Oxygen and the Cambrian (Evolution)
DAVID: (under "Cellular intelligence"): Yes, all species can adapt, but are still the same species.
dhw: We are trying to explain speciation. Do you think it was sheer coincidence that oxygen appeared in large quantities and new species appeared at the same time? Or do you think the new species appeared BEFORE the increase in oxygen?
DAVID: Coincidence doesn't speciate. Oxygen was around in large amounts long before the Cambrian.
I’m glad you agree that it is NOT coincidence. What happened before the Cambrian is irrelevant to what happened during the Cambrian. If the oxygen theory is true, this leaves you with my second question: do you think your God created the new species “de novo” BEFORE the increase in oxygen? Here is an interesting article in support of the link between oxygen and speciation as well as extinction:
Rapid Oxygen Changes Fueled an Explosion in Ancient Animal ...
www.quantamagazine.org/rapid-oxygen-changes-fueled-an-explosion-in-ancient …
QUOTES: Geological slice by geological slice, the researchers compared the modeled oxygen levels and the diversity of fossils, revealing a volatile history. In the span of about 10 million years, between 524 and 514 million years ago, this shallow Siberian sea underwent five distinct oxygen spikes.
“These fluctuations are fairly extreme,” said He, explaining that each spike and dip constituted about a 50 percent increase or decrease in oxygen levels. “Previous studies suggest that oxygen levels during the Cambrian were about 40 percent of today’s atmospheric levels,” He said. “Fifty percent swings are pretty enormous.”
Each pulse of oxygenation corresponded with a local high in biodiversity, while dips in oxygen levels were associated with higher rates of extinction. For example, a pulse between 521 and 522 million years ago was associated with the appearance of numerous shelled animals, including trilobites and bivalved arthropods. A couple of million years later, the next pulse was coincident with a rise in large predatory arthropods and evidence of increased predatory behavior.
“The Cambrian explosion wasn’t a singular event. It happened in spurts, in rises and falls,” He said. “In our study, the rise and fall of oxygen levels correlated with these spurts of [evolutionary] radiation.”
For Wood, “The data pretty clearly show a positive correlation.” She added, “The more interesting question is: why?” One explanation is that these pulses of oxygenation rapidly expanded how much of the shallow seas were habitable. More physical space gives life more breathing room to diversify, literally and figuratively. According to He, each pulse of oxygen allowed an expansion of forms and ways of living. This in turn created more opportunity for ecological interactions, like “coevolutionary arms races” between sets of predators and prey, that could further accelerate diversification. (dhw's bolding)
I would regard this as typical of evolution in general: organisms RESPOND to environmental change in three possible ways: adaptation, innovation or death.
Oxygen and the Cambrian
by David Turell 
, Sunday, December 19, 2021, 15:30 (1068 days ago) @ dhw
edited by David Turell, Sunday, December 19, 2021, 15:42
DAVID: (under "Cellular intelligence"): Yes, all species can adapt, but are still the same species.
dhw: We are trying to explain speciation. Do you think it was sheer coincidence that oxygen appeared in large quantities and new species appeared at the same time? Or do you think the new species appeared BEFORE the increase in oxygen?
DAVID: Coincidence doesn't speciate. Oxygen was around in large amounts long before the Cambrian.
dhw: I’m glad you agree that it is NOT coincidence. What happened before the Cambrian is irrelevant to what happened during the Cambrian. If the oxygen theory is true, this leaves you with my second question: do you think your God created the new species “de novo” BEFORE the increase in oxygen? Here is an interesting article in support of the link between oxygen and speciation as well as extinction:
Rapid Oxygen Changes Fueled an Explosion in Ancient Animal ...
www.quantamagazine.org/rapid-oxygen-changes-fueled-an-explosion-in-ancient …
QUOTES: Geological slice by geological slice, the researchers compared the modeled oxygen levels and the diversity of fossils, revealing a volatile history. In the span of about 10 million years, between 524 and 514 million years ago, this shallow Siberian sea underwent five distinct oxygen spikes.
“These fluctuations are fairly extreme,” said He, explaining that each spike and dip constituted about a 50 percent increase or decrease in oxygen levels. “Previous studies suggest that oxygen levels during the Cambrian were about 40 percent of today’s atmospheric levels,” He said. “Fifty percent swings are pretty enormous.”
Each pulse of oxygenation corresponded with a local high in biodiversity, while dips in oxygen levels were associated with higher rates of extinction. For example, a pulse between 521 and 522 million years ago was associated with the appearance of numerous shelled animals, including trilobites and bivalved arthropods. A couple of million years later, the next pulse was coincident with a rise in large predatory arthropods and evidence of increased predatory behavior.
“The Cambrian explosion wasn’t a singular event. It happened in spurts, in rises and falls,” He said. “In our study, the rise and fall of oxygen levels correlated with these spurts of [evolutionary] radiation.”
For Wood, “The data pretty clearly show a positive correlation.” She added, “The more interesting question is: why?” One explanation is that these pulses of oxygenation rapidly expanded how much of the shallow seas were habitable. More physical space gives life more breathing room to diversify, literally and figuratively. According to He, each pulse of oxygen allowed an expansion of forms and ways of living. This in turn created more opportunity for ecological interactions, like “coevolutionary arms races” between sets of predators and prey, that could further accelerate diversification. (dhw's bolding)
dhw: I would regard this as typical of evolution in general: organisms RESPOND to environmental change in three possible ways: adaptation, innovation or death.
