Pondering the Precambrian #42

Proterozoic:

NeoProterozoic:

Changes to the carbon cycle and environment  were detected from the Ediacaran/Cambrian boundary in China.

Using boron to detect the salinity of the paleooceans gives some interesting twists.

Evolution of multiple basins from the Neoproterozoic are described.

Is there a biochemical signal dividing metazoan clades into two?

Did animal-like embryos predate actual metazoans (animals).

How NOT to become a metazoan.

A Cryogenian interglacial deposit has been found in China.

When did the Sturtian glaciation begin during the Cryogenian in South China?

Mesoproterozoic:

Where was South China in the Nuna/Columbia and Rodinia supercontinents during the Mesoproterozoic?

The Stenian Copper Harbor and Nonesuch Formations have a marine origin.

PaleoProterozoic:

Evidence of explosive basalt volcanism found from the paleoproterozoic.

In French Guiana, a gold rich Rhyacian Period formation has been found.  It contains sedimentary layers within the volcanic ones.  Are they fossiliferous?

After the Lomagundi-Jatuli Event, the carbon-sulfur cycle seemed to return to strong activity in the aftermath in the Rhyacian/Orosirian Periods.

Archean:

It appears during the GOE, the ocean basins remained anoxic.

Earth's magnetic field may have been in place during the Archean.

Evidence of subduction from the Late Archean comes from Australia.

The Kaapvaal Craton may be a remnant of the Pilbara Craton that split off in the MesoArchean.

Extraterrestrial impacts might have triggered bursts in plate tectonics.

Ancient microbes played an important role in warming the early Earth.

Hadean:

The impact history of Earth should NOT be correlated to other planets in the solar system.

Origin of Life:

There is a hyperacidic, hypersaline geothermal system in Dallol, Ethiopia that is lifeless and that has implications for the origin of life.

DNA is only one of several possible genetic information molecules.

Lifelike chemistry has been created in the lab.

Ribose and other sugars have been found in meteorites.

Some of the earliest animal fossils are possibly chemical 'gardens' that produce pseudofossils.

Pondering the Precambrian #41

Proterozoic:

Glauconite is rare is precambrian deposits of the Bhima Basin.  Why?

NeoProterozoic:

There is evidence of the oxygen and other environmental conditions across the Ediacaran/Cambrian boundary from southern China.

Could the marine waters have been highly alkali at the terminal Ediacaran?

Cloudina acted as an anchor for Ediacaran reefs.

Sulfur and carbon cycles from the Ediacaran formations of the Lower Yangtze block.

Oxygen levels during the NeoProterozoic were transient.

There were two episodes of phosogenesis in the ocean water of the Doushantou formation.

The Doushantou and Datangpo formations from the Ediacaran and Cryogenian have been argued to represent evidence of photosynthetic productivity during the Snowball Earth episodes.  This is probably wrong.

There is evidence from India of biofilms from the Neoproterozoic.

The microfossils of the Katanga Supergroup are probably pseudofossils, alas.

Boxonia bearing stromatolites from Mongolia suggest variation in their formation compared to others.

Ediacaran Biota-like disc fossils have been found in the Cryogenian, 80 million years earlier than ever before.

The Cryogenian basin deposits of south China suggest massive hydrothermal activity during the Sturtian Glaciation (Snowball Earth).

What was the stratosphere of the Snowball Earth like?

The Tonian Callana Group has a carbon anomaly that does not match the one observed at Bitter Springs.

MesoProterozoic:

There is evidence of the breakup of the Columbia Supercontinent from Brazil.

PaleoProterozoic:

Kimberlites from the Siderian suggest there is an isolated mantle reservoir.  And may be fingerprints of the ancient makeup of the world's geology.

There was a very long lived tectono-magmatic event 1.8 billion years ago.

The geochronology of the Hart Dolerite of Australia is documented.

Archean:

There is evidence of oceanic crust subduction from the NeoArchean.

There is also evidence of mountain building from the NeoArchean.

There is evidence of a subduction/accretion/collision event at the end of the NeoArchean, confirming full blown plate tectonics were in progress at that time frame.

Mesoarchean deposits from islands suggest the pelagic environment was rich in boron.

Paleoarchean microfossils show a continuous cell wall amongst other characteristics.

Can Xenon help determine if the carbon traces in ancient rocks is biogenic or not?

