Small primitive mammals live alongside a Triceratops, pre-extinction. A softshell turtle climbs up a log, unaware that its freshwater surroundings will shelter it from the asteroid.
Illustration © Henry Sharpe.
This, the second paper, published in 2022 that utterly refutes creationism on several different levels, reports evidence that particularly undermines their claim that an omnibenevolent god created a world fine-tuned for life.
This belief arises from a deeply ignorant, rose-tinted view of the world — one that conveniently ignores history and habitually attributes anything bad to something else: sin, free will, or other theological constructs that, by their own narrative, could only have applied after some supposed “fall”.
In reality, even a superficial understanding of Earth’s history — 99.9975 % of which took place before creationism’s legendary “Creation Week” — reveals that the planet is anything **but** fine-tuned for life. Life on Earth has repeatedly been subjected to mass extinctions triggered by geological and cosmological catastrophes that wreaked havoc on the environment, often at a pace too rapid for most species to adapt.
One of the most famous of these events was the meteor impact in what is now the Yucatán Peninsula, 66 million years ago. This strike plunged the planet into a “nuclear winter” as atmospheric dust blotted out the Sun. Within weeks, almost all large species were exterminated, leaving only the avian dinosaurs — likely shielded by insulating feathers — and early mammals, protected by their insulating fur.
But as this recent paper shows, the dinosaurs were thriving in a healthy, biodiverse environment in which they were the dominant species right up until the moment the meteor struck. Had they shared the creationists’ mindset, they might well have concluded that Earth was “fine-tuned” for them too.
The evidence for this comes from an international team of palaeontologists and ecologists, including researchers from University of Oulu (Finland), Universidade de Vigo (Spain), University of Washington (Seattle, USA), University College London (UK), New Mexico Museum of Natural History and Science (USA), and University of Edinburgh (UK).
Major Mass Extinctions in Earth’s History.Their findings are explained in a University of Edinburgh news release.
Event Approx. Date (million years ago) Likely Causes Major Groups Affected End-Ordovician extinction ~443 Ma Rapid glaciation and sea-level fall, followed by anoxia (oxygen depletion) ~85 % of marine species; many brachiopods, trilobites, bryozoans, and graptolites Late Devonian extinction ~372–359 Ma Global cooling, anoxia in oceans, possibly linked to plant expansion and changes in atmospheric CO₂ ~75 % of species; many reef-building organisms, trilobites, ammonites, jawless fish End-Permian extinction (“The Great Dying”) ~252 Ma Massive volcanic activity (Siberian Traps), global warming, ocean acidification and anoxia ~90–96 % of marine species and ~70 % of terrestrial vertebrates; trilobites, many insects, most amphibians End-Triassic extinction ~201 Ma Volcanism from Central Atlantic Magmatic Province, CO₂ rise, global warming ~80 % of species; many large amphibians and marine reptiles, conodonts Cretaceous–Paleogene extinction event (K–Pg) 66 Ma Meteor impact at Chicxulub crater, volcanic activity (Deccan Traps), global cooling ~75 % of species; non-avian dinosaurs, ammonites, marine reptiles, many plants (Bonus: Holocene extinction) (ongoing) ~11.7 ka–present Human activity: habitat loss, overexploitation, climate change Rapid loss of vertebrate species, especially large mammals, amphibians, and birds
Key Takeaways
- These events were global, often occurring over geologically short time spans.
- Most were triggered by natural phenomena — volcanism, meteor impacts, or climate shifts.
- Extinctions affected marine life most severely, though terrestrial life was also repeatedly decimated.
- Each event reset the ecological landscape, paving the way for new evolutionary radiations.
Dinosaurs were on the up before asteroid downfall
Dinosaurs dominated the world right up until a deadly asteroid hit the earth, leading to their mass extinction, some 66 million years ago, a study reveals.
Fresh insights into the habitats and food types that supported the dinosaurs suggest that their environments were robust and thriving, until the fateful day, at the end of the Cretaceous period.
Small primitive mammals live alongside a Triceratops, pre-extinction. A softshell turtle climbs up a log, unaware that its freshwater surroundings will shelter it from the asteroid.Illustration © Henry Sharpe.
Strong evidence
The findings provide the strongest evidence yet that the dinosaurs were struck down in their prime and were not in decline, at the time the asteroid hit.
Scientists have long debated why non-bird dinosaurs, including Tyrannosaurus rex and Triceratops, became extinct – whereas mammals and other species such as turtles and crocodiles survived.
