WFS News: Early trilobites had stomachs?

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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.”

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 Read more at: https://phys.org/news/2017-09-early-trilobites-stomachs-fossil.html#jCp

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

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 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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Source:phys.org/news/2017-09-early-trilobites-stomachs-fossil.html

WFS News: Tracking brain-skull transition from dinosaurs to birds

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The dramatic, dinosaur-to-bird transition that occurred in reptiles millions of years ago was accompanied by profound changes in the skull roof of those animals — and holds important clues about the way the skull forms in response to changes in the brain — according to a new study.

It is the first time scientists have tracked the link between the brain’s development and the roofing bones of the skull. The findings appear in the Sept. 11 edition of the journal Nature Ecology and Evolution.

These are CT scan images of the skull roof (front bone in pink, parietal in green) and brain (in blue) of, top to bottom, a chicken, the birdlike dinosaur Zanabazar, the primitive dinosaur Herrerasaurus, and Proterosuchus, an ancestral form that diverged before the bird/crocodile split. Credit: Yale University

These are CT scan images of the skull roof (front bone in pink, parietal in green) and brain (in blue) of, top to bottom, a chicken, the birdlike dinosaur Zanabazar, the primitive dinosaur Herrerasaurus, and Proterosuchus, an ancestral form that diverged before the bird/ crocodile split.    Credit: Yale University

“Across the dinosaur-bird transition, the skull transforms enormously and the brain enlarges. We were surprised that no one had directly addressed the idea that the underlying parts of the brain — the forebrain and midbrain — are correlated or somehow developmentally related to the overlying frontal and parietal bones,” said co-senior author Bhart-Anjan Singh Bhullar, an assistant professor of geology and geophysics at Yale University and assistant curator of vertebrate paleontology and vertebrate zoology at the Yale Peabody Museum of Natural History.

Matteo Fabbri, a graduate student in Bhullar’s lab, is the first author of the study.

Although previous studies have shown a general relationship between the brain and skull, associations between specific regions of the brain and individual elements of the skull roof have remained unclear. This has led to conflicting theories on some aspects of skull development.

Bhullar and his colleagues set out to trace the evolution of brain and skull shape not simply in the dinosaurs closest to birds, but in the entire lineage leading from reptiles to birds. They discovered that most reptile brains and skulls were markedly similar to each other. It was the dinosaurs most closely related to birds, as well as birds themselves, that were divergent, with enlarged brains and skulls ballooning out around them.

“We found a clear relationship between the frontal bones and forebrain and the parietal bones and midbrain,” Bhullar said. The researchers confirmed this finding by looking at embryos of lizards, alligators, and birds using a new contrast-stained CT scanning technique.

“We suggest that this relationship is found across all vertebrates with bony skulls and indicates a deep developmental relationship between the brain and the skull roof,” Bhullar said. “What this implies is that the brain produces molecular signals that instruct the skeleton to form around it, although we understand relatively little about the precise nature of that patterning.”

Bhullar added: “Ultimately, one of the important messages here is that evolution is simpler and more elegant than it seems. Multiple seemingly disparate changes — for instance to the brain and skull — could actually have one underlying cause and represent only a single, manifold transformation.”

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  1. Matteo Fabbri, Nicolás Mongiardino Koch, Adam C. Pritchard, Michael Hanson, Eva Hoffman, Gabriel S. Bever, Amy M. Balanoff, Zachary S. Morris, Daniel J. Field, Jasmin Camacho, Timothy B. Rowe, Mark A. Norell, Roger M. Smith, Arhat Abzhanov, Bhart-Anjan S. Bhullar. The skull roof tracks the brain during the evolution and development of reptiles including birds. Nature Ecology & Evolution, 2017; DOI: 10.1038/s41559-017-0288-2
  2. Yale University. “Scientists track the brain-skull transition from dinosaurs to birds.” ScienceDaily. ScienceDaily, 11 September 2017.

