Thursday, October 1, 2009

Ancient Rainforests Resilient To Climate Change.


ScienceDaily (Oct. 1, 2009) — Climate change wreaked havoc on the Earth’s first rainforests but they quickly bounced back, scientists reveal. The findings of the research team, led by Dr Howard Falcon-Lang from Royal Holloway, University of London, are based on spectacular discoveries of 300-million-year-old rainforests in coal mines in Illinois, USA.
Preserved over vast areas, these fossilized rainforests in Illinois are the largest of their kind in the world. The rocks at this site - in which the rainforests occur - contain evidence for climate fluctuations. During cold ‘ice ages’, fossils show that the tropics dried out and rainforests were pushed to the brink of extinction. However, rainforests managed to recover and return to their former glory.
Dr Falcon-Lang, from the Department of Earth Sciences, worked with colleagues at the Smithsonian Institution and Illinois Geological Survey. In their paper published in the journal Geology, they show that rainforest species all but vanished at the height of the ice ages. Yet they also reveal that the coal beds that formed shortly after, as the climate warmed, contain abundant rainforest species.
Falcon-Lang said, ‘These discoveries radically change our understanding of the Earth’s first rainforests. We used to think these were stable ecosystems, unchanged for tens of millions of years. Now we know they were incredibly dynamic, constantly buffeted by climate change’.
The research may also shed light on how climate change will affect the Amazon rainforest in the future. Dr Falcon-Lang commented, ‘If we can understand how climate shaped rainforests in the distant past, we can infer how they will respond in the future. We’ve shown that within certain limits, rainforests are resilient to climate change; however, extreme climate change may push rainforests beyond a point of no return’.
The work is part of a five-year project funded by the UK’s Natural Environment Research Council and aims to study how climate change affected the Earth’s first rainforests. These ancient rainforests date from the Carboniferous period, 300 million years ago, when most of the world's coal resources were formed.
Adapted from materials provided by
University of Royal Holloway London, via AlphaGalileo.

Archaeologists Discover Amphitheatre In Excavation Of Portus, Ancient Port Of Rome.

ScienceDaily (Oct. 1, 2009) — University of Southampton archaeologists leading a major excavation of Portus, the ancient port of Rome, have uncovered the remains of an amphitheatre-shaped-building, solving a mystery which has puzzled experts for over 140 years.
The excavation team, working in collaboration with the British School at Rome, is conducting the first ever large-scale dig at Portus on the banks of a hexagonal shaped man-made lake which formed the 2nd century harbour, near the Italian capital.
"When the site was visited by archaeologist Rodolfo Lanciani in the 1860s he marked on his plans the remains of a theatre, but subsequently no trace of the building could be found," says Portus Project Director and leading expert in Roman Archaeology at the University of Southampton, Professor Simon Keay.
"Our team has rediscovered this 'theatre' and proved it was in fact a building more akin to an amphitheatre. Lanciani had only found half of the structure, leading him to misinterpret its shape and function."
Funded by the Arts and Humanities Research Council, experts from Southampton have been working with colleagues from the BSR, The Italian Archaeological Superintendency for Ostia and the University of Cambridge, to carry out extensive excavation at Portus. They have uncovered a large Roman warehouse, the 'amphitheatre' and what the team have identified as an Imperial palace. This is likely to have played host to renowned emperors such as Hadrian.
Portus was Rome's gateway to the Mediterranean for most of the Imperial period and played a key role in funnelling food, slaves, wild animals, marble and all manner of luxury goods from across the Mediterranean and beyond to the citizens of Rome. It was vital to the survival of the Empire and the only real 'transport hub' serving the city.
"The 'amphitheatre' we have discovered was similar in ground area to the Pantheon in Rome, but it is unclear exactly what it was used for," continues Professor Keay.
"Gladiatorial combat may have taken place there - wild beast baiting, the staging of mock sea battles, or it may have been a form of Roman 'folly', shaped like an amphitheatre, but used as a monumental garden. It is unusual to find this type of building so close to a harbour."
Having solved one riddle, archaeologists have now uncovered another; the white marble head of a statue unearthed at the site of once-luxurious rooms close to the 'amphitheatre'. It is thought the head dates back to the 2nd or early 3rd century, however it is less clear who it depicts.
"The elderly bearded male wearing a flat skull-cap could suggest it is Ulysses, however it is equally possible it is a representation of one of the Greek sailors who accompanied him on his travels. For the moment his identity remains a mystery," concludes Professor Keay.
Part of the 'Portus Project' involves the work of the University of Southampton's Archaeological Computing Research Group. They are producing computer generated images which bring the port to life and provide archaeologists with a valuable 'tool' with which to explore the site. The University of Southampton and the BSR are jointly using ground-penetrating radar and other techniques to map buried buildings and other structures. The Portus Project has also been undertaking a geophysical survey of the Isola Sacra, an island to the south of Portus, and has found a major new canal and traces of Rome's marble yards.
Research has been underway at Portus for several years and Professor Keay hopes to continue working there. "This is one of the most important archaeological sites in the world," he says.
"Certainly it should be rated alongside such wonders as Stonehenge and Angkor Wat in Cambodia. So much of this Imperial port has been preserved and there is much more to learn about its role in supplying Rome and in the broader economic development of the Roman Mediterranean."
Adapted from materials provided by
University of Southampton, via AlphaGalileo.

