TATACARA TREATMENT SAMPEL FOSIL MAKRO

Pengelolaan sampel untuk mendapatkan fosil merupakan tahap akhir yang menentukan keberhasilan memisahkan fosil dari batuan. Seorang paleontologist dengan intuisinya hendaknya mampu menduga jenis batuan yang banyak mengandung fosil, sedikit mengandung fosil dan tidak mengandung fosil (barren fosil), khususnya untuk keberadaan fosil mikro. Untuk fosil makro, karena ukurannya relatif besar dapat langsung dilihat di lapangan. Perlakuan untuk mendapatkan fosil makro, agak  berbeda dengan fosil mikro. Pada saat akan bekerja di lapangan jangan dilupakan mempersiapkan peralatan lapangan, dalam bentuk palu geologi, pahat kecil, kuas, kantong sampel yang tahan air secukupnya, larutan HCl 0,1 N, buku catatan lapangan, pensil, spidol waterprof, pisau lipat dan alat GPS. Demi keselamatan pada saat di lapangan, memakai pakaian lapangan, sepatu lapangan dan topi lapangan, sarung tangan, sangat dianjurkan untuk dipergunakan, dan membawa obat-obatan PPPK. Jangan lupa juga peta topografi/peta geologi untuk ploting lapangan dan kompas geologi.

 

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PERLAKUAN PADA FOSIL MAKRO

Persiapkan palu geologi, pahat kecil, kuas, dan kantong sampel yang tahan air, dan larutan HCl 0,1 N, buku catatan lapangan, pensil dan alat GPS. Palu geologi diperlukan jenis palu batuan sedimen (dengan salah satu ujungnya berbentuk pahat), bersama dengan pahat dipergunakan untuk melepas fosil dari batuan. Bekerjalah dengan hati-hati, karena  pada umumnya fosil yang didapatkan  dalam kondisi relatif  lapuk dan mudah pecah. Sesudah fosil terlepas dari batuan, keringkan fosil yang masih dalam keadaan kotor dengan cara dijemur di panas matahari, dan ditempatkan  pada  para-para yang berlubang-lubang. Apabila fosil sudah dalam keadaan kering, bersihkan “tubuh fosil” dengan kuas yang telah dipersiapkan. Perlakukan fosil dengan baik, bersihkan semua “kotoran” yang menempel.

Catatan

Jangan sekali-kali membersihkan fosil dengan larutan asam keras [(HCl 0,1 N) sekalipun]. Larutan asam ini akan bereaksi dengan kalsium karbonat yang merupakan komposisi utama fosil. Bila ini dilakukan permukaan fosil akan rusak, hiasan (ornament) pada fosil dapat larut dan hilang. Larutan HCl, ditempatkan pada botol khusus, yang berlabel HCl, yang mudah dibawa, tutup botol mudah dibuka dan ditutup rapat. Bila kulit tangan terkena larutan HCl, segera cuci dengan air. Bungkus HCl dengan bungkus plastik dan tempatkan di tas lapangan. Jangan sekali-kali menyimpan larutan HCl dalam saku celana atau baju, karena  dapat mengakibatkan kantong berlubang bila terkena larutan HCl yang “bocor” dari tutup botol. Larutan HCl dapat dibeli di apotek dengan kadar 1 Normal ( 1 N), yang mudah menguap dan sangat reaktif. Untuk keperluan tugas lapangan larutan HCl, 1 Normal tersebut diencerkan dengan air distilasi (aquadestilata atau dapat juga memperguanakan air minum kemasan dalam botol). 

MEMBUAT LARUTAN HCl 0,1 N

Larutan HCl yang disediakan oleh toko bahan kimia/ apotek umumnya sangat kental dengan tingkat kepekatan 1  (satu) Normal,  biasa ditulis 1 N. Larutan asam ini mudah sekali menguap dan berbahaya bila terhirup oleh manusia. Disamping itu larutan HCl 1 (satu) N juga sangat reaktif, bila terkena kulit mengakibatkan kulit mengelupas dan bila terkena kain, kain akan terbakar dan berlubang. Oleh sebab itu larutan HCl yang dibawa ke lapangan tingkat kepekatannya harus diturunkan dengan cara diencerkan.

