What is Mass Extinction? Are we heading towards other extinction?

Climate change was at the root of some of the major extinction events of the past.

by

Dr. Nitish Priyadarshi

Presently environmentalists are concerned about the imbalance caused by human activity and industrial growth in the ecosystem, as it is slowly inundating the forest cover, thereby reducing considerably the area of natural habitat of animal and plant life. It is also affecting adversely the human community in general as it disturbs the natural cycles of critical materials such as water, oxygen, nitrogen or carbon dioxide. Biocide is occurring at an alarming rate. Experts say that at least half of the world’s current species will be completely gone by the end of the century. Wild plant-life is also disappearing. Most biologists say that we are in the midst of an anthropogenic mass extinction. Numerous scientific studies confirm that this phenomenon is real and happening right now. Should anyone really care? Will it impact individuals on a personal level? Scientists say, “Yes!”
Are we heading towards other extinction as it happened in geological past?

Two main sorts of extinction are recognized – background extinction and mass extinction. The focus here is on mass extinction, observed at intervals throughout Phanerozoic history.

Embedded in the fossil record is a story of adaptation and recovery following catastrophic episodes in which many species become extinct within a geologically short time. Such episodes are called mass extinctions. Most people are aware that the dinosaurs became extinct about 65 million years ago, at the boundary between the Cretaceous (K) and Tertiary (T) periods. But many are not aware that other animal and plant species were also affected. Approximately one-quarter of all known animal families living at the time, including marine and land dwelling species, became extinct at the end of the Cretaceous period. This mass disappearance of species is clearly evident in the fossil record. It is the reason that early paleontologists selected this particular stratigraphic horizon to represent a major boundary in the geological timescale.

The great K-T extinction is not unique, nor was it the most dramatic of such occurrences. There have been at least 5 and possibly as many as 12 mass extinctions during the past 250 million years. The most devastating of these occurred 245 million years ago at the end of the Permian period, when as many as 96 percent of all species died out. Another great extinction occurred at the end of the Triassic period, and several earlier extinctions affected marine organisms.

What causes mass extinctions? Some evidence suggests that the K-T extinction may have been caused by a giant meteorite impact. If an extraterrestrial body such as a meteorite or a comet 10 km in diameter struck the Earth, it could cause massive environmental devastation. The effects could include earthquakes, tsunamis, widespread fires, acid rain, atmospheric particulates that might cause global darkness, and intense climate changes. Evidence for these and related effects has been found in the K-T boundary. Throughout the world the boundary is also marked by a thin layer of clay that is rich in the element iridium (Ir). This is consistent with an influx of extraterrestrial material, because meteorites contain a great deal of iridium compared to the amount contained in terrestrial rocks.

It is possible that a meteorite impact caused the K-T extinction, but the causes of other major extinctions are not as clear. Many scientists feel that some extinctions-particularly the great marine extinctions of the Paleozoic era-were more likely caused by climatic or other environmental changes than by catastrophic events such as meteorite impacts.

The first event recognized by at least some paleontologists as mass extinction actually occurred in Precambrian time. Its exact timing is uncertain, but it happened near the very end of the Proterozoic era. The organisms most notably involved were the soft bodied Ediacarans, although some species of algae seem to disappear at about the same time. If such an event occurred, what was it cause? Sediments from this time period have been examined carefully for excess Ir, which might record an impact, but none has been found. With the available (admittedly scanty) evidence, the best explanation seems to be that the preferred habitat of the Ediacaran animals- shallow water environments-was drastically reduced in amount because of falling sea levels. Analysis of the sediments still preserved from late in Precambrian time suggest that there were repeated cycles of rising and lowering water levels. One of the largest lowerings, also known as regression, during this time appears to coincide with the extinction of the Ediacarans.

Indeed, it is widely believed that sea level change, particularly the lowering of sea level, was a major factor in many of the extinctions in the geologic record. Biological activity is typically high in shallow seas, and times of high sea level provide abundant habitats for marine life, but when the seas withdraw, many of these organisms become extinct. The total range of sea level fluctuations over the past six hundred million years appears to have been very large, at least 200 meters.

