CLIMATE TEMPERATURE RISE
A tsunami from a bolide (extra terrestrial object) impact would have overturned anoxic (lacking oxygen) [Wignall and Twitchet, 1996] water along thousands of miles of coastline and thus brought methane and carbon dioxide into the atmosphere. However, I suspect that the bulk of the sudden rise in organically derived atmospheric carbon dioxide at the Permian’s close as determined by isotopic analysis of carbon was from a drastic overturn of the anoxic ocean [Knoll, et al, 1960] [Kajiwara, et al, 1994] by a sudden cooling of the surface water. The drop in heavy carbon isotope [Gruszczynski, 2003] could not have been from volcanic action or oxidation of land biomass alone. The ocean at the end of the Permian was thought to be anoxic [Kajiwara, 1994, et al] right up to the limit of the wave action [Wignall & Twitchet, 1996][Isozaki, 1997]. A large comet is the most likely bolide for the end Permian extinctions because at the highest energies comets dominate the bolides [Toon, et al, 1997, p45]. Also the iridium anomaly just above the boundary was weak [Kajiwara, et al, 1994] and has been discredited as extraterrestrial recently [Koeberl, et al 2004]. A large comet would in a couple of seconds have turned itself and a couple of hundred cubic kilometers of the ocean water under it into incandescent steam. Huge quantities of this incandescent steam would erupt out through the hole created in the atmosphere by the entry of the bolide and either be hurled high into space or sent into orbit around the earth. Indeed, if the bolide is energetic enough, it could push the atmosphere aside out to the horizon even without the hole [Toon, et al, 1997, p48]. At first it would be so hot and pervasive that it would warm the earth with an energy output comparable to the sun for a few tens of minutes [Toon, et al, 1997, p63] except on the opposite side of the earth where it may have heated up even higher again in a small area by colliding with itself. It would not remain hot very long once spread out over vast areas. As soon as it cooled it would crystallize into tiny ice crystals at high altitudes which would block the sun's light for a few weeks. In addition, there could be smoke from forest fires ignited by molten rock in a ballistic orbit [Alvarez, et al, 1995] which reheated upon reentering the earth's atmosphere. This smoke can block the sun's rays and also cause significant additional cooling. It could have positive feedback on its source in the sense that the blockage of the sun would prevent convection rainfall so that the fires could rage on unchecked in many areas. The situation would be similar to the forest fires that raged unchecked recently in Indonesia in today's world. It is possible that, if the ocean were shallow enough or the bolide large enough, considerable dust from fracturing of the earth could be blown into the stratosphere and above which could conceivably be equal to 30% of the bolide's mass [Toon, et al, 1997, p56]. This would add considerably to the blockage of the sun. There is a good chance that there were a couple of large hits on land at this time, something like the comets that hit Jupiter recently, which would have contributed considerable dust. This is because there were a couple of huge flood basalts in Siberia at this time [Reichow, et al, 2002], which may have been caused by a comet impact [Rampino and Stothers, 1998] or much more likely by disruption from earthquake waves at the antipodes of an impact thought to have occurred in the south Atlantic Ocean between Africa and South America [Alper, 1994], but more likely just north of Ellsworth land in Antarctica. That would be similar to the what was proposed by my son for the known large terrestrial impacts. Also there has been discovered an impact crater west of Australia about this time. Such massive flows are unlikely from the usual tectonic processes. If one of the hits was in an area high in chlorides it has been proposed that halocarbons could have removed the ultraviolet blocking ozone layer [Visscher, et al, 2001]. This orbiting and stratospheric debris could have blocked the sun for several weeks but would probably decline rapidly after a month [Toon, et al, 1997, p57]. If so, the chilled surface water would have caused a massive overturn of the carbon dioxide and methane rich anoxic ocean. It has been proposed that 5 degrees centigrade change for the water at high latitudes is the transition point for such an overturn [Wilde & Berry, 1984, p155]. The organically derived carbon released into the atmosphere that would have resulted, would have made even the huge amounts released by the enormous tsunamis from the initial impact pale in comparison because vast, worldwide expanses of ocean water would be involved, not just a shore side strip. When a cold air mass at minus 9.5 degrees centigrade settled over the Gulf of Mexico off southern Texas recently, the bay waters froze over in less than a week. There is no reason to believe that there would not be a similar effect back then. This cold water would displace to the surface enormous amounts of water from the anoxic region below. This could, added to the tsunami overturn, easily account for the sudden spike of atmospheric carbon derived from organic material at the boundary of the Permian and Triassic and explain why previous spikes in light carbon at the close had been so much less intense, since they may have depended on tsunamis only. The precipitation of calcium carbonate at this time [Heydari, et al, 2003] may have been partly permitted by the loss of carbon dioxide from the oceans.
