AgnosticWeb.com

Back to the forum index

Linear

Ediacaran organisms preceed the Cambrian Explosion. Note how simple they are in the pictures shown. Frond forms, very simple. So how do we explain the enormous complexity in the Cambrian. Increasing oxygenation is a small answer, not anything complete. How did the presence of more oxygen cause that huge jump in complexity? Darwinism has no answer.-http://www.nature.com/nature/journal/v470/n7334/full/nature09810.html?WT.ec_id=NATURE-20110217

4289 views

Ediacaran organisms preceed the Cambrian Explosion. Note how simple they are in the pictures shown. Frond forms, very simple. So how do we explain the enormous complexity in the Cambrian. Increasing oxygenation is a small answer, not anything complete. How did the presence of more oxygen cause that huge jump in complexity? Darwinism has no answer.
> 
> http://www.nature.com/nature/journal/v470/n7334/full/nature09810.html?WT.ec_id=NATURE-2... in a post awhile back (couldn't find it to verify) I'd asked what caused the jump in complexity and you said more oxygen. Seems to me I may have asked what caused more oxygen and you said more plants? (I might be wrong about how the conversation went) Were more plants the reason for more oxygen? If so, how is it more plants came about? More water? Going backwards in time is always a bummer. [Like what came first, the chicken or the egg?] Just wondering?-bb

4271 views

Ediacaran organisms preceed the Cambrian Explosion. Note how simple they are in the pictures shown. Frond forms, very simple. So how do we explain the enormous complexity in the Cambrian. Increasing oxygenation is a small answer, not anything complete. How did the presence of more oxygen cause that huge jump in complexity? Darwinism has no answer.
> > 
> > http://www.nature.com/nature/journal/v470/n7334/full/nature09810.html?WT.ec_id=NATURE-2... 
> David, in a post awhile back (couldn't find it to verify) I'd asked what caused the jump in complexity and you said more oxygen. Seems to me I may have asked what caused more oxygen and you said more plants? -I remember our conversation. And it is always the oxygen that is pointed to as a cause. But a lot more had to happen. Those Ediacaran pictures helped make my point. Look at how simple they are compaired to what appeared in the Cambrian.http://denisdutton.com/newsweek_coolingworld.pdf

4283 views


> > David, in a post awhile back (couldn't find it to verify) I'd asked what caused the jump in complexity and you said more oxygen. Seems to me I may have asked what caused more oxygen and you said more plants? 
> 
> I remember our conversation. And it is always the oxygen that is pointed to as a cause. But a lot more had to happen. Those Ediacaran pictures helped make my point. Look at how simple they are compaired to what appeared in the Cambrian.http://denisdutton.com/newsweek_coolingworld.pdf-A new entry in the Cambrian debate. Plancton caused the huge jump in oxygen in the atmosphere:-http://wattsupwiththat.com/ 2/22/11

4267 views


> > > David, in a post awhile back (couldn't find it to verify) I'd asked what caused the jump in complexity and you said more oxygen. Seems to me I may have asked what caused more oxygen and you said more plants? 
> > 
> > I remember our conversation. And it is always the oxygen that is pointed to as a cause. But a lot more had to happen. Those Ediacaran pictures helped make my point. Look at how simple they are compaired to what appeared in the Cambrian.http://denisdutton.com/newsweek_coolingworld.pdf
> 
> A new entry in the Cambrian debate. Plancton caused the huge jump in oxygen in the atmosphere:
> 
> http://wattsupwiththat.com/ 2/22/11-I read this article and it seems to say that upheavals in the earths crust (volcanic activity/earthquakes?) is what created the increase in plankton that caused more oxygen. Does this then mean when we have earthquakes and volcanic activity now more oxygen is a by-product? We sure could use more O2!

4268 views

A new entry in the Cambrian debate. Plancton caused the huge jump in oxygen in the atmosphere:
> > 
> > http://wattsupwiththat.com/ 2/22/11
> 
> I read this article and it seems to say that upheavals in the earths crust (volcanic activity/earthquakes?) is what created the increase in plankton that caused more oxygen. Does this then mean when we have earthquakes and volcanic activity now more oxygen is a by-product? We sure could use more O2!-Volcanoes are a major source of CO2. Co2 and plankton use photosysthesis to make oxygen. Oxygen is about 20% of our atmosphere, and hasn't changed much in many many centuries. Cyanobacteria also make oxygen the same way, and appear early in evolution and are being studied to understand evolution.- http://www.the-scientist.com/news/display/58023/

4248 views

These clumps of cells are extremely well preserved, but it is not clear what they represent, early animals or not:

https://www.sciencedaily.com/releases/2017/05/170503213547.htm

"The Weng'an Biota is a fossil Konservat-Lagerstätte in South China that is around 600 million-years-old and provides an unparalleled snapshot of marine life during the interval in which molecular clocks estimate that animal groups had evolved.

"However, all fossil evidence from this time has met with controversy.

"Dr John Cunningham from the University of Bristol's School of Earth Sciences, said: "Dated at around 600 million years old, these rocks preserve an assemblage of microscopic fossils, perfectly-aged to be candidates for the oldest evidence of animal life.

"'These fossils aren't recognisable as remains of fully grown animals, but some resemble embryos, ranging from single cells to clusters of thousands.