The spectacular nature of events at the Cretaceous-Tertiary boundary has tended to obscure the overwhelming importance of the Permian-Triassic extinctions, which saw the end of most of the species then existing in the oceans. The devastation on land was only moderately less extreme. The nature of life on earth was radically changed, and the effects are with us today in the form of all living plants and animals. The cause of this event – or events- are unclear, but it is generally acknowledged that rather severe conditions would have been required to exterminate such a large fraction of life on earth.

The picture that seems to be emerging from Permian-Triassic studies is very different from that of the K-T boundary. The Permian-Triassic record is one of complex extinction patterns in the face of complex and partly interrelated environmental change. No heat, clear-cut culprit has been identified, but much has been learned about the mechanisms of extinction. Nevertheless, the links between cause and effect are still quite tenuous.

The Permian–Triassic (P–Tr) extinction event, informally known as the Great Dying, was an extinction event that occurred 251.4 million years ago, forming the boundary between the Permian and Triassic geologic periods. It was the Earth's most severe extinction event, with up to 96 percent of all marine species and 70 percent of terrestrial vertebrate species becoming extinct; it is the only known mass extinction of insects. Fifty-seven percent of all families and 83% of all genera were killed. Because so much biodiversity was lost, the recovery of life on earth took significantly longer than after other extinction events. This event has been described as the "mother of all mass extinctions". The pattern of extinction is still disputed, as different studies suggest one to three different pulses. There are several proposed mechanisms for the extinctions; the earlier peak was likely due to gradualistic environmental change, while the latter was probably due to a catastrophic event. Possible mechanisms for the latter include large or multiple bolide impact events, increased volcanism, or sudden release of methane hydrates from the sea floor; gradual changes include sea-level change, anoxia, increasing aridity, and a shift in ocean circulation driven by climate change.
Triassic–Jurassic extinction event - 205 Ma at the Triassic-Jurassic transition. About 23% of all families and 48% of all genera (20% of marine families and 55% of marine genera) went extinct. Most non-dinosaurian archosaurs, most therapsids, and most of the large amphibians were eliminated, leaving dinosaurs with little terrestrial competition. Non-dinosaurian archosaurs continued to dominate aquatic environments, while non-archosaurian diapsids continued to dominate marine environments. The Temnospondyl lineage of large amphibians also survived until the Cretaceous in Australia (e.g., Koolasuchus).
At least half of the species now known to have been living on Earth at that time went extinct. This event vacated ecological niches, allowing the dinosaurs to assume the dominant roles in the Jurassic period. This event happened in less than 10,000 years and occurred just before Pangaea started to break apart.
Statistical analysis of marine losses at this time suggests that the decrease in diversity was caused more by a decrease in speciation than by an increase in extinctions.

Several explanations for this event have been suggested, but all have unanswered challenges:
1. Gradual climate change or sea-level fluctuations during the late Triassic. However, this does not explain the suddenness of the extinctions in the marine realm.
2. Asteroid impact, but no impact crater has been dated to coincide with the Triassic–Jurassic boundary (the impact responsible for the annular Manicouagan Reservoir occurred about 12 million years before the extinction event).
3. Massive volcanic eruptions, specifically the flood basalts of the Central Atlantic Magmatic Province, would release carbon dioxide or sulfur dioxide and aerosols, which would cause either intense global warming (from the former) or cooling (from the latter).


The Late Devonian extinction was one of five major extinction events in the history of the Earth's biota. A major extinction occurred at the boundary that marks the beginning of the last phase of the Devonian period, the Famennian faunal stage, (the Frasnian-Famennian boundary), about 364 million years ago, when nearly all of the fossil agnathan fishes suddenly disappeared.