Rumusan untuk mengencerkan adalah: V₁xN₁ = V₂xN_2. Apabila diinginkan N₂=0,1 N, sedang larutan HCl yang dipunyai semula kadarnya 1 Normal, maka  persamaan dapat dituliskan sebagai berikut:

V₁ = 10 cc, N₁ = 1 N, sedang kadar HCl yang diinginkan adalah 0,1 N, maka:

V1x N1 = V2X N2    à 10 cc X 1 N = 100 cc x 0,1 N

Artinya, pada larutan HCl, 0,1 Normal, ditambahkan padanya sebanyak  sebanyak 90 cc  air sehingga secara keseluruhan menjadi 100 cc air. Disarankan pada saat mngencerkan dengan memanfaatkan gelas ukur (yang ada skalanya).

Apabila tahapan  pembersihan fosil tersebut telah selesai dilakukan, tempatkan fosil dalam kantong yang sudah disediakan, dan cantumkan keterangan fosil yang meliputi:

• Lokasi (nama geografi, kedudukan lokasi, ketinggian tempat-tentukan dengan GPS, nama Formasi batuan).
• Tanggal, bulan, dan tahun perolehan fosil
• Nama fosil (dalam kedudukan taksonomi)
• Nomor koleksi fosil (dengan kode dan nomor)

Agar informasi yang berkaitan dengan fosil tersebut tidak hilang, tulisan ditempatkan pada permukaan kantong, dituliskan dengan spidol waterprof, satu lembar tulisan pada kertas dengan urutan seperti tersebut tersebut di atas, dituliskan dengan spidol waterproof dan dimasukkan pada kantong plastik, usahakan kertas tidak basah terkena air dan tempatkan dalam kantong yang sudah diisi fosil. Apabila kantong contoh terbuat dari kain, tuliskan keterangan seperlunya pada kain tersebut. Apabila dimungkinkan dalam satu kantong dipergunakan untuk menyimpan satu jenis fosil yang sama. Dalam hal fosil yang tidak dapat disimpan dalam kantong (karena terlalu besar, misalnya fosil gading gajah), informasi tentang fosil dapat dituliskan pada permukaan fosil. Fosil dibuatkan kotak khusus terbuat dari kayu. Apabila mungkin tuliskan nomor koleksi pada fosil deskripsi singkat mengenai fosil tersebut sedang keterangan yang lain dapat dituliskan pada log book fosil. Penulisan hal-hal tersebut di atas, segera dilakukan, jangan sekali-kali menunda pekerjaan, satu dan lain hal karena ingatan anda tentang informasi yang berkaitan dengan fosil tersebut masih baik. Timbul pertanyaan: bagaimana  bila kantong contoh mempergunakan kantong plastik. Untuk itu pilih kantong plastik yang tebal, transparan. Pergunakan kantong plastik dobel, masukan kertas catatan diantara lembaran plastik. Perlu diingat: sampel yang disimpan tanpa nomor dan informasi pelengkapnya tidak mempunyai nilai geologi.

MANUSIA PURBA PUNAH KARENA MALAS

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Ivan JDD

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Diterbitkan 20.45, 12/08/2018

Ilustrasi manusia purba. | Procy /Shutterstock

Homo erectus pertama kali muncul pada dua juta tahun lalu dan punah sekitar 50.000 hingga 100.000 tahun lalu.

Homo erectus adalah hominid awal pertama yang menjadi penjelajah global sejati. Mereka diketahui bermigrasi dari Afrika ke Eurasia, menyebar hingga ke Georgia, Sri Lanka, Tiongkok, dan Indonesia.

Namun, menurut penelitian terbaru yang diterbitkan pada jurnal PLOS One, 27 Juli 2018, spesies Homo erectus ternyata cukup malas dan enggan beradaptasi dengan perubahan lingkungan jika dibandingkan dengan hominid lain--misalnya Neanderthal.

Live Science, Jumat (10/8/2018), melaporkan para arkeolog dari Australian National University menganalisis ribuan artefak yang baru ditemukan dan digali dari situs penggalian di Semenanjung Arab di Saffaqah modern, Arab Saudi, pada 2014 untuk mencari tahu alasan kepunahan spesies itu.

Temuan mereka menunjukkan bahwa spesies Homo erectus di daerah itu sebenarnya sudah berupaya seminimal mungkin untuk membuat alat dan mencari persediaan. Padahal manusia purba ini hidup di wilayah yang memiliki akses mudah ke batu dan air.

