dhw: The Cambrian Explosion is indeed a mystery, as Darwin acknowledged. But I don’t think this article even begins to solve it.

QUOTE: “Contrary to a classical hypothesis, our interpretations place the Shuram excursion, and any coeval animal evolutionary events, in a predominantly anoxic global ocean.” Co-author Christian Bjerrum commented “Specifically, it means that we need to rethink a lot of the things that we believed to be true from our childhood learning. And textbooks need to be revised and rewritten. So, if not extra oxygen, what triggered the era’s explosion of life? Perhaps the exact opposite”.

“Perhaps.” This is pure sensationalism.

QUOTE: Some even went further and suggested to “forget everything you thought you knew about how life evolved on Earth” (Ralls 2023) because it “turns out we might be very wrong about how life arose on Earth” (Harrison 2023).

The Cambrian has nothing to do with the origin of life. More sensationalism.

QUOTE: His hypothesis (Towe 1970, 1981, also see: Saul 2009) is basically that two entirely new amino acids (i.e., hydroxyproline and hydroxylysine), which are required for the formation of structural glycoproteins such as collagen in metazoans, could only form under oxygen rich conditions and that explains the late origin of complex multicellular life after the “boring billion” of only bacterial and protist life. (dhw’s bold)

A totally different theory which emphasizes the richness of oxygen as an essential feature of the “explosion”, in keeping with current theory. I’ve read the whole article, and one reason why the authors attack this theory is:

QUOTE: 1.The availability of the two new amino acids may be a necessary condition for complex multicellular life but certainly not a sufficient condition to explain the sudden origin of numerous new body plans, which required new genetic code (Paps & Holland 2018) for new proteins, new tissues, and new complex organs as well as new ontogenetic pathways.

Precisely the same objection can be raised against their own theory. How does a lack of oxygen produce new body plans?

QUOTE: “The Cambrian explosion is real and its consequences set in motion a sea-change in evolutionary history” (Conway Morris, 2000; Nichols et al., 2006).

Not even Darwin denied its reality or its consequences!

QUOTE: "the abrupt appearance of animal body plan disparity stubbornly remains an unsolved problem for Darwinism.”

Agreed. And this article does not provide a solution to the problem. Whether the explosion was triggered by an increase or a decrease in oxygen is still not enough to explain HOW all the new body plans arose.

Exactly the point. Those pesky guys popped up out of nowhere.

QUOTE: “Contrary to a classical hypothesis, our interpretations place the Shuram excursion, and any coeval animal evolutionary events, in a predominantly anoxic global ocean.” Co-author Christian Bjerrum commented “Specifically, it means that we need to rethink a lot of the things that we believed to be true from our childhood learning. And textbooks need to be revised and rewritten. So, if not extra oxygen, what triggered the era’s explosion of life? Perhaps the exact opposite”.

“Perhaps.” This is pure sensationalism.

QUOTE: Some even went further and suggested to “forget everything you thought you knew about how life evolved on Earth” (Ralls 2023) because it “turns out we might be very wrong about how life arose on Earth” (Harrison 2023).

The Cambrian has nothing to do with the origin of life. More sensationalism.

QUOTE: His hypothesis (Towe 1970, 1981, also see: Saul 2009) is basically that two entirely new amino acids (i.e., hydroxyproline and hydroxylysine), which are required for the formation of structural glycoproteins such as collagen in metazoans, could only form under oxygen rich conditions and that explains the late origin of complex multicellular life after the “boring billion” of only bacterial and protist life. (dhw’s bold)

A totally different theory which emphasizes the richness of oxygen as an essential feature of the “explosion”, in keeping with current theory. I’ve read the whole article, and one reason why the authors attack this theory is:

QUOTE: 1.The availability of the two new amino acids may be a necessary condition for complex multicellular life but certainly not a sufficient condition to explain the sudden origin of numerous new body plans, which required new genetic code (Paps & Holland 2018) for new proteins, new tissues, and new complex organs as well as new ontogenetic pathways.

Precisely the same objection can be raised against their own theory. How does a lack of oxygen produce new body plans?

QUOTE: “The Cambrian explosion is real and its consequences set in motion a sea-change in evolutionary history” (Conway Morris, 2000; Nichols et al., 2006).

Not even Darwin denied its reality or its consequences!

QUOTE: "the abrupt appearance of animal body plan disparity stubbornly remains an unsolved problem for Darwinism.”

Agreed. And this article does not provide a solution to the problem. Whether the explosion was triggered by an increase or a decrease in oxygen is still not enough to explain HOW all the new body plans arose.

https://evolutionnews.org/2023/12/3-story-of-2023-textbook-wisdom-on-origin-of-multicel...

"a new study (Ostrander et al. 2023) by group of researchers from Denmark has overturned decades of evolutionary dogma and claims the exact opposite: “oxygen didn’t trigger multicellular organisms” (Anonymous 2023, UCPH 2023). What this study found was instead clear evidence of a lower oxygen content correlated with the Avalon Explosion of the Ediacaran biota. The authors summarize their surprising findings as: “Contrary to a classical hypothesis, our interpretations place the Shuram excursion, and any coeval animal evolutionary events, in a predominantly anoxic global ocean.” Co-author Christian Bjerrum commented “Specifically, it means that we need to rethink a lot of the things that we believed to be true from our childhood learning. And textbooks need to be revised and rewritten. So, if not extra oxygen, what triggered the era’s explosion of life? Perhaps the exact opposite” (Anonymous 2023, UCPH 2023). Some even went further and suggested to “forget everything you thought you knew about how life evolved on Earth” (Ralls 2023) because it “turns out we might be very wrong about how life arose on Earth” (Harrison 2023). (my bold)

"Incidentally, a few days ago I received a personal message from my paleobiologist colleague Dr. Ken Towe, a retired former senior scientist at the Smithsonian Institution, who had read a recent article of mine at Evolution News on the Cambrian Explosion (Bechly 2023). He suggested that he has found a solution to the problem of the sudden appearance of complex body plans in the Cambrian, which supports the biological and biochemical evolution needed to make the multicellular connective tissues and the strengthening required for the larger higher forms of life to suddenly appear. His hypothesis (Towe 1970, 1981, also see: Saul 2009) is basically that two entirely new amino acids (i.e., hydroxyproline and hydroxylysine), which are required for the formation of structural glycoproteins such as collagen in metazoans, could only form under oxygen rich conditions and that explains the late origin of complex multicellular life after the “boring billion” of only bacterial and protist life.