A second strong pulse closed the Devonian period. Overall, 19% of all families and 50% of all genera went extinct. Although it is clear that there was a massive loss of biodiversity towards the end of the Devonian, the extent of time during which these events took place is uncertain, with estimates ranging from 500,000 to 15 million years, the latter being the full length of the Famennian. Nor is it clear whether it concerned two sharp mass extinctions or a series of smaller extinctions, though the latest research suggests multiple causes and a series of distinct extinction pulses through an interval of some three million years. Some consider the extinction to be as many as seven distinct events, spread over about 25 million years, including particularly notable extinctions at the ends of the Givetian, Frasnian, and Famennian stages.
By the late Devonian, there were plants, insects, and amphibians on land, fish in the seas, and huge reefs built by corals and stromatoporoids. The extinction seems to have only affected marine life. The causes of these extinctions are unclear. The leading theories suggest that changes in sea level and ocean anoxia, possibly triggered by global cooling or oceanic volcanism, were most likely responsible, although the impact of an extraterrestrial body such as a comet has also been considered. Some statistical analysis suggests that the decrease in diversity was caused more by a decrease in speciation than by an increase in extinctions.

The Ordovician–Silurian extinction event or quite commonly the Ordovician extinction, was the third-largest of the five major extinction events in Earth's history in terms of percentage of genera that went extinct and second largest overall in the overall loss of life. Between about 450 Ma to 440 Ma, two bursts of extinction, separated by one million years, appear to have happened . This was the second biggest extinction of marine life, ranking only below the Permian extinction. At the time, all known life was confined to the seas and oceans More than 60 per cent of marine invertebrates died including two-thirds of all brachiopod and bryozoan families. Particularly affected were brachiopods, bivalves, echinoderms, bryozoans, and corals. The immediate cause of extinction appears to have been the continental drift of a significant landmass into the south polar region, causing a global temperature drop, glaciation, and consequent lowering of the sea level, which destroyed species' habitats around the continental shelves. Evidence for this was found through deposits in the Sahara Desert. When Gondwana passed over the south pole in the Ordovician, global climatic cooling occurred to such a degree that there was widespread continental glaciation. This glaciation event also caused a lowering of sea level worldwide as large amounts of water became tied up in ice sheets. A combination of this lowering of sea level, reducing ecospace on continental shelves, in conjunction with the cooling caused by the glaciation itself are likely driving agents for the Ordovician mass extinction. These extinctions are currently being intensively studied; the most commonly accepted theory is that they were triggered by the onset of a long ice age, perhaps the most severe glacial age.

There was other theory too regarding extinction. Scientists from the University of Kansas and NASA have suggested that the initial extinctions could have been caused by a gamma ray burst originating from an hypernova within 6,000 light years of Earth (within a nearby arm of the Milky Way Galaxy). A ten-second burst would have stripped the Earth's atmosphere of half of its ozone almost immediately, causing surface-dwelling organisms, including those responsible for planetary photosynthesis, to be exposed to high levels of ultraviolet radiation. This would have killed many species and caused a drop in temperatures. While plausible, there is no unambiguous evidence that such a nearby gamma ray burst has ever actually occurred.

New Theory On Largest Known Mass Extinction In Earth's History:

The largest mass extinction in the history of the earth could have been triggered off by giant salt lakes, whose emissions of halogenated gases changed the atmospheric composition so dramatically that vegetation was irretrievably damaged. An international team of scientists has reported in the most recent edition of the Proceedings of the Russian Academy of Sciences (Dokladi Earth Sciences). At the Permian/Triassic boundary, 250 million years ago, about 90 percent of the animal and plant species ashore became extinct. Previously it was thought that volcanic eruptions, the impacts of asteroids, or methane hydrate were instigating causes.
The new theory is based on a comparison with today's biochemical and atmospheric chemical processes. According to Dr. Ludwig Weißflog from the Helmholtz-Center for Environmental Research (UFZ) "Our calculations show that airborne pollutants from giant salt lakes like the Zechstein Sea must have had catastrophic effects at that time".

