Friday, July 30, 2010

REMARKABLE FOSSIL CAVE SHOWS HOW ANCIENT MARSUPIALS GREW

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The discovery of a remarkable 15-million-year-old Australian fossil limestone cave packed with even older animal bones has revealed almost the entire life cycle of a large prehistoric marsupial, from suckling young in the pouch still cutting their milk teeth to elderly adults.

In an unprecedented find, a team of University of New South Wales [Sydney Australia] researchers in has unearthed from the cave floor hundreds of beautifully preserved fossils of the extinct browsing wombat-like marsupial Nimbadon lavarackorum, along with the remains of galloping kangaroos, primitive bandicoots, a fox-sized thylacine and forest bats.

By comparing the skulls of 26 different Nimbadon individuals that died in the cave at varying stages of life the team has been able to show that its babies developed in much the same way as marsupials today, probably being born after only a month's gestation and crawling to the mother's pouch to complete their early development.

Details of the find at a site known as AL90 in the famous Riversleigh World Heritage fossil field in Queensland are published in the Journal of Vertebrate Paleontology, by a team led by Dr Karen Black, of the UNSW School of Biological, Earth and Environmental Sciences. The research was supported by the Xstrata Community Partnership Program North Queensland and the Australian Research Council.

"This is a fantastic and incredibly rare site," says Dr Black. "The exceptional preservation of the fossils has allowed us to piece together the growth and development of Nimbadon from baby to adult. So far 26 skulls - ranging in age from suckling pouch young and juveniles right through to elderly adults - have been recovered, as well as associated skeletons.

"The animals appear to have plunged to their deaths through a vertical cave entrance that may have been obscured by vegetation and acted as a natural pit-fall trap. These animals – including mothers with pouch young - either unwittingly fell to their deaths or survived the fall only to be entombed and unable to escape.

"The ceiling and walls of the cave were eroded away millions of years ago, but the floor of the cave remains at ground level. We have literally only scratched its surface, with thousands more bones evident at deeper levels in the deposit.'

The site is also scientifically important because it documents a critical time in the evolution of Australia's flora and fauna when lush greenhouse conditions were giving way to a long, slow drying out that fundamentally reshaped the continent's cargo of life as rainforests retreated.

Dr Black notes that the Nimbadon skulls also reveal that early in life, the emphasis of its growth was on the development of bones at the front of the face, to help the baby to suckle from its mother. As it grew older and its diet changed to eating leaves, the rest of the skull developed and grew quite massive by way of a series of bony chambers surrounding the brain.

Team member Professor Mike Archer says: "Yet we found that its brain was quite small and stopped growing relatively early in its life. We think it needed a large surface area of skull to provide attachments for all the muscle power it required to chew large quantities of leaves, so its skull features empty areas, or sinus cavities. Roughly translated, this may be the first demonstration of how a growing mammal 'pays' for the need to eat more greens - by becoming an 'airhead'.

"The abundance of Nimbadon fossils also suggests that they travelled in family groups or perhaps even larger gatherings: it's possible that this also reflects the beginning of mob behaviour in herbivorous marsupials, such as we see today in grey kangaroos."

(Photo: Karen Black)

University of New South Wales

MAYA KING’S TOMB DISCOVERED IN GUATEMALA

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A well-preserved tomb of an ancient Maya king has been discovered in Guatemala by a team of archaeologists led by Brown University’s Stephen Houston. The tomb is packed with carvings, ceramics, textiles, and the bones of six children, who may have been sacrificed at the time of the king’s death.

The team uncovered the tomb, which dates from about 350 to 400 A.D., beneath the El Diablo pyramid in the city of El Zotz in May. The news was made public yesterday during a press conference in Guatemala City, hosted by the Ministry of Culture and Sports, which authorized the work.

Before making the actual discovery, Houston said the team thought “something odd” was happening in the deposit they were digging. They knew a small temple had been built in front of a sprawling structure dedicated to the sun god, an emblem of Maya rulership. “When we sunk a pit into the small chamber of the temple, we hit almost immediately a series of ‘caches’ — blood-red bowls containing human fingers and teeth, all wrapped in some kind of organic substance that left an impression in the plaster. We then dug through layer after layer of flat stones, alternating with mud, which probably is what kept the tomb so intact and airtight.”

Then on May 29, 2010, Houston was with a worker who came to a final earthen layer. “I told him to remove it, and then, a flat stone. We’d been using a small stick to probe for cavities. And, on this try, the stick went in, and in, and in. After chipping away at the stone, I saw nothing but a small hole leading into darkness.”

They lowered a bare light bulb into the hole, and suddenly Houston saw “an explosion of color in all directions — reds, greens, yellows.” It was a royal tomb filled with organics Houston says he’d never seen before: pieces of wood, textiles, thin layers of painted stucco, cord.

“When we opened the tomb, I poked my head in and there was still, to my astonishment, a smell of putrification and a chill that went to my bones,” Houston said. “The chamber had been so well sealed, for over 1600 years, that no air and little water had entered.”

The tomb itself is about 6 feet high, 12 feet long, and four feet wide. “I can lie down comfortably in it,” Houston said, “although I wouldn’t want to stay there.”

It appears the tomb held an adult male, but the bone analyst, Andrew Scherer, assistant professor of anthropology at Brown, has not yet confirmed the finding. So far, it seems likely that there are six children in the tomb, some with whole bodies and probably two solely with skulls.