"'The preservation is so exquisite, that even sub-cellular structures can be identified, including possible nuclei.

......."'But with the lack of adult forms that could indicate their identity, paleontologists have to rely on information from cellular anatomy to determine whether these tiny fossils belong to animals or to a different group."

"Now scientists have reviewed all the evidence pointing towards an animal identity of the Weng'an fossils.

"Their findings have revealed that none of the characteristics previously used to define the fossils as animals are actually unique to animals alone, opening up the possibility for alternative identifications.

"Professor Philip Donoghue, another Bristol co-author, added: "Many proponents of animal affinity have argued that the Y-shaped junctions between the cells in the fossils are an important animal character, but this a feature common to many multicellular groups, including algae, that are very distant relatives of animals."

"Dr Cunningham added: "It could be that the fossils belong to other groups, such as algae, and these possibilities need to be investigated carefully."

"Despite these results, paleontologists are continuing to make new discoveries from the Weng'an Biota, and these are helping to refine our knowledge of evolution during the Ediacaran.

Comment: the key issue for our discussion is that just prior to the pre-Cambrian era the Ediacarans are extremely primitive in comparison to the very complex Cambrian organisms that suddenly appear with a huge gap not demonstrating any sign of gradual development. Darwin knew this fact was the most direct threat to his evolutionary theory and assumed the gradual forms would be found.

3807 views

Very simple organisms not related to any organisms we know about. Could they possibly be mobile? No proof:

https://www.scientificamerican.com/article/reverse-engineering-mysterious-500-million-y...

"When large, complex fossils were discovered in the Ediacaran, researchers naturally expected that many of them would represent early relatives of the same animal groups that had been recognized in the Cambrian. But these Ediacarans seem completely distinct from modern animals.

"For instance, the rangeomorphs were a collection of leaf- and mat-like organisms with a unique fractal architecture, constructed from a series of branching “frond” elements, each a few centimeters long, each of which is itself composed of smaller, identical frond elements.

"Another – Tribrachidium – was a small hemispherical organism possessing three raised branches that meet at the top of the organism and which curved toward the margin in a counterclockwise direction.

"So how do oddballs like these fit in with what came before and what came after? We just haven’t been able to place them on any evolutionary tree.

***

"We’ve abandoned all assumptions about what they might be related to, and instead tried to answer more fundamental questions. For instance, did they move? How did they feed? How did they reproduce? By answering these questions, we can begin to understand their biology and ecology, which in turn may provide hints as to how these organisms are related to other multicellular lifeforms.

***

"With modern species, researchers can study fluid flows around living animals. But for organisms that have been extinct for over half a billion years—such as the Ediacara biota—virtual simulations using CFD are the only approach.

***

"Our recent work with the enigmatic Ediacaran fossil Parvancorina is an example of this approach. Parvancorina is a simple-looking, shield-shaped organism typically 1-2 centimeters in length, with an anchor-like series of ridges on its top surface. Although it’s been interpreted in a variety of ways, most scientists have assumed that it was fixed on the seafloor—what we call sessile. No one has seen any limbs preserved withParvancorina and it’s never been found in association with fossilized tracks or trails.

***

"We also used these simulations to calculate drag in different orientations. Although talking about front and back ends in Parvancorina is slightly problematic (because we can’t even tell whether it had anything resembling a head and tail), we usually think of the shield end as the front. We showed that the drag experienced by Parvancorina was typically lower when it was placed front-on to current, compared to when it was placed side-on. This is also bad news if you’re a sessile organism, because it leaves you open to being ripped from the sediment in strong currents.

"The inference from these two observations is clear: Parvancorina was better adapted to life as a mobile, rather than a sessile, organism.

One of the most important techniques at our disposal is computational fluid dynamics (CFD), a method for virtually simulating fluid flows around objects using computers.

***

"The knowledge that it was mobile will help us work out where this fossil fits in the tree of life.

"Second, the inference that Parvancorina was mobile, but nonetheless left no trace of its movement, is important—it means that many other Ediacaran fossils that we’ve assumed were sessile may actually have been mobile as well. This may require us to reimagine Ediacaran ecosystems as much more dynamic and, by extension, much more complex than we previously thought."

Comment: Hope always springs eternal with Darwinist scientists. Make The very simple Ediacarans seem more complex and shrink the Cambrian Explosion Gap, the major point which is totally against the Darwin interpretation of gradual evolution. What this study shows is that the animal may prefer a specific orientation in relation to water flow, and settle on the bottom that way, nothing more. What the article makes quite clear is the Cambrians have no precursor.

3739 views

Two more types are found:

https://phys.org/news/2018-06-creatures-dawn-animal-life.html

"two new animals discovered by a UC Riverside-led team of researchers:
Obamus coronatus, a name that honors President Barack Obama's passion for science. This disc-shaped creature was between 0.5-2 cm across with raised spiral grooves on its surface. Obamus coronatus did not seem to move around, rather it was embedded to the ocean mat, a thick layer of organic matter that covered the early ocean floor.

"Attenborites janeae, named after the English naturalist and broadcaster Sir David Attenborough for his science advocacy and support of paleontology. This tiny ovoid, less than a centimeter across, was adorned with internal grooves and ridges giving it a raisin-like appearance.