I'm sure I presented this article here when it appeared, and my comment remains the same as before. First, thanks for re-finding it. Second: oxygen levels, when high, allow for more complex organisms. But the drive for complexity comes from something else, which we debate. I'll stick with God.
As the article says: He [researcher] emphasizes that increased oxygen isn’t the sole cause of increased diversity. Once complexity evolved, it could compound itself, driven by ecological interactions. But He argues that for this to be possible, higher oxygen levels were necessary. I agree. Not causing but allowing
https://www.quantamagazine.org/rapid-oxygen-changes-fueled-an-explosion-in-ancient-anim... (this address should work, the one above didn't)
Oxygen and the Cambrian
dhw: We are trying to explain speciation. Do you think it was sheer coincidence that oxygen appeared in large quantities and new species appeared at the same time? Or do you think the new species appeared BEFORE the increase in oxygen?
DAVID: Coincidence doesn't speciate. Oxygen was around in large amounts long before the Cambrian.
dhw: I’m glad you agree that it is NOT coincidence. What happened before the Cambrian is irrelevant to what happened during the Cambrian. If the oxygen theory is true, this leaves you with my second question: do you think your God created the new species “de novo” BEFORE the increase in oxygen? Here is an interesting article in support of the link between oxygen and speciation as well as extinction:
[…]
dhw: I would regard this as typical of evolution in general: organisms RESPOND to environmental change in three possible ways: adaptation, innovation or death.
DAVID: I'm sure I presented this article here when it appeared, and my comment remains the same as before. First, thanks for re-finding it. Second: oxygen levels, when high, allow for more complex organisms. But the drive for complexity comes from something else, which we debate. I'll stick with God.
As the article says: He [researcher] emphasizes that increased oxygen isn’t the sole cause of increased diversity. Once complexity evolved, it could compound itself, driven by ecological interactions. But He argues that for this to be possible, higher oxygen levels were necessary. I agree. Not causing but allowing.
I also agree. As I pointed out before, you cannot have diversity if you do not have life forms that can diversify! The question remains: do you believe your God designed the new species de novo BEFORE conditions changed or in response to the new conditions?
DAVID: https://www.quantamagazine.org/rapid-oxygen-changes-fueled-an-explosion-in-ancient-anim... (this address should work, the one above didn't)
Thank you.
Oxygen and the Cambrian
by David Turell , Monday, December 20, 2021, 15:43 (1067 days ago) @ dhw
dhw: We are trying to explain speciation. Do you think it was sheer coincidence that oxygen appeared in large quantities and new species appeared at the same time? Or do you think the new species appeared BEFORE the increase in oxygen?
DAVID: Coincidence doesn't speciate. Oxygen was around in large amounts long before the Cambrian.
dhw: I’m glad you agree that it is NOT coincidence. What happened before the Cambrian is irrelevant to what happened during the Cambrian. If the oxygen theory is true, this leaves you with my second question: do you think your God created the new species “de novo” BEFORE the increase in oxygen? Here is an interesting article in support of the link between oxygen and speciation as well as extinction:
[…]
dhw: I would regard this as typical of evolution in general: organisms RESPOND to environmental change in three possible ways: adaptation, innovation or death.DAVID: I'm sure I presented this article here when it appeared, and my comment remains the same as before. First, thanks for re-finding it. Second: oxygen levels, when high, allow for more complex organisms. But the drive for complexity comes from something else, which we debate. I'll stick with God.
As the article says: He [researcher] emphasizes that increased oxygen isn’t the sole cause of increased diversity. Once complexity evolved, it could compound itself, driven by ecological interactions. But He argues that for this to be possible, higher oxygen levels were necessary. I agree. Not causing but allowing.I also agree. As I pointed out before, you cannot have diversity if you do not have life forms that can diversify! The question remains: do you believe your God designed the new species de novo BEFORE conditions changed or in response to the new conditions?
Always in anticipation of future requirements for use. Our mainly unused giant brain for almost 300,000 years is one example.
DAVID: https://www.quantamagazine.org/rapid-oxygen-changes-fueled-an-explosion-in-ancient-anim... (this address should work, the one above didn't)dhw: Thank you.
Oxygen and the Cambrian: gills appear
by David Turell , Wednesday, February 09, 2022, 14:15 (1016 days ago) @ David Turell
A new Chinese find, early gills from 520 million years ago:
http://www.sci-news.com/paleontology/erratus-sperare-10530.html?utm_source=feedburner&a...
"Erratus sperare lived in what is now China during the Early Cambrian epoch, some 520 million years ago.
"Its fossilized remains were discovered at the Chengjiang Fossil Site, a UNESCO World Heritage Site located in the Chinese province of Yunnan.
***
"Modern water dwelling arthropods have biramous limbs, legs that have two parts — one for breathing and one for walking — but how such specialized limbs evolved was a mystery.
"Some of the earliest fossil arthropods, like Anomalocaris, had swimming flaps that may have doubled as gills.
"But, until now, paleontologists didn’t know how arthropods made the jump from these specialized flaps to the biramous limbs of modern arthropods.
"Erratus sperare provides the missing link between stem-Euarthropoda and Deuteropoda — arthropods that used such specialised flaps and those with biramous limbs.
"According to Dr. Legg and his co-authors, the ancient arthropod had both limbs and flaps.
“'Fish aren’t the only organisms that have gills! Arthropods have gills too… they just have them on their legs,” Dr. Legg said.
“'When it came to arthropods, however, we just weren’t sure where these gills came from.”