"Mereka tampaknya tidak menginspirasi mendorong diri mereka. Saya tidak mendapatkan bukti bahwa mereka adalah seorang penjelajah sejati, mereka tidak memiliki rasa penasaran yang sama seperti kita sekarang," kata Dr. Ceri Shipton kepada Sky News(10/8).

Dia menambahkan bahwa ini adalah bukti bagaimana spesies itu membuat perkakas batu yang mereka temukan tergeletak di sekitar tempat tinggal mereka. Persoalannya, batunya berkualitas rendah.

Sebagian besar perkakas batu dibuat dari batu yang lebih jelek dari perkakas pada peradaban berikutnya. Padahal, ada area bebatuan yang berkualitas lebih baik meski membutuhkan perjalanan yang cukup jauh dari permukiman mereka.

"Ketika kami melihat batu karang di sana tidak ada tanda-tanda aktivitas apa pun, tidak ada artefak dan tidak ada penggalian batu. Mereka tahu itu ada di sana, tetapi karena mereka memiliki cukup sumber daya yang cukup untuk mereka, jadi 'mengapa harus repot-repot?" lanjut Shipton.

Hal ini berbeda dengan pembuat perkakas batu pada periode selanjutnya, termasuk Homo sapiens awal dan Neanderthal. Mereka mendaki gunung untuk menemukan batu berkualitas baik dan mengangkutnya dalam jarak jauh.

"Sampel sedimen menunjukkan lingkungan di sekitar mereka berubah, tetapi mereka melakukan hal yang sama dengan peralatan mereka," kata Dr. Shipton. Berbeda dengan spesies yang lebih maju, Homo erectus cenderung menggunakan alat "generik" tunggal untuk hampir semua pekerjaan.

Namun, kemampuan Homo erectus untuk membuat perkakas sudah jauh lebih maju daripada manusia purba di belahan dunia lain. Mereka sudah bisa membuat kapak genggam.

Manusia purba jenis Homo erectus ini kuat dan terampil. Mereka berkembang di wilayah ini selama beberapa waktu. Tetapi, begitu dasar sungai mengering dan ada sedimentasi di sungai, Homo erectus justru mati karena mereka minim inisiatif.

"Mereka tidak pernah berada sangat jauh dari sumber air bersih," kata Dr. Shipton.

"Kami juga menemukan bahwa teknologi mereka untuk membuat perkakas batu sangat konservatif. Mereka menggunakan strategi yang sama untuk membuat alat dalam menghadapi lingkungan yang berubah. Jadi, mereka tidak hanya malas tetapi juga sangat konservatif," ujarnya dikutip Science Daily (10/8).

Shipton mengatakan lebih lanjut bahwa kepunahan Homo erectus disebabkan karena mereka tidak memilki kemampuan untuk merencanakan masa depan.

"Mereka hanya merencanakan untuk beberapa jam ke depan, atau mungkin untuk hari berikutnya. Sedangkan Homo sapiens dan Neanderthal merencanakan lebih jauh ke depan, seperti rencana migrasi musiman," pungkasnya

What caused the mass extinction of Earth's first animals?

Unravelling mystery of the Ediacaran-Cambrian transition

Date:

June 27, 2018

Source:

Arizona State University

Summary:

Fossil records tell us that the first macroscopic animals appeared on Earth about 575 million years ago. Twenty-four million years later, the diversity of animals began to mysteriously decline, leading to Earth's first know mass extinction event. A research team is helping to unravel this mystery and understand why this extinction event happened, what it can tell us about our origins, and how the world as we know it came to be. 

 

 

Fossil records tell us that the first macroscopic animals appeared on Earth about 575 million years ago. Twenty-four million years later, the diversity of animals began to mysteriously decline, leading to Earth's first know mass extinction event.

Scientists have argued for decades over what may have caused this mass extinction, during what is called the "Ediacaran-Cambrian transition." Some think that a steep decline in dissolved oxygen in the ocean was responsible. Others hypothesize that these early animals were progressively replaced by newly evolved animals.
The precise cause has remained elusive, in part because so little is known about the chemistry of Earth's oceans that long ago.
A research team, led by scientists from Arizona State University and funded by NASA and the National Science Foundation, is helping to unravel this mystery and understand why this extinction event happened, what it can tell us about our origins, and how the world as we know it came to be. The study, published in Science Advances, was led by ASU School of Earth and Space Exploration graduate student Feifei Zhang, under the direction of faculty member Ariel Anbar and staff scientist Stephen Romaniello.

