Rosa Rubicondior: Refuting Creationism - A Mass Extinction 252 Million Years Before 'Creation Week'

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Image: Mark P. Witton

March: Amphibians bounce-back from Earth’s greatest mass extinction | News and features | University of Bristol

The thing about mass extinctions, apart from the fact that they occurred so long before creationists dogma says there was even a universe, is that they refute any notions of a planet fine-tuned for life, or any notions of a perfect creator creating all life as it is today. In fact, it was the growing interest in palaeontology and the growing realisation that the fossil record contained so many extinct species, which caused people to start to question the notion of divine creation by a perfect god.

It was also the existence of so many intermediate fossils and series showing progressive change over time that fostered the idea of evolutionary change, although, until Darwin and Wallace thought of evolution by natural selection, how it worked was a matter of speculation.

The end-Permian mass extinction was one of the most significant events in the history of life on Earth - a history, 99.9975% of which occurred before creationists think their little god created the small flat planet with a dome over it in the Middle East, that creationists like to imagine was the entire universe.

However, fortunately for subsequent life on the planet, and without whom it is unlikely that humans would exist, a handful of species survived, most notably some amphibians.

Tell me all about the end-Permian mass extinction event, 252 million years ago, and the species that survived it, please. The end-Permian mass extinction, also known as the Great Dying, occurred around 252 million years ago, marking the boundary between the Permian and Triassic periods. It is the most significant extinction event in Earth's history, with an estimated 90-96% of all marine species and around 70% of terrestrial species going extinct. The event caused a massive reshaping of Earth's ecosystems, leading to a major reorganization of life on the planet.

Causes of the End-Permian Mass Extinction

The exact causes of the end-Permian mass extinction are still debated, but a combination of factors likely played a role:

Volcanic Activity: Massive volcanic eruptions in the Siberian Traps (a large volcanic province in modern-day Siberia) released vast amounts of carbon dioxide (CO₂), sulphur dioxide (SO₂), and other gases into the atmosphere. The increased CO₂ likely caused global warming, while the SO₂ could have led to acid rain and a reduction in solar radiation, creating a harsh environment.
Climate Change: The increase in greenhouse gases from volcanic activity led to a dramatic rise in global temperatures (possibly up to 10°C). This warming likely triggered a cascade of environmental changes, such as ocean acidification, disruption of the carbon cycle, and the collapse of ecosystems.
Oceanic Anoxia: The warming of the oceans may have led to a reduction in oxygen levels, causing vast regions of the oceans to become anoxic (lacking oxygen). This would have been deadly for marine life.
Methane Release: Warming could have also triggered the release of methane from the ocean floor, further exacerbating global warming in a feedback loop.
Impact Events: Some evidence suggests that meteorite impacts may have contributed to the extinction, though this theory is less widely accepted than others.
Impact on Life

The end-Permian extinction event had devastating effects on both marine and terrestrial ecosystems:

Marine Life: The majority of marine species went extinct, including trilobites, brachiopods, and many forms of coral. Reef ecosystems collapsed due to the rise in ocean temperatures and acidification, leading to the extinction of reef-building organisms.
Terrestrial Life: On land, the extinction affected many groups, including large amphibians, early reptiles, and synapsids (mammal-like reptiles). Plant life was also severely impacted, with many species of ferns and seed plants disappearing.
Species that Survived

Despite the catastrophic loss of biodiversity, some species and groups managed to survive the end-Permian mass extinction and eventually diversify in the aftermath:

Therapsids: These were mammal-like reptiles, and while many species went extinct, some survived. They would later evolve into the first true mammals in the Triassic period.
Archosaurs: This group, which includes the ancestors of crocodiles, dinosaurs, and birds, emerged in the aftermath of the extinction and became dominant during the Mesozoic era.
Amphibians: While many amphibian groups were decimated, some survived, particularly those adapted to aquatic environments. These included early frogs and salamanders.
Sharks: Some shark species survived the extinction, and their lineages would go on to thrive throughout the Mesozoic era.
Bivalves and Brachiopods: Although many species went extinct, certain bivalves (such as clams) and some brachiopods survived and diversified after the event.
Conifers and Ferns: While many plant species disappeared, some conifers (early gymnosperms) and ferns were able to survive and later become the dominant plant life in the Triassic.
Insects: Insects as a whole were highly resilient to the extinction event. Many insect groups survived and continued to thrive after the extinction, with significant diversification in the Triassic.
Ecological Recovery