“Thanks to this new fossil, Erratus sperare, we now have a much clearer idea,” he added.
“'These gills also probably went on to evolve into the wings of insects and the lungs of terrestrial arthropods like spiders so were a very important innovation.'”
Comment: These animals had to utilize oxygen somehow. This is probably the beginning.
Oxygen and the Cambrian: in the pre-Cambrian
by David Turell , Sunday, October 16, 2022, 17:33 (767 days ago) @ David Turell
Wildly fluctuating according to a new study:
https://phys.org/news/2022-10-fluctuating-oxygen-animal-evolution.html
"Oxygen levels in the Earth's atmosphere are likely to have "fluctuated wildly" 1 billion years ago, creating conditions that could have accelerated the development of early animal life, according to new research.
"Scientists believe atmospheric oxygen developed in three stages, starting with what is known as the Great Oxidation Event around 2 billion years ago, when oxygen first appeared in the atmosphere. The third stage, around 400 million years ago, saw atmospheric oxygen rise to levels that exist today.
"What is uncertain is what happened during the second stage, in a time known as the Neoproterozoic Era, which started about 1 billion years ago and lasted for around 500 million years, during which time early forms of animal life emerged.
"The questions scientists have tried to answer are: Was there anything extraordinary about the changes to oxygen levels in the Neoproterozoic Era that may have played a pivotal role in the early evolution of animals? Did oxygen levels suddenly rise or was there a gradual increase?
"Fossilized traces of early animals—known as Ediacaran biota, multi-celled organisms that required oxygen—have been found in sedimentary rocks that are 541 to 635 million years old.
"To try and answer the questions, a research team at the University of Leeds supported by the Universities of Lyon, Exeter and UCL, used measurements of the different forms of carbon, or carbon isotopes, found in limestone rocks taken from shallow seas. Based on the isotope ratios of the different types of carbon found, the researchers were able to calculate photosynthesis levels that existed millions of years ago and infer atmospheric oxygen levels.
"As a result of the calculations, they have been able to produce a record of oxygen levels in the atmosphere over the last 1.5 billion years, which tells us how much oxygen would have been diffusing into the ocean to support early marine life.
***
"He added, "The early Earth, for the first 2 billion years of its existence, was anoxic, devoid of atmospheric oxygen. Then oxygen levels started to rise, which is known as the Great Oxidation Event. (my bold)
***
"But our study shows oxygen levels were far more dynamic. There was an oscillation between high and low levels of oxygen for a long time before early forms of animal life emerged. We are seeing periods where the ocean environment, where early animals lived, would have had abundant oxygen—and then periods where it does not.
"Dr. Benjamin Mills, who leads the Earth Evolution Modeling Group at Leeds and supervised the project, said, "This periodic change in environmental conditions would have produced evolutionary pressures where some life forms may have become extinct and new ones could emerge."
"Dr. Mills said the oxygenated periods expanded what are known as "habitable spaces"—parts of the ocean where oxygen levels would have been high enough to support early animal life forms.
"He said, "It has been proposed in ecological theory that when you have a habitable space that is expanding and contracting, this can support rapid changes to the diversity of biological life.
"'When oxygen levels decline, there is severe environmental pressure on some organisms which could drive extinctions. And when the oxygen-rich waters expand, the new space allows the survivors to rise to ecological dominance."
"These expanded habitable spaces would have lasted for millions of years, giving plenty of time for ecosystems to develop." (my bold)
Comment: Note the first bold. Early life had little if any oxygen to use. The second bold notes ecosystems had to develop.
Oxygen and the Cambrian: in the pre-Cambrian
QUOTES (with dhw's bolds):
"Oxygen levels in the Earth's atmosphere are likely to have "fluctuated wildly" 1 billion years ago, creating conditions that could have accelerated the development of early animal life, according to new research."
"What is uncertain is what happened during the second stage, in a time known as the Neoproterozoic Era, which started about 1 billion years ago and lasted for around 500 million years, during which time early forms of animal life emerged.
"Fossilized traces of early animals—known as Ediacaran biota, multi-celled organisms that required oxygen —have been found in sedimentary rocks that are 541 to 635 million years old.
"This periodic change in environmental conditions would have produced evolutionary pressures where some life forms may have become extinct and new ones could emerge."
"It has been proposed in ecological theory that when you have a habitable space that is expanding and contracting, this can support rapid changes to the diversity of biological life. (
"These expanded habitable spaces would have lasted for millions of years, giving plenty of time for ecosystems to develop." (DAVID’s bold)
DAVID: Early life had little if any oxygen to use. The second bold notes ecosystems had to develop.
The quotes all seem to me to create a unified picture: quite clearly, oxygen was an all-important factor in the evolution of new species. Early forms of animal life emerged before the Cambrian Explosion, but fluctuations could have accelerated their development as well as causing many comings and goings of species – and hence of ecosystems. An ecosystem is simply a collection of plants and animals in a particular area. It doesn’t “have to develop” – it develops, and it changes or disappears when for whatever reason the interrelationships change their balance. These changes can occur rapidly, but if environmental conditions (here the emphasis is on oxygen) remain stable, then of course ecosystems can develop. I don’t know if the article takes into account the theory that the transition from Ediacaran to Cambrian fauna lasted for 410,000 years, but I would still propose that if this period was long enough for your God to have produced the diversity, it would also have been long enough for the thousands and thousands of generations of intelligent organisms to do the same. And over the subsequent millions of years, and with the expansion of habitable places, of course there was plenty of time for species to develop new ecosystems.