***

"In the hierarchical taxonomic classification system, the Ediacara Biota are not yet organized into families, and little is known about how they relate to modern animals. About 50 genera have been described, which often have only one species.

"'The two genera that we identified are a new body plan, unlike anything else that has been described," Droser said. "We have been seeing evidence for these animals for quite a long time, but it took us a while to verify that they are animals within their own rights and not part of another animal."

"The animals were glimpsed in a particularly well-preserved fossil bed described in another paper published by Droser's group that will be included in the Flinders Ranges issue of AJES. The researchers dubbed this fossil bed "Alice's Restaurant Bed," a tribute to the Arlo Guthrie song and its lyric, "You can get anything you want at Alice's Restaurant."

"'I've been working in this region for 30 years, and I've never seen such a beautifully preserved bed with so many high quality and rare specimens, including Obamus and Attenborites," Droser said. "

Comment: More simple Ediacaran forms that do not remove the gap, and are not obvious precursors of the Cambrian organisms, even though on a time passage basis they must be.

3304 views

The Ediacarans are simple animal forms which lived well into the Cambrian era, but they do explain the gap in body complexity:

https://phys.org/news/2018-08-evolution-rethink-scientists-closer-earth.html

"Fossils of Stromatoveris psygmoglena are found in only one place in the world: Chengjiang county, China. This region is known for exceptionally well-preserved Cambrian fossils from 518m years ago.

***

"While the fossil record most often preserves only hard shells or bones, some special sites like Chengjiang preserve the remains of soft-bodied animals, such as Stromatoveris psygmoglena. Originally described in 2006 from eight known specimens, we examined over 200 new fossils of the organism that have since been discovered by researchers from Northwest University, China, and dated to the Cambrian period.

"The way in which fossils of the Ediacaran Period were preserved has been another of their mysteries. These fossils often show signs of bending, twisting and tearing, suggesting that they preserve soft-bodied organisms without hard parts. However, there is rarely anything left of the soft tissues themselves.

"Instead, they left moulds in the surrounding sediment, a little like a footprint on the beach. In contrast, the newly examined Cambrian fossils of Stromatoveris psygmoglena retain carbon-based tissue, allowing us to see the detailed and internal anatomy of the body itself.

***

"The analysis showed that Stromatoveris psygmoglena and seven key members of the Ediacaran biota share very similar anatomies, including multiple, branched fronds which radiate outwards like seaweed, uniting them all in a new group of early animals called Petalonamae. The name means "Nama Petals" and was chosen to honour biologist Hans Pflug and his work on the Ediacaran biota in Namibia, a reference to the petal-like fronds which, Pflug noted, distinguish these unusual animals.

***

"Because members of the Ediacaran biota can now be classed as animals, we can date the origin of the animal kingdom to at least the time when these fossils appeared. The oldest members of these groups are known as "rangeomorphs" and appear in the fossil record approximately 571m years ago, in the late Ediacaran Period.

"This means that animal species were diversifying well before the Cambrian explosion. It may also mean that the search for animal origins should now focus on the time before this, in the early Ediacaran and even more ancient geological periods. Based on this, animals may have originated much earlier than the traditional reading of the fossil record had suggested.

"This study also has key implications for the ecology and eventual extinction of the petalonamids. Many Ediacaran species have not been found in later rocks leading some researchers to think that they were a "failed experiment" in evolution, disappearing by the beginning of the Cambrian. Indeed, this was my own view until I saw the remarkable new fossils of Stromatoveris psygmoglena.

"The inclusion of this Cambrian animal among the petalonamids changes the picture of the Ediacaran biota. Stromatoveris psygmoglena shows that the petalonamids were alive and well over 20m years into the Cambrian period and did not go extinct at its outset, as had been thought.

"Even more intriguing, more than 200 fossils of Stromatoveris psygmoglena have now been found, despite the fact that it lacked hard parts which are usually most easily preserved. This indicates that this species was an important member of its shallow marine ecosystem rather than a rare or marginal survivor."

Comment: Still no explanation for the gap in morphology and physiology.

3204 views

David: Misprint and correction: The Ediacarans are simple animal forms which lived well into the Cambrian era, but they do [not] explain the gap in body complexity:

https://phys.org/news/2018-08-evolution-rethink-scientists-closer-earth.html

"Fossils of Stromatoveris psygmoglena are found in only one place in the world: Chengjiang county, China. This region is known for exceptionally well-preserved Cambrian fossils from 518m years ago.

***

"While the fossil record most often preserves only hard shells or bones, some special sites like Chengjiang preserve the remains of soft-bodied animals, such as Stromatoveris psygmoglena. Originally described in 2006 from eight known specimens, we examined over 200 new fossils of the organism that have since been discovered by researchers from Northwest University, China, and dated to the Cambrian period.

"The way in which fossils of the Ediacaran Period were preserved has been another of their mysteries. These fossils often show signs of bending, twisting and tearing, suggesting that they preserve soft-bodied organisms without hard parts. However, there is rarely anything left of the soft tissues themselves.