Based on the findings the researchers were able to form their new hypothesis: At the end of the Permian Age the emissions of halogenated gases from the Zechstein Sea and other salt seas were responsible in a complex chain of events for the world's largest mass extinction in the history of the earth, in which about 90 percent of the animal and plant species of that time became extinct.

The Holocene extinction is the widespread, ongoing extinction of species during the present Holocene epoch. The large number of extinctions span numerous families of plants and animals including mammals, birds, amphibians, reptiles and arthropods; a sizeable fraction of these extinctions are occurring in the rainforests. Between 1500 and 2009 CE, 875 extinctions have been documented by the International Union for Conservation of Nature and Natural Resources However, since most extinctions go undocumented, scientists estimate that during the 20th century, between 20,000 and two million species actually became extinct, but the precise total cannot be determined more accurately within the limits of present knowledge. Up to 140,000 species per year (based on Species-area theory) may be the present rate of extinction based upon upper bound estimating.
In broad usage, Holocene extinction includes the notable disappearance of large mammals, known as megafauna, starting 10,000 years ago as humans developed and spread. Such disappearances have normally been considered as either a response to climate change, a result of the proliferation of modern humans, or both.
Over 10,000 scientists in the World Conservation Union have compiled data showing that currently 51 per cent of known reptiles, 52 per cent of known insects, and 73 per cent of known flowering plants are in danger along with many mammals, birds and amphibians. It is likely that some species will become extinct before they are even discovered, before any medicinal use or other important features can be assessed. A new study suggests that global warming could threaten one-fourth of the world's plant and vertebrate animal species with extinction by 2050.

The causes of biocide are a hodge-podge of human environmental “poisons” which often work synergistically, including a vast array of pollutants, pesticides, a thinning ozone layer which increases ultra-violet radiation, human induced climate change, habitat loss from agriculture and urban sprawl, invasions of exotic species introduced by humans, illegal and legal wildlife trade, light pollution, and man-made borders among other many other causes.

There is considerable circumstantial evidence that climate change was at the root of some of the major extinction events of the past. Competition, especially competition for food, is another reason for extinction, although it is unlikely to be a dominant one in mass extinctions. It has been argued that competition was responsible for the minor role played by mammals during the Mesozoic.

The list of possible agents of mass extinction is quite long. It contains mechanisms ranging from the exotic to the ordinary; some examples are explosion of a nearby Supernova, which would have bathed the earth in lethal radiation, the effects of plate tectonics moving continents into and out of favorable climatic belts, and the rise and fall of sea level.

Summary:

Major Extinction Events
1. 488 million years ago : a series of mass extinctions at the Cambrian-Ordovician transition (the Cambrian-Ordovician extinction events) eliminated many brachiopods and conodonts and severely reduced the number of trilobite species.

2. 444 million years ago : at the Ordovician-Silurian transition two Ordovician-Silurian extinction events occurred, and togther these are ranked by many scientists as the second largest of the five major extinctions in Earth's history in terms of percentage of genera that went extinct.

3. 360 million years ago : near the Devonian-Carboniferous transition (the Late Devonian extinction) a prolonged series of extinctions led to the elimination of about 70% of all species. This was not a sudden event the period of decline lasted perhaps as long as 20 million years, and there is evidence for a series of extinction pulses within this period.

4. 251 million years ago : at the Permian-Triassic transition Earth's worst mass extinction (the P/Tr or Permian-Triassic extinction event) killed 53% of marine families, 84% of marine genera, about 96% of all marine species and an estimated 70% of land species (including plants, insects, and vertebrate animals). The "Great Dying" had enormous evolutionary significance: on land it ended the dominance of the mammal-like reptiles and created the opportunity for archosaurs and then dinosaurs to become the dominant land vertebrates; in the seas the percentage of animals that were sessile dropped from 67% to 50%. The whole of the late Permian was a difficult time for at least marine life - even before the "Great Dying", the diagram shows a late-Permian level of extinction large enough to qualify for inclusion in the "Big Five".

