Origins of animals, plants, fungi, new research


This 18 June 2018 video says about itself:

Phylogenomic-wide studies of evolutionarily conserved structures of protein domains suggest Archaea is the first domain of life to diversify from a stem line of descent and co-evolve with ancestors of Bacteria and Eukarya. The proposed co-evolutionary scenario by J. T. Staley and G. Caetano-Anollés challenges popular cell fusion and two-domain of life scenarios derived from sequence analysis.

For more, read the full article here.

From Molecular Biology and Evolution (Oxford University Press):

Scientists identify rare evolutionary intermediates to understand the origin of eukaryotes

September 11, 2019

Summary: A new study provides a key insight into a milestone event in the early evolution of life on Earth — the origin of the cell nucleus and complex cells. Scientists peered deep inside current living cells, known as Archaea – the organisms that are believed to most closely resemble the ancient intermediates between bacteria and the more complex cells that we now know as eukaryotic cells.

A new study by Yale scientists provides a key insight into a milestone event in the early evolution of life on Earth — the origin of the cell nucleus and complex cells called eukaryotes.

While simple prokaryotic bacteria formed within the first billion years of the Earth, the origin of eurkaryotes, the first cells with nuclei, took much longer. Dating back to between 1.7 and 2.7 billion years ago, an ancient prokaryote was first transformed with a compartment, the nucleus, designed to keep their DNA material more protected from the environment (such as harmful UV damage). From this ancient event, relatively simple organisms, such as bacteria were transformed into more sophisticated ones that ultimately gave rise to all modern animals, plants and fungi.

The details of this key event have remained elusive for many years because not a single transitional fossil has been found to date.

Now, in a study led by Dr. Sergey Melnikov, from the Dieter Söll Laboratory in the Department of Molecular Biophysics and Biochemistry at Yale University, has finally found these missing fossils. To do so, they relied not on unearthing clay or rocks but peering deep inside current living cells, known as Archaea — the organisms that are believed to most closely resemble the ancient intermediates between bacteria and the more complex cells that we now know as eukaryotic cells.

These transitional forms are nothing like the traditional fossils we think of, such as dinosaur bones deposited in the ground or insects trapped in amber. Known as ribosomal proteins, these particular transitional forms are about 100-million times smaller than our bodies. Melnikov and his colleagues discovered that ribosomal proteins can be used as living “molecular fossils”, whose ancient origin and structure may hold the key to understanding the origin of the cell nucleus.

“Simple lifeforms, such as bacteria, are analogous to a studio apartment: they have a single interior space which is not subdivided into separate rooms or compartments. By contrast, more complex organisms, such as fungi, animals, and plants, are made up of cells that are separated into multiple compartments,” explained Melnikov. “These microscopic compartments are connected to one another via ‘doors’ and ‘gates’. To pass through these doors and gates, the molecules that inhabit living cells must carry special ID badges, some of which are called nuclear localization signals, or NLSs.”

Seeking to better understand when NLS-motifs might have emerged in ribosomal proteins, the Yale team assessed their conservation among ribosomal proteins from the three domains of life.

To date, NLS-motifs have been characterized in ten ribosomal proteins from several eukaryotic species. They compared all of the NLS-motifs found in eukaryotic ribosomal proteins (from 482 species) and tried to find a match in bacteria (2,951 species) and Archaea (402 species).

Suprisingly, they found four proteins — uL3, uL15, uL18, and uS12 — to have NLS-type motifs not only in the Eukarya but also in the Archaea. “Contrary to our expectations, we found that NLS-type motifs are conserved across all the archaeal branches, including the most ancient superphylum, called DPANN,” said Melnikov.

But since Archaea don’t have nuclei, the logical question which then arose was, why do they have these IDs? And what was the original biological function of these IDs in non-compartmentalized cells?”

“If you think about an equivalent to our discovery in the macroscopic world, it is similar to discoveries made during the last century of bird-like dinosaurs such as Caudipteryx zoui,” said Melnikov. “These ancient flightless birds have illustrated that it took multiple millions of years for dinosaurs to develop wings. Yet, strikingly, for the first few million years their wings were not good enough to support flight.”