"Instead, they left moulds in the surrounding sediment, a little like a footprint on the beach. In contrast, the newly examined Cambrian fossils of Stromatoveris psygmoglena retain carbon-based tissue, allowing us to see the detailed and internal anatomy of the body itself.

***

"The analysis showed that Stromatoveris psygmoglena and seven key members of the Ediacaran biota share very similar anatomies, including multiple, branched fronds which radiate outwards like seaweed, uniting them all in a new group of early animals called Petalonamae. The name means "Nama Petals" and was chosen to honour biologist Hans Pflug and his work on the Ediacaran biota in Namibia, a reference to the petal-like fronds which, Pflug noted, distinguish these unusual animals.

***

"Because members of the Ediacaran biota can now be classed as animals, we can date the origin of the animal kingdom to at least the time when these fossils appeared. The oldest members of these groups are known as "rangeomorphs" and appear in the fossil record approximately 571m years ago, in the late Ediacaran Period.

"This means that animal species were diversifying well before the Cambrian explosion. It may also mean that the search for animal origins should now focus on the time before this, in the early Ediacaran and even more ancient geological periods. Based on this, animals may have originated much earlier than the traditional reading of the fossil record had suggested.

"This study also has key implications for the ecology and eventual extinction of the petalonamids. Many Ediacaran species have not been found in later rocks leading some researchers to think that they were a "failed experiment" in evolution, disappearing by the beginning of the Cambrian. Indeed, this was my own view until I saw the remarkable new fossils of Stromatoveris psygmoglena.

"The inclusion of this Cambrian animal among the petalonamids changes the picture of the Ediacaran biota. Stromatoveris psygmoglena shows that the petalonamids were alive and well over 20m years into the Cambrian period and did not go extinct at its outset, as had been thought.

"Even more intriguing, more than 200 fossils of Stromatoveris psygmoglena have now been found, despite the fact that it lacked hard parts which are usually most easily preserved. This indicates that this species was an important member of its shallow marine ecosystem rather than a rare or marginal survivor."

Comment: Still no explanation for the gap in morphology and physiology.

3167 views

A well-known Ediacaran has cholesterol in a 580 myo fossil form:

https://phys.org/news/2018-09-fat-million-years-reveals-earliest.html

"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 Ph.D. 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.

***

"'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.'"

Comment: Animals had to come on the scene at some point in evolution, but the gap in complexity of form between the two periods, Ediacaran and Cambrian is still just as large.

3061 views

A segmented bilaterian that could move and burrow:

https://www.nature.com/articles/d41586-019-02556-x?utm_source=Nature+Briefing&utm_c...

"More than half a billion years ago, a strange, worm-like creature died as it crawled across the muddy sea floor. Both the organism and the trail it left lay undisturbed for so long that they fossilized. Now, they are helping to revise our understanding of when and how animals evolved.

"The fossil, which formed some time between 551 million and 539 million years ago, in the Ediacaran period, joins a growing body of evidence that challenges the idea that animal life on Earth burst onto the scene in an event known as the Cambrian explosion, which began about 539 million years ago.

“'It is just pushing things further and further back into the Ediacaran,” says Rachel Wood, a geoscientist at the University of Edinburgh, UK. The Cambrian explosion no longer appears to be such an abrupt event in the history of life on Earth, she says. An analysis of the fossil, along with a few dozen similar specimens found in the same rock sequence in southern China, is published in Nature1.

***

" ...it’s exceptionally rare to find a dead animal preserved at the end of a trail it made when alive, he says. Second, the fossil dates to a crucial moment in the evolution of animal life.
And third: “It’s such a bizarre-looking organism,” says Darroch. The creature, which has been named Yilingia spiciformis and was up to 27 centimetres long, seems to be a biologically complex animal with a distinct front and rear end. “We don’t really have many of those from the Ediacaran,” he says.

***

"Some Ediacaran organisms have been recognized as animals despite their peculiar anatomy, which suggests that animal life began millions of years before the Cambrian explosion.

"Yilingia spiciformis fits into that picture and pushes the idea further. With a segmented body that is symmetrical down its length, it has an anatomy that is more obviously similar to that of Cambrian animals, says Shuhai Xiao, a palaeontologist at Virginia Tech in Blacksburg and a co-author of the study.

"What’s more, the trail demonstrates that Y. spiciformis could crawl over the sea floor like a modern animal. Palaeontologists have found only few pieces of evidence that the strange organisms of the Ediacaran were similarly mobile. Collectively, Xiao’s team’s findings mean that Y. spiciformis looked and behaved like a Cambrian animal — despite living up to 12 million years before what is usually considered the start of the Cambrian explosion.

***

"Exactly which animal lineage Y. spiciformis belonged to is unclear. The researchers suggest it might be a relative of insects and crustaceans such as shrimp and lobsters, because it seems to have leg-like structures. If further analysis shows that those structures are actually an artefact of the fossilization process, the animal might instead be some sort of primitive segmented worm.

“'There’s a third possibility,” says Xiao: it could be an ancestor to both groups. The idea that segmented worms and shrimp-like creatures all evolved from a single group of segmented animals dates back to the nineteenth century, but it’s controversial because most researchers now think that shrimp-like animals are more closely related to nematode worms and other creatures that grow by shedding an exoskeleton."