The cold and fires themselves could account for some of the terrestrial floral extinction at the close of the Permian. However, they would not have extinguished land plants which come up from roots, were in their seed phase, were in sheltered spots, nor many from high latitudes. Even most palm trees survived the Texas cold wave mentioned above. The cold could not have been too severe because marine fish faired worse than fresh water fish [Darlington, 1965, p151], probably the marine fish because of the anoxic marine over turn or starvation when algae were momentarily deprived of sun light. Also it has been proposed that toxic fly ash from burning of coal by the Siberian lava flows may have contributed somewhat as well [Grasby]. However, what happened when the orbit of the dust and ice decayed from colliding with each other and gas moving in opposite directions, and settled or washed out from other causes, could have been ruinous for land plants. With a much increased content of carbon dioxide in the atmosphere the earth would rapidly heat up in a matter of weeks past the settling of the ice, snow, and dust. Not too many months later the initial carbon would undoubtedly be joined by much of the huge supply of methane ice crystals in the ocean sediments similarly to the way it is thought to have happened in the Eocene [Sexton] . In addition, removal of snow cover at high latitudes could have released carbon dioxide [Smith, 2003] and also increased sunlight absorption by dust on the ice or similarly the way it is thought to have happened in late Cretaceous [Otto-Bleisner] or on snowball Earth by a huge Australian meteorite at the initiation of the Cambrian. Metabolism of vegetation by prototermites would have added significantly to the rise of carbon dioxide [Zimmerman]. Also I suspect that prototermites caused a considerable loss of tree cover and mulch, and allowed sunlight down to the soil, which could conceivably have caused an even higher rise in atmospheric temperature than the carbon dioxide. You can easily confirm this phenomenon by touching a stone walk in full sun and adjacent grass or tree leaves in full sun, and noting the dramatic difference in temperature. In an area in Oregon where fire bared the soil, there was a temperature difference between burned and unburned adjacent areas that rose to as much as 20 degrees centigrade [Running]. Also leaves in warm climates have adaptations in warm climates that lower leaf temperatures toward their optimum photosynthetic temperature, [Helliker], which should lower climate temperature a little, and thus cause warming when the plants are removed in low latitudes. It has been proposed that the average temperature rose 5 degrees on the basis of oxygen isotope analysis [Holser, et al, 1989, p41]. There would be little chance for the plants to migrate to a higher latitude in such a short time, which all told could not have been more than two or three years. It is not even likely that many could even have migrated up the side of a mountain in time. I suspect that this temperature rise was a considerable part of the extinction of plant life as observed on the fossil record, and the cause of the migration to higher latitudes of the plants which survived. Vegetation moved north in eastern Asia [Wang].[Wang (2nd reference) ].