The study, led by an international team of paleontologists and ecologists, analysed 1,600 fossil records from North America to find fresh answers.
Researchers modelled the food chains and ecological habitats of animals that lived on land and in freshwater during the last several million years of the Cretaceous and the first few million years of the Paleogene period, which followed the asteroid strike.
Diversification
Paleontologists have long known that many small mammals lived alongside the dinosaurs. But this research reveals that these mammals were diversifying their diets, adapting to their environments and becoming more important components of ecosystems as the Cretaceous unfolded. Meanwhile, the dinosaurs were entrenched in stable ecological niches to which they were supremely well adapted.
Mammals did not just take advantage of the dinosaurs dying, experts say. They were creating their own advantages through diversifying – by occupying new ecological niches, evolving more varied diets and behaviours and rapidly adapting to endure small shifts in climate.
Survival
Experts say these behaviours probably helped them to survive the asteroid strike, as they were better suited than the dinosaurs to cope with the radical and abrupt destruction.
Dinosaurs were going strong, with stable ecosystems, right until the asteroid suddenly killed them off. Meanwhile, mammals were diversifying their diets, ecologies and behaviours while dinosaurs were still alive. So it wasn’t simply that mammals took advantage of the dinosaurs dying, but they were making their own advantages, which ecologically preadapted them to survive the extinction and move into niches left vacant by the dead dinosaurs.
Professor Steve Brusatte, senior author.
School of GeoSciences
University of Edinburgh, UK.
Our study provides a compelling picture of the ecological structure, food webs, and niches of the last dinosaur-dominated ecosystems of the Cretaceous period and the first mammal-dominated ecosystems after the asteroid hit. This helps us to understand one of the age-old mysteries of paleontology: why all the non-bird dinosaurs died, but birds and mammals endured.
Jorge García-Girón, first author
Geography Research Unit
University of Oulu, Finland.
And Department of Biodiversity and Environmental Management
University of León, Spain.
It seems that the stable ecology of the last dinosaurs actually hindered their survival in the wake of the asteroid impact, which abruptly changed the ecological rules of the time. Conversely, some birds, mammals, crocodilians, and turtles had previously been better adapted to unstable and rapid shifts in their environments, which might have made them better able to survive when things suddenly went bad when the asteroid hit.
Alfio Alessandro Chiarenza, co-lead author
Department of Ecology and Animal Biology
University of Vigo, Spain.
Publication:
Abstract
It has long been debated why groups such as non-avian dinosaurs became extinct whereas mammals and other lineages survived the Cretaceous/Paleogene mass extinction 66 million years ago. We used Markov networks, ecological niche partitioning, and Earth System models to reconstruct North American food webs and simulate ecospace occupancy before and after the extinction event. We find a shift in latest Cretaceous dinosaur faunas, as medium-sized species counterbalanced a loss of megaherbivores, but dinosaur niches were otherwise stable and static, potentially contributing to their demise. Smaller vertebrates, including mammals, followed a consistent trajectory of increasing trophic impact and relaxation of niche limits beginning in the latest Cretaceous and continuing after the mass extinction. Mammals did not simply proliferate after the extinction event; rather, their earlier ecological diversification might have helped them survive.
INTRODUCTION
Sixty-six million years (Ma) ago, one of the largest and most transformative cataclysms of the Phanerozoic occurred, when a ~10-km-wide extraterrestrial bolide struck the Yucatán Peninsula, in the Gulf of Mexico (1–4). This impact caused a panoply of ecological and environmental catastrophes, including tsunamis and wildfires, as well as global darkness (i.e., an “impact winter”) due to the injection of sunlight-blocking debris and climate-forcing gases into the atmosphere (1, 5, 6). These upheavals destabilized all trophic levels and triggered severe extinctions that spread devastation worldwide (2). In terrestrial environments, all non-avian dinosaurs, “archaic” birds, and pterosaurs vanished following the impact (7–9), while other groups, such as mammals (10, 11) and squamates (12), suffered considerable losses. On the other hand, groups such as freshwater salamanders, turtles, and crocodylians seemingly survived nearly unscathed (13). In the aftermath of this Cretaceous/Paleogene (K/Pg) mass extinction, surviving lineages recovered relatively rapidly (13–16), accompanied by concomitant ecospace shifts that favored their expansion into vacated niches and large-scale explosive radiations in placental mammals (17, 18), neornithine birds (8, 19), and squamates (20), laying the foundations for the diverse range of faunas that we share the planet with today.
