Tuesday, January 20, 2015

Ancient Scorpions may have Lived in Water but Walked on Land

Paleontologists have hypothesized that scorpions evolved on the seafloor, but some recently discovered fossils have scientists reconsidering exactly how it happened. Eramoscorpius brucensis, possibly the second oldest known scorpion at 430 million to 433 million years old, appears to have lived primarily in water and occasionally spent time on land, putting scorpions on dry ground much earlier than previously thought.

There’s a clear evolutionary advantage to spending time on land – scorpions molt, and they’re extremely vulnerable during the process; leaving the sea would allow them to avoid predators until their new exoskeleton formed. However, walking on dry ground requires having land-legs.

Before E. brucensis, ancient scorpions had leg structures similar to those of crabs (horseshoe crabs are one of the closest living relatives of ancient scorpions), and, like crabs today, moved around on the tips of their foot segment. They would’ve needed water to help support their weight. E. brucensis had a leg structure similar to what scorpions have today; meaning their legs could’ve supported their body on land. So why not just live on dry ground? Their digestive systems lacked coxapophyses, which helps modern scorpions consume prey on land, suggesting E. brucensis still needed to eat in the water.

Further evidence of this dual existence comes from the quarries in Ontario where most of the fossils are from. They’re filled with fossils of sea creatures, suggesting E. brucensis mostly lived in the water as well. However, the rocks surrounding the scorpions have ripples that imply brief exposure to air. Also, the position of the fossil scorpions suggests empty molted exoskeletons rather than a carcass, and it’s much easier for exoskeletons to fossilize on land than in the sea.
If E. brucensis did indeed live in the water and walk on land, then scorpions developed their first adaption for living out of the sea much earlier than previously thought. The evolution of scorpions is still under debate and more research is needed.

Photo Credit: David Rudkin, Royal Ontario Museum

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Ridiculous storm photo !

Astronaut Sam Cristoforetti arrived on the International Space Station in November. From my perspective, she had some big shoes to fill in terms of photography; astronauts Reid Wiseman, Alexander Gerst, and Chris Hadfield set a high bar in finding and capturing spectacular and artful scenes of the planet Earth out the ISS windows. 

These photos of Tropical Cyclone Bansi are remarkable and some of the most amazing shots from the ISS yet. In the first off-center photo, the light bursts illuminating the storms eyewall are lightning, the light is bouncing from side to side off of the wall clouds. The faint green band is airglow – light released from ionized oxygen heated by the sun.

In the second photo, taken directly above the storm, a lightning burst flashes near the eye of the storm and some of the light from that bolt has slipped across the clouds of the eyewall to illuminate the hole in the storm.

This storm is expected to remain out to sea and weaken without threatening land. Make sure you followhttps://twitter.com/AstroSamantha on that network to see if she can find a better shot than these. That will take some effort. 

Did the mega volacano kill the dinosaurs ?

The Cretaceous-Paleogene/Tertiary extinction event (K-Pg or K-T as it is known by geologists) was previously thought to be the only mass extinction out of the “big five” not attributable to volcanism. Instead, the currently accepted theory linked a meteorite impact near present-day Chicxulub, Mexico as the lone cause (known as the Alvarez hypothesis), although there is growing support for volcanic activity as a second major factor. Now, new research led by Brian Schoene of Princeton University has added further evidence that non-avian dinosaurs were actually wiped out by volcanism rather than a meteorite collision some 66 million years ago, confirming what some geoscientists, such as Dewey McLean, long suspected.

The Deccan Traps, a massive flood basalt in India, has long been known as a series of volcanic events that occurred at around the time of extinction, but the majority believed that they erupted too early on to have had a significant effect. Scientists have now tightened the timeline of the main sequence of eruptions, which now appear to have happened very soon before - geologically speaking - the extinction, with new precision rock dating evidence (using U-Pb dating in zircons) showing that the main phase of eruptions occurred within 250,000 years of extinction, rather than millions.

This new timeline is very important, as the volcanic gases now believed to be responsible for dramatic, extinction-inducing climate change (particularly sulfur dioxide) would have been released very shortly before, and during (up to 750,000 years) the time of the K-Pg extinction. It adds weight to the idea that volcanism was the primary cause of extinction, with the meteor impact as the icing on the cake. During it's active phase, the Deccan Traps volcano released over 1.1 million km3 (264,000 cu mi) of lava, with layer upon layer of basalt culminating in a depth of 2,000 m (6,562 ft) thick. Since then, it has gradually been eroded down to 512,000 km3 (123,000 cu mi).

Scientists are now working on further constraining the timing of eruptions and using this data to refine computer-based environmental change models. This will enable researchers to better determine the individual as well as cumulative effects of Deccan Traps volcanism and Chicxulub meteorite impact on Earth.

Past articles:
Deccan Traps: http://on.fb.me/1ByYtnX &http://on.fb.me/1ByYtnX
Did a comet cause extinction?:http://on.fb.me/14FWelu
K-Pg event: http://on.fb.me/1xuvbk5 &http://on.fb.me/1uaQff9
end-Permian extinction event - http://tmblr.co/Zyv2Js18raAV1
Image credit: by Nichalp, 2007 (http://bit.ly/1B8kHyg) Used under CC licensing.

Further reading:
Deccan Traps - http://bit.ly/1BcXWcx &http://bit.ly/1sHvLzn
Did the Traps wipe out the dinosaurs?http://bit.ly/1G4hEKz & http://bit.ly/17QFBWo
Original paper by Schone et. al. - http://bit.ly/1C66iS8(paywalled)

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