Before 'Lucy,' There Was 'Ardi': First Major Analysis Of Early Hominid Published In Science.


ScienceDaily (Oct. 1, 2009) — In a special issue of Science, an international team of scientists has for the first time thoroughly described Ardipithecus ramidus, a hominid species that lived 4.4 million years ago in what is now Ethiopia.
This research, in the form of 11 detailed papers and more general summaries, will appear in the journal's 2 October 2009 issue. Science is published by AAAS, the nonprofit science society.
This package of research offers the first comprehensive, peer-reviewed description of the Ardipithecus fossils, which include a partial skeleton of a female, nicknamed "Ardi."
The last common ancestor shared by humans and chimpanzees is thought to have lived six or more million years ago. Though Ardipithecus is not itself this last common ancestor, it likely shared many of this ancestor's characteristics. For comparison, Ardipithecus is more than a million years older than the "Lucy" female partial skeleton of Australopithecus afarensis. Until the discovery of the new Ardipithecus remains, the fossil record contained scant evidence of other hominids older than Australopithecus.
Through an analysis of the skull, teeth, pelvis, hands, feet and other bones, the researchers have determined that Ardipithecus had a mix of "primitive" traits, shared with its predecessors, the primates of the Miocene epoch, and "derived" traits, which it shares exclusively with later hominids.
Because of its antiquity, Ardipithecus takes us closer to the still-elusive last common ancestor. However, many of its traits do not appear in modern-day African apes. One surprising conclusion, therefore, is that it is likely that the African apes have evolved extensively since we shared that last common ancestor, which thus makes living chimpanzees and gorillas poor models for the last common ancestor and for understanding our own evolution since that time.
"In Ardipithecus we have an unspecialized form that hasn't evolved very far in the direction of Australopithecus. So when you go from head to toe, you're seeing a mosaic creature, that is neither chimpanzee, nor is it human. It is Ardipithecus," said Tim White of the University of California Berkeley, who is one of the lead authors of the research.
"With such a complete skeleton, and with so many other individuals of the same species at the same time horizon, we can really understand the biology of this hominid," said Gen Suwa of the University of Tokyo, Project paleoanthropologist and also a lead Science author.
"These articles contain an enormous amount of data collected and analyzed through a major international research effort. They throw open a window into a period of human evolution we have known little about, when early hominids were establishing themselves in Africa, soon after diverging from the last ancestor they shared with the African apes," said Brooks Hanson, deputy editor, physical sciences, at Science.
"Science is delighted to be publishing this wealth of new information, which gives us important new insights into the roots of hominid evolution and into what makes humans unique among primates," said Hanson.
The special collection of Science articles begins with an overview paper that summarizes the main findings of this research effort. In this article, White and his coauthors introduce their discovery of over 110 Ardipithecus specimens including a partial skeleton with much of the skull, hands, feet, limbs and pelvis. This individual, "Ardi," was a female who weighed about 50 kilograms and stood about 120 centimeters tall.
Until now, researchers have generally assumed that chimpanzees, gorillas and other modern African apes have retained many of the traits of the last ancestor they shared with humans – in other words, this presumed ancestor was thought to be much more chimpanzee-like than human-like. For example, it would have been adapted for swinging and hanging from tree branches, and perhaps walked on its knuckles while on the ground.
Ardipithecus challenges these assumptions, however. These hominids appear to have lived in a woodland environment, where they climbed on all fours along tree branches – as some of the Miocene primates did -- and walked, upright, on two legs, while on the ground. They do not appear to have been knuckle-walkers, or to have spent much time swinging and hanging from tree-branches, especially as chimps do. Overall, the findings suggest that hominids and African apes have each followed different evolutionary pathways, and we can no longer consider chimps as "proxies" for our last common ancestor.
"Darwin was very wise on this matter," said White.
"Darwin said we have to be really careful. The only way we're really going to know what this last common ancestor looked like is to go and find it. Well, at 4.4 million years ago we found something pretty close to it. And, just like Darwin appreciated, evolution of the ape lineages and the human lineage has been going on independently since the time those lines split, since that last common ancestor we shared," White said.
This special issue of Science includes an overview article, three articles that describe the environment Ardipithecus inhabited, five that analyze specific parts of Ardipithecus' anatomy, and two that discuss what this new body of scientific information may imply for human evolution.
Altogether, forty-seven different authors from around the world contributed to the total study of Ardipithecus and its environment. The primary authors are Tim White of the University of California, Berkeley, Berhane Asfaw of Rift Valley Research Service in Addis Ababa, Giday WoldeGabriel of Los Alamos National Laboratory, Gen Suwa of the University of Tokyo, and C. Owen Lovejoy of Kent State University.
"These are the results of a mission to our deep African past," said WoldeGabriel, who is also Project co-Director and geologist.
This research was funded by the National Science Foundation, the Institute of Geophysics and Planetary Physics of the University of California at Los Alamos National Laboratory (LANL), the Japan Society for the Promotion of Science, and others.
Adapted from materials provided by
American Association for the Advancement of Science, via EurekAlert!, a service of AAAS.