Even so, the plants were not as severely affected as were the animals, probably because plants are usually capable of living longer without nutrients, water, or reasonable temperature in addition to having many hibernating forms. The Triassic is the only age of the phanerozoic (back to the Cambrian) which has no evidence of ice [Faure, et al,1995] Southern China became a virtual desert with only shrubby vegetation growing along the side of ponds and streams on a sandy plain [Wang, 1996], indeed, there were extensive deserts in the Triassic [Hosher, 1987, p174] probably created by the termites. The river channels became braided because of loss of vegetation stabilizing the banks [Archie p 274]. This sparse growth could explain the lack of forest fire fossil evidence [Belcher]. It also could explain why crurotarsi relatives of dinosaurs, which sprawled on the ground, were able to compete with upright dinosaurs for millions of years [Brusatte], since distance visibility and forward motion would not have been as obstructed by dense vegetation. Keep in mind that it is unlikely that the dinosaur ancestors held their bodies horizontally since their center of gravity is forward of their hips. They stood upright like us or at least at a 45 degree angle. I suspect the shrubby growth was a result of wood eating prototermites to a considerable extent as well as the heat and dryness, which heat and dryness were probably created at least partly by the loss of vegetation itself allowing the sun light to get to the soil.
EFFECT on PROTOTERMITES
These events are not likely to have had much of an extinction effect on those wood roaches and prototermites which lived underground or bored into tree trunks. Amitermitinae (now merged with Termitinae) subfamily of termites survive below freezing temperatures for short periods in present day Texas. Termites are characteristically warm climate insects, so the subsequent temperature rise would be unlikely to be ruinous in most areas either. They would be seriously affected by a long drought in those days because it was probably before they had developed the ability to bore down to the water table. However, in the short drought of the dust and smoke winter the soil would probably not dry out much because it remained cool [Toon, et al, 1997, p61] and there must have been quite a few places where the water table was close to the surface to act as survival centers. They would certainly not be lacking in food at first in a world with widespread plant destruction since primitive species are and probably were largely a wood eating or saprophytic (eat dead vegetation) organism. Therefore they could have assisted materially toward creation of the above barren conditions if they existed and had evolved species capable of living in monsoon areas.
The warming of the ocean has a positive feedback on atmospheric carbon dioxide in that the extensive methane hydrate ice in the sediments would melt and the methane boil off [Kvenvolden, 1993]. This would place considerable additional upward pressure on the sudden temperature rise. Present day methane deposits are said to contain more energy than all other fossil fuel combined [Suess, et al, 1999].
It is possible that the primitive termite progenitors were a considerable part of the reason the conifers with their poisons and sticky resins, and live tissue on the periphery of the trunk became more successful. Angiosperms have a similar trunk and their progenitors undoubtedly also go back to the Permian (as what plants do not?), I suspect on the Ontong Java Plateau.
It is quite conceivable that some of these wood roaches and/or prototermites could attack susceptible live trees. If this ancient vegetation lacked poisons in the wood against insects or cellulose digesting microorganisms, even possibly most conifers, it is highly unlikely that the wood roaches and/or termites would fail to eat it. Modern Porotermes causes great loss of alpine forests, up to 80% in New South Wales [Gay & Calaby 1970, p401] in spite of over 250 million years of subsequent plant evolution. If something like this were occurring, one would suspect that there would be some sign of it in the fossil trees, which in the early part of the Triassic became largely coniferous [Retallack, 1995]. A tree trunk excavation has been discovered in Arizona which is believed to be a termite nest [Hasiotis & Dubiel, 1995] (or social wood roach nest?) from the Triassic, 200 million years old, which is only 40 million years or so past the end of the coal hiatus. During the Triassic coal hiatus in the beginning of the Triassic it was possible to find stump impressions up to 45 cm (17.7 in) and root impressions up to 18 cm (7 in) in south Australia, but no roots or logs. The soil was extremely low in organic matter and there was no detritus at all [Retallack 1997]. The soil had no modern similarities, although some Madagascar soils may be fairly similar. Perhaps it will be possible to find some ancient wood which is not degraded enough to mask its chemical composition and thus it’s possibilities for insect repulsion.