It is widely postulated that the extinction of the non-avian dinosaurs resulted in empty niches and novel ecological opportunities for surviving organisms. This paradigm is based almost exclusively on taxonomic (11, 21), morphological (10, 22), and phylogenetic (14, 23) evidence. Mass extinctions, however, act on the structure and function of ecosystems. Much less understood is how the ecology of dinosaurs, mammals, and other terrestrial animals changed in the lead-up to and aftermath of the extinction event. Focusing on functional and trophic ecology, rather than on the classic trends in biostratigraphic ranges (24), can help disentangle the potential ecological drivers of survivorship and recovery. Understanding the ecological dynamics of the latest Cretaceous faunal components is central to answering two long-standing questions. First, were non-avian dinosaurs in long-term decline before their end-Cretaceous demise (9, 25–31)? Second, why were some members of the terrestrial and freshwater biota (e.g., mammals, lizards, neornithine birds, and crocodylians) able to survive the mass extinction but not others?
These questions can be addressed by modeling long-term patterns in food webs (31, 32) and ecospace occupancy dynamics (i.e., the multidimensional combination of paleoenvironmental conditions under which species developed) (29, 33). Direct fossil evidence of trophic interactions is still limited (32, 34), but methodological advances in network theory (35) and ecological niche partitioning (36) might hold the key to long-standing questions about food web stability and the functional roles of species in ancient ecosystems, both of which are at the core of modern evolutionary and ecological research (34, 37–39). Although the application of these emerging approaches is not yet commonplace in paleontology, a few studies have demonstrated that they are ideal tools for revealing species habitat distributions in deep time (6, 29, 33, 40) and the tempo and mode of ecological reorganization after mass extinctions (37–39).
Here, we quantify the magnitude of ecological change before and after the K/Pg boundary, from the Campanian stage of the Late Cretaceous to the Danian stage of the early Paleogene (83.6 to 61.6 Ma ago). Our analyses are based on a spatiotemporally and taxonomically standardized presence-only dataset (Fig. 1A), comprising more than 1600 fossil occurrences representing more than 470 genera of cartilaginous and bony fish, salamanders, frogs, albanerpetontids, lizards, snakes, champsosaurs, turtles, crocodylians, dinosaurs (including birds), and mammals (e.g., table S1) across the best sampled region representing this interval (9), the Western Interior of North America [sensu Gardner and DeMar (41)]. This region includes the highly fossiliferous western subcontinent, Laramidia, which, during much of the Late Cretaceous, was separated from its eastern counterpart, Appalachia, by an epicontinental seaway stretching from present-day Alaska to Mexico. Using a spatially explicit Markov network approach (Fig. 1, B and C) (42, 43) and state-of-the-art Earth System models (Fig. 1D) (44–46), in combination with multivariate niche-modeling techniques (Fig. 1E) (47), we simulate how inferred trophic dynamics and niche occupancy patterns shaped the trajectories of North American continental ecosystems across the latest Cretaceous and during the recovery from the mass extinction. By doing so, we explicitly test whether (i) shifts in food web architecture underwent major restructuring before and after the K/Pg extinction, including whether some trophic guilds were more prone to these shifts than others; and (ii) any of these changes were associated with fluctuations in the realized niche space, helping to explain why some groups survived and others went extinct across the K/Pg boundary.
Fig. 1. Graphical scheme synthesizing the essential statistical routines used to reconstruct food web dynamics and quantify ecological niche partitioning in a set of hypothetical Maastrichtian (72.1 to 66.0 Ma ago) dinosaur communities across the ancient landscape of Laramidia.
Briefly, (A) our dataset represents the record of North American tetrapod faunas, in which taxa were assigned to different trophic guilds using three ecological parameters (broad habitat-use types, body size, and feeding habits). We then built on (B) empirical spatial covariations to explore a map of dependencies between the residual signals of the Sørensen dissimilarities (i.e., n × n β-diversity matrices, n being the number of fossil localities s) without any a priori network structure (35, 99). (C) Conditional dependencies using partial correlation networks were estimated from the variance-covariance and precision matrices, and the overall importance of every trophic group on the food web architecture was inferred using the weighted degrees (50) and eigenvector centrality scores (51). Then, (D) we used a combination of state-of-the-art Earth System models (44–46) to create the paleoclimatic, land surface, and paleogeographical envelopes, and (E) ran the outlying mean index (OMI) approach (47) to obtain the marginality of species distributions (i.e., the Euclidean distances between the position of each group’s species center of gravity, the colored points within each polygon, and the average paleoenvironmental conditions O) and the realized species niche breadth (i.e., the corresponding polygon extent or the range of habitat conditions used by species). In this example, (C) partial correlation networks showed strong interactions between herbivorous and faunivorous dinosaurian guilds (34). (E) Giant theropods and their largest prey used relatively similar habitat conditions, although megaherbivores occupied a larger part of the available niche as a result of their potentially more cosmopolitan distribution in North America (133). Silhouettes and pictures were obtained from Wikimedia Commons (see Acknowledgments).