The fingerprints of Ur, the earliest supercontinent, are in the Bastar Craton in India.

Hadean:

The energy budget and structure of the earth get modeled during and after the Thea impact.

Origin of Life:

Bacterial gene duplicates are more common in eukaryotes than expected.

Is there a relation between hydrothermal chemistry and the origin of cellular life?

META:

Archaea's biochemistry may give hints as to ancient ocean temperature.

A large virus may have helped make the first eukaryote allow endosymbiosis allowing for the evolution of photosynthesis in eukaryotes.

Pondering the Precambrian #39

Proterozoic:

NeoProterozoic:

Global microfossil changes across the Ediacaran/Cambrian are characterized.

A new method of characterizing oxygen availability across the Ediacaran/Cambrian boundary has been found.

The lack of attention to taphonomy can mislead about the late Ediacaran fossils.

Data from Argentina covers the Ediacaran's oxygenation event.

Simulations of Ernettia suggest it was a filter feeder and fed better in groups.

Has there been a case of lateral gene transfer detected in bilaterians?

Ancient paralogies suggest jellyfish are a sister group to all other metazoans.

Green algae transitioned to macroscopic growth multiple times, but only as recently as the NeoProterozoic.

There is evidence of strange magmatism in the Sahara from the Ediacaran 580 million years ago.

An astronomical time scale for the middle/upper Doushantuo Formation has been established.

Braided rivers were not the rule prior to the evolution of plant life despite previous thought.

The Paleo Hunan Ocean was completely closed by 830 million years ago during the Tonian.

Evidence of two carbon excursions are detected in Tonian deposits in Namibia.

MesoProterozoic:

A new model suggests a sluggish, tepid mesoproterozoic ecosystem.

A very large igneous magmatic province has been found in South Africa from Stenian of South Africa.  These provinces are associated with mass extinctions like the Permian and Triassic/Jurassic.

An impact has been found in Scotland dating from the Mesoproterozoic.

Was anaerobic photosynthesis the reason for the delayed rise in oxygen in Earth's atmosphere?

PaleoProterozoic:

Iron stones were laid down by iron oxidizing bacteria during the Statherian.

There is evidence of deep subduction from North China from the Paleoproterozoic.

There is also evidence of a significant back arc continental collision during the Orosirian in the North China Craton.

There is evidence, according to Retallack, of macroscopic terrestrial life from the Orosirian.

The shape of the Dhala Crater in India from the Rhyacian is reconstructed.

Paleoproterozoic dolomites shed some light on the evolution of marine chemistry.

Archean:

The early Earth's oceans may not have been as hot as originally thought.

Compared to later granites, Archean granites had relatively unstable compositions.

Archean sulfur isotopes from Australia's Fraser Zone have unexplained ratios and amounts.

Did the subduction of the oceanic basins take place during the mesoarchean?

Could continents have existed from the dawn of the Archean, during the Eoarchean?

Eoarchean hydrothermal vent boron deposits give some insight to the origin of life.

Origin of Life:

Peptides can form without amino acids.

Could microscopic bubbles (interfaces) have helped kickstart life?

Pondering the Precambrian #27

Proterozoic:

NeoProterozoic:

Did a massive volcanic eruption trigger the Gaskiers Glaciation?

Deposits from British Columbia may be evidence of deep sea conditions just prior to the Gaskiers Glaciation.

Fossil fats from the Cryogenian may actually be from algae instead of sponges.

Amoebozoa diversified earlier than expected during the Tonian 750 million years ago.

How were banded iron formations created in Egypt from the NeoProterozoic?

Was the Cambrian Explosion really that big a deal? Or did it really originate in the Ediacaran?

First record of carbonates with spherulites and cone-in-cone structures from the Ediacaran of Norway has been found.

MesoProterozoic:

The Yili Block was likely located in the NW margin of the supercontinent Rodinia.

PaleoProterozoic:

The apparent cyclical deposition of the Dales Gorge Member banded iron formation appears to be related to sea level rise and fall or tectonic activity.

The Vempalle Formation dolomites of India appear to have more in common with Phanerozoic carbonates than Proterozoic ones.

There's a sedimentation record from 2.27 BYA to 1.96 BYA in West Africa with evidence of volcanic ash and activity in the layers.

The first drillings into the Temagami Anomaly have uncovered potential links to the Sudbury Impact.