Similarly, the study by Melnikov and colleagues suggests that, even though NLSs may not initially have emerged to allow cellular molecules to pass through microscopic doors and gates between cellular compartments, they could have emerged to fulfill a similar biological function — to help molecules get to their proper biological partners.

As Melnikov explains: “Our analysis shows that in complex cells the very same IDs that allow proteins to pass through the microscopic gates are also used to recognize biological partners of these proteins. In other words, in complex cells, the IDs fulfill two conceptually similar biological functions. In the Archaea, however, these IDs play just one of these functions — these IDs, or NLSs, help proteins to recognize their biological partners and distinguish them from the thousands of other molecules that float in a cell.”

But what led to the evolution of these IDs among cellular proteins in the first place?

As Melnikov explains, “When life first emerged on the face of our planet, the earliest life forms were likely made of a very limited number of molecules. Therefore, it was relatively easy for these molecules to find one specific partner among all the other molecules in a living cell. However, as cells grew in size and complexity, it is possible, even probable, that the old rules of specific interactions between cellular molecules had to be redefined, and this is how the IDs were introduced into the structure of cellular proteins — to help these proteins identify their molecular partners more easily in the complex environment of a complex cell. Coming back to the analogy with bird-like dinosaurs, our study illustrates the remarkable similarity between how evolution happens in the macroscopic world and how evolution happens in the world that Darwin never saw — the microscopic world of invisible molecules that inhabit living cells.”

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Precambrian animal fossils, trails discovery


This 2014 David Attenborough video says about itself:

The first animal on the planet – Dickinsonia

The fossils of the first animal can be found in the Ediacara Hills in South Australia. This animal is called Dickinsonia. It was a cushion-like creature that lay on the seafloor. Its size ranged from a penny to a bath mat. It crept around very slowly to look for food.

This 4 September 2019 video says about itself:

A 550 million-year-old worm could shed light into how life on earth started moving. The creature, discovered in southern China, was among the earliest animals capable of movement – a “monumental event” in evolution, the international team that found him noted. The primitive bug was dug up on the banks of the Yangtze River in western Hubei Province.

It was a millipede-like creature a quarter-inch to an inch wide and up to four inches long. The creepy crawly moved by dragging its body across the muddy ocean floor, resting occasionally along the way.

The animal was an elongated narrow creature with 50 or so body segments, a left and right side, a back and belly, with a head and a tail. Only a few creatures from this time – known geologically as the late Ediacaran – have been shown to have roamed about.

Evidence of their movement comes from trackways and burrows rather than actual remains, making the new species particularly historic. The remarkable fossil even includes the worm’s final trail which the international team describe as a “death march”. The animal has been called Yilingia spiciformis, which means spiky Yiling bug after a nearby city.

From Virginia Tech university in the USA:

Ancient animal species: Fossils dating back 550 million years among first animal trails

September 4, 2019

Summary: A geoscientist calls the unearthed fossils, including the bodies and trails left by an ancient animal species, the most convincing sign of ancient animal mobility, dating back about 550 million years.

In a remarkable evolutionary discovery, a team of scientists co-led by a Virginia Tech geoscientist has discovered what could be among the first trails made by animals on the surface of the Earth roughly a half-billion years ago.

Shuhai Xiao, a professor of geosciences with the Virginia Tech College of Science, calls the unearthed fossils, including the bodies and trails left by an ancient animal species, the most convincing sign of ancient animal mobility, dating back about 550 million years. Named Yilingia spiciformis — that translates to spiky Yiling bug, Yiling being the Chinese city near the discovery site — the animal was found in multiple layers of rock by Xiao and Zhe Chen, Chuanming Zhou, and Xunlai Yuan from the Chinese Academy of Sciences’ Nanjing Institute of Geology and Palaeontology.