***

"As we have just seen above, new research suggests that, contrary to seventy years of Darwinian consensus science, the appearance of multicellular life did not correlate with higher oxygen content but indeed with a lower one. Also, experimental research had previously challenged the so-called oxygen control hypothesis for the origin of multicellular life (Bozdag et al. 2021, News Staff 2021)

***

"Here is what Professor Derek Briggs, a world-renowned expert on Cambrian fossils, has to say on this issue: “We now know that the sudden appearance of fossils in the Cambrian (541–485 million years ago) is real and not an artefact of an imperfect fossil record” (Briggs 2015). Likewise, Zhang & Shu (2021) admitted that “multiple sources of evidence are strongly suggestive of a real evolutionary event being recorded rather than an artifact of an imperfect fossil record.” Cabej (2020) put it even more clearly: “Nevertheless, now, 150 years after The Origin, when an incomparably larger stock of animal fossils has been collected, Darwin’s gap remains, the abrupt appearance of Cambrian fossils is a reality, and we are still wondering about the forces and mechanisms that drove it. Despite the fact that, from time to time, a small number of students have questioned the reality of the Cambrian explosion on the same ground as Darwin, today’s consensus is that Cambrian explosion is a scientific fact” (Linnemann et al., 2019). And, “The Cambrian explosion is real and its consequences set in motion a sea-change in evolutionary history” (Conway Morris, 2000; Nichols et al., 2006).

"the abrupt appearance of animal body plan disparity stubbornly remains an unsolved problem for Darwinism. However, the new research of Ostrander et al. (2023) points to an even bigger problem, which is the dubious scientific status of Darwinian evolutionary theory itself that arguably seems to be compatible with any conceivable observations and thus unfalsifiable and heuristically worthless. If more than seventy years of consensus endorsed increased oxygen as trigger of multicellular life, and then scientists simply cheer for the progress of science (Harrison 2023) when the exact opposite correlation is found, there is something fundamentally wrong with the theory. Demonstration of a grandiose failure of a theory may be scientific progress, but it certainly cannot be forged into a success for this very theory. Maybe it’s time to look for a new theory that better explains the empirical data instead of producing decades of fallacious research."

Comment: This research is quite specific, that the origin of the Cambrian was preceded by very anoxic oceans. Quote "Contrary to a classical hypothesis, our interpretations place the Shuram excursion, and any coeval animal evolutionary events, in a predominantly anoxic global ocean." https://onlinelibrary.wiley.com/doi/10.1111/gbi.12557 Darwin's hope to solve the gap has not happened.

https://www.newscientist.com/article/2396825-ocean-life-surged-500-million-years-ago-du...

"A period of global cooling around 500 million years ago may have triggered Earth’s largest surge in marine biodiversity.

"The Great Ordovician Biodiversification Event marked a dramatic explosion in marine biodiversity between approximately 490 and 440 million years ago, resulting in the emergence of several new orders, families and genera of life that we still see today, such as sea stars and sea urchins.

“'[It] is one of the key diversifications of life in Earth history, often referred to as ‘diversity’s big bang’,” says David Harper at Durham University, UK, who wasn’t involved in the study.

"Proposed ideas for what sparked the event include sea level rises induced by continental drift, an increase in atmospheric oxygen and even meteors.

"Another possible explanation is the global cooling that occurred during the period, which earlier studies found reduced tropical sea surface temperatures from around 40°C to 30°C (104°F to 86°F). Now, Daniel Ontiveros at the University of Lille in France and his colleagues have found that this was probably the case.

"The team combined a climate model, based on fossil data and our knowledge of land configuration at the time, with an ecological model that mapped biodiversity patterns in the oceans.

"The combined model suggests that, as the oceans cooled, they became more conducive to life, leading to the rapid emergence of new species. Existing species also moved from waters around the north and south poles towards the equator.

“'At the start of the Ordovician, the ocean was very warm,” says Ontiveros. “Only a few species could withstand the high temperatures.” That is why aquatic life was mostly constrained to the colder, higher latitudes at the beginning of the Ordovician, he says. As the climate cooled, tropical waters became more habitable."

Comment: more forms with no precursors. This period exactly follows the Cambrian.

https://phys.org/news/2023-05-rare-fossils-gap-evolution-major.html

"Exceptionally well-preserved fossils from the Cambrian period have helped fill a gap in our understanding of the origin and evolution of major animal groups alive today.

"A new analysis of fossils belonging to an extinct invertebrate called Rotadiscus grandis have helped place this species in the animal tree of life, revealing how some characteristics of living species may have evolved independently rather than originating in a single common ancestor.

"Half a billion years ago, an unusual-looking animal crawled over the sea floor, using tentacles to pick up food particles along the way.

"Known as Rotadiscus grandis, this animal lived during the Cambrian period when a burst of evolutionary activity is thought to have given rise to many of the major animal groups we see today.

"The ancient remains of Rotadiscus were first discovered over 30 years ago, but the incomplete specimens made it challenging to determine their evolutionary significance.

"Now, a new study published in Current Biology describes Rotadiscus grandis in far more detail after rare, exceptionally preserved fossils were unearthed from the Chengjiang biota in Yunnan Province in China. The 518-million-year-old fossils have shone a new light on the evolution of early members of major animal groups.

***

"Many animals from this period possessed unique anatomies that look very different to anything seen today. But the patchiness of the fossil record often makes deciphering what these species are or where they fit into the tree of life challenging for paleontologists.

"In the past, Rotadiscus and its closest fossil relatives have been placed in a number of different groups, including the sea cucumbers and jellyfish. But the new fossils of Rotadiscus from Chengjiang are helping to clear this up.

"The Chengjiang biota is famous for its exceptionally preserved Cambrian fossils. The likely reason is that these animals were buried by a mudflow very rapidly while they were still alive, entombing them and preventing decay by bacteria and scavenging by other animals.

"The new Rotadiscus fossils are no exception, as their extraordinary preservation has revealed structures in more detail than had previously been observed, such as traces of possible nerves in the tentacles and a new double spiral structure.

***

"The new evolutionary tree including Rotadiscus and other fossils has helped the researchers reconstruct the evolution of major animal traits. One feature that was of particular significance was the presence of a tail extending posteriorly to the anus.

