Big fish, little fish in Permian-Triassic mass extinction


This video says about itself:

The Permian-Triassic extinction event, informally known as the Great Dying, was an extinction event that occurred 252 million years ago, forming the boundary between the Permian and Triassic geologic periods, as well as the Paleozoic and Mesozoic eras.

It is the Earth’s most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It is the only known mass extinction of insects. Some 57% of all families and 83% of all genera became extinct. Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after any other extinction event, possibly up to 10 million years.

Catastrophe by Tony Robinson (2008).

From the University of Bristol in England:

Size not important for fish in the largest mass extinction of all time

June 30, 2017

Understanding modern biodiversity and extinction threats is important. It is commonly assumed that being large contributes to vulnerability during extinction crises.

However, researchers from the University of Bristol and the Chengdu Center of the China Geological Survey, have found that size played no role in the extinction of fish during the largest mass extinction of all time.

The study focused on the evolution of bony fishes during the Permian-Triassic mass extinction 252 million years ago. During this crisis, as many as 90 percent of all species on Earth were killed by massive climate change triggered by huge volcanic eruptions in Russia.

The erupted gases led to worldwide acid rain and atmospheric warming of as much as 20 degrees centigrade. This killed plants, and soil was stripped by rainfall and washed into the sea. Oceans were also heated and life fled from the tropics.

It was expected that a key feature in extinction would have been body size: the large animals would suffer heat and starvation stress first. However, in the new paper, published in Palaeontology, it is shown that larger fish were no more likely to go extinct than small fish.

The study used a detailed summary of all information on fossil fish through a span of over 100 million years, from well before to well after the disaster. Body size information was identified for over 750 of these fishes, and multiple calculations were carried out to allow for variations in the shape of the evolutionary tree and the exact dating of all the species. The result was clear — body size did not provide any advantages or disadvantages to fish during the crisis.

Lead researcher Dr Mark Puttick from the Natural History Museum and University of Bristol’s School of Earth Sciences, explained: “These results continue the trend of recent studies that suggest body size played no role in determining which species survive or go extinct. This is the opposite result we would expect, but provides increasing support for previous studies that show body size plays no role in extinction selectivity.”

The team explored the largest dataset used in an analysis of this type and applied a range of computational evolutionary models to understand these patterns in deep time. The models take account of uncertainties in the quality of the fossil data and the reconstructed evolutionary tree, and the result was clear.

Professor Michael Benton, also from the University of Bristol, added: “These are exciting results. What is important also is that we were able to deploy new methods in the study that take greater account of uncertainties.

“The methods are based around a detailed evolutionary tree so, unlike most previous work in the field, we paid attention to the relationships of all the species under consideration.”

Professor Shixue Hu, leader of the China Geological Survey: “It’s great to see this new analytical work. We were able to include many new fossils from our exceptional biotas in China, and we can see the full impact of the extinction and the subsequent recovery of life during the Triassic.”

Mammal-like reptile’s brain, new research


Kawingasaurus fossilis at Museum of Paleontology, Tuebingen, Germany

From the Universität Duisburg-Essen in Germany:

A skull with history: A fossil sheds light on the origin of the neocortex

June 26, 2017

According to a recent study an early relative of mammals already possessed an extraordinarily expanded brain with a neocortex-like structure. This has been discovered by Michael Laaß from the Institute of General Zoology at the University of Duisburg-Essen (UDE).

Today, mammals possess large and efficient brains. But, what was the bauplan of the brain of their far relatives, the therapsids? When and why evolved the neocortex?

For his doctoral thesis the palaeontologist Michael Laaß invesitgated a ca. 255 million years old fossil skull of the therapsid Kawingasaurus fossilis in collaboration with Dr. Anders Kaestner from the Paul Scherrer Institute in Switzerland by means of neutron tomography and reconstructed the internal cranial anatomy in 3D.

The results were amazing: The relative brain volume of Kawingasaurus was about two or three-times larger than in other non-mammalian therapsids. Laaß: “Interestingly, Kawingasaurus already possessed a large forebrain with two distinct cerebral hemispheres.” Obviously, a neocortex-like structure at the forebrain similar to the mammalian neocortex was present in this animal.

Why is this brain structure evolved in Kawingasaurus? “Kawingasaurus was a burrower and special sensory adaptations were crucial for life under ground,” explained the UDE scientist. For example, this therapsid possessed frontally placed eyes, which were probably useful for binocular vision in dimlight environments as it is known from modern cats and owls. Furthermore, extremely ramified trigeminal nerve endings penetrated the snout, which might be an indication for a well developed sense of touch. The inner ear vestibules were also very large, which suggests that Kawingasaurus was well adapted to detect seismic vibrations from the ground.

Laaß: “These special sensory adaptaions also required a more efficient neural processing of the brain than in other therapsids.” It seems reasonable that these special adaptations of the sense organs and the brain to underground life triggered the expansion of the brain. Interestingly, a similar scenario for the origin of the neocortex has been also proposed for early mammals. Consequently, the recent study at the UDE supports this hypothesis.

Moreover, the new discovery also shows that a neocortex-like structure already developed in the therapsid Kawingasaurus about 25 million years earlier before the emergence of the first mammals. However, Kawingasaurus was not a direct ancestor of mammals. Consequently, neocortex-like structures evolved several times independently in pre-mammalian and mammalian evolution.