The findings are published in the latest issue of Nature. The trials are from the same rock unit and are roughly the same age as bug-like footprints found by Xiao and his team in a series of digs from 2013 to 2018 in the Yangtze Gorges area of southern China, and date back to the Ediacaran Period, well before the age of dinosaurs or even the Pangea supercontinent. What sets this find apart: The preserved fossil of the animal that made the trail versus the unknowable guesswork where the body has not been preserved.

“This discovery shows that segmented and mobile animals evolved by 550 million years ago,” Xiao said. “Mobility made it possible for animals to make an unmistakable footprint on Earth, both literally and metaphorically. Those are the kind of features you find in a group of animals called bilaterans. This group includes us humans and most animals. Animals and particularly humans are movers and shakers on Earth. Their ability to shape the face of the planet is ultimately tied to the origin of animal motility.”

The animal was a millipede-like creature a quarter-inch to an inch wide and up to 4 inches long that alternately dragged its body across the muddy ocean floor and rested along the way, leaving trails as loing as 23 inches. The animal was an elongated narrow creature, with 50 or so body segments, a left and right side, a back and belly, and a head and a tail.

The origin of bilaterally symmetric animals — known as bilaterians — with segmented bodies and directional mobility is a monumental event in early animal evolution, and is estimated to have occurred the Ediacaran Period, between 635 and 539 million years ago. But until this finding by Xiao and his team, there was no convincing fossil evidence to substantiate those estimates. One of the recovered specimens is particularly vital because the animal and the trail it produced just before its death are preserved together.

Remarkably, the find also marks what may be the first sign of decision making among animals — the trails suggest an effort to move toward or away from something, perhaps under the direction of a sophisticated central nerve system, Xiao said. The mobility of animals led to environmental and ecological impacts on the Earth surface system and ultimately led to the Cambrian substrate and agronomic revolutions, he said.

“We are the most impactful animal on Earth,” added Xiao, also an affiliated member of the Global Change Center at Virginia Tech. “We make a huge footprint, not only from locomotion, but in many other and more impactful activities related to our ability to move. When and how animal locomotion evolved defines an important geological and evolutionary context of anthropogenic impact on the surface of the Earth.”

Rachel Wood, a professor in the School of GeoSciences at University of Edinburgh in Scotland, who was not involved with the study, said, “This is a remarkable finding of highly significant fossils. We now have evidence that segmented animals were present and had gained an ability to move across the sea floor before the Cambrian, and more notably we can tie the actual trace-maker to the trace. Such preservation is unusual and provides considerable insight into a major step in the evolution of animals.”

The study was supported by the Chinese Academy of Sciences, the National Natural Science Foundation of China, the U.S. National Science Foundation, and the National Geographic Society.

Dickinsonia, world’s oldest animals, new study


This 20 September 2018 video from Australia says about itself:

Is Dickinsonia our oldest ancestor?

Scientists from ANU have discovered molecules of fat in an ancient fossil to reveal the earliest confirmed animal in the geological record that lived on Earth 558 million years ago. The strange creature called Dickinsonia, which grew up to 1.4 metres in length and was oval shaped with rib-like segments running along its body, was part of the Ediacara Biota that lived on Earth 20 million years prior to the ‘Cambrian explosion’ of modern animal life.

From the Australian National University:

Mystery shrouding oldest animal fossils solved

March 25, 2019

Scientists from The Australian National University (ANU) have discovered that 558 million-year-old Dickinsonia fossils do not reveal all of the features of the earliest known animals, which potentially had mouths and guts.

ANU PhD scholar Ilya Bobrovskiy, lead author of the study, said the study shows that simple physical properties of sediments can explain Dickinsonia’s preservation, and implies that what can be seen today may not be what these creatures actually looked like.

“These soft-bodied creatures that lived 558 million years ago on the seafloor could, in principle, have had mouths and guts — organs that many palaeontologists argue emerged during the Cambrian period tens of millions of years later¨, said Mr Bobrovskiy from the ANU Research School of Earth Sciences.

“Our discovery about Dickinsonia — and many other Ediacaran fossils — opens up new possibilities as to what they actually looked like.”