"Scientists originally believed that a post-anal tail was present in the common ancestor of all fish and acorn worms. However, as Rotadiscus lacks a post-anal tail it now seems that this trait may have evolved independently within these different groups.

"This process is known as convergent evolution, where the same feature evolves separately multiple times, often in response to similar environmental or ecological pressures.

"'Through our analysis, we can fill an evolutionary gap with Rotadiscus and its relatives," says Imran. "This is important because one of the goals for paleontologists is to try to understand the tree of life and how things are related to one another.'"

Comment: major work filing gaps in the evolutionary tree. But the study continues to demonstrate how stark the Cambrian gap really is. Unchanged since Darwin's time, all developments studying the source organisms of all our current species show the complexity of animals without precursors. Where did their brains come from??? is one question of very many. It all points to a designer at work, doesn't it?

https://www.scientificamerican.com/article/five-eyed-nozzle-nosed-oddity-lingered-far-b...

"More than a century ago paleontologist Charles Doolittle Walcott uncovered a very strange fossil in Canada. The finger-sized animal was utterly alien compared to anything around today: it looked like a lobster tail with five eyes and a nozzlelike trunk at one end. This 508-million-year-old organism, named Opabinia regalis, seemed an isolated expression of evolution running riot back in the Cambrian period—before a mass extinction swept such oddities away. But now scientists have discovered that such enigmatic creatures survived for tens of millions of years longer than previously thought.

"Only last year Harvard University paleontologist Joanna Wolfe and her colleagues described the second such specimen ever found, called Utaurora. This creature, unearthed in Utah, was related to Opabinia and lived at a similar time. But the day this find was published, Wolfe saw a photograph taken by fellow researcher Stephen Pates that would fundamentally change these organisms’ story. Pates had just found a third Opabinia-like creature in Wales—in rocks about 40 million years younger than the first two specimens. This oddball would have lived when more modern-looking animals, such as snails, cephalopods and corals, were on the rise.

***

"Mieridduryn lived during the Ordovician period, as Earth’s oceans were starting to resemble something a little more familiar to us today. Various other Cambrian oddities are now known to have lived beyond the mass extinction into that new era—and researchers are still investigating how they did so, as well as why they ultimately vanished. “We have more questions now about how opabiniids may have survived and what kinds of environments or life histories they were restricted to,” Wolfe says. And now she has an additional 40’million years’ worth of rocks to examine for clues."

Comment: this animal lived on forever through the all mass extinctions. Obviouslty didn't need to evolve in order to survive. Constant evolution is not required.

https://phys.org/news/2023-01-ancient-fossils-evolution-sea-worm.html

"Ancient fossils have shed new light on a type of sea worm linking it to the time of an evolutionary explosion that gave rise to modern animal life.

"Researchers at Durham University, UK, and Northwest University, Xi'an, China, examined 15 exceptionally preserved fossils of the annelid worm Iotuba chengjiangensis dating from the early Cambrian period 515 million years ago.

"The fossilized remains included evidence of the worms' guts and kidneys and revealed they had an unexpectedly complex structure similar to that of other annelid worms.

"The researchers say this means that annelids—or segmented worms—diversified into different lineages some 200 million years earlier than previously thought and were part of the evolutionary leap known as the Cambrian explosion.

"The Cambrian explosion saw a huge rise in organisms between 540 and 530 million years ago—as shown by fossil records—and saw the appearance of many of the major groups that make up animal life on Earth.

"Study co-author Dr. Martin R. Smith, in the Department of Earth Sciences, Durham University, said, "We know that the main animal lines we see today emerged during the Cambrian explosion, but we always thought annelid worms were late to the party, and their major subgroups didn't begin to diversify until nearly 200 million years later.

"'But the amazingly preserved fossils we have studied and the structure of these amazing little creatures challenge this picture, and show that annelid worms—including Iotuba chengjiangensis—seemed to follow the pattern of events initiated by the Cambrian explosion.

***

"Dr. Smith added, "These families are like the top rungs on an evolutionary ladder. For these groups to have appeared so early in the day, there must have been a dramatic unseen origin of modern annelid diversity in the heat of the Cambrian explosion.

"'It turns out that many of the annelids we know and love today may have begun to evolve much sooner than we think."

"Research lead author Dr. Zhifei Zhang, Northwest University, Xi'an, China said, "Annelids are one of the largest and most successful phyla of animals that are flourishing in both terrestrial and marine ecosystems with the most diversified living lineage, Polychaeta, living in the sea.

"'The most well-known are, for example, earth worms, leeches and clam worms. There are also at least 20,000 species and 80 families of Polychaete in the modern sea. However, their earliest geological records of fossils in Cambrian deposits, even in the well-known Konservat-Lagerstätten are quite rare.

"'Is this because the delicate worms didn't exist, or simply didn't preserve? Our research gives the first insightful answer: biodiversification of the segmented worms occurs much earlier than thought before.'"

Comment: the Cambrian gap marches on with this new finding about this worm family. Sudden appearance of marked complexity. The gap never changes and is not explained by any natural series of events

https://phys.org/news/2022-11-million-year-old-fossil-defies-textbook-explanation.html

"A study published in Science—led by Nicholas Strausfeld, a Regents Professor in the University of Arizona Department of Neuroscience, and Frank Hirth, a reader of evolutionary neuroscience at King's College London—provides the first detailed description of Cardiodictyon catenulum, a wormlike animal preserved in rocks in China's southern Yunnan province. Measuring barely half an inch (less than 1.5 centimeters) long and initially discovered in 1984, the fossil had hidden a crucial secret until now: a delicately preserved nervous system, including a brain.

"To our knowledge, this is the oldest fossilized brain we know of, so far," Strausfeld said.

"Cardiodictyon belonged to an extinct group of animals known as armored lobopodians, which were abundant early during a period known as the Cambrian, when virtually all major animal lineages appeared over an extremely short time between 540 million and 500 million years ago. Lobopodians likely moved about on the sea floor using multiple pairs of soft, stubby legs that lacked the joints of their descendants, the euarthropods—Greek for "real jointed foot." Today's closest living relatives of lobopodians are velvet worms that live mainly in Australia, New Zealand and South America.