Oxygen and the Cambrian: in the pre-Cambrian
by David Turell , Monday, October 17, 2022, 16:54 (766 days ago) @ dhw
QUOTES (with dhw's bolds):
"Oxygen levels in the Earth's atmosphere are likely to have "fluctuated wildly" 1 billion years ago, creating conditions that could have accelerated the development of early animal life, according to new research."
"What is uncertain is what happened during the second stage, in a time known as the Neoproterozoic Era, which started about 1 billion years ago and lasted for around 500 million years, during which time early forms of animal life emerged."Fossilized traces of early animals—known as Ediacaran biota, multi-celled organisms that required oxygen —have been found in sedimentary rocks that are 541 to 635 million years old.
"This periodic change in environmental conditions would have produced evolutionary pressures where some life forms may have become extinct and new ones could emerge."
"It has been proposed in ecological theory that when you have a habitable space that is expanding and contracting, this can support rapid changes to the diversity of biological life. (
"These expanded habitable spaces would have lasted for millions of years, giving plenty of time for ecosystems to develop." (DAVID’s bold)
DAVID: Early life had little if any oxygen to use. The second bold notes ecosystems had to develop.
dhw: The quotes all seem to me to create a unified picture: quite clearly, oxygen was an all-important factor in the evolution of new species. Early forms of animal life emerged before the Cambrian Explosion, but fluctuations could have accelerated their development as well as causing many comings and goings of species – and hence of ecosystems. An ecosystem is simply a collection of plants and animals in a particular area. It doesn’t “have to develop” – it develops, and it changes or disappears when for whatever reason the interrelationships change their balance. These changes can occur rapidly, but if environmental conditions (here the emphasis is on oxygen) remain stable, then of course ecosystems can develop. I don’t know if the article takes into account the theory that the transition from Ediacaran to Cambrian fauna lasted for 410,000 years, but I would still propose that if this period was long enough for your God to have produced the diversity, it would also have been long enough for the thousands and thousands of generations of intelligent organisms to do the same. And over the subsequent millions of years, and with the expansion of habitable places, of course there was plenty of time for species to develop new ecosystems.
What I note is the Ediacaran period is from 635 million to 541 million years ago. All it produced are strange, stalked animals with no motility. 410,000 year later the Cambrian starts in full bloom with all sorts of motile animals appearing in rapid succession. Not your view at all.
Oxygen and the Cambrian: in the pre-Cambrian
I don’t want to repeat all the quotes and comments of yesterday’s posts, as I have some new quotes and comments for today!
DAVID: What I note is the Ediacaran period is from 635 million to 541 million years ago. All it produced are strange, stalked animals with no motility. 410,000 year later the Cambrian starts in full bloom with all sorts of motile animals appearing in rapid succession. Not your view at all.
I’m getting confused, because I don’t know what exactly is supposed to be the significance of the 410,000-year transition period. Perhaps you would explain what you think your God did during that time. Meanwhile, in my effort to gain a bit of enlightenment, I’ve found these two interesting articles. The first concerns a research project (the bolds are mine):
Co-Evolution of Life and Environment During the …
https://www.frontiersin.org/research-topics/31295
(It’s …..During the Ediacaran-Cambrian Transition)
QUOTES: The Ediacaran-Cambrian transition is a crucial time interval for the evolution of animal life on Earth. Throughout this interval new ecosystems formed and novel bodyplans proliferated.. At the end of the Ediacaran there was a significant extinction event, though some forms including tubular fossils and acritarchs survived into the Phanerozoic. Substantial environmental and geological change also occurred during the Ediacaran-Cambrian transition, including, possibly, increasing oxygen levels, along with other chemical changes in the oceans. All of these events were accompanied by the proliferation of metazoan phyla in the early Cambrian, which were at least partially triggered by the significant environmental and geological changes at the Ediacaran-Cambrian transition, but in turn themselves influenced sedimentary environments and ocean chemistry.
Though a large number of studies of the biotic and abiotic changes, and their relationship, during this interval have been conducted, questions remain and new data are continually being gathered. Thus, here we call for more studies with the purpose of expanding understanding of this key time period in the history of life and its environmental and geological context.
The link between “novel bodyplans” and environmental conditions is always a feature, and so it would seem that the process of innovation had already begun during the transition period. However, it was interrupted by a significant extinction event, and the process began again in the early Cambrian. We therefore have proliferation during the 410,000 years of changing conditions, and further proliferation during the early Cambrian. The “extinction event” interrupted what would otherwise have been a continuous process, but interestingly we come now to the second article:
Paleontologists Find Evolutionary Link between Ediacaran and …
https://www.sci.news/paleontology/ediacaran-early-cambrian-metazoans...
Paleontologists Find Evolutionary Link between Ediacaran and Early Cambrian Multicellular Animals
QUOTES: Paleontologists have described the first three-dimensional preservation of soft tissue in Namacalathus hermanastes, a skeletal metazoan (multicellular animal) that lived some 547 million years ago (Ediacaran period) in what is now Namibia, and established a strong evolutionary link between Ediacaran and early Cambrian metazoans.
Prior to the new study, it had proven difficult to trace links with earlier animals because their soft tissues — which provide vital clues about the animals’ ancestry — almost always break down over time.
They found that Namacalathus hermanastes was an early ancestor of species that appeared during the Cambrian explosion/b]. Among them are types of prehistoric worms and mollusks.
“These are exceptional fossils, which give us a glimpse into the biological affinity of some of the oldest animals,” Professor Wood said.
