massive tsunami followed the impact, Keller said.

"Careful documentation of results that are reproducible and verifiable will uncover what really happened," Keller said. "This study takes an important step in that direction."

Much of the new data comes from a trench dug out of low-lying hills in northeastern Mexico at a site called El Peñon. A group of Princeton undergraduates accompanying Keller on a field trip to Mexico in 2004 excavated the area and uncovered the new evidence. Keller and her team have been analyzing that evidence for the last several years.

Understanding what caused the dinosaurs to disappear remains a great mystery. Theories attempting to explain it include asteroid or cometary impacts, volcanoes, global climate change, rising sea levels and supernova explosions. Scientists know that at a point about 65 million years ago, some phenomenon triggered mass extinctions on the land and oceans.

This event defines the boundary between the older Mesozoic Era, the "Age of Reptiles," and the modern Cenozoic Era, the "Age of Mammals." On a finer geological scale, the disappearances occurred between the Cretaceous (K) period and the Tertiary (T) period. As a result, scientists refer to this time as the K-T boundary.

At many locations, the K-T boundary is clearly visible in rock formations, which contain a thin layer of clay rich in the element iridium. Because iridium is more common in asteroids and comets than on Earth, scientists proposed in 1980 that an asteroid or comet must have struck Earth just at the boundary and caused the mass extinction of dinosaurs and many other animals. They thought they had found the culprit when they discovered the Chicxulub impact crater in Mexico's northern Yucatan.

Keller began studying the K-T boundary in 1984 -- the year she arrived at Princeton. She discovered that the evidence for the asteroid theory was not so clear. In field investigations, she and her team of students and collaborators found populations of Cretaceous age foraminifera, one-celled ocean organisms that evolved rapidly during select geological periods, living on top of the impact fallout from Chicxulub. The fallout from the asteroid that struck Chicxulub is visible as a layer of glassy beads of molten rock that rained down after the impact. If this impact caused the mass extinction, then the foraminifera above the impact glass beads should have been the newly evolved species of the Tertiary age.

Using these fossil remains to construct a timeline, she and her team were able to date the surrounding geologic features and begin to piece together proof that the impact occurred 300,000 years before the great extinction.

Over the years, Keller's group has amassed evidence for as many as four major events widely separated in time in that area of Mexico as well as in Texas. The oldest of the four events is the Chicxulub impact, seen by the fallout of glass beads. The second is about 150,000 years later and seen in a layer of sandstone with Chicxulub impact glass beads that were transported from shallow shore areas into deep waters during a sea level fall and was commonly interpreted as a tsunami generated by the Chicxulub impact. About 100,000 to 150,000 years later, the third event struck at the time of the K-T boundary with its iridium layer and mass extinction. This event may represent a second large impact or massive volcanism. The fourth event is possibly a smaller impact as evidenced by another iridium layer about 100,000 years after the mass extinction.

Advocates of the Chicxulub impact theory suggest that the impact crater and the mass extinction event only appear far apart in the sedimentary record because an earthquake or tsunami caused slumps and mixing of sediments surrounding the Gulf of Mexico. To date no evidence of major disturbance has been found in the sediments.

Keller says her team's newest research, however, confirms what she has found in earlier studies -- that the sandstone complex that overlays the impact layer was not deposited over hours or days by a tsunami but over a long time period. From El Peñon in Mexico and other sites listed in the new study, the scientists were able to calculate that between 13 and 30 feet of sediments were deposited at a rate of about an inch per thousand years after the impact. These sediments separating the impact layer from the sandstone complex and the overlying mass extinction were formed by normal processes. There is evidence of erosion and transportation of sediments in the sandstone layers, but no evidence of structural disturbance, Keller said.

Also at El Peñon, the researchers found 52 species present in sediments below the impact layer and counted all 52 still present in the layer above it, indicating that the impact has not had the devasting biotic effect on species diversity as has been suggested. "Not a single species went extinct as a result of the Chicxulub impact," Keller said.

In contrast, she noted, at a nearby site known as La Sierrita where the K-T boundary, iridium anomaly and mass extinction are recorded, 31 out of 44 species disappeared from the fossil record at the K-T boundary.

"Keller and colleagues continue to amass detailed stratigraphic information supporting new thinking about the Chicxulub impact and the mass extinction at the end of the Cretaceous," said Richard Lane, program director in the National Science Foundation's division of earth sciences, which funded the research. "The two may not be linked after all."

Keller suggests that the massive volcanic eruptions at the Deccan Traps in India may be responsible for the extinction, releasing massive amounts of dust and gases that could have blocked sunlight, altered climate and caused acid rain. The fact that the Chicxulub impact seems to have had no effect on biota, she said, despite its 6-mile-in-diameter size, indicates that even large asteroid impacts may not be as deadly as imagined.

She regards the latest evidence as sufficiently convincing and compelling to allow her to move on and investigate further the evidence for Deccan volcanism as being at the root of dinosaur extinction. But she does not expect her teams' present work will stop the raging debate at the heart of this controversy.

"The decades-old controversy over the cause of the K-T mass extinction will never achieve consensus," Keller said. But consensus, she added, is not a precondition to advancing science and unraveling truth. "What is necessary is careful documentation of results that are reproducible and verifiable," she said.

credited to esciencenews.com