***

"'From the 1880s, biologists noted the clearly segmented appearance of the trunk typical for arthropods, and basically extrapolated that to the head," Hirth said. "That is how the field arrived at supposing the head is an anterior extension of a segmented trunk."

"'But Cardiodictyon shows that the early head wasn't segmented, nor was its brain, which suggests the brain and the trunk nervous system likely evolved separately," Strausfeld said.

"Cardiodictyon was part of the Chengjiang fauna, a famous deposit of fossils in the Yunnan Province discovered by paleontologist Xianguang Hou. The soft, delicate bodies of lobopodians have preserved well in the fossil record, but other than Cardiodictyon none have been scrutinized for their head and brain, possibly because lobopodians are generally small. The most prominent parts of Cardiodictyon were a series of triangular, saddle-shaped structures that defined each segment and served as attachment points for pairs of legs. Those had been found in even older rocks dating back to the advent of the Cambrian.

"'That tells us that armored lobopodians might have been the earliest arthropods," Strausfeld said, predating even trilobites, an iconic and diverse group of marine arthropods that went extinct around 250 million years ago.

***

"In their new study, the authors not only identified the brain of Cardiodictyon but also compared it with those of known fossils and of living arthropods, including spiders and centipedes. Combining detailed anatomical studies of the lobopodian fossils with analyses of gene expression patterns in their living descendants, they conclude that a shared blueprint of brain organization has been maintained from the Cambrian until today.

"'By comparing known gene expression patterns in living species," Hirth said, "we identified a common signature of all brains and how they are formed."

***

"'At a time when major geological and climatic events were reshaping the planet, simple marine animals such as Cardiodictyon gave rise to the world's most diverse group of organisms—the euarthropods—that eventually spread to every emergent habitat on Earth, but which are now being threatened by our own ephemeral species.'"

Comment: A brain is so complex, how did the first ones evolve? Design explains all.

https://www.sciencealert.com/ancient-weird-wonders-could-be-leftovers-from-the-cambrian...

"Researchers dug up two fossils belonging to ancient, flappy, and snouted arthropod relatives from what's now a sheep field near Llandrindod Wells in Wales.

"At only 13 and 3 millimeters (about 0.5 and 0.1 inches), these minuscule fossils from the Ordovician period may not seem like much to look at, but their familiarity kept paleontologists up at night.

"The fossils look like opabiniids – extinct soft-bodied animals with snouts – yet they were dated to 40 million years after any known opabiniid fossil.

***

"Dinocaridida, which include opabiniids and radiodonta, were abundant after the Cambrian explosion; these creatures scuttled through an ocean-dominated Earth around 500 million years ago.

"They looked a bit like trilobites, but all had a skirt of swim-flaps around their bodies; some had stalks and other weird head appendages. Opabinia earned the title of "weird wonder" with its confusing and otherworldly appearance thanks to five eyes and a bizarre clawed trunk.

"Dinocaridida are thought to have descended from the same shared 'parent' group of animals to deuteropods, ancient arthropods that gave rise to classifications that would include spiders, insects, and crustaceans.

"While the new finds shared several features with opabiniids, they had some striking differences, too.

"University of Cambridge paleontologist Stephen Pates and colleagues named the largest of the newly described animals Mieridduryn bonniae, but have yet to classify the smaller one as they're uncertain if it's a different species or a younger form of the other.

"'The size of the smaller specimen is comparable to some modern arthropod larvae – we had to take into account this possibility in our analyses," explains Harvard University phylogeneticist Joanna Wolfe.

"The tiniest specimen shared a fanned tail with blades similar to Opabiniids, and all had similar 'legs', but the new finds also had snouts – proboscises – with features seen in radiodonta.

***

"However, "the best-supported position for our Welsh specimens, whether considered as one or two species, were more closely related to modern arthropods than to opabiniid," says Pates.

"In this case, the proboscis may have resulted from a fusion between the first two head limbs that were reduced in later related animals to eventually become insect mouth flaps, while the radiodonts found a different use for these limbs, keeping them separate.

"The fate of the first two head appendages is of particular interest because they have provided these scuttling life forms the ability to occupy so many different roles on Earth, from filter feeding to apex predators. So researchers credit them for the unmatched success of arthropods on Earth.

"Either scenario would shed light on the evolution of arthropods which currently account for more than 85 percent of all known animal species on our planet. But we'll need to discover more 'weird wonders' to clarify this mysterious branch on the tree of life."

Comment: it helps to fill a minor gap in the arthropod group branch. Supports dhw's comment new fossils will always be found, but a major find of fossils to fill the Cambrian gap is very unlikely at this late stage of fossil hunting.

https://www.sciencealert.com/incredible-discovery-has-finally-revealed-the-first-animal...

"Several fortuitous fossils from China have defied the odds and are now providing archeologists with a real glimpse into early lifeforms that lived about 514 million years ago.

"The fossils have preserved the soft tissue of four worm-like marine creatures belonging to the species Gangtoucunia aspera.

"Initially, scientists thought this extinct genus was a relative of living annelid worms (such as earthworms), which are horizontally segmented. However, these new results suggest Gangtoucunia is more closely related to polyp cnidarians, like jellyfish, sea anemones, and coral.

***

"'This really is a one-in-million discovery. These mysterious tubes are often found in groups of hundreds of individuals, but until now, they have been regarded as 'problematic' fossils because we had no way of classifying them," says paleobiologist Luke Parry from the University of Oxford.

"'Thanks to these extraordinary new specimens, a key piece of the evolutionary puzzle has been put firmly in place."

"'This really is a one-in-million discovery. These mysterious tubes are often found in groups of hundreds of individuals, but until now, they have been regarded as 'problematic' fossils because we had no way of classifying them," says paleobiologist Luke Parry from the University of Oxford.

"'Thanks to these extraordinary new specimens, a key piece of the evolutionary puzzle has been put firmly in place."

***

"'Intriguingly," the authors note, "we do not recover a close relationship between Gangtoucunia in a clade with other medusozoans with calcium phosphate exoskeletons, suggesting that tube-building materials could have a complex early evolutionary history, possibly due to convergent losses and reduction of calcium phosphate in skeletons as it became less available through the Palaeozoic."

"In other words, external skeletons probably didn't arise just once but probably evolved several times in multiple different lineages.

***

"Even from the little evidence scientists have found, it is clear that tube-shaped animals were popping up before the explosion of animal diversity that once took our life by storm. What triggered their expansion remains an open question, though predation is one possibility.