Ediacara biota were strange creatures that lived on the seafloor 571 to 541 million years ago. They grew up to two metres long and include the earliest known animals as well as colonies of bacteria.

The fact that Dickinsonia and other Ediacara biota fossils were preserved at all in the geological record has been a big mystery — until now.

The team, which includes scientists from Russian institutions, discovered how Ediacara biota fossils were preserved, despite the macroorganisms not having skeletons or shells.

“As the organisms decayed, softer sediment from below gradually flowed into the forming void, creating a cast”, Mr Bobrovskiy said.

“Now we know that what we are looking at is an impression of a soft organic skeleton that may have been anywhere within Dickinsonia’s body. What we’re seeing could be a part of Dickinsonia’s bottom, the inside of its body or part of its back.”

Mr Bobrovskiy said Dickinsonia had different types of tissues and must have been a true animal, a Eumetazoa, the lineages eventually leading to humans.

Co-researcher and RSES colleague Associate Professor Jochen Brocks said the team used a melting cast of a Death Star made of ice to show the physical properties of sediments that enabled the soft-bodied Ediacara biota to be preserved.

“This process of fossilisation could tell us more about what Ediacara biota were and how they lived,” he said.

“These fossils comprise our best window into earliest animal evolution and are the key to understanding our own deep origins.”

Ancient organic matter of biological origin has been tracked in multiple samples of rock spanning over 2,000 million years of Earth’s history, according to researchers: here.

Primitive ponds may have provided a suitable environment for brewing up Earth’s first life forms, more so than oceans, a new study finds. Researchers report that shallow bodies of water, on the order of 10 centimeters deep, could have held high concentrations of what many scientists believe to be a key ingredient for jump-starting life on Earth: nitrogen: here.

DNA, the hereditary material, may have appeared on Earth earlier than has been assumed hitherto. Chemists now show that a simple reaction pathway could have given rise to DNA subunits on the early Earth: here.

Pre-Cambrian sponges, world’s oldest animals discovered


This July 2013 video says about itself:

A number of sponge-like fossils occur in the fossil record, many of which were originally described as sponges. A few of these are presented here. Charles D. Walcott was one of the first paleontologists to get involved with many of these, some of which are found in very ancient strata of the Precambrian.

Walcott’s Atikokania was one of these, it’s now considered to be a pseudofossil (false fossil) much like the previously described Eozoon canadense (the so called “Dawn Animal of Canada”).

Sponges are an ancient group of animals; however, their presence before the Cambrian Period is questionable.

That was then. However, now …

From the University of California – Riverside in the USA:

Sponges on ancient ocean floors 100 million years before Cambrian period

Molecular fossil evidence

October 15, 2018

Researchers at the University of California, Riverside, have found the oldest clue yet of animal life, dating back at least 100 million years before the famous Cambrian explosion of animal fossils.

The study, led by Gordon Love, a professor in UCR’s Department of Earth Sciences, was published today in Nature Ecology & Evolution. The first author is Alex Zumberge, a doctoral student working in Love’s research group.

Rather than searching for conventional body fossils, the researchers have been tracking molecular signs of animal life, called biomarkers, as far back as 660-635 million years ago during the Neoproterozoic Era. In ancient rocks and oils from Oman, Siberia, and India, they found a steroid compound produced only by sponges, which are among the earliest forms of animal life.

“Molecular fossils are important for tracking early animals since the first sponges were probably very small, did not contain a skeleton, and did not leave a well-preserved or easily recognizable body fossil record”, Zumberge said. “We have been looking for distinctive and stable biomarkers that indicate the existence of sponges and other early animals, rather than single-celled organisms that dominated the earth for billions of years before the dawn of complex, multicellular life.”

The biomarker they identified, a steroid compound named 26-methylstigmastane (26-mes), has a unique structure that is currently only known to be synthesized by certain species of modern sponges called demosponges.

“This steroid biomarker is the first evidence that demosponges, and hence multicellular animals, were thriving in ancient seas at least as far back as 635 million years ago,” Zumberge said.