5. 200 million years ago : at the Triassic-Jurassic transition (the Triassic-Jurassic extinction event) about 20% of all marine families as well as most non-dinosaurian archosaurs, most therapsids, and the last of the large amphibians were eliminated.

6. 65 million years ago : at the Cretaceous-Paleogene transition (the K/T or Cretaceous-Tertiary extinction event) about 50% of all species became extinct. It has great significance for humans because it ended the reign of the dinosaurs and opened the way for mammals to become the dominant land vertebrates; and in the seas it reduced the percentage of sessile animals again, to about 33%. The K/T extinction was rather uneven some groups of organisms became extinct, some suffered heavy losses and some appear to have got off relatively lightly.

7. Present day : the Holocene extinction event. A 1998 survey by the American Museum of Natural History found that 70% of biologists view the present era as part of a mass extinction event, possibly one of the fastest ever. Some, such as E. O. Wilson of Harvard University, predict that man's destruction of the biosphere could cause the extinction of one-half of all species in the next 100 years. Research and conservation efforts, such as the IUCN's annual "Red List" of threatened species, all point to an ongoing period of enhanced extinction, though some offer much lower rates and hence longer time scales before the onset of catastrophic damage. The extinction of many megafauna near the end of the most recent ice age is also sometimes considered a part of the Holocene extinction event.

Reference:

Bambach, R.K.; Knoll, A.H.; Wang, S.C. (December 2004). "Origination, extinction, and mass depletions of marine diversity". Paleobiology 30 (4): 522–542.

Barry, Patrick L. (January 28, 2002). "The Great Dying". Science@NASA. Science and Technology Directorate, Marshall Space Flight Center, NASA.

Bowring SA, Erwin DH, Jin YG, Martin MW, Davidek K, Wang W (1998). "U/Pb Zircon Geochronology and Tempo of the End-Permian Mass Extinction". Science 280 (1039): 1039–1045.

Cloud, P. 1987. Oasis in space, earth history from beginning. W.W. Norton & Company, New York.

Jin YG, Wang Y, Wang W, Shang QH, Cao CQ, Erwin DH (2000). "Pattern of Marine Mass Extinction Near the Permian–Triassic Boundary in South China". Science 289 (5478): 432–436.

Jr. Dickey, J. S. 1996. On the rocks. John Wiley & Sons, Inc. New York.

Labandeira CC, Sepkoski JJ (1993). "Insect diversity in the fossil record". Science 261 (5119): 310–5.

Macdougall, J.D. 1996. A short history of planet earth, mountains, mammals, fire, and ice. John Wiley & Sons, Inc. New York.

Sole, R. V., and Newman, M., 2002. "Extinctions and Biodiversity in the Fossil Record - Volume Two, The earth system: biological and ecological dimensions of global environment change" pp. 297-391, Encyclopedia of Global Enviromental Change John Wiley & Sons.

Wanjek, Christopher (April 6, 2005). "Explosions in Space May Have Initiated Ancient Extinction on Earth". NASA. http://www.nasa.gov/vision/universe/starsgalaxies/gammaray_extinction.html. Retrieved 2008-04-30.

http://science.nasa.gov/headlines/y2002/28jan_extinction.htm. Retrieved March 26, 2009.
http://en.wikipedia.org/wiki/Extinction_event
http://en.wikipedia.org/wiki/Permian%E2%80%93Triassic_extinction_event
http://en.wikipedia.org/wiki/Late_Devonian_extinction
http://en.wikipedia.org/wiki/Ordovician%E2%80%93Silurian_extinction_event
http://www.sciencedaily.com/releases/2009/03/090330102659.htm
http://news.nationalgeographic.com/news/2006/04/0412_060412_global_warming.html
http://en.wikipedia.org/wiki/Triassic%E2%80%93Jurassic_extinction_event
http://www.dailygalaxy.com/my_weblog/2008/02/the-6th-great-m.html
http://en.wikipedia.org/wiki/Holocene_extinction
http://www.newscientist.com/article/dn4797-earth-faces-sixth-mass-extinction.html
http://life7.beyondgenes.com/

Some scientists disagree with Global Warming Theory.