DECLINE in SEA LEVEL
It could be that the decline in sea level that took place at the end of the Permian allowed wood roaches, or more likely prototermites (that is to say, wood roaches with a soldier caste), to reach Australia across narrow water gaps and thus put an end to the coal measures on that continent. A true worker caste is not necessary to define a termite and was late in developing, largely in species which consume their wooden nests [Higashi, et al, 1991]. Flying insects generally are good colonizers of islands [Carlquest, 1965; p22]. However soil borne termites have not been able to reach oceanic islands, probably because they are poor fliers and have an instinct to head for the surface before a couple of kilometers. So wood roaches or prototermites, which ate humus or litter, could have had a similar difficulty in crossing oceans, especially if they had no wings as present day wood roaches are devoid of. If any wood roaches had been able to nest in trees one would suspect that they could cross ocean barriers as modern Kalotermitidae termites do. However this would have depended on the direction of ancient ocean currents and vicissitudes of climate, which in early Permian were extremely cold in the early Indian Ocean [Haughton, 1963]. The sea level had been steadily declining during the last half of the Permian. Perhaps flow of the asthenosphere from under the Arctic Ocean toward the huge Siberian lava eruptions [Renee], which I suspect may have been from disruption of the crust at the antipode of a huge meteorite impact, and movement of mantle materials toward the Appalachian and Ural Mountain uplifts from under adjacent oceans and inland seas were responsible. This could conceivably have permitted numerous migrations of terrestrial organisms from time to time as connections became available but not across the Tethys (an ancient Asian ocean near the equator) or Antarctic water. At the close of the Permian there was an even quicker drop in sea level, the sharpest in history [Hosher, et al, 1987][Holser, 1989, p42]. There had been many salt deposits in Permian basins in the last half [Knauth, 1998]. There are large salt basins in the southwest United States and a very large basin is suspected in central Canada, now eroded away [Dott and Batten, 1971, p398]. Possibly the Tsunami opened up some of these basins, evaporation from which would have previously delayed the sea level decline, and thus account for that quicker drop at the end. This or something like this would account for a subsequent rapid rise when the inland sea created evaporated again after barriers were reestablished. Whatever caused the fall in sea level, I suspect that it was this fall which permitted the prototermites to spread to Australia over the Tethys Ocean and other areas and thus cause the coal hiatus to appear simultaneously around the world. Degradation of carbonate deposits exposed on continental shelves [Merico] may have given an additional temporary boost in atmospheric carbon dioxide and thus enabled some additional routes of spread by its warming effect. The soldier caste could not have arisen independently in Australia because it evolved only once [Bourke, 1995]. The rise in temperature caused by the rise in atmospheric carbon dioxide and baring of soils may also have made possible spread of prototermites through now much closer spaced Antarctic Ocean islands and through Antarctica. If so, they would have had to move along an island chain or an interrupted isthmus because there are no fresh water fish common to Tasmania and Tierra del Fuego [Darlington, 1965, p151]. Emerson believed that Porotermes and Stolotermes migrated through Antarctica in the Permian or early Mesozoic [Emerson, 1955, p476] and Weesner [Weesner, 1960] suggests the Triassic for that migration. He also believes that Mastotermitidae may go back to the Permian [Weesner, 1960]. If so, it would probably had to have been near the Permian's close or the Triassic when the weather warmed up because Antarctica has been near the South Pole for a long time [Darlington, 1965, p152], probably always. The presence of structures very similar to above ground earthen termite nests in early Jurassic South Africa indicates that they became highly evolved during the Triassic [Bordy]. This would indicate that prototermites go back a long way, easily to early Triassic.