The work builds from a 2009 study by Love’s team, which reported the first compelling biomarker evidence for Neoproterozoic animals from a different steroid biomarker, called 24-isopropylcholestane (24-ipc), from rocks in South Oman. However, the 24-ipc biomarker evidence proved controversial since 24-ipc steroids are not exclusively made by demosponges and can be found in a few modern algae. The finding of the additional and novel 26-mes ancient biomarker, which is unique to demosponges, adds extra confidence that both compounds are fossil biomolecules produced by demosponges on an ancient seafloor.

The study also provides important new constraints on the groups of modern demosponges capable of producing unique steroid structures, which leave a distinctive biomarker record. The researchers found that within modern demosponges, certain taxonomic groups preferentially produce 26-mes steroids while others produce 24-ipc steroids.

“The combined Neoproterozoic demosponge sterane record, showing 24-ipc and 26-mes steranes co-occurring in ancient rocks, is unlikely attributed to an isolated branch or extinct stem-group of demosponges”, Love said. “Rather, the ability to make such unconventional steroids likely arose deep within the demosponge phylogenetic tree but now encompasses a wide coverage of modern demosponge groups.”

A single enzyme found in early single-cell life forms could explain why oxygen levels in the atmosphere remained low for two billion years during the Proterozoic eon, preventing life colonizing land: here.

World’s oldest animal discovery in Russia


This 20 September 2018 Australian National University says about itself:

Is Dickinsonia our oldest ancestor?

Scientists from ANU have discovered molecules of fat in an ancient fossil to reveal the earliest confirmed animal in the geological record that lived on Earth 558 million years ago. The strange creature called Dickinsonia, which grew up to 1.4 metres in length and was oval shaped with rib-like segments running along its body, was part of the Ediacara Biota that lived on Earth 20 million years prior to the ‘Cambrian explosion’ of modern animal life.

From Australian National University:

Fat from 558 million years ago reveals earliest known animal

September 20, 2018

Scientists from The Australian National University (ANU) and overseas have discovered molecules of fat in an ancient fossil to reveal the earliest confirmed animal in the geological record that lived on Earth 558 million years ago.

The strange creature called Dickinsonia, which grew up to 1.4 metres in length and was oval shaped with rib-like segments running along its body, was part of the Ediacara Biota that lived on Earth 20 million years prior to the ‘Cambrian explosion‘ of modern animal life.

ANU PhD scholar Ilya Bobrovskiy discovered a Dickinsonia fossil so well preserved in a remote area near the White Sea in the northwest of Russia that the tissue still contained molecules of cholesterol, a type of fat that is the hallmark of animal life.

Lead senior researcher Associate Professor Jochen Brocks said the ‘Cambrian explosion’ was when complex animals and other macroscopic organisms — such as molluscs, worms, arthropods and sponges — began to dominate the fossil record.

“The fossil fat molecules that we’ve found prove that animals were large and abundant 558 million years ago, millions of years earlier than previously thought”, said Associate Professor Jochen Brocks from the ANU Research School of Earth Sciences.

“Scientists have been fighting for more than 75 years over what Dickinsonia and other bizarre fossils of the Edicaran Biota were: giant single-celled amoeba, lichen, failed experiments of evolution or the earliest animals on Earth. The fossil fat now confirms Dickinsonia as the oldest known animal fossil, solving a decades-old mystery that has been the Holy Grail of palaeontology.”

Mr Bobrovskiy said the team developed a new approach to study Dickinsonia fossils, which hold the key between the old world dominated by bacteria and the world of large animals that emerged 540 million years ago during the ‘Cambrian explosion‘.

“The problem that we had to overcome was finding Dickinsonia fossils that retained some organic matter”, said Mr Bobrovskiy from the ANU Research School of Earth Sciences.

“Most rocks containing these fossils such as those from the Ediacara Hills in Australia have endured a lot of heat, a lot of pressure, and then they were weathered after that — these are the rocks that palaeontologists studied for many decades, which explained why they were stuck on the question of Dickinsonia’s true identity.”