They say it is natural.

by

Dr. Nitish Priyadarshi

Rising temperature are already the clearest sign of climate change. So far, according to the IPCC, global average temperatures have risen 0.6⁰ C above the pre-industrial average. Nine of the hottest years on record have occurred since 1988; six of the first eight months of 1998 were the warmest since records began in 1866; and July 1998 was the hottest month ever.

Scientists who assess the planet’s health see indisputable evidence that earth has been getting warmer, in some cases rapidly. Most believe that human activity, in particular the burning of fossil fuels and the resulting buildup of green house gases in the atmosphere, have influenced this warming trend. In the past decades scientists have documented record-high average annual surface temperatures and have been observing other signs of change all over the planet: in the distribution of ice, and in the salinity, levels, and temperatures of the oceans.

Everywhere on earth ice is changing. The famed snows of Kilimanjaro have melted more than 80 percent since 1912. Glaciers in the Garhwal Himalayas in India are retreating so fast that researchers believe that most central and eastern Himalayan could virtually disappear by 2035. Artic sea ice has thinned significantly over the fast half century, and its extent has declined by about 10 percent in the past 30 years.

This is one of the aspect of the global warming which most of scientists believe is man made. There is small minority of atmospheric and other scientists who disagree with this general scientific consensus. According to these scientists we still know too little about natural climate variables that could change the assessment (up or down). In addition, computer models used to predict climate change are improving but still are not reliable.

They also point out that some signs of global warming may not necessarily be caused by human activities. For example, while many glaciers are shrinking, others are growing. Also, glaciers shrink and grow naturally over long periods of time for reasons that are largely unknown.

Finally, they contend that global warming may be a lot less damaging than many people think and can be beneficial for some regions. For example, some countries may be able to increase crop productivity because of more rainfall and longer growing seasons.

They also claim that more carbon dioxide in the atmosphere could increase the rate of photosynthesis in areas with adequate amounts of water and other soil nutrients. This would remove more carbon dioxide from the atmosphere and help slow atmospheric warming.

However recent studies cast doubt on such a generalization for two reasons. First, this effect would slow as the plants reach maturity and take up less carbon dioxide. Second, it is a temporary effect. When the plants die and are decomposed or burned, the carbon they stored is returned to the atmosphere as carbon dioxide.

Are we heading towards major disaster or it is a simply a natural shifting of climate as it happened in the geological past. During the last 2 billion years the Earth's climate has alternated between a "Ice House", like today's world, and a steaming "Hot House", like the world of the dinosaurs. Jurassic climate stayed warm and became more humid. The polar areas were ice-free during this Period.

The history of earth’s climate is characterized by change. Times of glaciations on the earth have been followed by warm intervals and the duration in years of both cold and warm intervals has varied by several orders of magnitude.

What ever may be the truth we have no options but we have to opt wait and watch theory if we don’t stop carbon emission recklessly. But it is also true that the climate of the earth is changing from the time of its birth from hot to cold and cold to hot. Earlier too the earth has passed through global warming due to natural causes, but this time we the humans are culprits for the changes. When man-made factors are added to the natural ones, the ecosystem may be damaged beyond repair.

New species of spiders in Ranchi city.

