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Fossils from the Lower Cambrian Yu'anshan Formation at Mafang (Figs. A-K) and Ercaicun (Fig. L) near Haikou, Kunming. All bar scales 10 mm except: C, I, 5 mm; L, 1 mm. Abbreviations: an, antenna; ap, appendage; as, axial spine; ex, exopodite; eye, compound eye; fc, free cheek; hs, head shield; leg, tentacle-like leg; te, trunk end. A) Three lobopodians (arrowed separately in different colors) of Microdictyon sinicum coexisting with their host Eldonia eumorpha (RCCBYU 10414). B) Fuxianhuia protensa (RCCBYU 10192), an adult with three juveniles (arrows). C) Eoredlichia intermedia with one free cheek detached (RCCBYU 10199). D) Four laterally compressed Leanchoilia illecebrosa (RCCBYU 10193). E) Concentration of exoskeletons of Yunnanocephalus yunnanensis (RCCBYU 10366). F) Dense accumulation of Yunnanozoon lividum (RCCBYU 10418). G) Eoredlichia intermedia (RCCBYU 10190). H) Xandarella spectaculum (RCCBYU 10191), with head shield, antennae and appendages preserved in separate laminae. I) Naraoia longicaudata (RCCBYN 10367) with nonsymmetry gut fillings (arrow). J) Dorsoventrally compressed Leanchoilia illecebrosa (RCCBYU 10194). K) Paucipodia inermis (RCCBYU 10186) preserved across two thin layers marked by the dark shadow. L) Kunmingella douvillei (RCCBYU 10196) with outstretched appendages and trunk.
The bad news for creationism continues with the publication of yet another paper refuting one of their central dogmas - the lie that the so-called 'Cambrian Explosion' was a sudden creation of all the basic body plans of the major phyla, without ancestors, in a single act of magical design and creation.
The creationist argument of course depends on a deliberate misrepresentation of the metaphorical use of the word 'explosion' in this context, which is used in biology to describe a relatively rapid radiation of new taxa such as frequently happens when the potential evolutionary landscape changes due either to a major geological/cosmological event, or due to the evolution of new capabilities such as air-breathing and terrestrial existence or flight, or, in plants, new methods of fertilisation such as pollen, resulting in the explosive radiation of flowering plants.
Creationist frauds pretend it is used literally, to mean a sudden single event.
There was a lesser-known but similar 'explosive' increase in biodiversity during the Ordovician (approximately 485 to 443 million years ago) - the Great Ordovician Biodiversification ‘Event’ (GOBE).
The Cambrian explosion is a term used to describe a rapid diversification of animal life that occurred approximately 541 million years ago during the Cambrian Period. It is considered to be one of the most significant events in the history of life on Earth, as it marked the appearance of the first complex animal forms
The Cambrian Period, which lasted from approximately 541 to 485 million years ago, was characterized by a rapid increase in biodiversity, with the emergence of a wide variety of animal phyla. Fossil evidence from this period shows the appearance of many new body plans, including those of arthropods, mollusks, echinoderms, and chordates. The diversification of these groups was likely driven by a combination of environmental and evolutionary factors, including the availability of new ecological niches and the evolution of new genetic and developmental pathways.
The Ordovician Period, which followed the Cambrian Period, also saw a significant increase in biodiversity. This period lasted from approximately 485 to 443 million years ago and was characterized by the emergence of new marine animal groups, including the first jawless fish and the first land plants. The Ordovician Period was also marked by a series of major extinction events, including the end-Ordovician extinction, which resulted in the disappearance of approximately 85% of marine species.
Recent research has shed new light on the causes and mechanisms of the Cambrian and Ordovician biodiversity explosions. For example, studies of the genetic and developmental pathways that control animal development have shown that the evolution of novel body plans and structures may have been facilitated by changes in gene regulation and the duplication and diversification of key genes. Other studies have suggested that changes in the composition of the Earth's atmosphere, including increases in oxygen levels, may have played a role in the diversification of animal life during this time.
References:ChatGPT3. Tell me all about the Cambrian and Ordovician biodiversity explosion, with references, please.[Response to user question]
- Erwin, D. H. (2015). The Cambrian Explosion: The Construction of Animal Biodiversity. Roberts and Company Publishers.
- Sepkoski, J. (1997). Biodiversity: Past, Present, and Future. Journal of Paleontology, 71(4), 533-539. doi:10.1017/S0022336000040026
- Budd, G. E., & Jensen, S. (2017). The origin of the animals and a ‘Savannah’ hypothesis for early bilaterian evolution. Biological Reviews, 92(1), 446-473.
- Knoll, A. H. (2003). Life on a young planet: The first three billion years of evolution on Earth. Princeton University Press.
- Signor, P. W., & Lipps, J. H. (Eds.). (1982). Evolutionary paleoecology of the marine biosphere. University of California Press.
- Valentine, J. W., Jablonski, D., & Erwin, D. H. (1999). Fossils, molecules and embryos: new perspectives on the Cambrian explosion. Development, 126(5), 851-859.
- Gould, S. J. (1990). Wonderful life: The Burgess Shale and the nature of history. WW Norton & Company.