The Francevillian Biota of Rhyacian Gabon seems to have had something able to move.  Scientists have found evidence of trackways from shallow, oxygenated waters.

Archean:

Evidence from Mauritania suggests the Archean geophysics were as complicated as today.

Evidence of a breakup of a continent from the Archean.

There appears to be evidence of major crustal growth circa 2.6 BYA and 3.2 BYA.

There is evidence plate tectonics were active, despite prior theory, during the Archean.

MesoArchean:

There is evidence of a continental margin at the tail end of the MesoArchean in North China.

A subduction zone has been found from the MesoArchean/NeoArchean boundary.

Evidence of a continental rift was found in Hainan, China from the MesoArchean.

There is evidence of ephemeral oxygen oases in the Mesoarchean Ocean.

PaleoArchean:

South African barite deposits were not laid down in a marine environment, but from a spring.

Life was thriving during the paleoarchean 3.5 billion years ago.

EoArchean:

How the first continents formed in the EoArchean.

Hadean:

Was the Theia impact the reason for the heterogeneity of Earth's crust?

Origin of Life:

Was the repeated drying and wetting cycle of the margin of water the source of energy for the original polymerization of amino acids et al?

Did hydrogen peroxide play a crucial role in the origin of life?

Pluripotency and the origin of multicellular life.

Could the RNA world hypothesized never have existed?

Shallow pools of water might have been the original location for the origin of life, not the sea.

Pondering the Precambrian #25

Proterozoic:

NeoProterozoic:

Cobalt deposits may be 150 million years younger than previously thought and due to an orogenic event.

There's evidence suggesting scavenging was the origin of predation during the Ediacaran.

There's evidence of shifting from continental collision to a subduction in Africa during the Ediacaran.

There were very diverse microfossils from the Ediacaran Doushantuo Formation.

The fossilization method of the Ediacaran gets examined for the earliest metazoans.

Fossils from the Ediacaran site at Nilpena, Australia are biological snapshots of benthic communities.

Ediacaran discoid fossils from the Anti-Atlas Mountains in Africa have been found.

In the early Ediacaran ocean, there seems to have been a global zinc signature.

Did the complex forms of the Ediacaran arise in the benthic depths of the ocean because there were stable temperatures?

In China, the carbonate caps suggest a oxygen recovery after the Marinoan Glaciation ended.

The oxygen isotopes from the Cryogenian meteoric water are similar to today's.

A group attempts to model the global temperatures from the Tonian to the present.

MesoProterozoic:

Fossils from Brazil suggest two different microbial habitats from the Stenian at the site.

There is evidence of oxygenated lakes 1.1 billion years ago during the Stenian.

There is evidence of oxygenation in the form of red beds that were created during an orogeny around the Stenian/Ectasian boundary.

PaleoProterozoic:

Statherian microfossils from China suggest eukaryotes were moderately diverse by that point in time.

Evidence of the Huronian Glaciation has been discovered in China.  This may have been the first time a Snowball Earth scenario took place.

Phosphorite deposits appear to have come from a microbial reef in the Siderian of Australia.

Archean:

Features from 2.7 billion year old stromatolite formations hint at the presence of oxygen.

The is evidence of a shift from vertical to horizontal plate tectonics in the Archean.

During the Mesoarchean the bottom waters of the ocean appear to have been anoxic.

There appears to have been a cryptic craton core that emerged in the Paleoarchean.

Aerobic photosynthesis might have arisen 3.5 billion years ago during the Paleoarchean.

Origin of Life:

Abiotic amino acids from the Earth's mantle have been observed for the first time.

Are liquid crystal matrices an analog to the early protocells?

Pondering the Precambrian #11

Proterozoic:

NeoProterozoic:

The problematic Orbisiana fossil from the Ediacaran of Russia is reevaluated.

Ediacaran life formed complex ecological communities.

Dickinsonia is confirmed to be an Ediacaran animals.  In fossils from the White Sea, molecular traces of steroids were found.

There is more evidence of sponges being present on the sea floor during the Cryogenian.

Precambrian Research is doing a special issue on the Cryogenian and especially the Tonian/Cryogenian transition.

There is evidence of the Rodinia supercontinent breakup during the Tonian.

MesoProtoerozoic:

From during the Stenian, there is evidence of an intracontinental rift forming in Australia.

There is evidence the shallow waters of the MesoProterozoic were anoxic.