Comment: Certainly this animal is an early 'real animal', compared to the weird Ediacaran forms that might be animals. It is nowhere as complex as Cambrian species despite efforts of the author to close the Cambrian Explosion gap. I would suspect some early transitional forms between Ediacaran and Cambrian eras, as this simple one appears to be.

2024 views

Definite GI tract from late Ediacaran era found:

https://phys.org/news/2020-01-scientists-oldest-known-fossilized-digestive-tract.html

"A 550 million-year-old fossilized digestive tract found in the Nevada desert could be a key find in understanding the early history of animals on Earth.

"Over a half-billion years ago, life on Earth was comprised of simple ocean organisms unlike anything living in today's oceans. Then, beginning about 540 million years ago, animal structures changed dramatically.

"During this time, ancestors of many animal groups we know today appeared, such as primitive crustaceans and worms, yet for years scientists did not know how these two seemingly unrelated communities of animals were connected, until now. An analysis of tubular fossils by scientists led by Jim Schiffbauer at the University of Missouri provides evidence of a 550 million-year-old digestive tract—one of the oldest known examples of fossilized internal anatomical structures—and reveals what scientists believe is a possible answer to the question of how these animals are connected.

"'Not only are these structures the oldest guts yet discovered, but they also help to resolve the long-debated evolutionary positioning of this important fossil group," said Schiffbauer, an associate professor of geological sciences in the MU College of Arts and Science and director of the X-ray Microanalysis Core facility. "These fossils fit within a very recognizable group of organisms—the cloudinids—that scientists use to identify the last 10 to 15 million years of the Ediacaran Period, or the period of time just before the Cambrian Explosion. We can now say that their anatomical structure appears much more worm-like than coral-like.'"

Comment: A slight bite at the Cambrian Explosion gap. It is not surprising that late Ediacarans were the most advanced in the period.

1824 views

QUOTES: "A 55-million-year-old fossilized digestive tract found in the Nevada desert could be a key find in understanding the early history of animals on Earth.”

"An analysis of tubular fossils by scientists led by Jim Schiffbauer at the University of Missouri provides evidence of a 550 million-year-old digestive tract—one of the oldest known examples of fossilized internal anatomical structures—and reveals what scientists believe is a possible answer to the question of how these animals are connected."

DAVID: A slight bite at the Cambrian Explosion gap.

We should not underestimate the sheer amount of time involved in 550 million years! We regard even 100 years ago as another age! It’s surprising that any fossils survive that length of time with all the environmental factors that work on the bones and tissues of dead bodies! And yet fossils keep turning up. Maybe eventually there will be enough to constitute a big bite at the Cambrian Explosion gap.

1819 views

QUOTES: "A 55-million-year-old fossilized digestive tract found in the Nevada desert could be a key find in understanding the early history of animals on Earth.”

"An analysis of tubular fossils by scientists led by Jim Schiffbauer at the University of Missouri provides evidence of a 550 million-year-old digestive tract—one of the oldest known examples of fossilized internal anatomical structures—and reveals what scientists believe is a possible answer to the question of how these animals are connected."

DAVID: A slight bite at the Cambrian Explosion gap.

dhw: We should not underestimate the sheer amount of time involved in 550 million years! We regard even 100 years ago as another age! It’s surprising that any fossils survive that length of time with all the environmental factors that work on the bones and tissues of dead bodies! And yet fossils keep turning up. Maybe eventually there will be enough to constitute a big bite at the Cambrian Explosion gap.

The speed in developments through human actions in the last 200 years is blinding. The power of cooperating brains in action. On the other hand God took His time.

1821 views

Have some m ore advance in organ systems:

https://www.nature.com/articles/d41586-020-02985-z?utm_source=Nature+Briefing&utm_c...

"Palaeontologist Shuhai Xiao marvels at the tracks left by this creature, Yilingia spiciformis, and how they captured evidence of its movement. In his cluttered office at Virginia Tech in Blacksburg, he shows off a slab of beige resin — a reproduction of the fossil, which was found in China’s Yangtze Gorges region and is now kept in a Chinese research institute. The replica captures a snapshot of a moment from 550 million years ago. Xiao, whose team formally described Yilingia last year1, traces the bumpy tracks it made immediately before its death.

***

"Yilingia is not the only creature from that region to provide some of the earliest fossil evidence for an important animal feature. In 2018, Xiao and his team reported2 on tracks found in the Yangtze Gorges consisting of two parallel rows of dimples. The researchers propose that the trails were made by an animal from 550 million years ago that might have been able to burrow and had multiple pairs of appendages — which would make it one of the earliest-known animals with legs.

"These Chinese fossils hail from a time right before the Cambrian explosion, the evolutionary transformation when most of the animal groups that populate the planet today first made their appearance in the fossil record. Scientists long regarded the boundary between the Cambrian period and the Precambrian as a dividing point in evolution — a transition from a world in which simple, strange organisms flourished, to a time when the seas teemed with complex creatures that are the forebears of nearly everything that followed.

"But a growing number of findings reveal that the time slice just before the Cambrian, known as the Ediacaran (635 million to 541 million years ago), was a pivot point of animal evolution — a period that includes the earliest fossil records of anatomical innovations, such as guts and legs, and the first appearance of complex behaviours such as burrowing. The insights into the Ediacarans’ powers lend support to a provocative idea: that the Cambrian explosion, that iconic evolutionary burst, was actually less revolutionary than many had thought.