Palaeontologists normally study the structure of fossils, but Mr Bobrovskiy extracted and analysed molecules from inside the Dickinsonia fossil found in ancient rocks in Russia to make the breakthrough discovery.

“I took a helicopter to reach this very remote part of the world — home to bears and mosquitoes — where I could find Dickinsonia fossils with organic matter still intact”, Mr Bobrovskiy said.

“These fossils were located in the middle of cliffs of the White Sea that are 60 to 100 metres high. I had to hang over the edge of a cliff on ropes and dig out huge blocks of sandstone, throw them down, wash the sandstone and repeat this process until I found the fossils I was after.”

Associate Professor Brocks said being able to study molecules from these ancient organisms was a gamechanger.

“When Ilya showed me the results, I just couldn’t believe it,” he said.

“But I also immediately saw the significance.”

ANU led the research in collaboration with scientists from the Russian Academy of Science and the Max Planck Institute for Biogeochemistry and the University of Bremen in Germany.

Life on earth, Precambrian origins


This video says about itself:

Origin of Life – How Life Started on Earth

2 June 2016

Four and a half billion years ago, the young Earth was a hellish place—a seething chaos of meteorite impacts, volcanoes belching noxious gases, and lightning flashing through a thin, torrid atmosphere. Then, in a process that has puzzled scientists for decades, life emerged. But how?

[Follow] mineralogist Robert Hazen as he journeys around the globe. From an ancient Moroccan market to the Australian Outback, he advances a startling and counterintuitive idea—that the rocks beneath our feet were not only essential to jump-starting life, but that microbial life helped give birth to hundreds of minerals we know and depend on today. It’s a theory of the co-evolution of Earth and life that is reshaping the grand-narrative of our planet’s story.

From the University of Bristol in England:

A timescale for the origin and evolution of all of life on Earth

August 20, 2018

A new study led by scientists from the University of Bristol has used a combination of genomic and fossil data to explain the history of life on Earth, from its origin to the present day.

Palaeontologists have long sought to understand ancient life and the shared evolutionary history of life as a whole.

However, the fossil record of early life is extremely fragmented, and its quality significantly deteriorates further back in time towards the Archaean period, more than 2.5 billion years ago, when the Earth’s crust had cooled enough to allow the formation of continents and the only life forms were microbes.

Holly Betts, lead author of the study, from the University of Bristol’s School of Earth Sciences, said: “There are few fossils from the Archaean and they generally cannot be unambiguously assigned to the lineages we are familiar with, like the blue-green algae or the salt-loving archaebacteria that colours salt-marshes pink all around the world.

“The problem with the early fossil record of life is that it is so limited and difficult to interpret — careful reanalysis of some of the very oldest fossils has shown them to be crystals, not fossils at all.”

Fossil evidence for the early history of life is so fragmented and difficult to evaluate that new discoveries and reinterpretations of known fossils have led to a proliferation of conflicting ideas about the timescale of the early history of life.

Co-author Professor Philip Donoghue, also from Bristol’s School of Earth Sciences, added: “Fossils do not represent the only line of evidence to understand the past. A second record of life exists, preserved in the genomes of all living creatures.”

Co-author Dr Tom Williams, from Bristol’s School of Biological Sciences, said: “Combining fossil and genomic information, we can use an approach called the ‘molecular clock’ which is loosely based on the idea that the number of differences in the genomes of two living species (say a human and a bacterium) are proportional to the time since they shared a common ancestor.”

By making use of this method the team at Bristol and Mark Puttick from the University of Bath were able to derive a timescale for the history of life on Earth that did not rely on the ever-changing age of the oldest accepted fossil evidence of life.

Co-author Professor Davide Pisani said: “Using this approach we were able to show that the Last Universal Common Ancestor all cellular life forms, ‘LUCA’, existed very early in Earth’s history, almost 4.5 Billion years ago — not long after Earth was impacted by the planet Theia, the event which sterilised Earth and led to the formation of the Moon.