Where and when did the PaleoAsian Ocean form?   Another view.

PaleoProterozoic:

There is evidence Africa and Brazil were part of the Congo-Sao Francisco continent during the PaleoProterozoic and of mountain building from that timeframe.

Carbonatite found in China gives a precise time for the beginning of the breakup of the Columbia supercontinent during the Orosirian.

Archean:

There is evidence of sulfur munching microbes from NeoArchean hydrothermal system ~2.7 billion years ago.

The oldest known paleosols - soil fossils - may have been found and date from the EoArchean.

The trace fossils from the PaleoArchean attributed to life might NOT be anything of the sort.

Hadean:

Hadean into the Archean, Earth seems to have lost an ocean's worth of water.  Or at least the hydrogen from it.

There is evidence suggesting there might have been banded iron formations and chert deposits laid down in the Hadean.

Do plate tectonics date from the Hadean?!

Origin of Life:

A new timeline has been proposed for the evolution of life.

What was the origin of life in the Hadean to PaleoArchean?

What was the time period for the origin of life?

Aging may have been a fundamental property of life and dates from life's actual origin..

Could formamide been the original prebiotic solvent?

Did liquid crystals help with the formation of life?

The ancestral eukaryote is slowly being understood.

Ws early photosynthetic life on Earth purple?

Pondering the Precambrian #9

Proterozoic:

There is evidence from the Proterozoic that Earth's day was 18 hours long.

NeoProterozoic:

Ediacaran:

The evolution of biological productivity and primary producers across the Ediacaran/Cambrian boundary

The Hüttenberg Anomaly appears to have been evidence of the Ediacaran oxygenation event.

Oxygenation variations in the atmosphere and shallow waters in the Yangzte platform.

Did anoxia kill off the Ediacaran benthic communities?

The Doushantuo fossils from China get examined closer.

Bilateral animal trackways and metazoan burrows have been discovered in the Ediacaran Dengying formation.

Two new disc critters from the Ediacaran have been found.  One was named for Sir David Attenborough.  The other for Barrack Obama.

Why did rangeomorphs grew so large during the Ediacaran?

What caused the mass extinction of the Ediacaran Biota?

Cryogenian:

Argonite fans were present in the bottom sediments during the Marinoan Glaciation.

Tonian:

India and Suixian sedimentary group were connected and either were on the margin of the supercontinent of Rodinia or were on a separate plate.

MesoProterozoic:

Evidence of an island arc from the Calymmian has been found.

PaleoProterozoic:

Australia was not connected to Laurentia from 1.8 gya to 1.65 gya during the Nuna/Columbia supercontinet.

During a continent breakup, there appears to have been enhanced terrestrial input into Chinese carbonates.

There is evidence of oceanic crust subduction from China.

During the Siderian, continental microbes and their 'crusts' on rocks might have helped seed the oceans with nitrogen.

Archean:

NeoArchean:

Continents rising above the ocean changed the climate and environment, permanently, on earth.  

Did the dawn of plate tectonics trigger a NeoArchean Snowball Earth episode?

The interplay between crustal arcs and mantle plumes was important in the Archean.

There is no support of wide spread increases in oxygen in shallow waters from South Africa leading up to the Great Oxygenation Event.

MesoArchean:

There might be evidence of two separate turns of the Wilson Cycles in Chinese deposits during the Archean.

Yet, it seems crustal production was periodic prior to 2.7 gya.

PaleoArchean:

Evidence of microbial mats was found from the PaleoArchean.

Hadean:

The Earth might have been able to form a high silica crust during the Hadean, less than 350 million years after its formation.

Origin of Life:

How primordial life might have replicated itself.

Experimental Paleontology:

Fish eggs were used to test how precambrian embryos might have been silicified.  

Pondering the Precambrian #8

Proterozoic:

NeoProterozoic:

Some paleosols found in the Baltic were formed during the NeoProterozoic during an extended weathering event.

What came first?  High levels oxygen in the atmosphere or animals?  Animals.

Evidence encrusting became an ability of Metazoans during the Ediacaran.

Were the Beltanelliformis fossils of the Ediacaran just cyanobacteria colonies?

There is evidence of carbon isotopic excursions from the Ediacaran Bilara Group in India.

The Ediacaran carbon isotopic excursions in South China are associated with phosphite upwellings.

There is evidence of the Ediacaran glaciations from Morocco.