After the end-Permian extinction, it took millions of years for ecosystems to fully recover. The Triassic period saw the rise of new groups of organisms, with dinosaurs and mammals emerging as dominant forms of life. Ecosystem recovery was slow, and many niches were vacant for extended periods, allowing for the evolution of new species and groups.

In the ocean, the recovery of coral reefs was slow, with new species of corals evolving to fill the ecological void. On land, the extinction allowed for the rise of new plant groups, including the first true dinosaurs and early mammals, which would diversify and thrive in the Triassic and beyond.

Legacy of the End-Permian Extinction

The end-Permian mass extinction had a profound impact on the course of evolution, reshaping life on Earth. The extinction event wiped out many major groups, but it also paved the way for the rise of new species and groups, including the dinosaurs, which would go on to dominate life on Earth for the next 135 million years. The event also marked the beginning of the Mesozoic era, often referred to as the "Age of Dinosaurs."

This event is still studied by scientists today, as it serves as a powerful example of the impact of environmental changes and mass extinctions on the history of life.

Quite why this was so, and what qualities they had that enabled them to survive when 70% of terrestrial species and 90-95% of marine species went extinct has long been a mystery in evolutionary biology.

Now, research by Bristol University academics have shed light on this problem. They have just published their findings, open access, in the journal, Royal Society Open Science. Their work is explained in a Bristol University news item:

Amphibians bounce-back from Earth’s greatest mass extinction
Ancient frog relatives survived the aftermath of the largest mass extinction of species by feeding on freshwater prey that evaded terrestrial predators, University of Bristol academics have found.
In the study, published today in the journal Royal Society Open Science, their findings suggest the amphibians’ success lay in their generalist feeding ecology, enabling them to feed on a wide variety of prey despite the array of environmental changes happening all around them through the Triassic.

Broader examination of Triassic ecosystems also indicates that the freshwater habitats they preferred provided them with a relatively stable variety of food resources, allowing them to thrive while strictly terrestrial predators made do with meagre, unstable resource availability on land.

The end-Permian mass extinction event, 252 million years ago, was the largest ever, marked by the loss of as many as 90% of species. A key line of research has been to focus on the survivors and their fate in the Triassic, the timespan that followed the Permian.

One of the great mysteries has been the survival and flourishing of a major group of amphibians called the temnospondyls. These were predatory animals that fed on fishes and other prey, but were primarily linked to the water, just like modern amphibians such as frogs and salamanders. We know that climates then were hot, and especially so after the extinction event. How could these water-loving animals have been so successful?

Aamir Mehmood, first author
School of Biological Sciences
University of Bristol, Bristol, UK.

The Early Triassic was a time of repeated volcanic activity leading to long phases of global warming, aridification, reductions in atmospheric oxygen, acid rain and widespread wildfires, creating conditions so hostile that the tropics became devoid of animal life. This ‘tropical dead zone’ drastically impacted the distributions of both marine and terrestrial organisms.

We collected data on 100 temnospondyls that lived throughout the Triassic and wanted to look at how their ecologies changed. We measured their body sizes and features of the skulls and teeth that tell us about function.

Dr Suresh A. Singh, co-author.
School of Biological Sciences
University of Bristol, Bristol, UK.

Much to our surprise, we found that they did not change much through the crisis. The temnospondyls showed the same range of body sizes as in the Permian, some of them small and feeding on insects, and others larger. These larger forms included long-snouted animals that trapped fishes and broad-snouted generalist feeders. What was unusual though was how their diversity of body sizes and functional variety expanded about 5 million years after the crisis and then dropped back.