The nature of insect morphology makes the descent of termites from wood roaches or similar roaches (probably the fossil roaches which Tilyard found [Tilyard, 1917][Tilyard, 1937] ) highly probable. The presence of a social cellulose digesting roach or a prototermite in the early Triassic is probable from fossil evidence. It is certain from fossil evidence that termites arose by the Jurassic. A Permian fossil which was said to be a termite was an error as it was actually a cicada, an error probably from linguistic difficulty [Weesner, 1960]. Therefore the presence of social termites with a soldier caste in the early Triassic is very plausible and wood roaches or even prototermites with a soldier caste in the Permian possible somewhere. That these insects would have had considerable affects on the environment if present in large numbers is obvious from the effects of some of their descendants in the present day world. Large numbers of termites, if they arrived, are implied by the absence of efficient predators from the fossil record of the Permian and early Triassic capable of dealing with massed numbers of soldiers. The elaborateness of their intestinal flora coupled to the slowness of their growth [Keller and Genoud, 1997][Wood and Sands, Sands, 1978, p248] and small number of mature reproductives within each population of termites also implies large numbers of individuals in order for evolution to proceed at the necessary pace [Wright, 1931,p139, 142] to produce the number of genera now existing. The above effects could easily have included a small part of the increase in atmospheric carbon dioxide, a significant part of the decline in oxygen during the last part of the Permian, evolution of wood poisons and interior dead tissue in tree trunks, loss of soil mulch (detritus) and the Permian - Triassic coal hiatus, aridity, increased erosion [Sephton], and any secondary circumstances associated with those effects. Migrations around the world when sea level dropped, sea level drop possibly from opening dry, below sea level basins by a tsunami triggered by a large comet impact, may have contributed, by migration of prototermites, to some of the extinctions at the close of the Permian and the rise of the conifers, especially in the Southern Hemisphere. If you think prototermites did not create the effects on the conifers, coal and the soil organic matter, I am open to alternate plausible explanations.
By the Jurassic the ant had appeared and that insect was to become the chief predator of termites. It is conceivable that some of the ant's prototypes, especially parasitoid hymenoptera wasps, had already begun to have perceptible effect by early Triassic. The development of the ants' metapleural gland which secretes phenyl acetic acid, a fungicide and bacteriacide, was probably a large part of their successful occupation of soil [Holldobler, 1990, p30]. Before that their parasitoid Ichneumon predecessors may have put significant pressure on the roaches or prototermites. The ancestors of the parasitoids were present in the Permian. The evolution of these parasitoids may explain the end of the coal hiatus in the early Triassic. Parasitoids have an ovipositor (egg laying tube) inherited from herbivorous bark drilling ancestors. Associated with the tube are alkaline and acid glands. The alkaline is probably for pheromones to mark the host and the acid is for modifying the host's behavior. That ovipositor evolved into the ant's sting. If parasitoids did bring back the coal, their initial evolution must have taken place in or near Australia because the coal reappeared there first by several million years [Retallack, et al, 1996, p196]. Ancestors of the Evaniidae which parasitize roach eggs [Godfrey, 1994, p23] could have been the ones involved, and this may explain why termites evolved separated eggs except in Mastotermitidae.
We need not leave contemplation of these past events exclusively to speculation. Most of the insect orders which lived in the Permian have representatives with us today [Labandeira and Sephoski, 1993]. Experiments on islands, in biospheres, or screened enclosures would be real easy. It would be even easier for the Triassic since almost all the fundamental traits known today were started before its close and there have been no extinction of orders since its close [Labandeira and Sephoski, 1993].
REFERENCES are below
Continue to Permian Marine Phosphorus as caused by amphibians, especially dragonflies or to Jurrassic Marine Phosphorus as caused by runway building termites, or to the effect of runway builders and ant predators on the phosphorus of Cretaceous soils and vertebrates especially dinosaurs, or to Affect of Termites on the Paleocene and Modern World
Back to "Did theWood Roach Cause Permian Aridity, Red Soils, Conifer Rise, and coal hiatus?"
For links to information about the Permian age see this site.
LINKS TO EARTH and MARS GEOLOGY
---- The Canyons of Mars as Erosion by Rivers of Silicone Dust
---- For a hypothesis that explains the large volcanoes of Mars and the bulges associated with them. They are proposed as the disruption from the antipode (opposite side of a sphere) of a huge meteorite or comet impact.
----Cause of Indian Decca lava flows. Did disruption at the antipode (opposite side of a sphere) of a meteorite or comet impact cause the Decca (or Deccan) lava flows at the Cretaceous close and other large lava flows?.
---- The mid ocean ridges probably formed by shoving aside shallow plates by a wedge of basalt pushed up by molten and therefore light magma.
---- The earth’s ocean trenches probably formed by cold ocean bottom water creating a deep crack from thermal contraction, which then further contracted the rocks beneath the trench.
---- For a geological time scale.