“They help us trace the roots of the Cambrian explosion and the origin of modern animal groups.”
We have the usual clear explanation of why fossils are so rare, but if we have a strong evolutionary link between Ediacaran and Cambrian animals, who knows what other links might have come into existence during the period of transition? There’s no answer to that question, but research is ongoing, and so we should NOT jump to the conclusion that species sprang from nowhere without any precursors.
Oxygen and the Cambrian: in the pre-Cambrian
by David Turell , Tuesday, October 18, 2022, 16:31 (765 days ago) @ dhw
DAVID: What I note is the Ediacaran period is from 635 million to 541 million years ago. All it produced are strange, stalked animals with no motility. 410,000 year later the Cambrian starts in full bloom with all sorts of motile animals appearing in rapid succession. Not your view at all.
dhw: I’m getting confused, because I don’t know what exactly is supposed to be the significance of the 410,000-year transition period. Perhaps you would explain what you think your God did during that time.
That period is the time between the last Edicarans and the first Cambrians. God designed the Cambrians.
dhw: Meanwhile, in my effort to gain a bit of enlightenment, I’ve found these two interesting articles. The first concerns a research project (the bolds are mine):
Co-Evolution of Life and Environment During the …
https://www.frontiersin.org/research-topics/31295(It’s …..During the Ediacaran-Cambrian Transition)
QUOTES: The Ediacaran-Cambrian transition is a crucial time interval for the evolution of animal life on Earth. Throughout this interval new ecosystems formed and novel bodyplans proliferated.. At the end of the Ediacaran there was a significant extinction event, though some forms including tubular fossils and acritarchs survived into the Phanerozoic. Substantial environmental and geological change also occurred during the Ediacaran-Cambrian transition, including, possibly, increasing oxygen levels, along with other chemical changes in the oceans. All of these events were accompanied by the proliferation of metazoan phyla in the early Cambrian, which were at least partially triggered by the significant environmental and geological changes at the Ediacaran-Cambrian transition, but in turn themselves influenced sedimentary environments and ocean chemistry.
Though a large number of studies of the biotic and abiotic changes, and their relationship, during this interval have been conducted, questions remain and new data are continually being gathered. Thus, here we call for more studies with the purpose of expanding understanding of this key time period in the history of life and its environmental and geological context.
The link between “novel bodyplans” and environmental conditions is always a feature, and so it would seem that the process of innovation had already begun during the transition period. However, it was interrupted by a significant extinction event, and the process began again in the early Cambrian. We therefore have proliferation during the 410,000 years of changing conditions, and further proliferation during the early Cambrian. The “extinction event” interrupted what would otherwise have been a continuous process, but interestingly we come now to the second article:
Paleontologists Find Evolutionary Link between Ediacaran and …
https://www.sci.news/paleontology/ediacaran-early-cambrian-metazoans...Paleontologists Find Evolutionary Link between Ediacaran and Early Cambrian Multicellular Animals
QUOTES: Paleontologists have described the first three-dimensional preservation of soft tissue in Namacalathus hermanastes, a skeletal metazoan (multicellular animal) that lived some 547 million years ago (Ediacaran period) in what is now Namibia, and established a strong evolutionary link between Ediacaran and early Cambrian metazoans.
Prior to the new study, it had proven difficult to trace links with earlier animals because their soft tissues — which provide vital clues about the animals’ ancestry — almost always break down over time.They found that Namacalathus hermanastes was an early ancestor of species that appeared during the Cambrian explosion/b]. Among them are types of prehistoric worms and mollusks.
“These are exceptional fossils, which give us a glimpse into the biological affinity of some of the oldest animals,” Professor Wood said.
“They help us trace the roots of the Cambrian explosion and the origin of modern animal groups.”dhw: We have the usual clear explanation of why fossils are so rare, but if we have a strong evolutionary link between Ediacaran and Cambrian animals, who knows what other links might have come into existence during the period of transition? There’s no answer to that question, but research is ongoing, and so we should NOT jump to the conclusion that species sprang from nowhere without any precursors.
Finding one link does not explain the vast array of new phyla appearing so suddenly. A small link is not a gap buster.
Oxygen and the Cambrian: in the pre-Cambrian
DAVID: What I note is the Ediacaran period is from 635 million to 541 million years ago. All it produced are strange, stalked animals with no motility. 410,000 year later the Cambrian starts in full bloom with all sorts of motile animals appearing in rapid succession. Not your view at all.
dhw: I’m getting confused, because I don’t know what exactly is supposed to be the significance of the 410,000-year transition period. Perhaps you would explain what you think your God did during that time.
DAVID: That period is the time between the last Edicarans and the first Cambrians. God designed the Cambrians.
I know what the transition period is, and I know you think your God designed the Cambrians. I’m asking what you think your God did during the transition period. I shan’t reproduce the two very revealing articles, but will merely highlight the most relevant points:
QUOTE: The Ediacaran-Cambrian transition is a crucial time interval for the evolution of animal life on Earth. Throughout this interval new ecosystems formed and novel bodyplans proliferated.
The leading question is whether these novel bodyplans might provide missing links between Ediacaran and Cambrian species.
QUOTE: Though a large number of studies of the biotic and abiotic changes, and their relationship, during this interval have been conducted, questions remain and new data are continually being gathered.
It seems to me extremely important that one should not draw final conclusions so long as new data are being found. Don’t you agree?