Dr Armin Elsler, co-author
School of Biological Sciences
University of Bristol, Bristol, UK.

Due to the intense global warming of the first five million years of the Triassic, there is evidence that life on land and in the sea moved away from the tropics to avoid the heat.

Our work shows that the temnospondyls, unexpectedly, were able to cross the tropical dead zone. Fossils are known from South Africa and Australia in the south, as well as North America, Europe and Russia in the north. The temnospondyls must have been able to criss-cross the tropical zone during cooler episodes.

Professor Michael J. Benton, lead author
School of Biological Sciences
University of Bristol, Bristol, UK.

Their burst of success in the Early Triassic was not followed up. They coped with the hot conditions probably by having a low requirement for food, by being able to eat most prey animals, and by hiding in sparse water bodies. But when the ancestors of dinosaurs and of mammals began to diversify in the Middle Triassic, the temnospondyls began their long decline.

Aamir Mehmood.

Abstract
One of the mysteries of the Permian–Triassic mass extinction was the subsequent success of temnospondyls. Temnospondyls were key early tetrapods in the Carboniferous and Permian and hardly seem to be ideal pioneers in a tough post-extinction world. Did they survive because of some unusual adaptations or by occupying some limited part of the world? We explore temnospondyl success in the Triassic by comparing their functional ecomorphology and palaeogeographic distributions. We find that Early Triassic temnospondyls exhibited all skull sizes and shapes, reflecting a wide diversity of feeding modes: abundant parabolic-snouted forms, and less common longirostrine (long-snouted) and insectivorous (short-skulled) forms. In fact, morphospace occupation by temnospondyls increased dramatically from Late Permian to Early Triassic, and then decreased in the Middle Triassic, but without emphasis on one feeding mode or another. Nor is there any evidence for unusual patterns of evolution: Temnospondyli and subclade Trematosauria follow an Ornstein–Uhlenbeck evolutionary model, suggesting evolution towards a common skull shape. Metoposauroidea, Brachyopoidea and basal Stereospondyli evolved by the stasis model. Further, these Early Triassic temnospondyls did not occupy a limited part of the world; they show temperate distributions, but with some specimens in equatorial regions, contradicting the idea of a permanently impermeable tropical dead zone.

1. Introduction
The temnospondyls were a clade of some 300 species that existed from the Carboniferous to Cretaceous (350–120 Ma, million years ago). They were traditionally classed as amphibians but are more properly called anamniote tetrapods. Temnospondyls were mostly from 0.5 to 3 m long, but some giants reached 6 m, and they occupied various terrestrial, amphibious, and aquatic niches [1–5]. Temnospondyls flourished in the Carboniferous and Permian and declined in diversity in the Late Permian. The great mystery is that, although like so many other groups, they were hit hard by the Permian–Triassic mass extinction (PTME; 252 Ma), they diversified rapidly in the post-extinction ‘hothouse’ of the Early Triassic [6–8], giving rise to numerous lineages (figure 1a) that continued at diminishing diversity through the remainder of the Triassic, with a few species surviving into the Jurassic and Cretaceous. Early Triassic temnospondyls have been found in India, Pakistan, Greenland, Norway, Australia, South Africa and the USA [2,11–13], representing a mix of freshwater, terrestrial and, rarely, marine conditions: this highlights their Early Triassic diversity peak, which exceeded that of their previous diversity peak in the Early Permian [7].