Colourful spiders of Ranchi city.
By
Dr. Nitish Priyadarshi

Changes in temperature and mild winters have allowed the new species of spider to reproduce and invade gardens across Ranchi city of Jharkhand State of India. Called the "False Widow" its bite does not kill, but does cause intense pain and severe swelling. In other words, if you hate spiders, you have another reason to fear global warming.
Species have started turning up in the gardens and houses. This year peculiar thing is that different varities and colourful spiders are being seen in the backyards. Most of them seems to be migrated from other part of the country to this city or from other country like Europe and America.
Earlier we use to see only one or two types of spiders especially small and black. But from last few years spiders of different size and colours are seen. Though their numbers may be few but due to their exotic colours they are attracting people. Most interesting is the construction of the Silver Webs in the spiral form.
The pictures above very much resembles to Silver argiope (Argiope argentata) This spectacular orb-weaving spider is common in Southern California in the Fall, especially on prickly-pear plants. They are also found in Arizona, Central and South America as well as South Florida. The male is much smaller than the female. The spider includes zig-zag structures called stabilimenta in the orb web, probably in order to make it more visible to birds who might otherwise fly into it accidentally and destroy it. These critters can bite and leave a slight sting and itch on the victim, though they are not particularly dangerous.

From last several years like Parthenium grass, new species of the insects, frogs and even mosquitoes have been recognised in Ranchi city. Thanks to climate change, pollution and global warming.

The significance of insects in ecology needs no emphasis. Spiders also have a very significant role to play in the ecology by being exclusively predatory (Wise, 1993) and thereby regulate insect populations. All spiders are venomous but only a few species are venomous enough to harm humans. However, the venom of some spiders is useful in study of neuromuscular and cardiac pharmacology. It is likely that spider silk will be the material of the future as its silk is the toughest material known.
Spiders are ancient animals with a history going back many millions of years. They have always been with us, an ancient source of fear and fascination. They are abundant and widespread and are natural controllers of insect populations. Wherever you live, you're always close to a spider.

Spiders were among the earliest animals to live on land. Despite this their fossil record is relatively poor. They probably evolved about 400 million years ago from thick-waisted arachnid ancestors that were not long emerged from life in water. The first definite spiders, thin-waisted arachnids with abdominal segmentation and silk producing spinnerets, are known from fossils like Attercopus fimbriungus. This spider lived 380 million years ago during the Devonian Period, more than 150 million years before the dinosaurs.
By the Jurassic Period (191 - 136 million years ago), when dinosaurs roamed the earth, the sophisticated aerial webs of the orb weaving spiders had developed to trap the rapidly diversifying hordes of flying insects.

Reference:
Wise D H 1993 Spiders in Ecological Webs, Cambridge Univ. Press, London 342 pp
http://amonline.net.au/spiders/
http://amonline.net.au/spiders/diversity/what/origins.htm
http://nathistoc.bio.uci.edu/spiders/Argiope%20argentata.htm
http://smartpoodlepublishing.com/blog/?p=560

Mining and other operations destroying fossils of Jharkhand State of India.

Mining and other operations destroying fossils of Jharkhand State of India.

By
Dr. Nitish Priyadarshi

Large scale mining and other operations in Jharkhand State of India are destroying the plant fossils of the Jurassic and Permian age. Lack of proper preservation arrangements, coupled with reckless mining works are ruining “a veritable storehouse of geological history”. Fossils of Jurassic age in Rajmahal area of Jharkhand state are being used to build up roads. Due to lack of knowledge, awareness and government ignorance these fossils are dangerously set on the path to destruction.
Plant fossils of Permian age which are spread over Damodar Valley coalfields are also being destroyed due to mine blasting or crushed under the huge tyres of trucks.

The situation is a combination of factors including extensive mine blasting and natural weathering process whose ‘baleful impact upon the life of the plant fossils has not been minimized due to the indifference of the organization concerned.

“There is an urgent need to conserve the rich fossil site. It is essential to preserve the plant fossils in ancient conditions,”.

According to the recent report a Memorandum of Understanding was inked between the Jharkhand government, Birbal Sahni Institute of Palaeobotany (BSIP), Lucknow, and the National Building Construction Corporation, (NBCC), under the umbrella of the Department of Science and Technology of Government of India to establish the park. The Lucknow-based BSIP, a premier research centre in the field of palaeobotany, will provide scientific inputs and consultancy services to the park. But what about the fossils of Damodar Valley Coalfields? Decision of making fossil park has come too late. Till today most of the fossils have been destroyed .