Heading: Paleontologists Find Evolutionary Link between Ediacaran and Early Cambrian Multicellular Animals
QUOTE: They found that Namacalathus hermanastes was an early ancestor of species that appeared during the Cambrian explosion/..
QUOTE: “They help us trace the roots of the Cambrian explosion and the origin of modern animal groups.”
DAVID: Finding one link does not explain the vast array of new phyla appearing so suddenly. A small link is not a gap buster.
But an accumulation of links would gradually close the gap. We must always bear in mind (a) that preservation of fossils is extremely rare for obvious reasons, and (b) that new techniques of research as well as new discoveries of fossils are already providing such links. Who knows what else might be discovered during the next hundred/thousand years? But I am emphatically NOT wishing for such discoveries or even expecting them. I am as ignorant as you and everyone else about the gap. I am merely pointing out that we should not make any assumptions – and that includes your assumption that the gap can never be filled. `
Oxygen and the Cambrian: in the pre-Cambrian
by David Turell , Wednesday, October 19, 2022, 16:33 (764 days ago) @ dhw
DAVID: That period is the time between the last Edicarans and the first Cambrians. God designed the Cambrians.
dhw: I know what the transition period is, and I know you think your God designed the Cambrians. I’m asking what you think your God did during the transition period. I shan’t reproduce the two very revealing articles, but will merely highlight the most relevant points:
QUOTE: The Ediacaran-Cambrian transition is a crucial time interval for the evolution of animal life on Earth. Throughout this interval new ecosystems formed and novel bodyplans proliferated.
dhw: The leading question is whether these novel bodyplans might provide missing links between Ediacaran and Cambrian species.
What novel body plans? Only in the Cambrian.
QUOTE: Though a large number of studies of the biotic and abiotic changes, and their relationship, during this interval have been conducted, questions remain and new data are continually being gathered.dhw: It seems to me extremely important that one should not draw final conclusions so long as new data are being found. Don’t you agree?
Yes.
Heading: Paleontologists Find Evolutionary Link between Ediacaran and Early Cambrian Multicellular AnimalsQUOTE: They found that Namacalathus hermanastes was an early ancestor of species that appeared during the Cambrian explosion/..
QUOTE: “They help us trace the roots of the Cambrian explosion and the origin of modern animal groups.”
DAVID: Finding one link does not explain the vast array of new phyla appearing so suddenly. A small link is not a gap buster.
dhw: But an accumulation of links would gradually close the gap.
Only if Edicaran precursors appear for 37 original phyla in the Cambrian
dhw: We must always bear in mind (a) that preservation of fossils is extremely rare for obvious reasons, and (b) that new techniques of research as well as new discoveries of fossils are already providing such links. Who knows what else might be discovered during the next hundred/thousand years? But I am emphatically NOT wishing for such discoveries or even expecting them. I am as ignorant as you and everyone else about the gap. I am merely pointing out that we should not make any assumptions – and that includes your assumption that the gap can never be filled.
Find precursors for 37 individual complex phyla. With one so far, 36 to go. I think God just popped the first in early in late Edicaran time.
Oxygen and the Cambrian: in the pre-Cambrian
DAVID: That period is the time between the last Edicarans and the first Cambrians. God designed the Cambrians.
dhw: I know what the transition period is, and I know you think your God designed the Cambrians. I’m asking what you think your God did during the transition period. I shan’t reproduce the two very revealing articles, but will merely highlight the most relevant points:
QUOTE: The Ediacaran-Cambrian transition is a crucial time interval for the evolution of animal life on Earth. Throughout this interval new ecosystems formed and novel bodyplans proliferated.
dhw: The leading question is whether these novel bodyplans might provide missing links
between Ediacaran and Cambrian species.
DAVID: What novel body plans? Only in the Cambrian.
I am quoting the article. Who should I trust to know all the latest research, you or the author?
QUOTE: Though a large number of studies of the biotic and abiotic changes, and their relationship, during this interval have been conducted, questions remain and new data are continually being gathered.
dhw: It seems to me extremely important that one should not draw final conclusions so long as new data are being found. Don’t you agree?
DAVID: Yes.
Thank you.
Heading: Paleontologists Find Evolutionary Link between Ediacaran and Early Cambrian Multicellular Animals
QUOTE: They found that Namacalathus hermanastes was an early ancestor of species that appeared during the Cambrian explosion/..
QUOTE: “They help us trace the roots of the Cambrian explosion and the origin of modern animal groups.”
DAVID: Finding one link does not explain the vast array of new phyla appearing so suddenly. A small link is not a gap buster.
dhw: But an accumulation of links would gradually close the gap.
DAVID: Only if Edicaran precursors appear for 37 original phyla in the Cambrian.
Bearing in mind the extreme unlikelihood of ANY fossils surviving, I’d settle for just a few.
dhw: We must always bear in mind (a) that preservation of fossils is extremely rare for obvious reasons, and (b) that new techniques of research as well as new discoveries of fossils are already providing such links. Who knows what else might be discovered during the next hundred/thousand years? But I am emphatically NOT wishing for such discoveries or even expecting them. I am as ignorant as you and everyone else about the gap. I am merely pointing out that we should not make any assumptions – and that includes your assumption that the gap can never be filled.
DAVID: Find precursors for 37 individual complex phyla. With one so far, 36 to go. I think God just popped the first in early in late Edicaran time.
I’m in no position to find any! I rely on you to latch on to all the latest discoveries, though I suspect neither of us will be around for the next hundred/thousand years.
*****
Thank you for all the other posts. I have nothing to add.