The importance of oxygen
Today there is an abundance of oxygen, a vital component of life, throughout most of the Earth's oceans. But there is evidence to suggest that during the mass extinction event, there was a loss of dissolved oxygen in Earth's oceans, an effect called "marine anoxia."
To get a better understanding of the mass extinction event, the research team focused on studying this effect. They wanted to determine not only how much of the ocean was anoxic when the animals began to decline, but also whether marine anoxia contributed to the decline and eventual extinction of the early animals.
Integrating geochemical data and the Earth's fossil records
To determine the levels of marine anoxia and its effects, the research team used a novel approach of combining geochemical data and the Earth's fossil record to precisely match evolutionary and environmental events.
Typically, scientists determine ocean anoxia levels by looking at the abundance of pyrite, commonly known as "fool's gold," and other elements and minerals in ancient mud rocks. But mud rocks only provide clues to what may have happened at a single location. Scientists need to sample dozens of sites around the world to infer the big picture from mud rocks.
To overcome this, the team pioneered a new and more efficient approach. Rock samples of marine limestone were collected in the Three Gorges Area (Hubei Province) of the People's Republic of China. This area is known for having some of the best examples in the world from the Ediacaran Period. The rock samples for this study were deposited in a shallow marine environmental between 551 and 541 million years ago, and hold a record of the marine environmental changes that occurred when they were deposited.
Back at the lab, the team measured the uranium isotope variations in marine limestone and then then integrated the uranium isotope data and paleontological data from the same suite of rocks. Once the data were integrated, the team could clearly see that the episode of extensive marine anoxia coincided with the decline and the subsequent disappearance of early animals.
"This may have been most severe marine anoxic event in the last 550 million years," says Zhang. "Mathematical modeling of our data suggests that almost the entire seafloor was overlain by anoxic waters during the end of the Ediacaran Period

 

Is there a mass extinction in our future?
While our oceans currently have an abundance of oxygen, there has been a recent measurable rise in ocean anoxia, attributed by scientists to climate change. Advances in the study of ancient marine anoxia, like this one, then may help us understand and predict what lies ahead.
"The past is our best laboratory to understand the future" says co-author Anbar "It's sobering to see how often the mass extinctions of the past were preceded by increases in ocean anoxia. There is a lot we don't understand about climate change, but the things we do know are a big cause for concern."

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Story Source:
Materials provided by Arizona State University. Note: Content may be edited for style and length.

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Journal Reference:

1. Feifei Zhang, Shuhai Xiao, Brian Kendall, Stephen J. Romaniello, Huan Cui, Mike Meyer, Geoffrey J. Gilleaudeau, Alan J. Kaufman, Ariel D. Anbar. Extensive marine anoxia during the terminal Ediacaran Period. Science Advances, 2018; 4 (6): eaan8983 DOI: 10.1126/sciadv.aan8983

 

 

LINDUNGI KIMA

Digitasi Peta Menggunakan Surfer

Revising the story of the dispersal of modern humans across Eurasia

Technological advances and multidisciplinary research teams are reshaping our understanding of when and how humans left Africa -- and who they met along the way

 Map of sites and postulated migratory pathways associated with modern humans dispersing across Asia during the Late Pleistocene.

Credit: Bae et al. 2017. On the origin of modern humans: Asian perspectives. Science. Image by: Katerina Douka and Michelle O'Reilly

 

Most people are now familiar with the traditional "Out of Africa" model: modern humans evolved in Africa and then dispersed across Asia and reached Australia in a single wave about 60,000 years ago. However, technological advances in DNA analysis and other fossil identification techniques, as well as an emphasis on multidisciplinary research, are revising this story. Recent discoveries show that humans left Africa multiple times prior to 60,000 years ago, and that they interbred with other hominins in many locations across Eurasia

