Cambrian explosion

These animal groups lived in the ocean over half a billion years ago but were buried by a subterranean mudflow: Paleontologists found thousands of fossils in rocks on the bank of the Danshui river in Hubei province in southern China, where primitive forms of jellyfish, sponges, algae, anemones, worms and arthropods with thin whip-like feelers were entombed in an ancient underwater mudslide. The creatures are so well preserved in the fossils that the soft tissues of their bodies, including the muscles, guts, eyes, gills, mouths and other openings are all still visible. The 4,351 separate fossils excavated so far represent 101 species, 53 of them new.Ian Sample, “‘Mindblowing’ haul of fossils over 500m years old unearthed in China” at The Read More ›

The explosion lasted only about 20 million years, their research shows, and the subsequent 520 million years featured more even rates of change: At (or shortly before) the start of the Cambrian Period (541 million years ago), modern animals evolved. They rapidly diversified into all the major groups (phyla) of animals we see today, such as jellyfish and corals, segmented worms (such as earthworms), molluscs (such as snails), arthropods (such as crabs), and even vertebrates (backboned animals, which eventually included ourselves)… If modern animals first evolved at the very beginning of the Cambrian, then their global adaptive radiation took a mere 20 million years. While this is still substantial, it represents only 0.5% of the 3.5-billion-year history of life on Read More ›

Okay, okay, not bringing them to “life” but giving us a much better sense of life over half a billion years ago. The Canadian Rockies have, it turns out,  many more Cambrian sites than the big 1909 find that lay neglected at the Smithsonian so long: Each new stop has offered striking views of unfamiliar animals, many already described in high-profile papers: the little fish relative Metaspriggina, a vertebrate ancestor that Caron now speculates clustered in schools; the pincered Tokummia; and the ice cream cone–shaped fossils called hyoliths, which Caron’s Ph.D. student Joseph Moysiuk last year linked to shelled animals called brachiopods, some of which persist today. New finds in various parts of the world generate new interpretations: In fossils of the Read More ›

Explanations of the dramatic Cambrian explosion of life forms (540 million years ago) are a cottage industry, with arguments about oxygen a staple of the discussion. See, for example, Maverick theory: Cambrian animals remade the environment by generating oxygen Did a low oxygen level delay complex life on Earth? There was only a small oxygen jump Animals didn’t “arise” from oxygenation, they created it, researchers say Theory on how animals evolved challenged: Some need almost no oxygen New study: Oxygenic photosynthesis goes back three billion years Enough O2 long before animals? Life exploded after slow O2 rise? So the Cambrian really WAS an explosion then? and finally, Researchers: Cambrian explosion was not an explosion after all (When in doubt, insist that nothing happened.) And this Read More ›

From ScienceDaily: The creature belongs to an obscure and mysterious group of animals known as the chancelloriids, and scientists are unclear about where they fit in the tree of life. They represent a lineage of spiny tube-shaped animals that arose during the Cambrian evolutionary “explosion” but went extinct soon afterwards. In some ways they resemble sponges, a group of simple filter-feeding animals, but many scientists have dismissed the similarities as superficial. … It was surprisingly large in life (perhaps up to 50 cm or more) but had only a few very tiny spines. Its unusual “naked” appearance suggests that further specimens may be “hiding in plain sight” in fossil collections, and shows that this group was more diverse than previously Read More ›

Readers may remember a recent paper that tried to show that the Cambrian explosion was not really an explosion after all. From Gunter Bechly at ENST: The paper allegedly settles the case in favor of a more gradual pattern of appearance as predicted by Darwin’s theory. That would be big news indeed, if it were true. Darwinists bloggers are thrilled To judge from the hype, you might expect that the authors of the new paper have discovered a well-dated temporal transitional series of fossils, documenting a gradual evolution stretched out over a long period of time, rather than an explosive event. Well, far from that. Actually, the article presents no new fossil evidence, no new phylogenetic studies, nor any new Read More ›

From Harry Pettit at the Daily Mail: The ‘Cambrian explosion’ is one of the most significant events in the planet’s 4.5-billion-year history and ultimately led to the arrival of complex animals like humans. New research shows the event – which took place between 500 and 540 million years ago – was a much more gradual process than first thought. More. Via Eurekalert: A team based at Oxford University Museum of Natural History and the University of Lausanne carried out the most comprehensive analysis ever made of early fossil euarthropods from every different possible type of fossil preservation. In an article published today in the Proceedings of the National Academy of Sciences they show that, taken together, the total fossil record Read More ›