WFS News: Measuring a crucial mineral in the mantle

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University of Delaware professor Jessica Warren and colleagues from Stanford University, Oxford University and University of Pennsylvania, reported new data that material size-effects matter in plate tectonics.

Plate tectonics, the way the Earth’s plates move apart and come back together, has been used since the 1960s to explain the location of volcanoes and earthquakes.

The study (link here) published Wednesday, Sept. 13 in the American Association for the Advancement of Science journal Science Advances, resolves 40 years of disagreement in datasets about the strength of olivine, the most abundant mineral found in the upper 250 miles or so of the Earth, known as the mantle.

“Measuring the strength of olivine is critical to understanding how strong tectonic plates are, which, in turn, matters to how plates break and create subduction zones like those along the Cascadia plate, which runs down the west coast of Canada to the west coast of the United States,” said Warren, a geologist in the College of Earth, Ocean, and Environment. It’s also important for understanding how plates move around over the million-year time scales.

Olivine, the most abundant mineral found in the Earth's mantle, is considered to be a robust model of the interior of the Earth's composition. Credit: Evan Krape/ University of Delaware

Olivine, the most abundant mineral found in the Earth’s mantle, is considered to be a robust model of the interior of the Earth’s composition.Credit: Evan Krape/ University of Delaware

The paper demonstrated that olivine’s strength is size-sensitive and that olivine is stronger the smaller the volume that is measured, something that has been known in materials science for many metals and ceramics, but has not been studied in a geological material before.

Warren explained that the problem with studying rocks on the earth’s surface is that they are no longer subjected to the high pressures found inside the earth that cause materials to flow (like ice in a glacier). Recreating these elevated pressures in the laboratory is difficult, making it hard for scientists to study material strength in the lab.

The researchers used a technique, called instrumented nanoindentation, to measure olivine’s strength. The technique allowed them to recreate pressure conditions similar to those inside the earth by pressing a diamond tip that was carefully machined to a specific geometry into the olivine crystal to measure the material’s response. The diamond tips ranged in size from 5 to 20 microns (0.000001 meter). The researchers performed hundreds of indentation tests on tiny olivine crystals less than a centimeter square and found that the olivine crystal became weaker as the size of the diamond tip increased.

To validate this size-effect, the researchers reviewed the available literature data on the strength of olivine to determine the sizes and areas that had been tested in previous experiments dating to the late 1970s. The size-effect showed up in the old data, too.

“The reason 40 years’ worth of data don’t agree from one experiment to the next is because scientists were measuring different sizes or areas of olivine,” Warren said. “But if you plot the same information as a function of the sample size, the datasets, in fact agree, and display the same general trend — the larger the indentation in the material tested, the weaker the olivine becomes.”

Now that Warren and her colleagues understand this size-effect, they are turning their attention to how temperature affects the strength of olivine, and more broadly, on where tectonic plates might break and give rise to potential subduction zones.

Temperatures inside the earth are much hotter than on the surface and can range from 1,470 to 2,200 degrees Fahrenheit (800 to 1,200 degrees Celsius).

The team also will consider what role water plays in the structure of olivine minerals and rocks in the earth. According to Warren, current estimates suggest the earth contains the equivalent of 50 percent to 4 times the amount of water found in the global ocean.

“When geologists look at how faults buckle and deform, it is at a very small length scale where conditions in size effect really matter, just like our olivine tests in the laboratory,” Warren said. “But this size effect disappears when you get to a large enough length scale on tectonic plates, so we need to consider other things like when temperature and water begin to play a role.”

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Citation:University of Delaware. “Measuring a crucial mineral in the mantle: New research resolves 40 years of debate on the strength of olivine, the most abundant mineral in the Earth’s mantle.” ScienceDaily. ScienceDaily, 13 September 2017. <www.sciencedaily.com/releases/2017/09/170913192943.htm

WFS News: Trilobite-like arthropod Agnostus pisiformis.

