* Astronomy

Blobrana · L

Stromatolite

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RE: Ancient life

Blobrana · L

Earth's creatures come in all sizes, yet they (and we) all sprang from the same single-celled organisms that first populated the planet. So how on Earth did life go from bacteria to the blue whale?

"It happened primarily in two great leaps, and each time, the maximum size of life jumped up by a factor of about a million" - Jonathan Payne, assistant professor of geological and environmental science at Stanford.

Payne, along with a dozen other palaeontologists and ecologists at 10 different research institutions, pooled their existing databases, combed the scientific literature and consulted with taxonomic experts in a quest to determine the maximum size of life over all of geological time.
That might sound like a rather large undertaking, but, fortunately, the quest was made easier because even the professionals have a fascination with the size of the fossilised.

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Blobrana · L

A single-celled ball about the size of a grape may provide an explanation for one of the mysteries of fossil history.
Writing in Current Biology, researchers say the creature leaves tracks on the seabed which mirror fossilised tracks left up to 1.8 billion years ago.
Many palaeontologists believe only multi-celled organisms could have made these tracks.
This has been difficult to confirm as no multi-cellular fossils of such an age have ever been found.

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Blobrana · L

There's a powerful source of energy humming away inside a laboratory at the University of Alberta. The energy is ultra-violet light, and it packs the same spectrum of rays that kept this planet lifeless for billions of years.
Kurt Konhauser, professor of earth and atmospheric sciences, says he's using that light to recreate Earth's ancient atmosphere inside a box about the size of a kitchen dish washer.

"We're trying to find out how life evolved in the presence of ultra-violet radiation."

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Blobrana · L

An international team of scientists has discovered microscopic, magnetic fossils resembling spears and spindles, unlike anything previously seen, among sediment layers deposited during an ancient global-warming event along the Atlantic coastal plain of the United States.
The researchers, led by geobiologists from the California Institute of Technology (Caltech) and McGill University, describe the findings in a paper published online this week in the Proceedings of the National Academy of Sciences (PNAS).
Fifty-five million years ago, Earth warmed by more than 9 degrees Fahrenheit after huge amounts of carbon entered the atmosphere over a period of just a few thousand years. Although this ancient global-warming episode, known as the Paleocene-Eocene Thermal Maximum (PETM), remains incompletely explained, it might offer analogies for possible global warming in the future.
Perhaps in response to the environmental stress of the PETM, many land mammals in North America became dwarfed. Almost half of the common sea bottom-dwelling microorganisms known as foraminifera became extinct in newly warmer waters that were incapable of carrying the levels of dissolved oxygen for which they were adapted.

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Blobrana · L

Scientists have unearthed giant magnetic fossils, the remnants of microbes buried in 55-million-year-old sediment. The growth of these unusual structures during a period of massive global warming provides clues about how climate change might alter the behaviour of organisms.
Some bacteria, both living and fossilized, contain magnetite magnetic iron oxide crystals that the organisms are thought to use to navigate, orienting themselves along the magnetic field lines of the Earth. But the new fossils are "unlike any magnetite crystal ever described", says Dirk Schumann of McGill University in Montreal, Canada.

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Blobrana · L

A unique set of fossils indicates that 525 million years ago marine animals congregated in Earths ancient oceans, most likely for migration, according to an international team of scientists.
Fossil evidence of collective behaviour is extremely rare. But what makes the find even more intriguing is that it indicates that such behaviour was occurring at the beginning of the Cambrian explosion a major event that saw a vast profusion of complex organisms enter the fossil record for the first time.

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Blobrana · L

An analysis of a newly discovered caravan of crustaceans from half a billion years ago suggests that group behaviour evolved not long after animals themselves, say experts.
Fossilised chains of up to 20 crustaceans linked head-to-toe were discovered by a team research team palaeontologists, led by Hou Xian-Guang of China-based Yunnan University.
The discovery appeared to be the earliest record of any collective animal behaviour, and perhaps an adaptation to a migratory ocean lifestyle.

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Blobrana · L

Microbes may have lived in volcanic glasses that date back to the Archaean era (3.8 to 2.5 billion years ago). These organisms colonize glass in order to extract energy, eating metals such as iron or manganese contained within. As they do so, the chemolithoautrophs in volcanic glass may create etchings that remain long after their bodies decay and disappear.

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