A Slow Death in the P-T Extinction

Paleogeography in the northern hemisphere during the Permian-Triassic boundary extinction 252 million years ago. The West Blind Fiord (WBF) site on Ellesmere Island in the Canadian Arctic is shown in relation to the site of the Siberian Traps. Image Credit: Thomas Algeo
New research, supported in part by the NASA Exobiology and Evolutionary Biology (Exo/Evo) program, shows that mass extinctions need not be sudden events. In an extensive investigation of rock layers at West Blind Fiord on Ellesmere Island in the Canadian Arctic, the team revealed that Earth’s deadliest-known mass extinction took place in stages over hundreds of thousands of years.

The “Great Dying” occurred roughly 252 million years ago at the end of the Permian period, and resulted in the loss of 90 percent of Earth’s marine life. The evidence suggests that the event was linked to...

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Source: [University of Cincinnati]

February 9, 2012 / Posted by: Aaron Gronstal

The Day the Algae Died

The P-T mass extinction that almost cleared the planet of life 250 million years ago may have been instigated by populations of algae dying. According to one group of scientists, this die-off of large numbers of relatively simple life forms caused a crash in the ocean’s entire food web. As part of the Astrobiology: Exobiology and Evolutionary Biology program at NASA, the team of scientists will now be exploring signs of an early algae die-off about 1.5 million years before the main P-T extinction event.

Source: [astrobio.net]

December 13, 2010 / Written by: Michael Schirber

Evidence of Ancient Impact Preserved in Modern Sand

Detrital shocked minerals from the Vaal River, near the 2.0 Ga Vredefort Dome impact structure, South Africa. (A) Back-scattered electron (BSE) image of the external surface of a shocked zircon showing planar fractures. (B) Cathodoluminescence (CL) image of the polished interior of a shocked zircon showing three orientations of planar fractures. (C) Transmitted light image of a shocked quartz grain, with decorated planar features. (D) BSE image of a polished shocked monazite grain. The white arrows indicate orientations of planar deformations caused by impact pressures ranging from 10-50 GPa. Image credit: Aaron J. Cavosie, Univ. of Puerto Rico

Through NAI’s Minority Institution Research Support Program, scientists at the University of Puerto Rico and their collaborators have identified a unique record of an ancient meteorite impact event that is preserved in microstructures in detrital grains of quartz, zircon, and monazite in the Vaal River, South Africa. The sand samples were collected from the channel of the Vaal River near the two billion-year old Vredefort Dome impact structure, where impact-shocked minerals are known to occur in rocks.

This is the first report that impact shock-deformed minerals survive the process of uplift, erosion, and sedimentary transport. The unique...

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November 22, 2010 / Posted by: Daniella Scalice

Asteroid Impact Could Destroy Ozone Layer

New research funded by a NASA Exobiology grant is helping scientists understand what would happen to life on Earth if an asteroid crashed into the deep ocean. The model shows that a medium-sized asteroid could affect atmospheric chemistry on our planet, resulting in global ozone depletion. Ozone in Earth’s atmosphere helps protect living organisms from ultraviolet radiation. If ozone levels were depleted for a long period of time, life could face a difficult future.

Source: [Planetary Science Institute ]

October 27, 2010 / Posted by: Aaron Gronstal

Dinosaur-Killer was Soft on Algae

A view of the sea cliff at Stevns Klint, Denmark. Credit: R. Summons
The asteroid impact that many researchers claim was the cause of the dinosaur die-off was bad news for marine life at the time as well. But new research funded by NASA shows that microalgae – one of the primary producers in the ocean – bounced back from the global extinction in about 100 years or less.

Source: [astrobio.net]

October 2, 2009 / Written by: Michael Schirber

Echoes of Extinction

The mass extinction of the dinosaurs and many other organisms 65 million-years-ago has left lasting effects on the evolution of life on Earth. A team of NASA-funded researchers has performed a global study on marine bivalves, and the results indicate that these organisms began originating new species faster than ever following the end of the Cretaceous period.

Source: [Astrobiology Magazine]

February 13, 2009 / Posted by: Aaron Gronstal