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

With the help of an artist, a geology professor at Lund University in Sweden has figuratively speaking breathed life into one of science’s most well-known fossil species; Agnostus pisiformis. The trilobite-like arthropod lived in huge numbers in Scandinavia a half-billion years ago. Today, this extinct species provides important clues for science in several ways.

Despite its small size, Agnostus pisiformis is a remarkable and useful fossil. The extinct animal was just one centimetre in size when adult, but has been found exceptionally well-preserved and in large numbers. And it is not only the outer hard shells — even the animal’s soft tissue has been found so well preserved that it is possible to create extremely detailed sculptures that show what the tiny creature looked like.

Agnostus pisiformis. Credit: Esben Horn

 Agnostus pisiformis.  Credit: Esben Horn

“The sculptures have been greatly scaled up and show the animal’s complete anatomy down to the smallest detail, including all the extremities and antennae,” says Mats E. Eriksson, geology professor at Lund University.

Eriksson’s research focuses mainly on microscopic fossils and attempts, among other things, to reconstruct ecosystems that are several hundred million years old.

The sculptures were created in connection with a research article he wrote on Agnostus pisiformis. He was assisted by the Danish artist and designer, Esben Horn, whose company, 10 Tons, specialises in producing lifelike sculptures of both extant and extinct organisms for museums and institutions around the world.

The ancient Agnostus pisiformis is mainly known from Scandinavia, but it has been recorded also elsewhere, for example in England and Russia. Due to the fact that the species only lived for a limited period of time just over 500 million years ago, it is possible to use the fossilto date various rocks, which explains why Agnostus pisiformis is a celebrity within science.

However, the species is not only useful for researchers as a time reference, as it also gives them valuable insights into ancient life on Earth. This fossil is so well-preserved and occursin such large numbers that it is possible to understand its complete development, from juvenile to adult.

“The incredible degree of preservational detail means that we can grasp the entire anatomy of the animal, which in turn reveals a lot about its ecology and mode of life,” says Mats E. Eriksson.

He now hopes that the sculptures of Agnostus pisiformis will become part of a travelling exhibition on the long lost faunas that existed in the oceans more than 500 million years ago. He wants to spread the knowledge about early lifeduring what he regards as a very exciting time in Earth history. He also wants to highlight that palaeontology, that is, the study of fossils, is not just about dinosaurs.

“There were actually ecosystems seething with fantastic and bizarre life forms several hundred million years before the dinosaurs even appeared,” concludes Mats E. Eriksson.

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  1. Mats E. Eriksson, Esben Horn. Agnostus pisiformis — a half a billion-year old pea-shaped enigma. Earth-Science Reviews, 2017; 173: 65 DOI: 10.1016/j.earscirev.2017.08.004
  2. Lund University. “Celebrity fossil reveals all for science.” ScienceDaily. ScienceDaily, 15 September 2017. <www.sciencedaily.com/releases/2017/09/170915103550.htm

WFS News: fossils shed light animal evolution on Earth

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Scientists have discovered traces of life more than half-a-billion years old that could change the way we think about how all animals evolved on earth.

The international team, including palaeontologist from The University of Manchester, found a new set of trace fossils left by some of the first ever organisms capable of active movement. Trace fossils are the tracks and burrows left by living organisms, not physical remains such as bones or body parts.

The fossils were discovered in sediment in the Corumbá region of western Brazil, near the border with Bolivia. The burrows measure from under 50 to 600 micrometres or microns (?m) in diameter, meaning the creatures that made them were similar in size to a human hair which can range from 40 to 300 microns in width. One micrometre is just one thousandth of a millimetre.

Dr Russell Garwood, from Manchester’s School of Earth and Environmental Sciences, said: ‘This is an especially exciting find due to the age of the rocks — these fossils are found in rock layers which actually pre-date the oldest fossils of complex animals — at least that is what all current fossil records would suggest.’