"'A tubicolous mode of life seems to have become increasingly common in the Cambrian, which might be an adaptive response to increasing predation pressure in the early Cambrian," says paleobiologist and study author Xiaoya Ma from Yunnan University in China and the University of Exeter in the UK.

"'This study demonstrates that exceptional soft-tissue preservation is crucial for us to understand these ancient animals.'"

Comment: China is still the best source for new Cambrian discoveries.

https://www.sciencenews.org/article/ancient-worm-evolution-missing-link

"An ancient, armored worm may be the key to unraveling the evolutionary history of a diverse collection of marine invertebrates.

"Discovered in China, a roughly 520-million-year-old fossil of the newly identified worm, dubbed Wufengella, might be the missing link between three of the phyla that constitute a cadre of sea creatures called lophophorates.

"Based on a genetic analysis, Wufengella is probably the common ancestor that connects brachiopods, bryozoans and phoronid worms, paleontologist Jakob Vinther and colleagues report September 27 in Current Biology.

“'We had been speculating that [the common ancestor] may have been some wormy animal that had plates on its back,” says Vinther, of the University of Bristol in England. “But we never had the animal.”

"An ancient, armored worm may be the key to unraveling the evolutionary history of a diverse collection of marine invertebrates.

"Discovered in China, a roughly 520-million-year-old fossil of the newly identified worm, dubbed Wufengella, might be the missing link between three of the phyla that constitute a cadre of sea creatures called lophophorates.

"Based on a genetic analysis, Wufengella is probably the common ancestor that connects brachiopods, bryozoans and phoronid worms, paleontologist Jakob Vinther and colleagues report September 27 in Current Biology.

“'We had been speculating that [the common ancestor] may have been some wormy animal that had plates on its back,” says Vinther, of the University of Bristol in England. “But we never had the animal".

***

"A fossil like Wufengella had long been high on Vinther’s bucket list of fossils that he and his colleagues hoped to find. But “we always thought, ‘Well, we probably will never see that in real life,’” he says. Typically, such a creature would have spent its life in shallow water. Organisms don’t tend to preserve well there, decaying faster due to exposure to lots of oxygen. Vinther suggests that the Wufengella that his team found probably washed out to deep water in a storm.

"Now that the researchers have found one Wufengella, they hope to find more, in part to see if there are other varieties. And perhaps the team could identify even more distant ancestors further back on the tree of life that might connect lophophorates with other animal groups such as mollusks, Vinther says, further fleshing out how life on Earth is connected."

Comment: a great new find which may explain a gap in fossils of this special branch. It fits dhw's erstwhile wish to fill the whole Cambrian gap, but all it does it help fill a small gap inside the Cambrian era. The giant Cambrian gap remains intact.

https://www.livescience.com/cambrian-fossil-embryo-with-brain?utm_campaign=368B3745-DDE...

"Scientists uncovered something unexpected in the fossilized embryo of a worm-like creature from the Cambrian period: the remains of a tiny, doughnut-shaped brain in the primordial animal's head.

"The roughly 500 million-year-old fossil is an example of the marine species Markuelia hunanensis, an ancient cousin of penis worms (priapulids) and mud dragons (Kinorhyncha). To date, scientists haven't found fossils of the worm-like weirdos in their adult form, but researchers have uncovered hundreds of pristine embryos that capture different stages of the animals' early development. Each of these embryos measures only about half a millimeter (0.02 inch) across.

"'The thing about Markuelia is, it looks like a mini-adult — it actually looks like a miniature penis worm," which gives scientists an idea of what a mature M. hunanensis likely looked like, Philip Donoghue, a professor of paleobiology at the University of Bristol in England, told Live Science.

***

"The exceptional embryo was collected from a fossil deposit known as the Wangcun Lagerstätte in western Hunan, China. There, the teeny-tiny fossil had been encased in a large slab of limestone. Back at their lab at Peking University, Dong and his colleagues carefully dissolved this limestone rock with acid and then manually sorted through the microfossils in the residue.

***

"'Normally, we don't get preservation of the original anatomy of the organism; we just get the cuticle," meaning the animal's tough outer shell, Donoghue said of the X-rayed embryos. In addition, scientists often see thin lines of mineralization crosshatching the inside of each embryo; such lines are thought to be evidence of microbes that grew over the animal prior to its fossilization.

"Compared with what the team typically observed, the embryo that contained traces of nervous tissue looked starkly different. That embryo bore a clear, organized structure in its head, which the team interpreted to be the animal's ring-shaped brain. What's more, the fossil carried another distinctive structure in its tail, which the team took to be remnants of muscle.

***

"Based on the known relationship of M. hunanensis to animals like penis worms and mud dragons, scientists could reasonably expect its brain to be ring-shaped, so the authors' interpretation of the fossil makes sense, Strausfeld told Live Science. "Setting aside the improbability of [the brain's] fossilization, it would be surprising were it to exhibit a different morphology," the study authors noted in their report.

"Notably, this is the first time fossilized nervous tissue has been found in a so-called Orsten-style fossil, the authors added. Such fossils are usually less than 0.08 inch (2 mm) long, are found locked in nodules of limestone and are preserved through a mineralization process whereby the animals' tissue is replaced by calcium phosphate. This process produces a minuscule but highly detailed 3D fossil that typically only preserves the animal's cuticle, not its internal organs.

"'The most interesting thing about our paper is perhaps what it tells us about the potential for future discoveries," Donoghue said. "Nobody had foreseen that you could preserve brains or nervous tissues in calcium phosphate, and maybe it's just a matter of going back and looking for it in museum drawers.""

Comment: not closing any gap but confirming a brain in a Cambrian organism. A huge physiological leap from the Edicarans.

https://www.sciencealert.com/3-major-aquatic-animal-groups-can-trace-their-lineage-to-t...

"A bristly armored "worm" that scuttled across ocean reefs 518 million years ago is the ancestor to three aquatic animal groups that today live very different lifestyles, and it offers new clues about the explosion of diverse species at the time, a new study finds.

"An international team of researchers recently discovered the fossil of a species that gave rise to brachiopods, bryozoans, and phoronids; these three groups of filter-feeding marine creatures all fix themselves to the seafloor, but each group has highly specialized feeding structures and they look very different from one another.