And who was this man? Though the findings are still very new, the group believes the tomb is likely from a king they only know about from other hieroglyphic texts — one of Houston’s specialties in Maya archaeology. “These items are artistic riches, extraordinarily preserved from a key time in Maya history,” said Houston. “From the tomb’s position, time, richness, and repeated constructions atop the tomb, we believe this is very likely the founder of a dynasty.”

Houston says the tomb shows that the ruler is going into the tomb as a ritual dancer. He has all the attributes of this role, including many small ‘bells’ of shell with, probably, dog canines as clappers. There is a chance too, that his body, which rested on a raised bier that collapsed to the floor, had an elaborate headdress with small glyphs on them. One of his hands may have held a sacrificial blade.”

The stone expert on site, Zachary Hruby, suspects the blade was used for cutting and grinding through bone or some other hard material. Its surface seems to be covered with red organic residue. Though the substance still needs to be tested, “it doesn’t take too much imagination to think that this is blood,” Houston said.

“We still have a great deal of work to do,” Houston said. “Remember, we’ve only been out of the field for a few weeks and we’re still catching our breath after a very difficult, technical excavation. Royal tombs are hugely dense with information and require years of study to understand. No other deposits come close.”

(Photo: Arturo Godoy)

Brown University

AUTISM HAS UNIQUE VOCAL SIGNATURE, NEW TECHNOLOGY REVEALS

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A new automated vocal analysis technology could fundamentally change the study of language development as well as the screening for autism spectrum disorders and language delay, reports a study in the July 19 online Proceedings of the National Academy of Sciences.

The LENA™ (Language Environment Analysis) system automatically labeled infant and child vocalizations from recordings and thereafter an automatic acoustic analysis designed by the researchers showed that pre-verbal vocalizations of very young children with autism are distinctly different from those of typically developing children with 86 percent accuracy.

The system also differentiated typically developing children and children with autism from children with language delay based on the automated vocal analysis.

The researchers analyzed 1,486 all-day recordings from 232 children (or more than 3.1 million automatically identified child utterances) through an algorithm based on the 12 acoustic parameters associated with vocal development. The most important of these parameters proved to be the ones targeting syllabification, the ability of children to produce well-formed syllables with rapid movements of the jaw and tongue during vocalization. Infants show voluntary control of syllabification and voice in the first months of life and refine this skill as they acquire language.

The autistic sample showed little evidence of development on the parameters as indicated by low correlations between the parameter values and the children's ages (from 1 to 4 years). On the other hand, all 12 parameters showed statistically significant development for both typically developing children and those with language delays.

The research team, led by D. Kimbrough Oller, professor and chair of excellence in audiology and speech language pathology at the University of Memphis, called the findings a proof of concept that automated analysis of massive samples of vocalizations can now be included in the scientific repertoire for research on vocal development.

Although aberrations in the speech (or lack of it) of children with autism spectrum disorders has been examined by researchers and clinicians for more than 20 years, vocal characteristics are not included in standard criteria for diagnosis of autism spectrum disorders, said Steven F. Warren, professor of applied behavioral science and vice provost for research at the University of Kansas, who contributed to the study and was among the first to see the potential of the technology for autism spectrum disorders screening.

"A small number of studies had previously suggested that children with autism have a markedly different vocal signature, but until now, we have been held back from using this knowledge in clinical applications by the lack of measurement technology," said Warren.

Warren predicts that LENA, which allow the inexpensive collection and analysis of magnitudes of data unimagined in language research before now, could significantly impact the screening, assessment and treatment of autism and the behavioral sciences in general.

Since the analysis is not based on words, but rather on sound patterns, the technology theoretically could potentially be used to screen speakers of any language for autism spectrum disorders, Warren said. "The physics of human speech are the same in all people as far as we know."

Warren says that children with autism spectrum disorders can be diagnosed at 18 months but that the median age of diagnosis is 5.7 years in the United States.

"This technology could help pediatricians screen children for ASD to determine if a referral to a specialist for a full diagnosis is required and get those children into earlier and more effective treatments."

LENA is digital language processor and language analysis software. The processor fits into the pocket of specially designed children's clothing and records everything the child vocalizes but can reliably distinguish child vocalizations from its cries and vegetative sounds, other voices and extraneous environmental sounds.

Recordings with the device have been collected since 2006. Parents responded to advertisements and indicated if their children had been diagnosed with autism or language delay. A speech-language clinician employed by the project also evaluated many of the children with a reported diagnosis of language delay. Many of the parents of children with language delay and all of the children with autism supplied documentation from the diagnosing clinicians, who were independent of the research.

The recordings were made by the parents at home and in the other natural environments of the children, by simply turning the recorder on and placing in the special children's clothing, and then worn all day.

The discovery that it was possible to differentiate recordings of the autistic children from those of the typically developing children by the totally objective method of automated vocal analysis inspired the researchers to consider both the possibility of earlier screening and diagnosis and earlier intervention for children with autism.

"Autism interventions remain expensive and arduous. This tool may help us to develop cost-effective treatments and better understand how they work and how to keep them working," said Warren.

LENA could allow parents to continue and supplement language enrichment therapy at home and assess their own effectiveness for themselves, Warren said. "In this way, LENA could function similarly to the way a pedometer measures how much exercise one gets from walking."

University of Kansas

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