Oxygen and the Cambrian: in the pre-Cambrian
by David Turell , Thursday, October 20, 2022, 18:02 (763 days ago) @ dhw
dhw: The leading question is whether these novel bodyplans might provide missing links
between Ediacaran and Cambrian species.DAVID: What novel body plans? Only in the Cambrian.
dhw: I am quoting the article. Who should I trust to know all the latest research, you or the author?
The author is a science review editor, not a scientist. He and I are equils.
QUOTE: Though a large number of studies of the biotic and abiotic changes, and their relationship, during this interval have been conducted, questions remain and new data are continually being gathered.dhw: It seems to me extremely important that one should not draw final conclusions so long as new data are being found. Don’t you agree?
DAVID: Yes.
Thank you.
Heading: Paleontologists Find Evolutionary Link between Ediacaran and Early Cambrian Multicellular Animals
QUOTE: They found that Namacalathus hermanastes was an early ancestor of species that appeared during the Cambrian explosion/..
QUOTE: “They help us trace the roots of the Cambrian explosion and the origin of modern animal groups.”
DAVID: Finding one link does not explain the vast array of new phyla appearing so suddenly. A small link is not a gap buster.
dhw: But an accumulation of links would gradually close the gap.
DAVID: Only if Edicaran precursors appear for 37 original phyla in the Cambrian.
dhw: Bearing in mind the extreme unlikelihood of ANY fossils surviving, I’d settle for just a few.
I'm not sur[rised.
dhw: We must always bear in mind (a) that preservation of fossils is extremely rare for obvious reasons, and (b) that new techniques of research as well as new discoveries of fossils are already providing such links. Who knows what else might be discovered during the next hundred/thousand years? But I am emphatically NOT wishing for such discoveries or even expecting them. I am as ignorant as you and everyone else about the gap. I am merely pointing out that we should not make any assumptions – and that includes your assumption that the gap can never be filled.DAVID: Find precursors for 37 individual complex phyla. With one so far, 36 to go. I think God just popped the first in early in late Edicaran time.
dhw: I’m in no position to find any! I rely on you to latch on to all the latest discoveries, though I suspect neither of us will be around for the next hundred/thousand years.
*****
dhw: Thank you for all the other posts. I have nothing to add.
You are welcome.
Oxygen and the Cambrian: in the pre-Cambrian
dhw: The leading question is whether these novel bodyplans might provide missing links
between Ediacaran and Cambrian species.
DAVID: What novel body plans? Only in the Cambrian.
dhw: I am quoting the article. Who should I trust to know all the latest research, you or the author?
DAVID: The author is a science review editor, not a scientist. He and I are equals.
There seem to be several “topic editors” working on this research project, all of them from universities in China (where there are veritable treasure troves of ancient fossils).
Heading: Paleontologists Find Evolutionary Link between Ediacaran and Early Cambrian Multicellular Animals
DAVID: Finding one link does not explain the vast array of new phyla appearing so suddenly. A small link is not a gap buster.
dhw: But an accumulation of links would gradually close the gap.
DAVID: Only if Edicaran precursors appear for 37 original phyla in the Cambrian.
dhw: Bearing in mind the extreme unlikelihood of ANY fossils surviving, I’d settle for just a few.
DAVID: I'm not surprised.
And I’m not surprised that you want every single species to have left a complete fossil record of its evolution throughout hundreds of millions of years. Nothing less would shift you from your fixed beliefs. But at present, I only ask for open-mindedness. The Cambrian is still an unsolved mystery!
Oxygen and the Cambrian: in the pre-Cambrian
by David Turell , Friday, October 21, 2022, 17:39 (762 days ago) @ dhw
dhw: The leading question is whether these novel bodyplans might provide missing links
between Ediacaran and Cambrian species.DAVID: What novel body plans? Only in the Cambrian.
dhw: I am quoting the article. Who should I trust to know all the latest research, you or the author?
DAVID: The author is a science review editor, not a scientist. He and I are equals.
dhw: There seem to be several “topic editors” working on this research project, all of them from universities in China (where there are veritable treasure troves of ancient fossils).
The treasure trove has simply sharpened the Cambrian gap.
Heading: Paleontologists Find Evolutionary Link between Ediacaran and Early Cambrian Multicellular AnimalsDAVID: Finding one link does not explain the vast array of new phyla appearing so suddenly. A small link is not a gap buster.
dhw: But an accumulation of links would gradually close the gap.
DAVID: Only if Edicaran precursors appear for 37 original phyla in the Cambrian.
dhw: Bearing in mind the extreme unlikelihood of ANY fossils surviving, I’d settle for just a few.
DAVID: I'm not surprised.
dhw: And I’m not surprised that you want every single species to have left a complete fossil record of its evolution throughout hundreds of millions of years. Nothing less would shift you from your fixed beliefs. But at present, I only ask for open-mindedness. The Cambrian is still an unsolved mystery!
No it isn't. God designed it.
Oxygen and the Cambrian: in the pre-Cambrian
dhw: The leading question is whether these novel bodyplans might provide missing links
between Ediacaran and Cambrian species.
DAVID: What novel body plans? Only in the Cambrian.
dhw: I am quoting the article. Who should I trust to know all the latest research, you or the author?
DAVID: The author is a science review editor, not a scientist. He and I are equals.
dhw: There seem to be several “topic editors” working on this research project, all of them from universities in China (where there are veritable treasure troves of ancient fossils).