X-ray microtomography image of trace fossil in sediment. Credit: Luke Parry - University of Bristol

X-ray microtomography image of trace fossil in sediment.Credit: Luke Parry – University of Bristol

The fossils found date back to a geological and evolutionary period known as the Ediacaran-Cambrian transition. This was when the Ediacaran Period, which spanned 94 million years from the end of the Cryogenian Period, 635 million years ago, moved into the Cambrian Period around 541 million years ago. To put that into context, dinosaurs lived between 230 and 65 million years ago in the Mesozoic Era.

The Ediacaran-Cambrian transition is seen as extremely important period in evolutionary science and theory. Dr Garwood explains: ‘The evolutionary events during the Ediacaran-Cambrian transition are unparalleled in Earth history. That’s because current fossil records suggests that many animal groups alive today appeared in a really short time interval.’

However, the team suggest these burrows were created by ‘nematoid-like organisms’, similar to a modern-day roundworm, that used an undulating locomotion to move through the sediment, leaving these trace fossils behind. This is important because current DNA studies, known as ‘molecular clocks’, which are used to estimate how long ago a group animals originated, suggests the first animals appeared before these burrows. But this research, which has been published in Nature Ecology and Evolution, shows these trace fossils pre-date similar animals currently found in the fossil record.

Luke Parry, lead author from the University of Bristol, added: ‘Our new fossils show that complex animals with muscle control were around approximately 550 million years ago, and they may have been overlooked previously because they are so tiny’.

‘The fossils that we describe were made by quite complex animals that we call bilaterians. These are all animals that are more closely related to humans, rather than to simple creatures like jellyfish. Most fossils of bilaterian animals are younger, first appearing in the Cambrian period.’

To find such tiny fossils the team used X-ray microtomography, a special technique that uses X-rays to create a virtual, 3D model of something without destroying the original object.

Luke added: ‘Our discovery highlights an unexplored window for tracking animal evolution in deep time.’

  1. Luke A. Parry, Paulo C. Boggiani, Daniel J. Condon, Russell J. Garwood, Juliana de M. Leme, Duncan McIlroy, Martin D. Brasier, Ricardo Trindade, Ginaldo A. C. Campanha, Mírian L. A. F. Pacheco, Cleber Q. C. Diniz, Alexander G. Liu. Ichnological evidence for meiofaunal bilaterians from the terminal Ediacaran and earliest Cambrian of Brazil. Nature Ecology & Evolution, 2017; DOI: 10.1038/s41559-017-0301-9
  2. University of Manchester. “Half-a-billion-year-old fossils shed light animal evolution on Earth.” ScienceDaily. ScienceDaily, 11 September 2017.

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EVIDENCE OF NEOTECTONIC ACTIVITY ALONG THE EAST COAST OF INDIAN PENINSULA

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 388-12: EVIDENCE OF NEOTECTONIC ACTIVITY ALONG THE EAST COAST OF INDIAN PENINSULA                            ( ABSTRACT)
 
Riffin T Sajeev
Wednesday, 25 October 201709:00 AM – 06:30 PM
 
Washington State Convention Center – Halls 4EF
The eastern coastal plains of the Indian peninsula are studied meagerly based on its tectonic aspects.In the previous ventures, the author reported the paleochronological existence of a large estuary, on the basis of fossils of Crassostrea Sp. Dating back to the mio-pliocene Epoch. The author suggests that the paleo-estuary ceased in existence due to a marine regression caused by a regional uplift in between the present day trajectories of the rivers Thamirabharani and Nambiar. The natures of structural characteristics seen in the regional outcrops of the basin indicate a dominant neotectonic feature . Brittle slip faults are abundant in these rocky outcrops containing Khondalite beds. Shearing is visible almost anywhere. This may be caused by the near proximity of the study area with the Achankovil Shear Zone (AKSZ).
Partial Rock melting feature on outcrop .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Partial Rock melting feature on outcrop .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Partial Rock melting feature on outcrop .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Partial Rock melting feature on outcrop .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

strike slip fault 1 .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

                    strike slip fault 1 .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Rock bed feature .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Rock bed feature on outcrop .                              @World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Rock bed feature .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Rock bed feature .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Rock bed feature .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