“This is significantly earlier than the currently accepted oldest fossil evidence would suggest.

“Our results indicate that two “primary” lineages of life emerged from LUCA (the Eubacteria and the Archaebacteria), approximately one billion years after LUCA.

“This result is testament to the power of genomic information, as it is impossible, based on the available fossil information, to discriminate between the oldest eubacterial and archaebacterial fossil remains.”

The study confirms modern views that the eukaryotes, the lineage to which human life belongs (together with the plants and the fungi, for example), is not a primary lineage of life. Professor Pisani added: “It is rather humbling to think we belong to a lineage that is billions of years younger than life itself.”

In the beginning, life was small. For billions of years, all life on Earth was microscopic, consisting mostly of single cells. Then suddenly, about 570 million years ago, complex organisms including animals with soft, sponge-like bodies up to a meter long sprang to life. And for 15 million years, life at this size and complexity existed only in deep water. Scientists have long questioned why these organisms appeared when and where they did: in the deep ocean, where light and food are scarce, in a time when oxygen in Earth’s atmosphere was in particularly short supply. A new study from Stanford University, published Dec. 12 in the peer-reviewed Proceedings of the Royal Society B, suggests that the more stable temperatures of the ocean’s depths allowed the burgeoning life forms to make the best use of limited oxygen supplies: here.

An organic molecule detected in the material from which a star forms could shed light on how life emerged on Earth, according to new research led by Queen Mary University of London: here.

Most of Earth’s life-essential elements probably arrived with the planetary collision that produced the moon. Petrologists now conclude Earth most likely received the bulk of its carbon, nitrogen and other life-essential volatile elements from a collision with a Mars-sized planet more than 4.4 billion years ago: here.

3.5 billion years ago Earth hosted life, but was it barely surviving, or thriving? A new study carried out by a multi institutional team with leadership including the Earth-Life Science Institute (ELSI) of Tokyo Institute of Technology (Tokyo Tech) provides new answers to this question. Microbial metabolism is recorded in billions of years of sulfur isotope ratios that agree with this study’s predictions, suggesting life throve in the ancient oceans. Using this data, scientists can more deeply link the geochemical record with cellular states and ecology: here.

Clues from Canadian rocks formed billions of years ago reveal a previously unknown loss of life even greater than that of the mass extinction of the dinosaurs 65 million years ago, when Earth lost nearly three-quarters of its plant and animal species. Rather than prowling animals, this die-off involved miniscule microorganisms that shaped the Earth’s atmosphere and ultimately paved the way for those larger animals to thrive: here.

Until now, the Cambrian Explosion — which took place between 540 and 520 million years ago — was thought to have given rise to almost all the early ancestors of present-day animals. Scientists say, however, that it was probably just one in a series of similar events, the first of which took place at least 571 million years ago during the late Ediacaran Period: here.

Peptides, one of the fundamental building blocks of life, can be formed from the primitive precursors of amino acids under conditions similar to those expected on the primordial Earth, finds a new UCL study. The findings, published in Nature, could be a missing piece of the puzzle of how life first formed: here.

From microscopic life to big animals, prehistoric evolution


This video from Canada says about itself:

The Ediacaran Period: Glimpses of the Earth’s Earliest Animals

Royal Tyrrell Museum Speaker Series 2016

Calla Carbone – Royal Tyrrell Museum of Palaeontology “The Ediacaran Period: Glimpses of the Earth’s Earliest Animals”.

Originally published February 22, 2016.

From the University of Cambridge in England:

Why life on Earth first got big

June 25, 2018

Some of the earliest complex organisms on Earth — possibly some of the earliest animals to exist — got big not to compete for food, but to spread their offspring as far as possible.

The research, led by the University of Cambridge, found that the most successful organisms living in the oceans more than half a billion years ago were the ones that were able to ‘throw’ their offspring the farthest, thereby colonising their surroundings. The results are reported in the journal Nature Ecology and Evolution.