DAVID: The treasure trove has simply sharpened the Cambrian gap.
Sorry, but these scientists claim that there were plenty of novel bodyplans during the transition period, and new discoveries are being made all the time. And the second article provides an example which closes the gap:
Heading: Paleontologists Find Evolutionary Link between Ediacaran and Early Cambrian Multicellular Animals
DAVID: Finding one link does not explain the vast array of new phyla appearing so suddenly. A small link is not a gap buster.
dhw: But an accumulation of links would gradually close the gap.
DAVID: Only if Edicaran precursors appear for 37 original phyla in the Cambrian.
dhw: Bearing in mind the extreme unlikelihood of ANY fossils surviving, I’d settle for just a few.
DAVID: I'm not surprised.
dhw: And I’m not surprised that you want every single species to have left a complete fossil record of its evolution throughout hundreds of millions of years. Nothing less would shift you from your fixed beliefs. But at present, I only ask for open-mindedness. The Cambrian is still an unsolved mystery!
DAVID: No it isn't. God designed it.
You love to present your unproven (and probably unprovable) theories as facts. 
Oxygen and the Cambrian: in the pre-Cambrian
by David Turell , Saturday, October 22, 2022, 16:31 (761 days ago) @ dhw
edited by David Turell, Saturday, October 22, 2022, 16:40
dhw: Sorry, but these scientists claim that there were plenty of novel bodyplans during the transition period, and new discoveries are being made all the time. And the second article provides an example which closes the gap:
Heading: Paleontologists Find Evolutionary Link between Ediacaran and Early Cambrian Multicellular Animals
DAVID: Finding one link does not explain the vast array of new phyla appearing so suddenly. A small link is not a gap buster.
dhw: But an accumulation of links would gradually close the gap.
DAVID: Only if Edicaran precursors appear for 37 original phyla in the Cambrian.
dhw: Bearing in mind the extreme unlikelihood of ANY fossils surviving, I’d settle for just a few.
DAVID: I'm not surprised.
dhw: And I’m not surprised that you want every single species to have left a complete fossil record of its evolution throughout hundreds of millions of years. Nothing less would shift you from your fixed beliefs. But at present, I only ask for open-mindedness. The Cambrian is still an unsolved mystery!
DAVID: No it isn't. God designed it.
dhw: You love to present your unproven (and probably unprovable) theories as facts.
Faith has a role. Your faith is riveted to closing the gap that frightened Darwin.
Oxygen and the Cambrian: the role of pyrites
by David Turell , Saturday, June 08, 2024, 16:55 (166 days ago) @ David Turell
With the help of worms:
https://www.sciencealert.com/tiny-overlooked-creatures-may-have-triggered-explosion-of-...
"...rocks from Maryland, US, suggest an unlikely protagonist: prehistoric marine worms may have made an outsized contribution to the Great Ordovician Biodiversification Event.
"'It's really incredible to think how such small animals, ones that don't even exist today, could alter the course of evolutionary history in such a profound way," exclaims Johns Hopkins University geobiologist Maya Gomes.
"The US researchers found increased levels of a mineral called pyrite in a specific sediment level across nine sites in Chesapeake Bay. Pyrite requires a steady supply of oxygen to form from sediment minerals, but it also easily reacts with oxygen, stealing it from the oceans and then the atmosphere.
"But the more pyrite that does form and is then locked away under the ground, the more oxygen concentrations can build up. It is a useful proxy by which to measure oxygen levels from long ago.
"'It's kind of like Goldilocks," explains Johns Hopkins paleoclimatologist Kalev Hantsoo. "The conditions have to be just right. You have to have a little bit of mixing to bring the oxygen into the sediment, but not so much that the oxygen destroys all the pyrite and there's no net buildup."
"The levels of pyrite seen in the sediment suggest something was churning the ocean floor in such a way that it was keeping this mineral from stealing back too much of the increasing oxygen levels.
"Hantsoo and colleagues strongly suspect these early oceanic sediment mixers were the worms burrowing away, along with other creatures interacting with the seafloor.
"Worms and other life beneath the ground continue to play a massive role in bioturbation today – physically mixing up the top layers of soil, allowing fluid and oxygen exchange and cycling of other important nutrients, including iron, sulfur and carbon dioxide.
"The researchers updated previous models of prehistoric oxygen levels with their measures of bioturbation. The results suggest oxygen levels stayed stable for millions of years until they rose sharply during the Cambrian (beginning 538.8 million years ago) and Ordovician periods. These increases were greater than previous reconstructions suggested, but could not last indefinitely.
"'This increase in pyrite burial efficiency would have been temporary because intensifying bioturbation, in concert with rising [concentrations of O2], eventually would have introduced enough oxidizing power into the sediment pile to suppress pyrite retention," Hantsoo and team write.
"It wasn't until the second detected burst in pyrite burial, during the Ordovician, 485–445 million years ago, that Earth reached and then maintained near-modern levels of oxygen. This coincided with a 30-million-year period of rapid evolutionary changes leading to the creation of countless new species.
"There's always been this question of how oxygen levels relate to the moments in history where evolutionary forces are ramped up and you see a greater diversity of life on the planet," says Gomes.
"'With this work, we'll be able to examine the chemistry of early oceans and reinterpret parts of the geological record."
"It seems these bursts of oxygen, assisted by the worms' excavations, helped life's spectacular diversity boom on Earth."
Comment: an interesting theory based on solid work. To be clear, oxygen allowed diversification, but was not the cause of the Cambrian Explosion or the later diversifications.