"The Cambrian explosion “is just another phase of evolution”, says palaeobiologist Rachel Wood at the University of Edinburgh, UK. “It’s not a single flash event. It could not have happened without previous waves of innovation.”

***

"Now, most scientists are reaching agreement that the Ediacarans were a grab bag of disparate life forms, rather than the self-contained group proposed by Seilacher. “It’s inappropriate to consider them a failed experiment,” says palaeontologist Frances Dunn at the University of Oxford, UK. “They represent the ancestors, probably, of lots of different things.” Many scientists — although not all — are also signing up to the idea that some fraction of the Ediacaran organisms were probably animals, including some that don’t look like any animal alive today.

***

"More evidence that Ediacarans had guts comes from tubular organisms called cloudinids that arose around 550 million years ago. Using high-resolution X-ray imaging to peer inside cloudinids’ outer tubes, researchers saw a long, cylindrical feature, which the authors say is the oldest gut in the fossil record8. The team found this feature in a cloudinid that most probably belonged to the genus Saarina, and it bolsters the case that some cloudinids were animals with left–right symmetry8, says palaeobiologist and study co-author Jim Schiffbauer at the University of Missouri, Columbia. The gut’s shape and other clues hint that Saarina could be an early annelid, an animal grouping that includes modern earthworms.

***

"The burst of new species in the Cambrian “didn’t just come out of thin air”, says Wood. “It must have been derived from something in the Ediacaran.”

***

All of these findings tell a new story of animal evolution — but it is not yet clear whether the revision will stick. Some palaeontologists say that Wood’s argument, in trying to give the Ediacaran its due, gives short shrift to the Cambrian explosion — which marked the appearance of a vast number of creatures that fit clearly into modern animal groups. Xiao agrees that some Ediacaran animals survived into the Cambrian, but he argues that the big picture shows a mass die-off at the boundary between the two periods. And invertebrate palaeontologist Jean-Bernard Caron at the Royal Ontario Museum in Toronto, Canada, questions Wood’s tally of Ediacaran species that survived into the Cambrian. “We don’t really have the fossil record to support that,” he says. Wood responds that although the critique is fair, it’s clear that multiple Cambrian-style creatures first appeared in the Ediacaran.

Comment: A very important paper. As I view it, some complexity arising in the Ediacaran is not a surprise, but sehatg has been found is still a giant step away from the very complex Cambrian forms that are our precursors. Note the objections above warning not to overinterpret the new findings.

1504 views

Gunter Bechly again:

https://evolutionnews.org/2021/03/ediacarans-are-not-animals/

"Apart from Kimberella, there is no convincing evidence that the organisms studied by Evans et al. (2021) either represent Ediacaran animals at all, or belong to the attributed subgroups of the animal kingdom, as I have documented in my article series at length and in great detail. Dickinsonia is most likely not an animal and definitely has no bilateral symmetry but typical Ediacaran glide symmetry (Bechly 2018), Ikaria is a totally useless fossil that could be a protist or a coelenterate (Bechly 2020b), and even Kimberella remains a problematic organism that could be anything including a coelenterate-grade animal (Budd & Jensen 2017, Bechly 2020f). Also, Darroch et al. (2018: 660) recently concluded:

"Although the Dickinsonimorpha (V), Triradialomorpha (VI), and Bilateromorpha (VII) have all at one time been placed somewhere on the metazoan tree (e.g., the Dickinsonimorpha with Placozoa, see [59]), there has been no scientific consensus on these placements (Figure I). As a result, there is currently no basis for assigning these groups to the Metazoa."

Comment: whatever they are it will eventually reach a consensus opinion.

1401 views

Had what appear to be protruding tentacles:

https://www.livescience.com/jellyfish-relative-fossil-david-attenborough?utm_campaign=3...

"A bizarre, tentacled creature that lived in the deep ocean 560 million years ago resembled a goblet crammed full of wriggling fingers. It may be an ancient relative of modern jellyfish and the earliest known predator in the animal kingdom, analysis of a newly described fossil suggests.

"More than a decade ago, scientists uncovered a fossil of the purported jellyfish relative in an outcrop of volcanic and sedimentary rocks called the Bradgate Formation in Leicestershire, England. Located in Charnwood Forest, the outcrop formed about 557 million to 562 million years ago, during the Ediacaran period (635 million to 541 million years ago).

"This means that the newly identified fossil predates the Cambrian explosion, a 55-million-year episode in which life on Earth rapidly diversified.

***

"To date, the vast majority of Ediacaran fossils don't share structural features with any living animals, so they're generally thought to belong to extinct animal groups, Donoghue said. "This fossil's probably the oldest one recognized, with quite convincing evidence, to be a member of one of the living phyla," or large groups of related animals, Donoghue said.

***

""This is the first creature, the first animal that we're aware of that actually grew a skeleton," Wilby said. Its tentacle structure hints that A. attenboroughii likely fed on plankton and protists, which would make it the earliest known predator in the animal kingdom.