 Rock bed feature .                              @World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Rock bed feature .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Rock bed feature .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Boudins on rock @World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Boudins on rock @World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Scoria obtained from outcrop .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

                  Scoria obtained from outcrop .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Scoria obtained from outcrop .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Scoria obtained from outcrop .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Scoria obtained from outcrop .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Scoria obtained from outcrop .@World Fossil Society,Riffin T Sajeev,Russel T Sajeev

A second look at the trajectories of the rivers and drainage mentioned above and the structural features on the outcrops indicate that the uplift is neotectonically induced rather than shear induced.During site exploration, the author found rocks of volcanic origin distributed randomly over the study area. Till this date, the geological community had approached volcanic/ neo tectonic activities in this area only through speculations without any physical, visible evidence. The presences of chunks of volcanic rocks are an acute visual evidence of an event of volcanic nature. Through this study, the author aims to analyze the extent of uplift and its impact on the drainage systems of the rivers on its either side and their divide migration possibilities. The neotectonic aspects of the region are analyzed and any solid evidence of active volcanism is collected and studied. The study is primarily aimed to report the existence of neotectonic activity in the south eastern coast of India.
Author
 Periyar University
Final Paper Number 388-12 View Related Events
Day: Wednesday, 25 October 2017 Geological Society of America Abstracts with Programs. Vol. 49, No. 6doi: 10.1130/abs/2017AM-293786
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WFS facts: Why are fossilized hairs so rare?

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When most people hear the word fossil, they probably think of gigantic leg bones or sharp teeth. But, given the right conditions, after an animal dies even delicate body coverings like skin, hair and feathers can be preserved.

New research led by The University of Texas at Austin has found that when it comes to preserving these body parts, fossilized hair is rare — five times rarer than feathers — despite being an important tool for understanding ancient species. This finding has researchers trying to determine if the lack of hair in the fossil record has to do with physical traits that might make it more difficult for hair to fossilize, or an issue with scientists’ collection techniques that could lead to them missing important finds.

“This pattern of where and when we do find fossilized feathers and hairs can be used to inform where we look for future fossil discoveries,” said first author Chad Eliason, a researcher at the Field Museum of Natural History who conducted the research while a postdoctoral fellow at the UT Jackson School of Geosciences.

The study was published on Sept. 6 in the journal Proceedings of the Royal Society B. Co-authors include Julia Clarke, a professor in the Jackson School’s Department of Geological Sciences who led the study, and three Jackson School undergraduate students, Leah Hudson, Taylor Watts and Hector Garza.

Fossils of body coverings contain unique data on the ecology and lifestyle of extinct animals, including what color they might have been. They also might affect our understanding of when kinds of body coverings, such as feathers and hair, evolved. In this study, the researchers used data on fossil type and age to determine that hair probably evolved much earlier than current fossil samples indicate.

Fossil beds that preserve soft tissues like hair and feathers are called lagerstatte (‘fossil storehouses’ in German) and are rare on their own. The researchers were interested in understanding how frequently different types of body coverings were found preserved in these exceptional sites, which include the Yixian Formation in China and the Green River Formation in the western United States.

Eliason and his collaborators assembled the largest known database of fossilized body coverings, or integument, from land-dwelling vertebrates, a group known as tetrapods, collected from lagerstatte. They found that unlike feathers, hairs are extremely rare finds.

“Mammal hair has been around for more than 160 million years yet over that time we have very few records,” Eliason said.

This is a fossilized bird with some feathers intact. Credit: Julia Clarke/UT Austin

   This is a fossilized bird with some feathers intact.Credit: Julia Clarke/UT Austin

The rarity might be explained by feathers and hair containing different types of the protein keratin, which may impact the likelihood of fossilization. However, the study notes that the lack of hair samples could have nothing to do with fossilization, and be explained by the collecting behavior of paleontologists, with a single feather usually being much easier to identify than a single hair.