A review of recent research on dispersals by early modern humans from Africa to Asia by researchers from the Max Planck Institute for the Science of Human History and the University of Hawai'i at Manoa confirms that the traditional view of a single dispersal of anatomically modern humans out of Africa around 60,000 years ago can no longer be seen as the full story. The analysis, published in the journal Science, reviews the plethora of new discoveries being reported from Asia over the past decade, which were made possible by technological advances and interdisciplinary collaborations, and shows that Homo sapiens reached distant parts of the Asian continent, as well as Near Oceania, much earlier than previously thought. Additionally, evidence that modern humans interbred with other hominins already present in Asia, such as Neanderthals and Denisovans, complicates the evolutionary history of our species.
New model: Multiple dispersals of modern humans out of Africa, beginning as early as 120,000 years ago
The authors brought together findings from multiple recent studies to refine the picture of human dispersals out of Africa and into Asia. While scientists once thought that humans first left Africa in a single wave of migration about 60,000 years ago, recent studies have identified modern human fossils in far reaches of Asia that are potentially much older. For example, H. sapiens remains have been found at multiple sites in southern and central China that have been dated to between 70,000 and 120,000 years ago. Additional finds indicate that modern humans reached Southeast Asia and Australia prior to 60,000 years ago.
However, other recent studies do confirm that all present-day non-African populations branched off from a single ancestral population in Africa approximately 60,000 years ago. This could indicate that there were multiple, smaller dispersals of humans out of Africa beginning as early as 120,000 years ago, followed by a major dispersal 60,000 years ago. While the recent dispersal contributed the bulk of the genetic make-up of present-day non-Africans, the earlier dispersals are still evident.
"The initial dispersals out of Africa prior to 60,000 years ago were likely by small groups of foragers, and at least some of these early dispersals left low-level genetic traces in modern human populations. A later, major 'Out of Africa' event most likely occurred around 60,000 years ago or thereafter," explains Michael Petraglia of the Max Planck Institute for the Science of Human History.
Multiple interbreeding events
Recent genetic research has resolved the question of whether or not modern humans interbred with other ancient hominins -- they definitely did. Modern humans interbred not only with Neanderthals, but also with our recently-discovered relatives the Denisovans, as well as a currently unidentified population of pre-modern hominins. One estimate is that all present-day non-Africans have 1-4% Neanderthal heritage, while another group has estimated that modern Melanesians have an average of 5% Denisovan heritage. In all, it is now clear that modern humans, Neanderthals, Denisovans and perhaps other hominin groups likely overlapped in time and space in Asia, and they certainly had many instances of interaction.
The increasing evidence of interactions suggests that the spread of material culture is also more complicated than previously thought. "Indeed, what we are seeing in the behavioral record is that the spread of so-called modern human behaviors did not occur in a simple time-transgressive process from west to east. Rather, ecological variation needs to be considered in concert with behavioral variation between the different hominin populations present in Asia during the Late Pleistocene," explains Christopher Bae of the University of Hawai'i at Manoa.
In light of these new discoveries, our understanding of human movements across the Old World has become much more complex, and there are still many questions left open. The authors argue for the development of more complicated models of human dispersals and for conducting new research in the many areas of Asia where none has been done to date. Additionally, it will be important to review materials collected prior to the development of modern analytic methods, to see what more can now be learned from them. "Fortunately," states Katerina Douka, also of the Max Planck Institute for the Science of Human History, "there have been an increasing number of multidisciplinary research programs launched in Asia over the past few decades. The information that is being reported is helping to fill in the gaps in the evolutionary records."

Date:

December 7, 2017

Source:

Max Planck Institute for the Science of Human History

Summary:

Most people are now familiar with the traditional 'Out of Africa' model: modern humans evolved in Africa and then dispersed across Asia and reached Australia in a single wave about 60,000 years ago. However, technological advances in DNA analysis and other fossil identification techniques, as well as an emphasis on multidisciplinary research, are revising this story. Recent discoveries show that humans left Africa multiple times prior to 60,000 years ago, and that they interbred with other hominins in many locations across Eurasia

Early trilobites had stomachs, new fossil study finds Remarkable Chinese specimens contradict previous assumptions about trilobite digestive systems and evolution

his photo is of a specimen of the trilobite Palaeolenus lantenoisi from the Guanshan Biota in southern Yunnan Province, China. Rarely are internal organs preserved in fossils, but this specimen shows the digestive system preserved as reddish iron oxides. The digestive system is comprised of a crop (inflated region at top of specimen), lateral glands, and a central canal that runs along the length of the body; the iron oxides that extend beyond the fossil are the remains of gut contents that were extruded during preservation.