***

"If A. attenboroughii is indeed a member of Medusozoa, it would belong to a broader group of organisms known as the cnidarians, which also includes corals, sea pens and sea anemones. Prior to the new study, fossil evidence suggested that the basic "blueprint" for cnidarians didn't emerge until the Cambrian period. However, "what we're able to show here is that, at least 20 million years before that, the blueprint for cnidarians was actually set," Wilby said."

***

Comment: no surprise to find some advanced evolution in the Edicaran period. There may be gaps as has been discussed, but evolution is an ongoing process, not a complete stop and start. The Cambrian gap in phenotypical change remains enormous. dhw's sugestion of some advances in the Ediacaran is supported.

825 views

About 550 million years ago:

https://phys.org/news/2022-11-world-oldest-meal-unravel-mystery.html

"Ediacara biota are the world's oldest large organisms and date back 575 million years. ANU researchers found the animals ate bacteria and algae that was sourced from the ocean floor. The findings, published in Current Biology, reveal more about these strange creatures, including how they were able to consume and digest food.

"The scientists analyzed ancient fossils containing preserved phytosterol molecules—natural chemical products found in plants—that remained from the animals' last meal. By examining the molecular remains of what the animals ate, the researchers were able to confirm the slug-like organism, known as Kimberella, had a mouth and a gut and digested food the same way modern animals do. The researchers say it was likely one of the most advanced creatures of the Ediacarans.

"The ANU team found that another animal, which grew up to 1.4 meters in length and had a rib-like design imprinted on its body, was less complex and had no eyes, mouth or gut. Instead, the odd creature, called Dickinsonia, absorbed food through its body as it traversed the ocean floor.

"'Our findings suggest that the animals of the Ediacara biota, which lived on Earth prior to the 'Cambrian Explosion' of modern animal life, were a mixed bag of outright weirdos, such as Dickinsonia, and more advanced animals like Kimberella that already had some physiological properties similar to humans and other present-day animals," lead author Dr. Ilya Bobrovskiy, from GFZ-Potsdam in Germany, said.

"Both Kimberella and Dickinsonia, which have a structure and symmetry unlike anything that exists today, are part of the Ediacara biota family that lived on Earth about 20 million years prior to the Cambrian Explosion—a major event that forever changed the course of evolution of all life on Earth.

"'Ediacara biota really are the oldest fossils large enough to be visible with your naked eyes, and they are the origin of us and all animals that exist today. These creatures are our deepest visible roots," Dr. Bobrovskiy, who completed the work as part of his Ph.D. at ANU, said.

***

"'The energy-rich food may explain why the organisms of the Ediacara biota were so large. Nearly all fossils that came before the Ediacara biota were single-celled and microscopic in size," Professor Brocks said.

"Using advanced chemical analysis techniques, the ANU scientists were able to extract and analyze the sterol molecules contained in the fossil tissue. Cholesterol is the hallmark of animals and it's how, back in 2018, the ANU team was able to confirm that Ediacara biota are among our earliest known ancestors.

"The molecules contained tell-tale signatures that helped the researchers decipher what the animals ate in the lead up to their death. Professor Brocks said the difficult part was differentiating between the signatures of the fat molecules of the creatures themselves, the algal and bacterial remains in their guts, and the decaying algal molecules from the ocean floor that were all entombed together in the fossils.

"'Scientists already knew Kimberella left feeding marks by scraping off algae covering the sea floor, which suggested the animal had a gut. But it was only after analyzing the molecules of Kimberella's gut that we were able to determine what exactly it was eating and how it digested food," Professor Brocks said.

"'Kimberella knew exactly which sterols were good for it and had an advanced fine-tuned gut to filter out all the rest.

"'This was a Eureka moment for us; by using preserved chemical in the fossils, we can now make gut contents of animals visible even if the gut has since long decayed. We then used this same technique on weirder fossils like Dickinsonia to figure out how it was feeding and discovered that Dickinsonia did not have a gut.'"

Comment: compared to the Cambrian this one had a gut, no eyes or legs, so the new finding enforces the phenotypic gap.

691 views

A summary of several Ediacarans with a diet study:

https://www.cell.com/current-biology/fulltext/S0960-9822(22)01699-2?dgcid=raven_jbs_aip...

"Bobrovskiy et al. examine the biomarker composition of Ediacaran macrofossils
•
Kimberella and Calyptrina preserve molecular signatures of their gut content
•
Kimberella and Calyptrina shared a mixed diet of green algae and bacteria
•
Dickinsonia had no gut and potentially fed using external digestion

"Summary
The oldest animals appear in the fossil record among Ediacara biota communities. They prelude animal-dominated ecosystems of the Phanerozoic and may hold clues to the appearance of modern animal phyla in the Cambrian explosion. However, little is known about the phylogeny of the Ediacaran organisms and even less about their diet and feeding behavior. An exception is mollusc-like Kimberella, for which a fossilized gut, feeding traces, and even potential coprolites have been found. By contrast, Ediacaran organic-walled tubes, such as Sabellidites and Calyptrina, are thought to belong to tube worms comparable with modern Siboglinidae that have no gut but gain their nutrition from symbiotic bacteria. Here, we examine the gut contents of Ediacaran animals using biomarker molecules. We show that 558-million-year (Ma)-old tube worm-like Calyptrina and mollusc-like Kimberella possessed a gut and shared a diet of green algae and bacteria. Despite their ancient age, sterol metabolism within the gut of both organisms was already comparable to extant invertebrates. 8 Dickinsonia, one of the key Ediacaran animals, show no traces of dietary molecules, indicating a different feeding mode and possible external digestion analogous to modern Placozoa. Lipid biomarkers uncover a range of feeding strategies in Ediacaran communities, highlighting true eumetazoan physiology of some Ediacaran animals."