Evidence of the transition from anoxic oceanic conditions during the Cryogenian to the oxic in the Ediacaran as well as the great meltwater from the Cryogenian snowball has been found.

Evidence of the mixing of glacial waters with the anoxic ocean has been found in California from during the Cryogenian.

There appears to have been an oxygen spike during the early Tonian.

There are banded iron formations in early NeoProterozoic Hainan, China.

Can Nanosims be useful in examining organic walled microfossils from the NeoProterozoic?

It appears something was burrowing in the late Ediacaran of Mongolia, much earlier than previously thought.


Exploring the effect of oxygen on the formation of haze in the NeoProterozoic atmosphere.

MesoProterozoic:

The Upper Vindhyans formation in India dates from the Late MesoProterozoic.

Evidence from China suggests the oceans of the Ectasian were anoxic to suboxic.

There is also evidence of Ectasian/Calymmian boundary oceans having banded iron formations.

Evidence from China also suggests active hydrothermal systems put a lot of iron into the shallow seas during the break up of the Columbia supercontinent.

Does photosynthesis in modern plants date to the Stenian?

PaleoProterozoic:

It appears the oceans of the Siderian become oxygenated 250 million years BEFORE the atmosphere did.

There is evidence a snowball earth scenario unfolded during the Siderian as well.

It looks like there is evidence of a tsunami or a storm from the PaleoProterozoic.

Organic remains in granular iron formations suggest they might be biological in origin.

Paleoproterozoic stromatolites from South Africa were formed in a restricted basin.

Evidence of the Great Oxygenation Event comes from rock salt from Russia.

Archean:

The Late Heavy Bombardment is being questioned.

By the end of the NeoArchean, the first modern continents had formed.

There may be volcanogenic pseudofossils in the PaleoArchean formation at Pilbara.

There's evidence of an oceanic plateau from the Archean in Nunavut, Canada.

University of Tuebingen in Germany and the Chinese Academy of Sciences in Beijing experimentally attempted to recreate the ocean of the Archean to explain its banded iron formations.

When did life originate?  At the dawn of the Archean?  Or later?

Hadean:

What the nitrogen cycle of a prebiotic Earth might have been like.

META:

Chromium isotopes can give false data for oxygen levels.

Chemists have found a plausible formula for the origin of life in Prebiotic earth.

Argnine might have played an important role in the origin of life.

A new origin of life hypothesis has been forwarded.

Did volcanic eruptions spew enough sulfur dioxide to kick off the origin of life?

Manganese oxides can produce pseudofossils.

Constraining the Early Earth's climate and oceanic acidity.

When was the earliest life could have originated?

Did ice in the earliest Earth's ocean help facilitate the origin of life?

Oceanic tides may greatly decrease when supercontinents form.

Pondering the Precambrian #7

Proterozoic:

NeoProterzoic:

The Tarim Craton may have been connected to the North India Block rather than Australia within the supercontinent of Rodinia during the Tonian.

Has evidence of mountain building during the Tonian been found in Scotland?

The Tonian/Cryogenian transition seems to have been located in Svalbard.

How complete is the evidence of glaciations during the Cryogenian in Scotland?

How oxygenated was the ocean between the Snowball Earth episodes?

Caution with carbon-13 shifts are urged in Cryogenian deposits as they are deposit dependent.

Evidence of hydrothermal modification of a dolostone during the Marinoan Glaciations.

Was there a delayed oxygenation of the oceans from the Cryogenian to the Ediacaran?

Evidence from Mongolia's 540 million year old Khesen formation documents the rise of animals.

Evidence that Ediacaran Parvancorina was motile and could sense benthic currents.

Were there constant anoxic bottom waters during the Ediacaran?

Cyanobacterial-algal crusts have been found from Ediacaran paleosols.

MesoProterozoic:

Cyanobacterial microfossils are examined from Calymmian China.

Were tellurium and selenium weathered from sandstones into the Mesoproterozoic oceans?

PaleoProterozoic:

Biosignatures have been found for eukaryotes from Statherian China.

There is evidence of an impact in India during the Siderian.

Was there a subduction cessation during the Siderian in China?

More evidence of warm subduction during the Orosirian from Cameroon.

Was the Great Oxygenation Event really an abiotic process?!

There appears to have been gradual oxygenation in the oceans (in some cases) just prior to the GOE.