Abstract: We review the salient evidence consistent with or predicted by the Hoyle-Wickramasinghe (H-W) thesis of Cometary (Cosmic) Biology. Much of this physical and biological evidence is multifactorial. One particular focus are the recent studies which date the emergence of the complex retroviruses of vertebrate lines at or just before the Cambrian Explosion of ∼500 Ma. Such viruses are known to be plausibly associated with major evolutionary genomic processes. We believe this coincidence is not fortuitous but is consistent with a key prediction of H-W theory whereby major extinction-diversification evolutionary boundaries coincide with virus-bearing cometary-bolide bombardment events. A second focus is the remarkable evolution of intelligent complexity (Cephalopods) culminating in the emergence of the Octopus. A third focus concerns the micro-organism Read More ›

 Darwin’s Doubt deals with the Cambrian explosion of life forms about 550 million years ago. Philip Cunningham, who forwarded this link, notes, Stephen Meyer joins Michael to discuss the origins of life and the biology’s big bang, the Cambrian explosion. Animal forms come and go, but what links them as “acts of mind” (as Agassiz put it) is a “continuity of ideas,” not, says Meyer, the physical continuity that Darwin asserted. These are wonderful ways of putting things. Meyer also discusses the 2016 Royal Society meeting attended by a “spirited minority” of ID proponents, where one evolutionist put it that “criticism of neo-Darwinism is so early ’90s.” He meant that among scientists behind closed doors, neo-Darwinism itself is so Read More ›

Remember Gunter Bechly, the paleontologist who got erased from Wikipedia *? At ENST, he says, Based on the Darwinian narrative, we should expect not only that morphological complexity increases gradually in the fossil record, but we should also expect the same for complex animal behavior. This is because according to Darwinists, “Evolution not only is a gradual process as a matter of fact, but…it has to be gradual if it is to do any explanatory work” (Dawkins 2009). Charles Darwin himself strictly insisted on gradualism and famously quoted the Latin phrase “natura non facit saltus” (“nature does not make jumps”) no fewer than six times in his Origin of Species. He realized that any kind of significant saltational change would Read More ›

From ScienceDaily: In the history of life on Earth, a dramatic and revolutionary change in the nature of the sea floor occurred in the early Cambrian (541–485 million years ago): the “agronomic revolution.” This phenomenon was coupled with the diversification of marine animals that could burrow into seafloor sediments. Previously, the sea floor was covered by hard microbial mats, and animals were limited to standing on, resting on, or moving horizontally along those mats. In the agronomic revolution, part of the so-called Cambrian Explosion of animal diversity and complexity, vertical burrowers began to churn up the underlying sediments, which softened and oxygenated the subsurface, created new ecological niches, and thus radically transformed the marine ecosystem into one more like that Read More ›

From Jordana Cepelewicz at Quanta: For decades, researchers have commonly assumed that higher oxygen levels led to the sudden diversification of animal life 540 million years ago. But one iconoclast argues the opposite: that new animal behaviors raised oxygen levels and remade the environment. … n a paper published in the January issue of Geobiology, Butterfield braided fluid dynamics and ecology to present his case for animals driving oxygenation instead of the other way around. First, he argued, if there was enough oxygen to power unicellular eukaryotes 1.6 billion years ago — which was indeed the case — then there would have been enough to run a whole assortment of animals. He believes early multicellular organisms would have consisted of Read More ›

From Andrew Urevig at National Geogaphic: Contradicting some previous accounts, the team argues that this new evidence appears to show that the common ancestor of all panarthropods did not have a complex three-part brain—and neither did the common ancestor of invertebrate panarthropods and vertebrates. … That structure can be traced back through the fossil record. Kerygmachela’s relatively simple brain, preserved as thin films of carbon, includes only the foremost of the three segments present in living arthropods. The researchers are relying on the remarkably hardy tardigrade (water bear) as a surviving example. Not everyone agrees: Tardigrade brains may or may not develop based on segments at all, says Nicholas Strausfeld, a neuroscientist at the University of Arizona who was not Read More ›