Comment: we knew they had to eat and are early animals but not anywhere near as complex as Cambrian's

668 views

Changes in the Earth's changes do not develop Cambrian precursors:

https://www.science.org/doi/full/10.1126/sciadv.abi9643?et_rid=17445044&utm_campaig...

"Abstract
The rise of complex macroscopic life occurred during the Ediacaran Period, an interval that witnessed large-scale disturbances to biogeochemical systems. The current Ediacaran chronostratigraphic framework is of insufficient resolution to provide robust global correlation schemes or test hypotheses for the role of biogeochemical cycling in the evolution of complex life. Here, we present new radio-isotopic dates from Ediacaran strata that directly constrain key fossil assemblages and large-magnitude carbon cycle perturbations...These data calibrate the tempo of Ediacaran evolution characterized by intervals of tens of millions of years of increasing ecosystem complexity, interrupted by biological turnovers that coincide with large perturbations to the carbon cycle.

***

"The Ediacaran Period [635 to 539 million years (Ma) ago] is a pivotal period in Earth history, achiving the rise of complex macroscopic life. This evolutionary milestone occurred in the aftermath of extreme climate perturbations, the Cryogenian snowball Earth events, and amid several perturbations to the carbon cycle. These are recorded by large carbon-isotope excursions (CIEs) in marine carbonate records, defined as negative and positive deviations in the stratigraphic trend of carbonate-carbon isotope (δ13Ccarb) profiles. These perturbations have been documented worldwide and are commonly used to establish regional to global stratigraphic correlations. (my bold)

(From the discussion):

"Our new geochronological data provide the foundation for a refined global age model for the Ediacaran fossil record. Early Ediacaran fossils are dominated by acanthomorphic species alongside macroalgae and putative animal fossils from the Lantian biota. After 587.2 ± 3.6 Ma, there is an increase in the abundance and diversity of the acanthomorphic species, accompanied by the diverse embryos that exhibit complex development probably hosting total-group metazoan, and putative microscopic metazoans (e.g., sponges) in the Weng’an biota. Macroscopic complex Ediacaran organisms made their first appearance between 580 and 574 Ma ago, whereas rangeomorphs (including some stem-group eumetazoans) diversified between 574 and 564 Ma ago through the Shuram CIE, and the oldest known record of eumetazoan mobility appeared 564.8 Ma ago. Diversification of nonrangeomorphs and increased evidence for bilaterian mobility, as exemplified by the White Sea assemblage, are constrained by U-Pb dates of 557.3 ± 0.6 Ma and 553.0 ± 0.7 Ma. Following the 550-Ma CIE and postulated first pulse of extinction of Ediacaran taxa at the White Sea–Nama assemblage transition, skeletonized tubular fossils (cloudinids) and complex burrowing produced by bilaterian metazoans record the deep roots of the Cambrian explosion of metazoans alongside soft-bodied Ediacaran taxa. (my bold)

"Our age model presented for Ediacaran CIEs and fossil records provides the necessary chronometric context to test causal relationships, if any, between them. Independent of the drivers and global nature of the Ediacaran CIEs, the direct dates for Ediacaran fossil assemblages are a prerequisite for calibrating biostratigraphic records and improving the accuracy of molecular clock analysis to reconstruct the early evolutionary history of complex life. The emerging tempo of Ediacaran evolution is defined by assemblages of organisms with increasing ecosystem complexity that are relatively stable on tens of millions of year time scales, with new assemblages appearing across much shorter, discrete intervals. At the current resolution, these transitions in the fossil record coincide with CIEs, suggestive of a potential causal relationship between environmental perturbations recorded in the carbon cycle and biological turnovers."

Comment: note my bold. The Edicaran forms definitely advanced to macroscopic more complex forms and may have finally developed into early sponges, which represent first animal life. But that is it. What followed in the Cambrian were highly complex body forms with motility and complex organ systems and a crowning achievement, eyes! The gap remains despite this degree of research. Follow Bechly's advise and accept the collector's curve:

"The same approach is used by paleontologists for a statistical test of the completeness of the fossil record; it is called the collector’s curve. In most groups of fossils, we have reached this point of demonstrable saturation, where we can be pretty confident that the distinct discontinuities that we find are data to be explained and not just sampling artifacts. There is another reason why we know this: If the gaps and discontinuities in the fossil record were just artifacts, they should more and more dissolve with our greatly increasing knowledge of the fossil record. But the opposite is the case. The more we know, the more acute these problems have become. “Darwin’s doubt” did not get smaller over time but bigger, and if he were still alive, he would likely agree that the evidence simply does not add up, since he was much more prudent than many of his modern followers." (posted here)

You can wish for lost fossils, but it will remain a desperate wish.

1134 views

RSS Feed of thread

powered by my little forum