"The fossil species, named Wufengella bengtsoni, is a member of an older, shelled group of organisms called tommotiids, scientists reported in a new study.

***

"Brachiopods are shelled, bivalved creatures; bryozoans are soft-bodied with crowns of tentacles, and phoronids are encased in protective tubes made of chitin, a material that reinforces organic structures such as exoskeletons, beaks, and shells.

***

"The fossil was found at the Chengjiang Biota fossil site in Yunnan, a province in southwestern China. It's a rare find because animals such as this are typically not preserved well enough for paleontologists to study them in detail.

"'They were scuttling around on reefs in the shallow tropical waters that existed back then," Vinther said.

"In these ancient reef systems, dead animals usually were washed around until their bodies disintegrated, and their soft tissues often decayed in the reefs' oxygen-rich waters before fossilization could happen.

"'This particular animal, lucky for us, got washed down into deep water where it got buried in mud where it was preserved," Vinther said.

***

"While the researchers predicted W. bengtsoni's general body plan, some features in the fossil were a big surprise. It had flaps on its body that could have been used for suction purposes, to fix the animal to the reef when there were waves, Vinther speculated.

"The species also had long bristles on its sides that may have been used for sensing prey or as protection against predators.

"The study authors aren't sure what the animal ate, but its body wasn't adapted for filtering water or staying still, so they know it wasn't a filter feeder that attached to the seafloor like its descendants.

"The researchers are confident that it is the ancestor of brachiopods, bryozoans, and phoronids because it shared a similar skeleton with those groups. As life evolved in the Cambrian explosion, animals filled different ecological niches and adopted different body plans.

***

"'We're really seeing how these groups fit together, and how they evolved from a single common ancestor. It's taking us up a rung in the evolutionary tree," Smith added."

Comment: this is a great new find, but it just fills niche in a well-established story. dhw keeps hoping for something to remove the Cambrian gap. Not at all likely.

https://www.cell.com/current-biology/fulltext/S0960-9822(22)01455-5?dgcid=raven_jbs_aip...

"We describe the first articulated camenellan tommotiid, from the early Cambrian
•
Camenellans had seriated, annelid-like chaetal bundles and body outgrowths
•
Early lophophorates were armored, vagile animals prior to becoming sessile
•
Soft anatomy is vital for understanding the oldest skeletal fossils

"Among extant animals, Lophotrochozoa accounts for the majority of phyla. This bilaterian clade radiated rapidly during the Cambrian explosion, obfuscating its phylogenetic relationships and rendering many aspects of its early evolution uncertain. Many early lophotrochozoans are known only from isolated skeletal microfossils, “small shelly fossils,” often derived from larger animals with complex multi-element skeletons. The discovery of articulated fossils has revealed surprising insights into the animals from which these skeletal pieces were derived, such as paired shells in the mollusc Halkieria. Tommotiids are a key group of phosphatic early skeletal fossils that first appear in the late early Cambrian. Although their affinities were previously obscure, discoveries of partial scleritomes and investigations of growth and microstructure provide links with Brachiopoda7 and Phoronida, two of the lophophorate phyla. By contrast, the body plan of camenellan tommotiids remains a palaeontological mystery, with hypothetical reconstructions representing motile, benthic, dorsally armored worms. Here, we describe an articulated camenellan from the Cambrian Chengjiang Biota, China, revealing the morphology of the scleritome and the first soft tissues from an adult tommotiid. Wufengella carries two dorsal rows of sclerites in a highly asymmetric arrangement, flanked by smaller, cap-shaped sclerites. The scleritome was fringed by iterated fascicles of chaetae and two layers of flattened lobes. Phylogenetic analysis confirms that camenellans occupy a deep branch in lophophorate phylogeny, prior to the acquisition of a sessile lifestyle. Wufengella reveals direct evidence for a metameric body plan reminiscent of annelids early in the evolutionary history of lophophorates."

Commemt: a highly technical article, describing an early Cambrian the point being as usual, nothing like an Edicaran.

https://salvomag.com/article/salvo61/a-biological-big-bang

"New high-resolution age data narrows the date range for the paleon-tological event known as the Ediacaran-Cambrian transition to 410,000 years. A period of 410,000 years seems a long time to most people, but to scientists who study Earth's history and life, it's a mere moment. Discovery of a novel life-form that appeared within such a "moment" in the earliest days of the Cambrian era carries profound implications. When viewed in light of the measured "molecular clock" rate, this new finding presents a serious challenge to the commonly accepted story of life's slow, gradual development by natural processes alone.

***

"The Cambrian explosion, more than a half-billion years ago, saw the rapid appearance of mostly marine phyla, the first creatures to possess skeletons, digestive tracts, circulatory systems, and complex internal and external organs. They appeared very soon after sufficient oxygen became available in Earth's atmosphere and oceans to make their existence possible.

***

"The fossil record indicates that Ediacaran animals were the first to appear on Earth. They are characterized by tubular and frond-shaped filter feeders. The record also shows that Ediacaran fauna experienced a sudden mass extinction event. What followed almost immediately was the explosive appearance of vastly more complex Cambrian animals.

"Diazhao Chen's team, using the uranium-lead method, determined that the base portion of the Liuchapo Formation dates back 542.1 ± 5.0 million years.2 Using this same method, the mid-upper portion of this formation measured 542.6 ± 3.7 million years old.3 Five years later, Can Chen and his colleague Qinglai Feng refined this measurement (using a weighted-mean approach to measuring the uranium-lead zircon age) to demonstrate that the lower part of the Liuchapo Formation indeed marks the Ediacaran-Cambrian boundary.4 Their analysis reveals the boundary date to be 540.7 ± 3.8 [±6.6] million years ago. (The unbracketed error bar is the probable statistical error. The bracketed error bar represents the probable systematic error.)

"Ulf Linnemann and a team of fourteen geochemists provided an even more precise date for the end of the Ediacaran and the launch of the Cambrian. The team found a composite geological section of the Ediacaran-Cambrian boundary in southern Namibia. This site allowed for biostratigraphic as well as chemostratigraphic analysis, bracketed by radiometric dating.5 Their measurements constrained the date for the Ediacaran-Cambrian boundary to no earlier than 538.99 ± 0.21 million years ago and no later than 538.58 ± 0.19 million years ago.