A large igneous province is detected from India from the Rhyacian.

Was the early biosphere nutrient limited?

Archean:

Evidence from China, specifically the North China Craton, about the composition of NeoArchean sea water.

Inland lakes appear to have fostered the diversification of microbial life during the MesoArchean.

The oldest known paleosols (fossil soil) date from the PaleoArchean (3.46 billion years ago) and originate in Australia and may have formed from sulfuric acid weathering.

Could there be a problem with the cherts being used from the PaleoArchean to claim microbial life?

Or is there a definitive example of fossil life from the PaleoArchean?  Does that mean life is common in the universe?

Is some of Earth's magma ocean preserved in PaleoArchean rock?

META:

Exploring the Precambrian lithosphere of Zambia and Malawi.

The effect of paleoseawater chemistry on hydrothermal ridges.

Origin of Life:

The origin and diversification of the endosymbiont known as the mitochondria.

A new lineage of eukaryotes has given information on mitochondrial genome reduction.

Pondering the Precambrian #6

Proterozoic:

NeoProterozoic:

There is evidence of a potential blacksmoker vent from the NeoProterozoic.

Ocean subduction evidence has been found in China.

Comb Jellies appear to have be the oldest divergent, yet still living, branch of animals.

Ediacaran:

An Ediacaran protist fossil seems to show how those organisms' reproduction in action.

Evidence of the opening of the Iapetus Sea in Russia during the Ediacaran has been uncovered.

The submerged Batavian Knoll is a microcontinent with evidence of the assembly of Gondwana.

Biostratigraphical evidence is coming together for the Ediacaran from China.

The nuclei and nucleoli in the embryos found in Ediacaran China's Weng'an Biota.

Understanding the Ediacaran paleoecologies.

Should the extinction of Cloudina lucianoi mark the Ediacaran/Cambrian boundary?

Could Ediacaran rangeomorphs actually burrow?

Cryogenian:

It appears the Sturtian Snowball Earth episode began circa 717 million years ago.

Tonian:

The Tonian/Cryogenian boundary has been proposed for specific spots in Scotland.

A vase shaped microfossil has been found in the Tonian deposits around the world.

There appears to have been a mass extinction during the Tonian prior to the Snowball Earth episodes.

Mesoproterozoic:

There is evidence Archean granites were reworked and uranium deposited during the Calymmian in the Olympic Dam Breccia in Australia.

Eukaryote fossils were found in Calymmian deposits in China.

Are some fossils that are normally thought to be NeoProterozoic (Tonian/Cryogenian) found in the MesoProterozoic deposits of Russia?

At the dawn of the Mesoproterozoic, at the Statherian/Calymmian boundary, Australia made contact with northwestern Laurentia and began a long slide along its margin.

Paleoproterozoic:

Evidence of an island arc from the Paleoproterozoic came from West Africa.

There may have been two island arcs in Finland during the PaleoProterozoic.

How the Francevillian formation formed in the Rhyacian.

The microfossils of the Francevillian Biota get examined.

Evidence from India for proto continents in the Rhyacian.

Archean:

Findings from the NeoArchean from the North American Craton support local evidence of plate tectonics.

Did the development of carbonate platforms in the NeoArchean pave the way for the Great Oxygenation Event?

Is there evidence of biogenic atmospheric oxygen during the MesoArchean?

The emergence of the continents may have happened over multiple differentiation events.

Evidence of life was found in EoArchean sediments from Labrador, Canada.

Hadean:

Caution should be taken when examining Hadean zircons.

Did life form in warm little pools?

Scientists one Step Closer to Replicating the Primordial RNA World

Scientists at The Scripps Research Institute (TSRI) have taken a big step toward the laboratory re-creation of the "RNA world," which is generally believed to have preceded modern life forms based on DNA and proteins.

"This is probably the first time some of these complex RNA molecules have been synthesized with a ribozyme [a special RNA enzyme] since the end of the RNA world four billion years ago," said TSRI Professor Gerald F. Joyce, the senior author of the study.

The results from the study, reported this week in the online Early Edition of the Proceedings of the National Academy of Sciences, show the scientists have succeeded in creating a ribozyme that can basically serve both to amplify genetic information and to generate functional molecules.

The new ribozyme can replicate short lengths of RNA efficiently and perform transcription on even longer RNAs to make functional RNA molecules with complex structures--coming close to what scientists imagine in terms of an RNA replicator that could have supported life before modern biology, where protein enzymes now handle gene replication and transcription.

link.