Figure 1. Temnospondyls of the Triassic. (a) simplified phylogeny of the temnospondyl clades investigated here, with two paraphyletic assemblages, ’basal temnos’ and basal ’stereos’. Amphibamiformes are a clade within Dissorophoidea, comprising Micropholidae and Lissamphibia. Branches stemming from coloured nodes depict subclades of this node. (b) three functional groupings based on skull morphology: large parabolic skulls characteristic of generalists such as extant crocodilians; generalist insectivore with short and wide skulls as in modern frogs; and longirostrine, adapted for fast, weak bites usually in fish eating, as in modern gharials. Abbreviations: Stereo., Sterospondyli; Temno., Temnospondyli. Silhouette images from Phylopic (https://www.phylopic.org: Dmitry Bogdanov (Metoposaurus, Lydekkerina, Batrachosuchus, Pelorocephalus, Trematosaurus) all CC0 3.0; Steven Traver (Dendrobates) CC0 1.0). Nix Draws Stuff/Nix illustration (Eryops) CC0 4.0. Silhouette images from Wikimedia Commons (https://commons.wikimedia.org: Smokeybjb (Eolydekkerina magna, Deltasaurus kimberleyensis); Nobu Tamura (Gerrothorax BW and Wetlugasaurus BW) all CC0 3.0). Vector graphics: Mike Prince (Gharial) CC0 2.0; Momotarou2012 (Andrias japonicus) CC0 3.0; CDC (African Dwarf Frog) Public Domain. Skull Graphics vectorized by AM; Aphaneramma [9]; Cyclotosaurus [1] and Triadobatrachus [10].

The Early Triassic was a time of repeated volcanism leading to phases of global warming, aridification, reductions in atmospheric oxygen, acid rain and widespread wildfires [14], even creating conditions so hostile that the tropics became devoid of animal life; this ‘tropical dead zone’ (TDZ) [15] drastically impacted the distributions of both marine and terrestrial organisms [16–18]. Only when global climates stabilized, in the Middle Triassic, did other forms of life recover [19], but temnospondyls began their long decline. Their brief post-PTME flourish has seen temnospondyls labelled as ‘disaster taxa’ [6,7,13,20]. Nonetheless, temnospondyls remained prominent members of later Triassic faunas, even as climates fluctuated between humid equatorial monsoonal conditions and hot, dry, seasonal conditions [21].

How and why did temnospondyls undergo this second, Mesozoic, diversification? We explore three themes to seek answers. Were these earliest Triassic temnospondyls unusually small, an adaptation to post-extinction grim environmental conditions termed the ‘Lilliput effect’?—previous studies are equivocal [3,8,13]. Second, as ‘disaster taxa’ (early diversifying survivors of a mass extinction), we might expect that they would show some different adaptations from relatives that lived in more normal times, or that they would differ substantially in size, or occupy specific habitats and/or niches. Third, we might expect some evidence that these disaster taxa were successful in a particular region of the world where physical conditions and coeval faunal elements were favourable. Overlying all such studies are concerns about incompleteness of the data, and we consider this issue too.

The peak in temnospondyl diversity was identified in previous work [7,8] as well as expansion of morphospace represented by differing skull shapes [22–25]. Here, we explore the body size, feeding ecology, disparity, and biogeographic distributions of temnospondyl morphology through the Triassic. We apply a variety of computational approaches in morphometrics, and macroevolutionary and palaeobiogeographic modelling to establish an appropriate numerical regime in which to test hypotheses for temnospondyl success and decline following the PTME. Our aim is to understand changes in temnospondyl ecospace occupation through this time, the phylogenetic structure of such changing patterns, and overall global palaeogeographic distribution as the clade expanded and shrank in the early Mesozoic.

Mehmood Aamir, Singh Suresh A., Elsler Armin and Benton Michael J. (2025)
The ecology and geography of temnospondyl recovery after the Permian–Triassic mass extinction R. Soc. Open Sci. 12241200 http://doi.org/10.1098/rsos.241200

Copyright: © 2025 The authors.
Published by The Royal Society. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

Beyond the fact that this mass extinction occurred 252 million years before ‘Creation Week’, it is entirely incompatible with the idea of an Earth fine-tuned for life or species designed by an omnibenevolent, omniscient creator, there’s an additional challenge for creationists who cling to the absurd belief that mainstream biologists are on the verge of abandoning the Theory of Evolution in favor of their simplistic supernatural narrative. The scientists behind this study had no doubts that evolution provided the best explanation for the evidence. The only question was how this natural process led to an initial rapid diversification of the surviving temnospondyls, followed by a gradual decline over millions of years as dinosaurs emerged and thrived.

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