The database also allowed the researchers to conduct a type of statistical method called gap analysis, which models the probability of finding a fossil in a given time. The team found that feathers appear to have evolved very close to the earliest known examples in the fossil record, about 165 million years ago. However, hair and hair-like filaments found on pterosaurs probably evolved far earlier in the fossil record than currently known.

“The hunt is on,” said Clarke. “These data suggest we might expect to find records up to 100 million years earlier potentially.”

The team also applied a statistical approach called a time series analyses to study if climatic factors might explain gaps in the fossil record. They found that soft tissue preservation was most common when ancient sea levels were high.

“There is still a lot we don’t know about the chemistry of these deposits and why they are so uneven through time,” Clarke said. “But we can say that their uneven distribution across the world — most [sites] are in North America or Eurasia — is an artifact of where paleontologists looked. We have a lot more work to do.”

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

  1. Chad M. Eliason, Leah Hudson, Taylor Watts, Hector Garza, Julia A. Clarke. Exceptional preservation and the fossil record of tetrapod integument. Proceedings of the Royal Society B: Biological Sciences, 2017; 284 (1862): 20170556 DOI: 10.1098/rspb.2017.0556
  2. University of Texas at Austin. “Why are fossilized hairs so rare?.” ScienceDaily. ScienceDaily, 7 September 2017. <www.sciencedaily.com/releases/2017/09/170907142722.htm

WFS Facts: Toba catastrophe theory

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According to the Toba catastrophe theory, modern human evolution was affected by a recent, large volcanic event.

Within the last three to five million years, after human and other ape lineages diverged from the hominid stem-line, the human line produced a variety of human species.

Toba Super Eruption

 Toba Super Eruption

According to the Toba catastrophe theory, a massive volcanic eruption changed the course of human history by severely reducing the human population.

This may have occurred when around 70–75,000 years ago the Toba caldera in Indonesia underwent a category 8 or “mega-colossal” eruption on the Volcanic Explosivity Index.

This may have reduced the average global temperature by 3 to 3.5 degrees Celsius for several years and may possibly have triggered an ice age.

This massive environmental change is believed to have created population bottlenecks in the various species that existed at the time; this in turn accelerated differentiation of the isolated human populations, eventually leading to the extinction of all the other human species except for the branch that became modern humans.

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WFS News: ‘Living fossil fish’ not as old as we thought

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Polypterids are weird and puzzling African fish that have perplexed biologists since they were discovered during Napoleon’s expedition to Egypt in the late 1700s.

Often called living fossils, these eel-like misfits have lungs and fleshy pectoral fins, bony plates and thick scales reminiscent of ancient fossil fish, and flag-like fins along their back that are unique.

For several decades, scientists have placed polypterids down near the base of the family tree of ray-finned fish, a large group believed to have originated around 385 million years ago.

But a new study that used CT scans to probe three-dimensionally preserved fossil fish skulls shakes up the fish family tree by concluding that the emergence of polypterids occurred much later than researchers had thought. The findings also suggest that the origin of all modern ray-finned fish may have occurred tens of millions of years later than is generally believed.

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The skull of a 250 million year old fossil fish and a virtual model of its internal skeleton, along with a life reconstruction. Credit: Andrey Atuchin

The skull of a 250 million year old fossil fish and a virtual model of its internal skeleton, along with a life reconstruction.Credit: Andrey Atuchin

The international research team was led by Sam Giles of the University of Oxford and includes University of Michigan paleontologist Matt Friedman. A paper summarizing the findings is scheduled for publication Aug. 30 in Nature.

“This causes a shakeup in the fish family tree, which indicates that the ancestor shared by all ray-finned fishes lived tens of millions of years after previously thought, maybe in the aftermath of a mass extinction event around 360 million years ago that decimated many other groups,” said Friedman, an associate curator at the U-M Museum of Paleontology and an associate professor in the Department of Earth and Environmental Sciences.