Major plant fossils of the Permian age in Jharkhand State are Glossopteris, Gangmopteris, Schizoneura, Vertebraria, Noeggerathiopsis etc. Jurassic fossils are Lycoxylon indicum, Cladophlebis lobata, Ptilophyllum aquitifolium etc.

An angiosperm fruit of uncertain affinity and a questionable flower are reported from the Rajmahal Formation (Early Cretaceous) at the locality of Sonajori, Rajmahal Basin. The remains of ferns, Pentoxylales and conifers have been described previously from this locality. The significant addition of angiosperm megafossil remains confirms that flowering plants were evolving during the Early Cretaceous Epoch in India. The Sonajori assemblage seems to be the youngest fossil assemblage recovered so far from the Rajmahal Basin. It is tentatively dated as Barremian–Aptian.

Mr. Birbal Sahni was the first botanist to study extensively the flora of Indian Gondwana. He also explored the Rajmahal hills which is a treasury of fossils of ancient plants. Here he discovered some new genus of plants. The important and interesting ones are Homoxylon rajmehalense, Rajamahalia paradora and Williamsonia sewardiana.

Stromatolites in Jharkhand:
Stromatolites have the distinction of being by far the oldest indicators of organized life on earth, ranging back over 3 billion years. They occur all on continents in rocks from middle Precambrian to Holocene age. Stromatolites are laminated limestone structure of simple to complex form commonly attributed to debris-binding and biochemical processes of benthonic blue-green, green, and possibly, red algae.
Iron ore groups (Archaean age) of Jharkhand and bordering Orissa need pointed reference as they have the potential to constrain concepts of early evolution of life and also the age of the Iron Ore Group. These relate to the occurrence of palaeobiological remains and the extensive development of carbon phyllites that may have an organic carbon source.
These are found in the chert, jasper, haematite and dolomite beds in the iron-ore formations of the Noamundi-Joda area of Orissa bordering Jharkhand State. Good exposures of stromatolytic dolomite are also found at the base of the iron and manganese formations at Kasia and Belkundi. The stromatolites may be of the stratiform, nodular and columnar types.
Stromatolites have also been recorded Bachra coalfield in North Karanpura coalfield of Jharkhand state. It has been found in Talchir Formation (Permo-Carboniferous). The rock types of Talchir formation in order of superposition comprise tilloides and boulder beds, green shales and varvites with stromatolites. Stromatolites have been recorded by CMPDIL organization for the first time in this area.
They were the dominant life form on Earth for over 2 billion years. Today they are nearly extinct, living a precarious existence in only a few localities.



The term fossil is defined as remains of plants and animals which have existed on the earth in prehistoric times and are found preserved within sedimentary rocks or superficial deposits of the earth, not only mostly as petrified structures of organisms but also whatever was directly connected with or produced by these organisms.


Fossils are recognized as important useful tools since prehistoric times. Prehistoric men and medicine men of certain primitive cultures have believed them as magic sticks with mysterious powers and have used them to treat the evil spirits. Students concerned with the past of the earth have used as guide to reconstruct the geologic history of the earth. Paleontologists have used them in reconstructing the story of the plants and animals and of the past. They have also obtained useful information about when, where, and how the fossil animals and plants lived. Economic geologists have used the fossils as chief indicators in oil exploration.

Most of our knowledge about the climatic conditions in the geologic past comes from the study of the fossils. The presence of a fossils of warmer region in colder parts indicate that the latter once enjoyed a warm climate. The fossil ferns and other plants are usually found associated with coal deposits, which suggest warm and swampy conditions.

The concerned organizations should wake up to the bitter fact of gradual elimination of plant fossils from this region before it is too late.

“This is not to say that mining operations or other construction works in these regions should be stopped but they should be done more judiciously apart from setting up a chain of geological parks in Jharkhand to preserve plant fossils which are indisputably a treasure trove of information about the chronological history of the rocks.