Credit: © F. Chen

Exceptionally preserved trilobite fossils from China, dating back to more than 500 million years ago, have revealed new insights into the extinct marine animal's digestive system. Published today in the journal PLOS ONE, the new study shows that at least two trilobite species evolved a stomach structure 20 million years earlier than previously thought.Trilobites are one of the first types of animals to show up in large numbers in the fossil record," said lead author Melanie Hopkins, an assistant curator in the Division of Paleontology at the American Museum of Natural History. "Their exoskeletons were heavy in minerals, and so they preserved really well. But like all fossils, it's very rare to see the preservation of soft tissues like organs or appendages in trilobites, and because of this, our knowledge of the trilobite digestive system comes from a small number of specimens. The new material in this study really expands our understanding."

Trilobites are a group of extinct marine arthropods -- distantly related to the horseshoe crab -- that lived for almost 300 million years. They were extremely diverse, with about 20,000 species, and their fossil exoskeletons can be found all around the world. Most of the 270 specimens analyzed in the new study were collected from a quarry in southern Kunming, China, during an excavation led by Hopkins' co-author, Zhifei Zhang, from Northwest University in Xi'an.

Previous research suggests that two body plans existed for trilobite digestive systems: a tube that runs down the length of the trilobite's body with lateral digestive glands that would have helped process the food; or an expanded stomach, called a "crop," leading into a simple tube with no lateral glands. Until now, only the first type had been reported from the oldest trilobites. Based on this, researchers had proposed that the evolution of the crop came later in trilobite evolutionary history and represented a distinct type of digestive system.

The Chinese trilobite fossils, about 20 percent of which have soft tissue preservation, are dated to the early Cambrian, about 514 million years ago. Contradictory to the previously proposed body plans, the researchers identified crops in two different species within this material. In addition, they found a single specimen that has both a crop and digestive glands -- suggesting that the evolution of trilobite digestive systems is more complex than originally proposed.

The study backs up an earlier announcement made by a separate research team, which found evidence for the unusual crop and gland pairing in a single juvenile trilobite specimen from Sweden from the late Cambrian. But the Chinese material presents the oldest example of this complex digestive system in a mature trilobite, wiping away doubts that the dual structures might just be part of the animal's early development.

"This is a very rigorous study based on multiple specimens, and it shows that we should start thinking about this aspect of trilobite biology and evolution in a different way," Hopkins said.

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Story Source:

Materials provided by American Museum of Natural History.Note: Content may be edited for style and length.

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Journal Reference:

1. Melanie J. Hopkins, Feiyang Chen, Shixue Hu, Zhifei Zhang.The oldest known digestive system consisting of both paired digestive glands and a crop from exceptionally preserved trilobites of the Guanshan Biota (Early Cambrian, China). PLOS ONE, 2017; 12 (9): e0184982 DOI:10.1371/journal.pone.0184982
2. 
   

Did rapid sea-level rise drown fossil coral reefs around Hawaii?

This is a map showing the location of sample collection off of Kawaihae, Hawaii (blue sphere), and a slope profile (below) showing the backstepping younger and shallower terraces overlaying the targeted reef terrace 150m below sea level.

Credit: Bathymetry data from Monterey Bay Aquarium Research Institute, and figure by Kelsey Sanborn, University of Sydney

Scientists globally are investigating just how quickly sea-level rise can occur as a result of global warming and ice sheets melting.

Recent findings suggest that episodes of very rapid sea-level rise of about 20m in less than 500 years occurred in the last deglaciation, caused by periods of catastrophic ice-sheet collapse as Earth warmed after the last ice age about 20,000 years ago.

Lead author, PhD candidate at the University of Sydney, Kelsey Sanborn, has shown this sea-level rise event was associated with "drowning" or death of coral reefs in Hawaii.

The results are published in leading geosciences journalQuaternary Science Reviews.

The paper provides new evidence of a meltwater pulse (referred to as meltwater pulse 1-A), based on analysis of fossil coral reef samples from off the coast of Kawaihae, on the northwest of the Big Island of Hawaii.

Co-author Associate Professor Jody Webster, from the Geocoastal Research Group at the University of Sydney's School of Geosciences, said although this pulse was greater than current modelling predictions of sea-level rise over the next few hundred years, it provides an example of the risks rapid environmental change poses to our marine ecosystems.