HUMAN FEMALE EVOLUTION
For a hypothesis about human female evolution see this article.
SOME LINKS RELATED to HEALTH
There is information here about how to obtain a very comprehensive book called “POTASSIUM NUTRITION” and thus cure or prevent rheumatoid arthritis, heart disease, gout, and high blood pressure and ameliorate diabetes and high blood potassium.
Electrolyte regulation (sodium and potassium) ---- Purpose of cortisol ---- Copper Nutrition and Physiology ---- Cure most toothaches with anacardic acids in raw cashew nuts. ---- There is evidence that cell phones can produce tumors. Using remote ear phones would seem to be a good idea. ---- Fluoride in city water will cause fluorosis discoloration of teeth, weakened bones, damage to the kidneys and immune system, bone cancer, destruction of the thyroid gland and, worst of all, damage to the nerves resembling Alzheimer’s disease.
There is a free browser called Firefox, which is said to be less susceptible to viruses or crashes, has many interesting features, imports information from Iexplore while leaving Iexplore intact. You can also install their emailer. A feature that lists all the URLs on a viewed site can be useful when working on your own site.
There is a tool bar by Google that enables you to search for journal articles, search the internet from the page viewed, mark desired words, search the site, give page rank, etc.
There is a free program available which tells on your site what web site accessed you, which search engine, statistics about which country, statistics of search engine access, keywords used and their frequency. It can be very useful.
Alper J 1994 Earth's near-death experience. Earth Magazine, Jan94, Vol. 3 Issue 1, p42,
Alvarez W Claeys P Kieffer SW 1995 Emplacement of Cretaceous - Tertiary boundary shocked quartz from Chicxulub crater. Science 269; 930-935.
Archie A Lopez-GomezJ 2006 Late Permian to early Triassic transition in early central and NE Spain: Biotic and sedimentary characteristics. 261-280. in; Non-Marine Permian Biosratigraphy and Biochronology. Lucas SG Cassinis G Schneider JW, eds. Geological Society Special Publications 265, Geological Society Publishing House, Bath UK.
Becker L Poreda RJ, Basu AR, Pope KO T. Harrison M, Nicholson C, Iasky R 2004 Bedout: A Possible End-Permian Impact Crater Offshore of Northwestern Australia. Science 10; 1126.
Belcher CM McElwain JC 2008 limits for combustion in low O2 redefine paleoatmospheric predictions for the Mesozoic Science 321; 1197-1200.
Bordy EM Bumby AJ Catuneanu O Eriksson PG 2009 Possible trace fossils of putative termite origin in the Lower Jurassic (Karoo Supergroup) of South Africa and Lesotho. South African Journal of Science 105; vol. 9-10.
Bourke AFG Franks NR 1995 Social Evolution in Ants. Princeton University Press.
Brusatte SL Benton MJ Ruta M Lloyd GT 2008 Superiority, competition, and opportunism in the evolutionary radiation of dinosaurs. Science 321; 1485-1488.
Carlquist S 1965 Island Life. Natural History Press, Garden City,NY.
Darlington PJ 1965 Biogeography of the southern end of the world. Harvard University Press, Cambridge Mass.
Dott, R.H. and Batten, R.L. 1971 Evolution of the Earth, 4th ed. McGraw Hill, NY.
Emerson AE 1955 Symbiosis between roaches and protozoa. Review of LR Cleveland monograph. Ecology 16; 116-117.
Emerson AE 1955 Geographical origin and dispersions of termite genera. Fieldiana: Zool. 37; 465-521.
Faure K de Wit MJ Willis JP 1995 Late Permian global coal hiatus linked to 13C depleted CO2 flux into the atmosphere during final consolidation of Pangea. Geology 23; 507-510.
Gay FJ Calaby JH 1970 Termites of the Australian region. in; Krishna K Weesner FM eds. Biology of Termites, Vol. II Academic Press NY.
Godfrey HCJ 1994 Parasitoid's Behavioral and Evolutionary Ecology. Princeton University Press, Princeton.