Jorge García-Girón et al.
Shifts in food webs and niche stability shaped survivorship and extinction at the end-Cretaceous.
Sci. Adv. 8, eadd5040 (2022). DOI:10.1126/sciadv.add5040
Copyright: © [year] The authors.
Published by [publisher]. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
What this paper exposes, once again, is the fatal flaw in the “fine-tuning” argument beloved of creationists. If a benevolent creator deliberately designed a world to support life, it would hardly be one in which life is periodically and indiscriminately wiped out by catastrophic, natural events on a global scale. The idea that Earth was purpose-built for human life is not only anthropocentric but also demonstrably false. The geological and fossil records show a planet that is indifferent to the survival of its inhabitants, shaped by chance and natural forces — not design.
Mass extinctions have been among the most powerful forces shaping the history of life on Earth. Each one acted as a reset button on evolution, wiping out vast numbers of species and altering entire ecosystems. Far from being rare anomalies, these catastrophic events are woven throughout Earth’s deep history. They are not signs of a carefully adjusted biosphere designed to nurture life, but rather of a dynamic and often hostile planet where survival depends on adaptation — or sheer luck.
This repeated pattern of flourishing ecosystems abruptly collapsing under the weight of geological or cosmological disaster stands in stark contrast to the notion of a benevolent designer or a fine-tuned world. If the planet were designed for life, it would not periodically and indiscriminately exterminate most of its living inhabitants.
Equally significant is the timescale involved. Life has existed on this planet for around 3.8 billion years, but humans have occupied it for less than 0.01 % of that time. For the vast majority of Earth’s history, humans — or any large-brained primates — simply did not exist. Entire empires of life rose and fell before our species appeared. This immense sweep of deep time makes it clear that the planet was not created with humanity in mind. Rather, we are the beneficiaries of chance — the survivors of one particular ecological lottery, living in the aftermath of countless extinctions that paved the way for our evolution.
The “fine-tuning” argument relies on a selective, present-centred view of the world. But when viewed through the lens of palaeontology and geology, Earth’s true character emerges: a place of impermanence, upheaval, and indifference. Life thrives here not because the world was designed for it, but because life is resilient and adaptable enough to survive in spite of the planet’s volatility.
Earth is not fine-tuned for life; life is fine-tuned for Earth and evolution is the process that keeps it in tune.
Advertisement
What Makes You So Special? From The Big Bang To You
How did you come to be here, now? This books takes you from the Big Bang to the evolution of modern humans and the history of human cultures, showing that science is an adventure of discovery and a source of limitless wonder, giving us richer and more rewarding appreciation of the phenomenal privilege of merely being alive and able to begin to understand it all.
Ten Reasons To Lose Faith: And Why You Are Better Off Without It
This book explains why faith is a fallacy and serves no useful purpose other than providing an excuse for pretending to know things that are unknown. It also explains how losing faith liberates former sufferers from fear, delusion and the control of others, freeing them to see the world in a different light, to recognise the injustices that religions cause and to accept people for who they are, not which group they happened to be born in. A society based on atheist, Humanist principles would be a less divided, more inclusive, more peaceful society and one more appreciative of the one opportunity that life gives us to enjoy and wonder at the world we live in.
Amazon
Amazon
Amazon
Amazon
Amazon
Amazon
Amazon
Amazon
All titles available in paperback, hardcover, ebook for Kindle and audio format.
Prices correct at time of publication. for current prices.
No comments:
Post a Comment
Obscene, threatening or obnoxious messages, preaching, abuse and spam will be removed, as will anything by known Internet trolls and stalkers, by known sock-puppet accounts and anything not connected with the post,
A claim made without evidence can be dismissed without evidence. Remember: your opinion is not an established fact unless corroborated.