Was Mighty T. Rex 'Sue' Felled By A Lowly Parasite?

ScienceDaily (Sep. 30, 2009) — When pondering the demise of a famous dinosaur such as 'Sue,' the mighty Tyrannosaurus rex whose fossilized remains are a star attraction of the Field Museum in Chicago, it is hard to avoid the image of clashing Cretaceous titans engaged in bloody, mortal combat.
It is an image commonly promoted by museums and dinosaur aficionados. Sue's remains, in fact, exhibit holes in her jaw that some believed were battle scars, the result of conflict with another dinosaur, possibly another T. rex.
But a new study, published in the online journal PLoS ONE, provides evidence that Sue, perhaps the most famous dinosaur in the world, was felled in more mundane fashion by a lowly parasite that still afflicts modern birds. The study, conducted by an international team of researchers led by Ewan D.S. Wolff of the University of Wisconsin-Madison and Steven W. Salisbury of the University of Queensland, Australia, pins the demise of Sue and other tyrannosaurs with similar scars on an avian parasitic infection called trichomonosis, caused by a single-celled parasite that causes similar pathologies on the mandibles of modern birds, raptors in particular.
It is possible the infection in her throat and mouth may have been so acute that the 42-foot-long, 7-ton dinosaur starved to death, says Wolff, a vertebrate paleontologist and a third-year student at the UW-Madison School of Veterinary Medicine. Co-authors of the study include famed paleontologist John R. Horner of the Museum of the Rockies, which funded the study, and David J. Varricchio of Montana State University.
The focus of the new study was a survey of lesions on the jaws of Sue and nine other tyrannosaur specimens. The lesions had previously been attributed to bite wounds or, possibly, a bacterial infection.
"What drew my attention to trichomonosis as a potential candidate for these mysterious lesions on the jaws of tyrannosaurs is the manifestation of the effects of the disease in [bird] raptors," explains Wolff. "When we started looking at trichomonosis in greater depth, there was a story that matched some lines of evidence for transmission of the disease in tyrannosaurs."
In birds, trichomonosis is caused by a protozoan parasite called Trichomonas gallinae. It can be transmitted from birds such as pigeons, which commonly carry the parasite but often suffer few ill effects, to raptors such as falcons and hawks, where it causes serious lesions in the mandibles. The pattern of lesions, says Wolff, closely matches the holes in the jaws of tyrannosaurs and occurs in the same anatomical location.
The scars of combat among tyrannosaurs and other dinosaurs, Wolff notes, are not uncommon, but differ notably from the lesions that are the focus of the current study. The holes caused by trichomonosis tend to be neat and have relatively smooth edges, while bite marks are often messy, and they scar and puncture bone in ways that are not readily comparable.
Tyrannosaurs, notes Wolff, are known to have been gregarious, intermingling, fighting amongst themselves, and sometimes eating one another. Transmission of the parasite may have been through salivary contact or cannibalism, he says, noting that there is no known evidence of trichomonosis in other dinosaurs.
"This leads us to suspect that tyrannosaurs might have been the source of the disease and its transmission in its environment," Wolff says.
For the disease to manifest itself in the jaws of Sue and other tyrannosaurs, it would have had to be at an advanced stage as the parasite typically sets up housekeeping as a film in the back of the throat.
"The lesions we observe on Sue suggest a very advanced stage of the disease and may even have been the cause of her demise," says Wolff. "It is a distinct possibility as it would have made feeding incredibly difficult. You have to have a viable pharynx. Without that, you won't make it for very long, no matter how powerful you are."
Journal reference:
Ewan D. S. Wolff, Steven W. Salisbury, John R. Horner, David J. Varricchio. Common Avian Infection Plagued the Tyrant Dinosaurs. PLoS ONE, 2009; 4(9): e7288 DOI:
Adapted from materials provided by University of Wisconsin-Madison.