Extraordinary Claim: Venus COuld be the Source of Complex Life on Earth

The Venus Hypothesis

Author:

Cartwright

Abstract:

Current models indicate that Venus may have been habitable. Complex life may have evolved on the highly irradiated Venus, and transferred to Earth on asteroids. This model fits the pattern of pulses of highly developed life appearing, diversifying and going extinct with astonishing rapidity through the Cambrian and Ordovician periods, and also explains the extraordinary genetic variety which appeared over this period.

The Icy Moons of the Solar System may NOT be Friendly to Life Forming

Physicochemical Requirements Inferred for Chemical Self-Organization Hardly Support an Emergence of Life in the Deep Oceans of Icy Moons

Author:

Pascal

Abstract:

An approach to the origin of life, focused on the property of entities capable of reproducing themselves far from equilibrium, has been developed recently. Independently, the possibility of the emergence of life in the hydrothermal systems possibly present in the deep oceans below the frozen crust of some of the moons of Jupiter and Saturn has been raised. The present report is aimed at investigating the mutual compatibility of these alternative views. In this approach, the habitability concept deduced from the limits of life on Earth is considered to be inappropriate with regard to emerging life due to the requirement for an energy source of sufficient potential (equivalent to the potential of visible light). For these icy moons, no driving force would have been present to assist the process of emergence, which would then have had to rely exclusively on highly improbable events, thereby making the presence of life unlikely on these Solar System bodies, that is, unless additional processes are introduced for feeding chemical systems undergoing a transition toward life and the early living organisms.

Did RNA Develop in Linked Puddles?

The crucibles that bore out early building blocks of life may have been, in many cases, modest puddles.

Now, researchers working with that hypothesis have achieved a significant advancement toward understanding an evolutionary mystery -- how components of RNA and DNA formed from chemicals present on early Earth before life existed.

In surprisingly simple laboratory reactions in water, under everyday conditions, they have produced what could be good candidates for missing links on the pathway to the code of life.

And when those components joined up, the result even looked like RNA.

As the researchers' work progresses, it could reveal that much of the original chemistry that led to life arose not in fiery cataclysms and in scarce quantities, but abundantly and gradually on quiet, rain-swept dirt flats or lakeshore rocks lapped by waves.

In turn, their work could increase our understanding of the probability of life's existence elsewhere in the universe.

The research from the NSF/NASA Center for Chemical Evolution, headquartered at the Georgia Institute of Technology, is generously funded through a grant from the National Science Foundation and NASA. The recent results were published on April 25, 2016 in Nature Communications.

Pursuing the origins specifically of RNA, the close chemical relative of DNA, a research team led by Nicholas Hud, a professor in the School of Chemistry and Biochemistry at the Georgia Institute of Technology and director of the CCE, worked with a pair of potential chemical ancestors of the nucleobases of RNA.

For roughly half a century, scientists have hypothesized that life, which uses DNA to store genetic information, was preceded by life forms that used RNA very broadly. And RNA may have had a precursor, proto-RNA, with different but similar nucleotides (the "N" in RNA).

"Early Earth was a messy laboratory where probably many molecules like those needed for life were produced. Some survived and prospered, while others eventually vanished," Hud said. "That goes for the ancestors of RNA, too."

Using two molecules known as barbituric acid and melamine, the researchers formed proto-nucleotides so strongly resembling two of RNA's nucleotides that it is tempting to speculate that they are indeed their ancestors.

The two ingredients would have been readily abundant for reactions on a prebiotic Earth, Hud said. "And they would have been well suited for primitive information coding," he added.

Because of the resemblances and properties, some scientists already have speculated on an ancestral role for melamine and barbituric acid.

But the CCE scientists are careful not to jump to that conclusion just yet.

"To claim ancestry, we would have to show a mechanism by which these nucleotides we made in the lab could turn into the existing nucleotides in RNA," said Ram Krishnamurthy, Hud's collaborator from the Scripps Research Institute in La Jolla, California. "It's a complex path that we'd have to at least design on paper, and we're not there."

link.

Evidence of Biological Traces in Hadean Eon Zircons

Pondering the Precambrian #2

Precambrian in General:

The magnetic field of the Earth has been surprisingly consistent over the course of Deep Time despite the changes happening internally.