Grasby SE Sanei H Beauchamp B 2011 Catastrophic dispersion of coal fly ash into oceans during the latest Permian extinction. Nature Geoscience 4; 104-107.
Gruszczynski, M., Malkowski, K., Szaniawski, H., Cheng-Yuan, W. 2003 The carbon biogeochemical cycle across the Permian - Triassic boundary strata and its implications: isotope record from the Changhsingian Stage at Meishan, south China. Acta Geologica Polonica 53, 167-169.
Hasiotis, S.T. and Dubiel RF 1995 Termite (Insecta: Isoptera) nest ichnofossils from the upper Triassic Chinle formation, Petrified Forest National Park, Arizona. Ichnos 4: 12?-130.
Hasiotis ST Peterson CJ 1996 Termite (Insecta: Isoptera). Nests from the upper Jurassic Morrison Formation: evolutionary, paleoecolgical, paleoclimatic implications. Geological Society of America, Rocky Mountain Section, 48th Annual Meeting. Abstracts with programs. Geological Society of America Vol. 38, page 10, abstract #3843.
Haughton SH 1963 The Stratographic History of Africa South of the Sahara. Oliver & Boyd, Edinburgh.
Helliker BR Richter SL 2008 Subtropical to boreal convergence of tree-leaf temperatures. Nature 434; 511-514.
Heydari E Hassanzadeh J Wade WJ Ghazi AM 2003 Permian-Triassic boundary interval in the Abadeh section of Iran with implications for mass extinction: part I-sedimentology. Palaeo 193;405-423.
Higashi MN Yamamura N Abe T Burns TP 1991 Why don't all termite species have a sterile worker caste? Proceedings of the Royal Society of London, Series B. 246; 25-29.
Holldobler B Wilson EO 1990 The Ants. Belknap Press of Harvard University Press, Cambridge.
Holser WT Schonlaub H_P,Moses AJr Boekelmann K Klein P Magaritz MOrth CJ Fenninger A Jenny C Kralik M Mauritsch EP Schramm J_M Sattagger K Schmoller R 1989 A unique geochemical record at the Permian/Triassic boundary. Nature 337; 39.
Hosher WT Magaritz M Clark D 1987 Events near the Permian-Triassic boundary. Mod. Geol. 11; 155-180.
Isozaki I 1997 Permo - Triassic Boundary superanoxia and strattified superocean: Records from lost deep sea. Science 276; 235-276.
Kajiwara Y Yamahita S Ishida K Ishiga H Imai A 1994 Development of a largely anoxic stratified ocean and its temporary massive mixing at the Permian Triassic boundary supported by the sulfur isotopic record. Paleogeogr. Paleoclimatol. Paleocol. 111, 367-379.
Keller L Genoud M. 1997 Extraordinary life spans in ants: a test of evolutionary theories of aging. Nature 389; 958-960.
Knauth LP 1998 Salinity history of the earth's early ocean, Nature 395; 554-555.
Knoll AH Bambach RK Canfield DE & Grotzinger JP 1960 Comparative earth history and late Permian mass extinction. Science 273, 452-458.
Koeberl C Farley KA Peucker-Ehrenbrink B Stephton MA 2002 Geology 32; 1053-1056.
Kvenvolden, K.A. 1993. Gas Hydrates-Geological Perspective and Global Change. Reviews of Physics, 31: 173-187.
Labandeira CC Sepkoski CC 1993 Insect diversity in the fossil record. Science 261, 310.
Merico A Tyrrell T Wilson PA 2008 Eocene/Oligocene ocean de-acidification linked to Antarctic glaciation by sea kevel fall. Nature 452; 979-982.
Otto-Bleisner BL Upchurch Jr.GR 1997 Vegetation induced warming of high latitude regions during the late Cretaceous period. Nature 385; 804807.
Rampino MR Stothers RB 1988 Flood basalt volcanism during the past 250 million years. Science (ISSN 0036-8075), vol. 241, Aug. 5, 1988, p. 663-668.
