Menu
Land and oceans
White roofs could cool cities: study
Enzyme crystal helps crack HIV puzzle
Sugar sweetens decision making
Twilight zone secrets revealed
Astronomers spot asteroid collision
Algae master quantum mechanics
Protein 'ushers' key to beating malaria
Researchers spin artificial bee silk
New view of Pluto increases mystery
Cell's power packs came from within
Antarctic snow linked to WA dry
Termites inspire hydrophobic materials
Study shows why it's scary to lose money
Soil impact underestimated: climate study
Lack of oxygen forced fish's first breath
Harder Sudoku puzzles on the way?
Weed genes could help feed the world
Logging makes forests more flammable: study
Food crisis looms warn scientists
Tiny sensors track 'lost' objects
'Climategate' university orders review
'Plumbing' key to flowering success
New twist on solar cell design
Scientists set new temperature record
Dinosaur extinction caused by asteroid: study
A new study strengthens the claim that an asteroid impact ended the reign of the dinosaurs 65 million years ago.

The finding by an international team of 41 researchers is published today in the journal Science.

Fossil records clearly show a mass extinction event across the planet 65 million years ago, in which 70% of known species suddenly vanished.

The change is so dramatic, geologists use it to define the boundary, between the end of the Cretaceous and the start of the Palaeogene periods, as the K-T boundary event.

The idea that an asteroid was responsible for the end of the age of the dinosaurs was first proposed 30 years.

The first clue was the discovery of large amounts of the element iridium - rare on Earth, but common in meteorites and asteroids - appearing in a layer across the globe at the time of the K-T boundary event.
Smoking gun

In 1991, the discovery of a 200-kilometre wide impact crater at Chicxulub on Mexico's Yucatan Peninsula provided what many scientists believe is the 'smoking gun' supporting the asteroid impact theory.

But some scientists challenge this hypothesis, suggesting deposits of tiny glass-like blobs of melted impact material around Chicxulub, predate the extinction event by 300,000 years.

They suggest the Deccan Traps, unusually active volcanoes in what is now India, led to global cooling and acid rain, which caused the mass extinction.
Geologic record

In this latest study, researchers examined the sedimentary material around the impact site and found it was far too violently churned up to provide a reliable dating record.

They found that farther away from the impact site, the sedimentary material becomes a single layer at the K-T boundary, matching the composition of rocks at Chicxulub.

They also determined that despite evidence for relatively active volcanism in India, ecosystems showed only minor changes within the 500,000 years before the K-T boundary event.

Only at the boundary do things suddenly change.

They say the Deccan hypothesis is further weakened by atmospheric chemistry models, which show that while significant volumes of sulphur were emitted during each volcanic eruption, forming aerosols in the stratosphere, they dropped rapidly with only short-lasting environmental effects.

The researchers say the Chicxulub impact saw much larger volumes of sulphur, dust and soot released in a much shorter time frame, leading to extreme environmental changes such as darkening and cooling.
More questions

Palaeontologist Dr Steven Salisbury of the University of Queensland says extinction events are complicated.

"My own work in Antarctica shows little change at the K-T boundary," he says. "It's as if the asteroid impact came and went and didnít really change much."

Salisburyís research shows species numbers declined thousands of years before and after the K-T boundary event.

"That indicates a wider combination of factors contributed to the extinction rather than a single event," he says. "To claim otherwise is too big a bow to draw."

Print
Horny mother beetles fight for dung
Light-speed computing one step closer
Small asteroids 'just lumps of gravel'
Gene study reveals diverse gut zoo
Dinosaur extinction caused by asteroid: study
Study finds methane bubbling from Arctic
New view reveals Mars' icy history
Some nano-sunscreens 'come at a cost'
Dust bunnies could harbour toxic load
Aphid genome reveals its 'Achilles heel'
Tailored diet may slow down DNA damage
Scientist probe ballistic chameleon tongue
Moa eggshells yield ancient DNA
Toothbrush tech helps buses go green
Gene protects some Tassie devils from tumour
Smaller fish cope better with acidic water
Lunar mirror mystery solved
Parents give fewer bad genes than thought
Women on pill may live longer
Antarctic winds affect key ocean layer
Researchers uncover thalidomide mystery
Boost for evidence of early ocean
Ocean geoengineering may prove lethal
People leave unique 'germ print'
Rogue star on collision course
Butterflies 'fly early as planet warms'
Glaucoma may start in the brain
Tools push back dates for humans on Flores
Menu
Stem cell capsules to target broken bones
Ecstasy damages complex memory: study
Earliest animals flexed their muscles
Insomnia may shrink the brain: study
Experts call for 'resilience thinking'
Tutu's DNA could point to medical cures
Humble algae key to whale evolution
Happiness linked to healthy heart
Fewer cyclones, but more intense: study
Cosmic candles result of colliding stars
Flightless mosquitoes may curb dengue
Childhood poverty may leave its mark
Cautious response to technology strategy
Nanowire RAM to make ever-ready computers
Are non-smokers smarter than smokers?
There's iron in them thar Martian hills
'Shell Crusher' shark swam ancient oceans
Nanotechnology may tap into your mind
Small dogs originated in the Middle East
Brain 'hears' sound of silence
Swimmers 'may not understand' tsunami risk
Altruism surfaces on slow-sinking ship
Chile quake tops Haiti, but less deadly
Weedkiller 'makes boy frogs lay eggs'
Visit Statistics
http://google.com/

http://bing.com/

https://gepatit-info.top/

https://serdechnic.com/

https://buy-meds24.com/

https://dverirespekt.ru/

https://www.sribno.net/

https://undergroundcityphoto.com/

https://detskiezabolevaniya.com/

http://grafaman.ru/

http://innoslicon.com/html/product/index.htm

https://yginekologa.com/

https://yes-com.com/

https://www.baikaleminer.com/

https://bitmaein.com/shop

https://www.artdeko.info/

https://aerodizain.com/

http://xn--d1abj0abs9d.in.ua/

http://lider82.ru/

http://sta-grand.ru/

http://snabs.kz/

https://sky-mine.ru/

https://rybalka-opt.ru/

http://snegozaderzhatel.ru/

https://xn--e1aaajzchnkg.ru.com/

http://hit-kino.ru/

http://www.regionshop.biz/

https://xn--80aaafbn2bc2ahdfrfkln6l.xn--p1ai/

https://pp-budpostach.com.ua/

https://vykup-avto-krasnodar.ru/

https://gcup.ru/

https://mega-polis.biz.ua/

http://vanrise.com.ua/

http://infra-e.ru/

https://veterinariya.com/

https://ponosanet.com/

https://cariestop.com/

https://proartrit.com/

https://elonm.ru/

https://nakozhe.com/

https://spinanebolit.com/

http://zameskino.ru/

http://kinoprinc.ru/

http://pospektr.ru/

http://buypillsonline24h.com/

http://komputers-best.ru/

https://komp-pomosch.ru/