Eukaryotes appear to have acquired mitochondria late in the process of their evolution away from other forms of life.

Studying modern stromatolites gives insight to Precambian life.

What meandering rivers prior to terrestrial plant life were like.

NeoProterozoic:

Was an increase in UV light caused by rapidly flipping magnetic poles the root cause of the Cambrian Explosion?

NeoArchean:

Cerium anomalies in from NeoArchean Brazil suggest the ocean was mildly oxygenated before the Great Oxygenation Event.

MesoArchean:

Evidence subduction (and plate tectonics) were active during the MesoArchean .

PaleoArchean:

Evidence from Swaziland suggests the minerals found there do NOT support subduction (and plate tectonics) as being their source as was apparently thought previously.

Doubt is being cast on PaleoArchean carbon deposits, trace evidence of microbes, being really from the PaleoArchean.

EoArchean:

There is evidence 'proto' crust may have existed 3.8 billion years ago.

How to Test if Hydrothermal Vents Were the Origin of Life

Hydrothermal Conditions and the Origin of Cellular Life

Authors:

Deamer et al

Abstract:

The conditions and properties of hydrothermal vents and hydrothermal fields are compared in terms of their ability to support processes related to the origin of life. The two sites can be considered as alternative hypotheses, and from this comparison we propose a series of experimental tests to distinguish between them, focusing on those that involve concentration of solutes, self-assembly of membranous compartments, and synthesis of polymers.

Did Life Originate During the Hadean Prior to the end of the Late Heavy Bombardment?

UCLA geochemists have found evidence that life likely existed on Earth at least 4.1 billion years ago -- 300 million years earlier than previous research suggested. The discovery indicates that life may have begun shortly after the planet formed 4.54 billion years ago.

The research is published today in the online early edition of the journal Proceedings of the National Academy of Sciences.

"Twenty years ago, this would have been heretical; finding evidence of life 3.8 billion years ago was shocking," said Mark Harrison, co-author of the research and a professor of geochemistry at UCLA.

"Life on Earth may have started almost instantaneously," added Harrison, a member of the National Academy of Sciences. "With the right ingredients, life seems to form very quickly."

The new research suggests that life existed prior to the massive bombardment of the inner solar system that formed the moon's large craters 3.9 billion years ago.

"If all life on Earth died during this bombardment, which some scientists have argued, then life must have restarted quickly," said Patrick Boehnke, a co-author of the research and a graduate student in Harrison's laboratory.

Scientists had long believed the Earth was dry and desolate during that time period. Harrison's research -- including a 2008 study in Nature he co-authored with Craig Manning, a professor of geology and geochemistry at UCLA, and former UCLA graduate student Michelle Hopkins -- is proving otherwise.

"The early Earth certainly wasn't a hellish, dry, boiling planet; we see absolutely no evidence for that," Harrison said. "The planet was probably much more like it is today than previously thought."

link.

paper link.

Polymerizing Life's Building Blocks on Europa and Other icy Moons

Polymerization of building blocks of life on Europa and other icy moons

Authors:

Kimura et al

Abstract:

The outer solar system may provide a potential habitat for extraterrestrial life. Remote sensing data from the Galileo spacecraft suggest that the jovian icy moons, Europa, Ganymede, and possibly Callisto, may harbor liquid water oceans underneath their icy crusts. Although compositional information required for the discussion of habitability is limited because of significantly restricted observation data, organic molecules are ubiquitous in the universe. Recently, in-situ spacecraft measurements and experiments suggest that amino acids can be formed abiotically on interstellar ices and comets. These amino acids could be continuously delivered by meteorite or comet impacts to icy moons. Here, we show that polymerization of organic monomers, in particular amino acids and nucleotides, could proceed spontaneously in the cold environment of icy moons, in particular the Jovian icy moon Europa as a typical example, based on thermodynamic calculations, though kinetics of formation are not addressed. Observed surface temperature on Europa is 120 and 80 K in the equatorial region and polar region, respectively. At such low temperatures, Gibbs energies of polymerization become negative, and the estimated thermal structure of the icy crust should contain a shallow region (i.e., at a depth of only a few kilometers) favorable for polymerization. Investigation of the possibility of organic monomer polymerization on icy moons could provide good constraints on the origin and early evolution of extraterrestrial life.

a new Model for the Origin of Life