"The Linnemann team's date indicates that the Ediacaran-Cambrian boundary is 2 million years more recent than the dates proposed by Diazhao Chen's team and by Can Chen and Qinglai Feng. Though different, it is considered consistent, not discrepant, in that the three dates all agree within the error bars of each. What their findings more notably reveal is the brevity, or narrowness, of that boundary. According to the Linnemann team's measurements, the faunal transition from Ediacaran to Cambrian biota appears to have occurred within a time frame of a mere 410,000 years.

***

"The mid-Cambrian, 520–535 million years ago, is where paleontologists have discovered the greatest number and diversity of Cambrian species. It is this epoch that has the richest, most extensive fossil beds. Increasingly, however, paleontologists are discovering phyla they thought originated in the mid-Cambrian actually being found in the early Cambrian deposits.8

"These discoveries demonstrate that during the Cambrian period the diversification of higher taxa occurs before that in lower taxa. As paleontologists Douglas Erwin, James Valentine, and John Sepkoski have observed, "The major pulse of diversification of phyla occurs before that of classes, classes before that of orders, and orders before that of families."

"The transition from Ediacaran to Cambrian phyla in less than 410,000 years challenges all current and as yet conceivable naturalistic models for the evolution of life. Such a period would be far too brief for the extinction of one phylum and the appearance of a new one, let alone several. The differences between one phylum and another are not minor, and the observed processes by which current models propose that these changes occurred are too slow to account for them.

***

"The obvious challenge for naturalistic models for life's history is to explain why the fossil record, especially the record for the Cambrian animals, shows the exact opposite of what the naturalistic models predict. New phyla appear first, not last. These phyla appear suddenly and without direct evolutionary precursors. Astronomers have noted that many Cambrian phyla appear the moment oxygen in Earth's atmosphere reaches the minimum level (10 percent) necessary for these phyla to survive."

Comment: in the Grand Canyon each lower (older) layer is precisely next to the one above. Nothing inbetween So where are dhw's wished for tranitionasl forms? The Edicarans are very well known by now. They are animals that have no resemblance to the Cambrians, whose crazy abrupt appearances have more complex before simpler forms! That's reversed evolution! Contrary to accepted Darwin theories, which are slowly dying away.

https://www.sciencealert.com/we-ve-just-found-a-second-species-of-weird-extinct-animal-...

"Peering back hundreds of millions of years into the past can turn up some astonishing findings – as it has with the discovery of a second species of opabiniid, a soft-bodied arthropod with a segmented exoskeleton that lived on the seafloor during the Miaolingian (509-497 million years ago).

"The original opadiniid, Opabinia regalis, was first described over a century ago in 1912, and has several notable physical characteristics – not least the five eyes protruding on stalks from its head, a backwards-facing mouth, and its hollow, tubular proboscis.

"Now there's another: Opabinia regalis is not as unique a species as first thought, because it's been joined by Utaurora comosa. This creature was previously thought to belong to a different group of animals known as radiodonts, but has now been reclassified as an opabiniid after some extensive research.

***

"U. comosa was first described as a radiodont in 2008, having originally been discovered in a fossil site known as the Wheeler Formation in Utah. It's a few million years younger than Opabinia, and was found in a different location – Utah rather than Canada.

"While Utaurora shares characteristics and morphology with both radiodonts and Opabinia, the researchers behind the latest study decided to do some more digging. The team compared the Utaurora fossil with 43 other fossils, plus 11 living taxa, covering arthropods, radiodonts, and other panarthropods.

"Due to their similarities, it was originally thought that opabiniids and radiodonts had the same common ancestor, and were grouped as so-called 'dinocarids'.

"However, in the last 15 years or so, more tools for studying evolutionary history have been developed – and just as importantly, several new species of radiodonts have been found, highlighting the differences between these creatures and opabiniids.

***

"'But our phylogenetic dataset and analyses supported Utaurora as an opabiniid in 68 percent of the trees retrieved by analyzing the data, but only in 0.04 percent for a radiodont."

"While the front of the U. comosa fossil was poorly preserved, the researchers noted the intersegmental furrows along the back and the paired serrated spines on the tail. Together with the evolutionary tree analysis carried out by the team, a new species was brought into existence, half a billion years after its demise.

"'Dissection of the phylogenetic support demonstrates that while evidence for radiodont paraphyly is weak, Utaurora can be confidently reassigned to Opabiniidae," the researchers write in their paper.

"'The weirdest wonder of the Cambrian no longer stands alone."

"Now that the classification has been made, future research can use U. comosa to help trace back the evolution and ecology of the opainiid, and this is unlikely to be the last we hear of this strange-looking animal.

"The Opabinia shares a scientific history with another group of arthropods known as Anomalocaris, and both were originally described as 'weird wonders' of the Middle Cambrian age. Only now are the differences between them really emerging.

"'Now we know that these animals represent extinct stages of evolution that are related to modern arthropods," says Wolfe.

"'And we have tools beyond qualitatively comparing morphological features for a more definitive placement within the animal tree of life.'"

Comment: please note lots of fossil samples are lying around waiting for further study to place them in the right order.

https://www.livescience.com/fossilized-arthropods-contain-preserved-nervous-tissue?utm_...

"Two tiny fossils, each smaller than an aspirin pill, contain fossilized nerve tissue from 508 million years ago. The bug-like Cambrian creatures could help scientists piece together the evolutionary history of modern-day spiders and scorpions.

"Still, it's not clear exactly where these fossils — both specimens of the species Mollisonia symmetrica — fit on the arthropod evolutionary tree, said Nicholas Strausfeld, a regents professor in the Department of Neuroscience at the University of Arizona, who was not involved in the study.

"That's because some features, like the animals' eyes and nerve cords, can be clearly identified in the fossils, but other parts of the nervous system cannot be so easily spotted. In particular, it's unclear whether or not the animals carry a brain-like bundle of nerves called a synganglion, and without this key piece of evidence, their relation to other animals remains fuzzy, Strausfeld said.

***

"'It is … true that we do not have every single characteristic of the nervous system of this animal mapped out, because the fossils only tell us so much," Ortega-Hernández said. The researchers acknowledge this uncertainty in their new report, published Jan. 20 in the journal Nature Communications, and present a few different ideas as to how these fossils relate to ancient and modern-day critters. If more fossilized M. symmetrica are uncovered in the future, the species' place on the tree of life may eventually be resolved.

