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Ancient Earth


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#1
wjfox

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This thread is for general news/discussions about the formation and early evolution of our planet.

 

So basically anything from the Hadean (4.4 billion BCE) to the early Phanerozoic/Cambrian (~530 million BCE).

 

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Asteroids may have delivered half of the water in Earth's oceans

 

May 1, 2019
 

Over 70 percent of Earth’s surface is covered in water, almost all of which is in the oceans. But where did all this water come from? Several hypotheses seek to explain how water arrived on our planet in the early days of its formation, including the idea that molecular water leaked out of hydrated minerals on Earth, and the possibility that asteroids and comets delivered water to Earth.

New research in the journal Science Advances lends support to the asteroid hypothesis, suggesting that these rocky visitors could have delivered up to half of Earth’s water billions of years ago.

 

https://www.inverse....ple-earth-water

 

 

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#2
caltrek

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Scientists glimpse oddball microbe that could help explain rise of complex life

 

https://www.nature.c...02430-w#ref-CR1

 

Extract:

 

(Nature) Biologists have for the first time captured and grown an elusive type of microbe that is similar to those that might have given rise to all complex life on Earth.

 

In a preprint posted to the bioRxiv repository, scientists in Japan report that they have isolated and grown microbes from an ancient lineage of archaea — single-celled microbes that look, superficially, like bacteria but are quite distinct — that was previously known only from genomic sequences.

 

…One genome stood out. It was clearly a member of the archaea. But dotted throughout this genome were eukaryotic-like genes, suggesting to Ettema that this oddball could help to bridge the evolutionary gap between simpler microbes and eukaryotes. The researchers called it Lokiarchaea, after Loki, the trickster of Norse mythology.

 

Soon, other labs found additional Loki-like archaea, and together these formed the Asgard archaea, named after a mythological region inhabited by Norse gods. Although the organisms’ precise place in the tree of life remains contentious, many analyses pair Asgards and eukaryotes together, which could mean that some distant Asgard-like ancestor gave rise to all eukaryotes — everything from panda bears to portabello mushrooms.

 

…“We can’t just go back in time and observe what happened,” says Ettema. The Asgards we see today are not the same as the microbe that gave rise to eukaryotes. But he says that culturing more Asgards and studying what their eukaryotic-like genes actually do will give a fuller picture of the evolutionary tree, and help researchers to better infer how simple, single-celled organisms made the first giant leap towards complexity

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Archaea are often found in extreme environments, such as these chimneys on the summit of Giggenbach underwater volcano, off New Zealand.

Credit: New Zealand-American Submarine Ring of Fire 2005 Exploration, NOAA Vents Program


The principles of justice define an appropriate path between dogmatism and intolerance on the one side, and a reductionism which regards religion and morality as mere preferences on the other.   - John Rawls


#3
caltrek

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With a tip of the hat to Jessica for finding this article:

 

Genes that first enabled plants to grow leaves identified by scientists

 

https://phys.org/new...scientists.html

 

 

The genes that first enabled plants to grow shoots and conquer the land have been identified by University of Bristol researchers. The findings, published in Current Biology, explain how a 450-million years ago a switch enabled plants to delay reproduction and grow shoots, leaves and buds.

 

Over the course of half a billion years of evolution, plants have evolved from tiny and simple ground-hugging forms into diverse and complex varieties that abound the Earth today, from the garden rose to the 100-metre tall redwood tree. An international research team from the Universities of Bristol (UK), Lyon (France) and Palacký (Czech Republic) has now discovered the secrets of shoot evolution.

 

genesthatfir.jpg

 

Moss.

Credit: Dr Jill Harrison


The principles of justice define an appropriate path between dogmatism and intolerance on the one side, and a reductionism which regards religion and morality as mere preferences on the other.   - John Rawls


#4
Jessica

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Researchers discover oldest fossil forest in Asia

August 8, 2019
Source:
Cell Press



The Devonian period, which was 419 million to 359 million years ago, is best known for Tiktaalik, the lobe-finned fish that is often portrayed pulling itself onto land. However, the "age of the fishes," as the period is called, also saw evolutionary progress in plants. Researchers reporting August 8 in the journal Current Biology describe the largest example of a Devonian forest, made up of 250,000 square meters of fossilized lycopsid trees, which was recently discovered near Xinhang in China's Anhui province. The fossil forest, which is larger than Grand Central Station, is the earliest example of a forest in Asia.

Lycopsids found in the Xinhang forest resembled palm trees, with branchless trunks and leafy crowns, and grew in a coastal environment prone to flooding. These lycopsid trees were normally less than 3.2 meters tall, but the tallest was estimated at 7.7 meters, taller than the average giraffe. Giant lycopsids would later define the Carboniferous period, which followed the Devonian, and become much of the coal that is mined today. The Xinhang forest depicts the early root systems that made their height possible. Two other Devonian fossil forests have been found: one in the United States, and one in Norway.

"The large density as well as the small size of the trees could make Xinhang forest very similar to a sugarcane field, although the plants in Xinhang forest are distributed in patches," says Deming Wang, a professor in the School of Earth and Space Sciences at Peking University, co-first author on the paper along with Min Qin of Linyi University. "It might also be that the Xinhang lycopsid forest was much like the mangroves along the coast, since they occur in a similar environment and play comparable ecologic roles."

The fossilized trees are visible in the walls of the Jianchuan and Yongchuan clay quarries, below and above a four-meter thick sandstone bed. Some fossils included pinecone-like structures with megaspores, and the diameters of fossilized trunks were used to estimate the trees' heights. The authors remarked that it was difficult to mark and count all the trees without missing anything.

 


More:
https://www.scienced...90808111435.htm



#5
caltrek

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Earth's oldest crater found in Australia; asteroid may have helped thaw 'snowball Earth'

 

https://www.japantim...snowball-earth/

 

Introduction:

 

(Reuters) WASHINGTON – Scientists have identified Earth’s oldest-known impact crater, and in doing so may have solved a mystery about how our planet emerged from one of its most dire periods.

 

Researchers have determined that the 45-mile-wide (70-km) Yarrabubba crater in Australia formed when an asteroid struck Earth just over 2.2 billion years ago. The collision occurred at a time when the planet was believed to have been encased in ice and the impact may have driven climate warming that led to a global thaw.

 

“Looking at our planet from space, it would have looked very different,” said isotope geology professor Chris Kirkland of Curtin University in Australia, one of the researchers in the study published in the journal Nature Communications. “You would see a white ball, not our familiar blue marble.”

 

The researchers suspect the region was covered in an ice sheet up to 3 miles (5 km) thick at the time. They calculated that the violent asteroid strike may have transformed immense amounts of ice into water vapor — sending perhaps 200 billion tons of it billowing into the atmosphere. It would have served as a greenhouse gas trapping heat in the atmosphere.

 

The researchers are wondering whether this thaw helped shepherd Earth into a climate more favorable for the simple microbes that inhabited the planet at the time to thrive and evolve, possibly making it a pivotal event in the history of life on Earth.


The principles of justice define an appropriate path between dogmatism and intolerance on the one side, and a reductionism which regards religion and morality as mere preferences on the other.   - John Rawls





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