But for Yusfiq's --- In proletar@yahoogroups.com, "Jusfiq Hadjar" <harimau_ca...@...> wrote: > > > Bukan untuk Abbas Amin, Bang Mossad, Dipo, ndeboost, PAREWA PAREWA, > rezameutia, Roman Proteus, Tawang dll yang otaknya sudah pada rusak dan takut > mengikuti perkembangan penelitian paleontolog seperti dibawah ini. > > Web address: > http://www.sciencedaily.com/releases/2010/07/ > 100715105951.htm > Remarkable Fossil Cave Shows How Ancient Marsupials Grew > enlarge > > Skull of sheep-sized diprotodontid Nimbadon lavarackorum from the middle > Miocene cave deposit, AL90. (Credit: Karen Black, UNSW) > > ScienceDaily (July 18, 2010) â" 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." > Email or share this story: > | More > > Story Source: > > The above story is reprinted (with editorial adaptations by ScienceDaily > staff) from materials provided by University of New South Wales. The original > article was written by Bob Beale. > > Journal Reference: > > 1. Karen H. Black; Michael Archer; Suzanne J. Hand; Henk Godthelp. First > comprehensive analysis of cranial ontogeny in a fossil marsupial -- from a > 15-million-year-old cave deposit in northern Australia. Journal of Vertebrate > Paleontology, 2010; DOI: 10.1080/02724634.2010.483567 > > Need to cite this story in your essay, paper, or report? Use one of the > following formats: > APA > > MLA > University of New South Wales (2010, July 18). Remarkable fossil cave shows > how ancient marsupials grew. ScienceDaily. Retrieved July 19, 2010, from > http://www.sciencedaily.com /releases/2010/07/100715105951.htm > > Note: If no author is given, the source is cited instead. >
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