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Creationist misrepresentation of the Cambrian radiation, which actually took several million years to occur, was sadly given some impetus by Stephen J Gould's book "Wonderful Life", in which, as a palaeontologist, he tried to explain an illusion.
The illusion is caused by the way time is compressed in the geological column, combined with the rarity of fossilisation, to look like a record of relatively sudden change. Gould invented the term, 'punctuated equilibrium' to explain this illusion, but never came up with a process by which it could happen. Despite the lack of such a mechanism, many people outside biology came to believe that 'punctuated equilibrium' had somehow replaced Darwinian evolution. Unfortunately, the debate become entangled with nationalism as many Americans, resentful of the fact that the discoverers of the most profound theory in science were British, not American, believed that Gould had discovered an 'American' replacement for the 'British' Darwinian evolution.
And of course, creationists, who like nothing better than a dead scientist who can't answer back to misrepresent, now represent Gould as some sort of creationist who believed in magical intervention at key periods in evolutionary history, despite the fact that he frequently asserted that he still believed mutation plus Darwinian natural selection was the fundamental cause of evolved biodiversity.
The major change that probably triggered the pre-Cambrian radiation was the evolution of mobility. The preceding Ediacaran biota had been sedentary so anything that could move had a defenseless supply of food. That, in turn produced pressure to detect predators and evolve defensive structures such as shells and eyes (both to see predators and to detect prey).
But anyway, a very recent paper by a team of French, British, German and Chinese scientists, led by Thomas Servais of the Université de Lille, France has scuppered the idea that the Cambrian and Ordovician biota were anything other than the result of continuing evolutionary processes.
The team carried out a systematic review of biodiversity curves of marine organisms during the early Palaeozoic, including some based on data in the Paleobiology Database (PBDB) and the Geobiodiversity Database (GBDB), and concluded that evidence of a sudden events in the Cambrian and the Ordovician "were not visible in our biodiversity studies, because they are either regional, or only reflect a single group of organisms". Instead, their study "points towards a single, large-scale, long-term early Palaeozoic radiation of life that already started in the late Precambrian".
In the abstract to their paper, the team say:
AbstractAnother day, another science publication and another refutation of basic creationist claims. And another piece of science to be ignored, misrepresented and lied about by the frauds who lead the creationist cult.
The Cambrian ‘Explosion’, located by many authors between 540 and 520 million years ago (Ma), is considered to be an abrupt appearance in the fossil record of most animal phyla, with a sudden increase of complex morphologies across metazoan groups. In a few recent papers, the Great Ordovician Biodiversification ‘Event’ (GOBE) has similarly been restricted to a single dramatic biodiversification ‘event’ in the Darriwilian Stage of the Middle Ordovician Series, between 470 and 455 Ma, although historically the biodiversification is considered as an aggregation of radiation ‘events’ capturing a large and complex increase of taxonomic diversity of marine invertebrates covering the entire Ordovician. A review of biodiversity curves of marine organisms during the early Palaeozoic, including some based on data in the Paleobiology Database (PBDB) and the Geobiodiversity Database (GBDB), points towards a single, large-scale, long-term early Palaeozoic radiation of life that already started in the late Precambrian. An abrupt ‘explosion’ of diversity in the Cambrian or a significant ‘event’ in the Ordovician are not visible in our biodiversity studies, because they are either regional, or only reflect a single group of organisms. It is evident that the datasets remain incomplete, in particular those for many geographical areas and for several fossil groups, that are not covered by the PBDB and GBDB; also, such areas remain so far poorly or entirely unstudied. Some recently published biodiversity curves have to be considered with care, as the truly global diversity estimates of marine organisms during the early Palaeozoic remain elusive. Here, we argue that published curves of taxonomic richness, which show distinct periods of diversification, cannot sufficiently be disentangled from biases. We therefore question the existence of a distinct Cambrian ‘Explosion’ and global Ordovician ‘Event’ in the global datasets. Both terms, Cambrian ‘Explosion’ and Great Ordovician Biodiversification ‘Event,’ should be used as conceptional terms only. The first represents the appearance of almost all animal phyla during the late Precambrian and early Cambrian, whereas the second terminology embraces the numerous and complex radiations that occurred during the entire Ordovician.
Servais, Thomas; Cascales-Miñana, Borja; Harper, David A.T.; Lefebvre, Bertrand; Munnecke, Axel; Wang, Wenhui; Zhang, Yuandong
No (Cambrian) explosion and no (Ordovician) event: A single long-term radiation in the early Palaeozoic
Palaeogeography, Palaeoclimatology, Palaeoecology (2023), 111592. DOI: 10.1016/j.palaeo.2023.111592
© 2023 Elsevier B.V.
Reprinted under the terms of s60 of the Copyright, Designs and Patents Act 1988.
I think that you are being too kind to Gould. His "discovery" (among snails) of the pretentiously named punctuated equilibrium was merely an example of the fact that evolutionary change is accelerated among members of a trophic web when that web is altered by an event such as immigration of a new species. He also promoted his ridiculous "non-overlapping magisteria", which is why I was not surprised to see him jump with both feet into the mob savaging Edmund Wilson.
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