Prior to the Ediacaran period, between 635 and 541 million years ago, life forms were microscopic in size, but during the Ediacaran, large, complex organisms first appeared, some of which — such as a type of organism known as rangeomorphs — grew as tall as two metres. These organisms were some of the first complex organisms on Earth, and although they look like ferns, they may have been some of the first animals to exist — although it’s difficult for scientists to be entirely sure. Ediacaran organisms do not appear to have mouths, organs or means of moving, so they are thought to have absorbed nutrients from the water around them.

As Ediacaran organisms got taller, their body shapes diversified, and some developed stem-like structures to support their height.

In modern environments, such as forests, there is intense competition between organisms for resources such as light, so taller trees and plants have an obvious advantage over their shorter neighbours. “We wanted to know whether there were similar drivers for organisms during the Ediacaran period”, said Dr Emily Mitchell of Cambridge’s Department of Earth Sciences, the paper’s lead author. “Did life on Earth get big as a result of competition?”

Mitchell and her co-author Dr Charlotte Kenchington from Memorial University of Newfoundland in Canada examined fossils from Mistaken Point in south-eastern Newfoundland, one of the richest sites of Ediacaran fossils in the world.

Earlier research hypothesised that increased size was driven by the competition for nutrients at different water depths. However, the current work shows that the Ediacaran oceans were more like an all-you-can-eat buffet.

“The oceans at the time were very rich in nutrients, so there wasn’t much competition for resources, and predators did not yet exist”, said Mitchell, who is a Henslow Research Fellow at Murray Edwards College. “So there must have been another reason why life forms got so big during this period.”

Since Ediacaran organisms were not mobile and were preserved where they lived, it’s possible to analyse whole populations from the fossil record. Using spatial analysis techniques, Mitchell and Kenchington found that there was no correlation between height and competition for food. Different types of organisms did not occupy different parts of the water column to avoid competing for resources — a process known as tiering.

“If they were competing for food, then we would expect to find that the organisms with stems were highly tiered”, said Kenchington. “But we found the opposite: the organisms without stems were actually more tiered than those with stems, so the stems probably served another function.”

According to the researchers, one likely function of stems would be to enable the greater dispersion of offspring, which rangeomorphs produced by expelling small propagules. The tallest organisms were surrounded by the largest clusters of offspring, suggesting that the benefit of height was not more food, but a greater chance of colonising an area.

“While taller organisms would have been in faster-flowing water, the lack of tiering within these communities shows that their height didn’t give them any distinct advantages in terms of nutrient uptake”, said Mitchell. “Instead, reproduction appears to have been the main reason that life on Earth got big when it did.”

Despite their success, rangeomorphs and other Ediacaran organisms disappeared at the beginning of the Cambrian period about 540 million years ago, a period of rapid evolutionary development when most major animal groups first appear in the fossil record.

What caused the mass extinction of Earth’s first animals? Unravelling mystery of the Ediacaran-Cambrian transition. June 27, 2018, by Arizona State University. Fossil records tell us that the first macroscopic animals appeared on Earth about 575 million years ago. Twenty-four million years later, the diversity of animals began to mysteriously decline, leading to Earth’s first know mass extinction event. A research team is helping to unravel this mystery and understand why this extinction event happened, what it can tell us about our origins, and how the world as we know it came to be: here.

Scientists from The Australian National University (ANU) and overseas have discovered the oldest colours in the geological record, 1.1 billion-year-old bright pink pigments extracted from rocks deep beneath the Sahara desert in Africa. Dr Nur Gueneli from ANU said the pigments taken from marine black shales of the Taoudeni Basin in Mauritania, West Africa, were more than half a billion years older than previous pigment discoveries. Dr Gueneli discovered the molecules as part of her PhD studies. “The bright pink pigments are the molecular fossils of chlorophyll that were produced by ancient photosynthetic organisms inhabiting an ancient ocean that has long since vanished,” said Dr Gueneli from the ANU Research School of Earth Sciences: here.

Ediacara biota were forming complex communities tens of millions of years before the Cambrian explosion: here.