Reichow MK,1 Andrew D. Saunders,1* Rosalind V. White,1 Malcolm S. Pringle,2 Alexander I. Al'Mukhamedov,3 Alexander I. Medvedev,3 Nikolay P. Kirda 2002 40Ar/39Ar Dates from the West Siberian Basin: Siberian Flood Basalt Province Doubled. Science 296; 1846-1848.
Renne PR Basu AR 1991 Rapid Eruption of the Siberian Traps Flood Basalts at the Permo-Triassic Boundary Science 253; 176-79.
Retallack GJ (1995) Permian -Triassic life crises on land. Science 267, 77-79.
Retallack GJ Veevers JJ Morante R (1996) Global coal gap between Permian-Triassic extinctions and middle Triassic recovery of peat forming plants (review). Geological Society Am. Bull. 108, 195-207.
Retallack G 1997 Paleosols in the upper Narrabeen group of New South Wales as evidence of early Triassic paleoenvironments without exact modern analogs (review) Australian Journal of Earth Sciences 44; 185-281.
Running SW 2008 Ecosystem disturbance, carbon, and climate. Science 321; 652-653.
Sephton, M.A., Looy, C.V. Brinkhuis, H., Wignall, P.B., Jan W. de Leeuw, J.W., Visscher, H., 2005. Catastrophic soil erosion during the end-Permian biotic crisis. Geology, 33, no. 12, p. 941-944.
Sexton PF et al 2011 Eocene global warming events driven by ventilation oceanic dissolved organic carbon. Nature 471; 349-352.
Smith RMH 1995 Changing fluvial environments across the Permian - Triassic boundary at Karoo Basin, South Africa and possible extinctions. Palaeogeography, Palaeoclimatology, Paleoecology 117; 81-104.
Smith J 2003 Geophys. Res. Lett. 10; 1029.
Suess E, Bohrmann G, Greinert J, Lausch E 1999 Flammable ice. Scientific American 281; 77-83
Tilyard RJ (1917) Permian and Triassic insects from New South Wales. Proc. Linn. Soc. NSW 42, 721.
Tilyard RJ 1937 Kansas Permian insects.. Part XX the cockroaches, or order BlattariaI, II Am. Journal of Science 34; 169-202, 249-276.
Toon OB Turco RP Covey C 1997 Environmental perturbation caused by the impacts of asteroids and comets. Reviews of Geophysics (Am. Geophysical Union) 35; 41-78.
Visscher H Brinkhuis H Kueracher W Looy C Van Konijnenburg-Van Cittert J 2001 Raised UV-B stress at the time of the end-Permian biosphere crisis. Am. Geophysical Union, fall meeting. Abstract PP21B-0482.
Wang, Z.Q. 1996 Recovery of vegetation from the terminal Permian mass extinction in North China. Review of Paleobotany and Palynology 91: 121-142.
Wang ZQ 1996 Past global floristic changes – The Permian great Eurasian floral interchange. Palaeontology 39; 189-127.
Weesner FM 1960 Evolution biology of termites. Annual Review of Entomology. 5; 153-170.
Wignnall PB Hallam AI 1993 Griesbachian (earliest Triassic) paleoenvironmental changes in the salt range, Pakistan and southeast China and their bearing on the Permo-Triassic mass extinction, Paleogeogr. Paleoclimatol. Paleoecol. 102, 215-237.
Wignall PB Twitchett RJ 1996 Oceanic anoxia and the end Permian mass extinction. Science 272, 1155-1158.
Wilde, P.E. and Berry B.N. (1984) Destabilization of the oceanic density structure and its significance to marine extinction events. Paleogeography, Paleoclimatology, Paleoecology 48: 143.
Wood TG Sands WA 1978 The role of termites in ecosystems. in; Production Ecology of Ants and Termites. Brian MV ed. Cambridge University Press.
Wright, S., 1931, Evolution in Mendelian Populations. Genetics 16; 97-159.
Zimmerman, P.R., et al. 1982. Termites: A Potentially Large Source of Atmospheric Methane, Carbon Dioxide, and Molecular Hydrogen. Science 218: 563-65.