Ray-finned fish represent about half of all backboned animals on Earth. For every species of mammal, bird, reptile and amphibian on land, there is a species of bony fish in the ocean.

Polypterids include about a dozen species of African fish called bichirs and a single species of ropefish. They have long defied classification but are generally accepted to be the most primitive living ray-finned fish, separated from the other modern groups by a host of long-extinct fossil fish.

But the new CT study repositions polypterids on the fish evolutionary tree so they are “nestled neatly back more closely with other living ray-finned fishes, kicking a range of fossil ray-fins to a more distant branch of the evolutionary tree,” said Oxford’s Giles, first author of the Nature paper.

“These results change our understanding of when the largest living group of vertebrates evolved and allow us to iron out a lot of the wrinkles in our understanding of the sequence of evolutionary events.”

An enduring puzzle about polypterids has been the lack of early fossil evidence. The oldest fossil polypterids are just 90 million years old, leaving a gap of more than a quarter billion years in the fossil record. If polypterids are really as old scientists have believed, where’s the fossil evidence?

To get at some answers, the researchers examined high-definition computed tomography (CT) scans of Fukangichthys, a 230 million-year-old fossil fish from China that belongs to a widespread group of fossil fish called scanilepiforms.

Analysis of physical characteristics in three-dimensionally preserved Fukangichthys skulls, as well as an examination of DNA sequences from 12 genes, revealed that scanilepiforms are actually ancient cousins of polypterids. Scanilepiforms originated in the Triassic Period, 252 to 201 million years ago, when the first dinosaurs were evolving on land.

“While this finding extends the fossil record of polypterids, it also has some unexpected consequences,” U-M’s Friedman said. “It shows that many features of polypterids aren’t primitive at all, but rather are specializations that evolved later in their history.”

Said Oxford’s Giles: “Polypterids appear to have undergone several reversals in their evolution, which has clouded the view of their position in the fish family tree. It’s like if your brand new smart phone came with a rotary dialer and without Wi-Fi. We know it’s the latest handset, but its characteristics might lead us to thinking it’s an older model.”

This repositioning of the polypterids sends shock waves through the fish family tree and suggests that ray-finned fish may have emerged tens of millions of years later than scientists had thought, near the boundary between the Devonian and Carboniferous periods about 360 million years ago.

“Analyses like these are powerful tools and go to show that paleontology doesn’t always rely on the discovery of new fossils,” Giles said. “Re-examination of old fossils using new techniques is just as important for revitalizing our understanding of vertebrate evolution.”

The other authors of Nature paper are Guang-Hui Xu of the Chinese Academy of Sciences and Thomas Near of Yale University.

Giles was supported by a Junior Research Fellowship from Christ Church, Oxford, and a L’Oréal-UNESCO For Women in Science Fellowship. Xu was supported by the National Natural Science Foundation of China. Near was supported by the U.S. National Science Foundation and the Bingham Oceanographic Fund from the Peabody Museum of Natural History at Yale University. Friedman was supported by a Philip Leverhulme Prize and a Leverhulme Trust Project Grant, and by U-M’s Department of Earth and Environmental Sciences, Museum of Paleontology, and College of Literature, Science, and the Arts.

  1. Sam Giles, Guang-Hui Xu, Thomas J. Near, Matt Friedman. Early members of ‘living fossil’ lineage imply later origin of modern ray-finned fishes. Nature, 2017; DOI: 10.1038/nature23654
  2. University of Michigan. “Shaking up the fish family tree: ‘Living fossil’ not as old as we thought.” ScienceDaily. ScienceDaily, 30 August 2017. <www.sciencedaily.com/releases/2017/08/170830132232.htm

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WFS News: Machine learning predicts laboratory earthquakes

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By listening to the acoustic signal emitted by a laboratory-created earthquake, a computer science approach using machine learning can predict the time remaining before the fault fails.