"If we saw a sea-level rise in the future of a similar rate as this past event, it would likely devastate coral reefs and coastal systems," Associate Professor Webster said.

The fossil corals used in this study were collected by a team of technical rebreather scuba divers who dove down to 150 m below present sea level to access the fossil reef. At this depth, more than 130m deeper than where you could dive along their living shallow counterparts today, the divers recovered targeted shallow reef species that were alive over 14,700 years ago.

Lead author Ms Sanborn said this coral reef had been growing for thousands of years, during the initially gradual sea-level rise as the ice sheets of the last ice age began to melt.

"During the meltwater pulse, sea level rose more rapidly than the reef could grow, preventing the photosynthetic algae living within the corals from receiving enough sunlight. This caused the previously thriving fringing reef system to drown, and left it to be overgrown by deep-water algae and other marine life," she said.

Although uncertainty remains regarding how quickly coastal areas could be inundated around the world, understanding how these events occurred in the past are key to understanding the risks we face in the future.

"The fact that this meltwater pulse was large enough to drown a large, active Hawaiian reef system implies that extreme climate change and associated sea-level rise occurred quite rapidly," Ms Sanborn said.

This event is believed to have been brought about by catastrophic melting of the Greenland, and potentially also Antarctic, ice sheets.

"This may help us better predict the extent of future sea-level rise based on how vulnerable the Antarctic ice sheet is to collapse and melting," Ms Sanborn said.

The research was a collaborative effort between the University of Sydney, the University of Tokyo, the University of Florida, the University of Granada, the Monterey Bay Aquarium Research Institute, the University of Hawaii, and the Association for Marine Exploration.

Research Details

As part of the research, Ms Sanborn examined the evidence for reef drowning by identifying the coral reef species which grow within a specific depth range, and dating them using radiocarbon dating.

Taking into account the sinking of the island due to its volcanism, the relative-sea level history of Kawaihae was reconstructed.

The findings suggest that this reef was rapidly drowned by the combined effects of sinking of the island and global sea-level rise.

This is supported by other studies from around the world showing a rapid sea-level rise around 14,700 years ago.

tory Source:

Materials provided by University of Sydney. Note: Content may be edited for style and length.

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Journal Reference:

1. Kelsey L. Sanborn, Jody M. Webster, Yusuke Yokoyama, Andrea Dutton, Juan C. Braga, David A. Clague, Jennifer B. Paduan, Daniel Wagner, John J. Rooney, John R. Hansen.New evidence of Hawaiian coral reef drowning in response to meltwater pulse-1A. Quaternary Science Reviews, 2017; 175: 60 DOI:10.1016/j.quascirev.2017.08.022
2. https://www.sciencedaily.com/releases/2017/09/170928094213.htm

BARANG-BARANG SEPELE YANG BERMANFAAT BAGI GEOLOGIST SAAT DI LAPANGAN

Saat Geologist go to field umumnya hanya membawah barang-barang standar untuk observasi dan pengambilan sampel. Kejadian tidak terduga seringkali terjadi namun seringkali juga tidak.

Berikut ini barang-barang sepele yang bermanfaat saat geologist berada di lapangan (Bukan di base Camp)

1. Tea ( Tea Sariwangi yang sudah jadi/siap diminum) (Tea bisa berfungsi sebagai penahan racun ular, jika Anda digigit ular, siramkan tea di tempat gigitan ular tersebut. Tea bisa menahan racun ular atau dapat menormalkan untuk sementara racun tersebut sambil kita membawa korban ke PUSKESMAS/ RS terdekat.)

2. Silet (Silet dalam keadaan genting bisa dimanfaatkan sebagai penunjuk arah utara (Silet Goal) (Geologist jarang kehilangan arah/tersesat; meskipun kompas rusak, GPS tidak berfungsi dll, namun bisa kembali dengan selamat ke tempat tujuan. Hal ini mungkin disebabkan geologist punya daya ingat yang tinggi)) 

3.  Tisu Basa/Kering (Fungsi tisu sebenarnya banyak untuk kebersihan diri, misalnya kita mau BAB namun ditempat itu tak ada air (Tisu basa Cussons bisa jadi solusi dalam pembersihan)

4. Payung (Payung  bisa menjadi tempat kita bertedu di tengah terik matahari saat observasi, seperti yang dibahas pada artikel sebelumnya paparan sinar matahari bisa menyembakan kanker pada geologist saat berada di lapangan) 

5. Hand sanitizer (Hand sanitizer seperti lifebuoy  bisa kita gunakan di lapangan untuk membersikan tangan dari kotoran selesai mengorek-gorek sampel. Hand sanitizer lifebuoy dapat menghilangkan kuman 99,9 % di tengan kita sebelum kita makan )

6. Kantong Sampah (Saat dilapangan jangan buang sampah sembarangan, jika mau buang sampah buang saja dalam tas, kalau tidak mau tas kalian kotor, pakailah kantong sampah.)