***

"Scientists uncovered the first evidence of a fossilized arthropod brain from the Cambrian period about a decade ago, according to a 2012 report in the journal Nature Communications; arthropods are invertebrate animals in the phylum Arthropoda, a group that includes modern insects, crustaceans and arachnids, like spiders. Since that initial discovery 10 years ago, preserved nerve tissue has been found in more than a dozen Cambrian fossils, most of them arthropods, Ortega-Hernández said.

***

"The researchers suspect that the arthropod also had seven pairs of tiny appendages, two fangs and six pairs of little limbs; that's based on a 2019 study, published in the journal Nature, that described a fossil from a different species in the Mollisonia genus that bore such appendages. However, it's highly unusual to find Mollisonia fossils with intact limbs, and both fossils used in the new study lack appendages, Ortega-Hernández noted.

***

"In the Smithsonian fossil, a bulbous eye can be seen in the arthropod's head and a nerve cord can be clearly seen running down the length of its belly, with some nerves jutting out from its underside. In the Harvard specimen, one can see two huge, orb-like eyes on the head, and a bit of the nerve cord peeking out from beneath the animal's digestive tract, which obscures the rest of the cord.

"In both fossils, the study authors reported seeing optic nerves that run from the arthropods' eyes into the main body, but Strausfeld said the evidence for these nerves is "ambiguous," and ideally, these features would be clearer. And in both specimens, the authors noted that there's some sort of nerve tissue present in the head, but it's unclear whether this structure is a brain-like synganglion or something else entirely."

Comment: Another example of the complexity of Cambrian organisms with no precursors and the gap from the Edicaran layers is only 410,000 years, a blink of the eye in evolutionary terms.

https://phys.org/news/2022-01-combine-paleontology-fluid-physics-uncover.html

"Their research features strange, vase-like organisms (in the genus Ernietta) that lived in the Ediacaran era—approximately 635 million to 541 million years ago. These organisms lived in marine environments, where fluid dynamics drive the evolution of the organisms that inhabit them.

"This work brought two distinct areas of science together—paleontology and fluid dynamics, which describes the flow of liquids and gasses. "Paleontology is at its most exciting—and arguably most successful—when it works at the interface with other disciplines. In this case, it's fluid physics," Darroch said.

"Computer models of fluid dynamics that affect communities of organisms suggest that when isolated, larger individuals have better nutrient circulation in their body cavities than smaller individuals. However, when different sizes of individuals live together, larger ones can create beneficial conditions for smaller ones that are downstream. Gibson led this research, conducted within the Evolutionary Studies Initiative,

***

"'Perhaps the greatest benefit is that smaller Ernietta would be protected from adverse flow when downstream of larger ones, but they also consistently receive stronger cavity recirculation (probably aids in suspension feeding)," Gibson said. "Our simulations suggest that these sorts of ecological dynamics, which are well-known in living animals, also helped to structure Ediacaran communities composed of organisms that are entirely mysterious to us.'"

Comment: it is obvious how different an early Cambrian was like, as they actively hunted for food. Not the normal small step advance in evolution, which demands the recognition of fresh design.

https://www.science.org/content/article/early-ocean-predator-was-giant-swimming-head?ut...

"The half-meter-long arthropod, described in a study out today, was essentially a giant “swimming head” that prowled the Cambrian seas half a billion years ago, says Joseph Moysiuk, a paleontologist at the University of Toronto (U of T) who helped uncover the fossil in 2018. “The first word that comes to mind when I think of this new species is big.”

"Titanokorys gainesi, whose head takes up nearly half the length of its body, was covered in a domed, spike-tipped carapace that inspired its Latin name: “Titan’s helmet.” The creature likely swam along the ocean floor, Moysiuk says, flushing prey from the mud with appendages built like “baskets of spines” (see video, above). And whereas its spiky helmet might have helped with that digging, its eyes, which sat at the back of its carapace, facing straight up, would have been useless for finding prey. Those were probably for spotting other predators—threats to Titanokorys itself.

***

"Titanokorys belongs to a diverse group of arthropods called radiodonts that split from the ancestors of spiders, insects, and horseshoe crabs by 520 million years ago, soon after the Cambrian explosion of animal diversity. At a time when vertebrates—the lineage that led to us—were little more than pinkie-size fish, radiodonts terrorized the Cambrian seas. The ranks of these now extinct creatures included Anomalocaris, a predator with front-facing eyestalks and a pair of clawlike appendages on its face, and Cambroraster falcatus, the species with the sleek head carapace reminiscent of Han Solo’s spaceship.

"All radiodonts shared three traits, Caron says: a circular mouth that looks like a pineapple cross-section and contains flesh-ripping teeth, a pair of spiny appendages in front of the mouth, and large compound eyes. This new species fits all those traits onto a supersize, carapace-covered head. Allison Daley, a paleontologist at the University of Lausanne who was not involved in the new research, says she is “delighted” by the find.

***

"Finding Titanokorys at the same site as Cambroraster underscores the diversity of Cambrian ecosystems, Caron adds—and the remarkable abundance of predators. Earth’s early seas must have had enough prey to feed a large range of hunters coexisting in the same space, including some animals that have so far eluded paleontologists."

Comment: The Cambrian still has new organisms to find. Same old Darwinian specter, no predecessor like it.

https://www.sciencedaily.com/releases/2021/08/210819195030.htm

"'The Great Unconformity is one of the first well-documented geologic features in North America," Peak said. "But until recently, we didn't have a lot of constraints on when or how it occurred."

"Now, she and her colleagues think they may be narrowing in on an answer in a paper published this month in the journal Geology. The team reports that a series of small yet violent faulting events may have rocked the region during the breakup of an ancient supercontinent called Rodinia. The resulting havoc likely tore up the earth around the canyon, causing rocks and sediment to wash away and into the ocean.

***

"Roughly 700 million years ago, basement rock in the west seems to have risen to the surface. In the eastern half, however, that same stone was under kilometers of sediment.

"The difference likely came down to the breakup of Rodinia, a gigantic land mass that began to pull apart at about the same time, Peak said. The researchers results suggest that this major upheaval may have torn at the eastern and western halves of the Grand Canyon in different ways and at slightly different times -- producing the Great Unconformity in the process."

Comment: That gets rid of the previous rather lame theory: erosion