“At any given instant, the noise coming from the lab fault zone provides quantitative information on when the fault will slip,” said Paul Johnson, a Los Alamos National Laboratory fellow and lead investigator on the research, which was published today in Geophysical Research Letters.

“The novelty of our work is the use of machine learning to discover and understand new physics of failure, through examination of the recorded auditory signal from the experimental setup. I think the future of earthquake physics will rely heavily on machine learning to process massive amounts of raw seismic data. Our work represents an important step in this direction,” he said.

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Researchers at Los Alamos National Laboratory have developed a two-dimensional tabletop simulator that models the buildup and release of stress along an artificial fault. In this image, the simulator is viewed through a polarized camera lens, photo-elastic plates reveal discrete points of stress buildup along both sides of the modeled fault as the far (upper) plate is moved laterally along the fault. Credit: Los Alamos National Laboratory

Researchers at Los Alamos National Laboratory have developed a two-dimensional tabletop simulator that models the buildup and release of stress along an artificial fault. In this image, the simulator is viewed through a polarized camera lens, photo-elastic plates reveal discrete points of stress buildup along both sides of the modeled fault as the far (upper) plate is moved laterally along the fault.Credit: Los Alamos National Laboratory

Not only does the work have potential significance to earthquake forecasting, Johnson said, but the approach is far-reaching, applicable to potentially all failure scenarios including nondestructive testing of industrial materials brittle failure of all kinds, avalanches and other events.

Machine learning is an artificial intelligence approach to allowing the computer to learn from new data, updating its own results to reflect the implications of new information.

The machine learning technique used in this project also identifies new signals, previously thought to be low-amplitude noise, that provide forecasting information throughout the earthquake cycle. “These signals resemble Earth tremor that occurs in association with slow earthquakes on tectonic faults in the lower crust,” Johnson said. “There is reason to expect such signals from Earth faults in the seismogenic zone for slowly slipping faults.”

Machine learning algorithms can predict failure times of laboratory quakes with remarkable accuracy. The acoustic emission (AE) signal, which characterizes the instantaneous physical state of the system, reliably predicts failure far into the future. This is a surprise, Johnson pointed out, as all prior work had assumed that only the catalog of large events is relevant, and that small fluctuations in the AE signal could be neglected.

To study the phenomena, the team analyzed data from a laboratory fault system that contains fault gouge, the ground-up material created by the stone blocks sliding past one another. An accelerometer recorded the acoustic emission emanating from the shearing layers.

Following a frictional failure in the labquake, the shearing block moves or displaces, while the gouge material simultaneously dilates and strengthens, as shown by measurably increasing shear stress and friction. “As the material approaches failure, it begins to show the characteristics of a critical stress regime, including many small shear failures that emit impulsive acoustic emissions,” Johnson described.

“This unstable state concludes with an actual labquake, in which the shearing block rapidly displaces, the friction and shear stress decrease precipitously, and the gouge layers simultaneously compact,” he said. Under a broad range of conditions, the apparatus slide-slips fairly regularly for hundreds of stress cycles during a single experiment. And importantly, the signal (due to the gouge grinding and creaking that ultimately leads to the impulsive precursors) allows prediction in the laboratory, and we hope will lead to advances in prediction in Earth, Johnson said.

  1. Bertrand Rouet-Leduc, Claudia L. Hulbert, Nicholas Lubbers, Kipton M. Barros, Colin J Humphreys, Paul A. Johnson. Machine learning predicts laboratory earthquakes. Geophysical Research Letters, 2017; DOI: 10.1002/2017GL074677
  2. DOE/Los Alamos National Laboratory. “Machine-learning earthquake prediction in lab shows promise: Listening to faultline’s grumbling gives countdown to future quakes.” ScienceDaily. ScienceDaily, 30 August 2017. <www.sciencedaily.com/releases/2017/08/170830122545.htm

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