Fosil Manusia Purba Tertua Ditemukan, Teori Homo Sapiens Berubah

Fosil manusia purba modern (Homo sapiens) tertua berumur 300 ribu tahun. sciencealert.com. (Dikutip dari Tempo)

TEMPO.CO, Munchen - Fosil manusia purba modern (Homo sapiens) tertua kembali terungkap. Kali ini, ilmuwan berhasil mengungkap fosil H. sapiens berumur 300 ribu tahun. Ini 100 ribu tahun lebih tua ketimbang fosil H. sapiens yang pernah ditemukan. 

Ilmuwan menemukannya pertama kali pada 2004 di Situs Jebel Irhoud, Maroko. Pada penggalian kala itu mereka menemukan tengkorak, tulang tungkai, dan gigi. Fosil ini berasal dari tiga orang dewasa, satu remaja, dan satu anak-anak berumur sekitar delapan tahun.

"Tengkorak ini mirip dengan kita, hanya tempat otaknya berbentuk memanjang. Itu menunjukkan evolusi awal dari tempurung otak yang ada saat ini," tulis para ilmuwan dalam jurnal Nature edisi 7 juni 2017. Artikel tersebut berjudul "New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens".

Manusia Maroko ini memikili bentuk otak memanjang, tidak bulat seperti yang ada di manusia masa kini. Ahli paleoantropologi Max Planck Institute, Phillip Gunz, anggota tim, menyatakan bentuk wajah seperti itu sudah ada sejak lama di H. sapiens. Mungkin, kata dia, bentuk otak dan fungsinya berevolusi belakangan.

Sebelumnya, para arkeolog berpikir bahwa spesies H. sapiens tertua berasal dari Situs Omo Kibish di Ethiopia. Fosil yang pernah ditemukan di sana berumur 195 ribu tahun. Temuan ini membuat para ilmuwan berpikir bahwa manusia purba modern berasal dari Afrika timur.

Namun, data terbaru dari Situs Jebel Irhoud jelas mematahkan teori tersebut. "H.sapiens menyebar ke seluruh benua Afrika," kata ahli paleontologi dari Max Planck Institute for Evolutionary Anthropology, Jean-Jacques Hublin, yang juga anggota tim studi, seperti dikutip dari laman berita Science Alert.

Fosil manusia purba Maroko ini ditemukan dari satu lapisan tanah dengan tulang hewan, seperti kijang dan zebra. Juga, dengan perkakas baru yang berbentuk mata tombak dan pisau, serta sisa-sisa pembakaran kayu. Dari sisa-sisa bahan organik itulah umur fosil dapat diketahui.

Spesies H. sapiens merupakan satu-satunya manusia yang tertinggal. Sekitar 300 ribu tahun lalu, mereka mungkin berbagi tempat hidup dengan saudara yang ada di daratan Eurasia, H. neanderhalensis, dan manusia Denisova, subspesies H. sapiens.

Ilmuwan memprediksi H. sapiens pertama kali muncul tak lebih dari 650 ribu tahun lalu. Atau saat garis evolusi terbagi menjadi dua: H. sapiens dan H. neanderthalensis. 

Yang jelas temuan ini masih menyisakan misteri. Sebab, kalau dilihat karakteristik semua fosilmanusia purba yang pernah ditemukan, masing-masing memiliki fitur yang sama antara manusia purba modern dan manusia Neanderthal.

Belum ada bukti fosil yang kuat apakah keduanya pernah bertemu dan kawin-mawin, yang akhirnya mengaduk populasi di masing-masing spesies. Atau, perubahan dan fitur yang mirip tersebut karena evolusi panjang.

Sumber : Tempo. Co. Tekno JUM'AT, 09 JUNI 2017 | 11:55 WIB