Mammal-like reptiles, warm-blooded earlier than thought


This video says about itself:

19 May 2016

Ophiacodon (meaning “snake tooth”) is an extinct genus of synapsids belonging to the family Ophiacodontidae that lived from the Late Carboniferous to the Early Permian in North America and possibly Europe. The genus was named along with its type species O. mirus by paleontologist Othniel Charles Marsh in 1878 and currently includes five other species. As an ophiacodontid, Ophiacodon is one of the most basal synapsids and is close to the evolutionary line leading to mammals.

Music: Pianoman by Billy Joel.

From the University of Bonn in Germany:

Warm-bloodedness possibly much older than previously thought

Characteristic may have developed 20 million years earlier, study shows

May 18, 2017

Summary: Warm-bloodedness in land animals could have evolved much earlier than previously thought, suggests a study of the bones of the long-extinct mammal predecessor Ophiacodon.

Warm-bloodedness in land animals could have developed in evolution much earlier than previously thought. This is shown by a recent study at the University of Bonn, which has now been published in the journal Comptes Rendus Palevol.

People who like watching lizards often get the best opportunity to do so in the morning, as they can usually be found sunbathing at this time of day. This is because they rely on an external energy supply to reach their operating temperature. However, mice and other mammals make themselves nice and cozy in a different way: they burn calories and can even keep themselves warm during a bitterly cold winter’s night.

Mammals are thus referred to as warm-blooded. Until now, it was thought that the “body heater” was invented in four-legged land animals around 270 million years ago. “However, our results indicate that warm-bloodedness could have been created 20 to 30 million years earlier,” explains Prof. Martin Sander from the Steinmann Institute for Geology, Mineralogy and Paleontology at the University of Bonn.

Bones as a thermometer

For long-extinct animals, it is naturally not possible to simply determine body temperature using a thermometer. However, warm-bloodedness leaves behind tell-tale signs in fossils. It not only means that the animal is not reliant on the ambient temperature, but also enables faster growth. “And this is shown in the structure of the bones,” explains Sander.

Bones are composites of protein fibers, collagen, and a biomaterial, hydroxyapatite. The more orderly the arrangement of the collagen fibers, the more stable the bone, but the more slowly it normally grows as well. The bones of mammals thus have a special structure. This allows them to grow quickly and yet remain stable. “We call this bone form fibrolamellar,” says the paleontologist.

Together with his PhD student Christen D. Shelton (now at the University of Cape Town), the scientist looked at humerus bones and femurs from a long-extinct land animal: the mammal predecessor Ophiacodon. This lived 300 million years ago. “Even in Ophiacodon, the bones grew as fibrolamellar bones,” says Sander to summarize the analysis results. “This indicates that the animal could already have been warm-blooded.”

Ophiacodon was up to two meters long, but otherwise resembled today’s lizards — and not without good reason: mammals and reptiles are related; they thus share a predecessor. In the family tree, Ophiacodon is very close to the place where these two branches separate.

Were the first reptiles warm-blooded?

However, lizards, turtles and other reptiles living today are cold-blooded. Until now, it has been assumed that this was the original form of the metabolism — i.e. that the shared ancestor of both animal groups was cold-blooded. Warm-bloodedness would thus be a further development, which arose over the course of mammalian evolution.

However, Ophiacodon appears a very short time after the division between mammals and reptiles. “This raises the question of whether its warm-bloodedness was actually a completely new development or whether even the very first land animals before the separation of both branches were warm-blooded,” says Sander. That is just speculation. However, if this theory is correct, we would have to drastically correct our image: the first reptiles would then also have been warm-blooded — and would have only discarded this type of metabolism later.

‘Mass extinctions killed less wildlife than thought’


This video from Britain says about itself:

Catastrophe – The Permian Extinction

The Permian-Triassic extinction event, informally known as the Great Dying, was an extinction event that occurred 252 million years ago, forming the boundary between the Permian and Triassic geologic periods, as well as the Paleozoic and Mesozoic eras. It is the Earth’s most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It is the only known mass extinction of insects. Some 57% of all families and 83% of all genera became extinct. Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after any other extinction event, possibly up to 10 million years.

Presented by Tony Robinson.

Originally published in 2008 by Channel 4

That was the prevalent view in 2008. And now …

From the Proceedings of the National Academy of Sciences of the United States of America:

Estimates of the magnitudes of major marine mass extinctions in earth history

Steven M. Stanley

October 3, 2016

Significance

This paper shows that background extinction definitely preceded mass extinctions; introduces a mathematical method for estimating the amount of this background extinction and, by subtracting it from total extinction, correcting estimates of losses in mass extinctions; presents a method for estimating the amount of erroneous backward smearing of extinctions from mass extinction intervals; and introduces a method for calculating species losses in a mass extinction that takes into account clustering of losses. It concludes that the great terminal Permian crisis eliminated only about 81% of marine species, not the frequently quoted 90–96%. Life did not almost disappear at the end of the Permian, as has often been asserted.

Abstract

Procedures introduced here make it possible, first, to show that background (piecemeal) extinction is recorded throughout geologic stages and substages (not all extinction has occurred suddenly at the ends of such intervals); second, to separate out background extinction from mass extinction for a major crisis in earth history; and third, to correct for clustering of extinctions when using the rarefaction method to estimate the percentage of species lost in a mass extinction. Also presented here is a method for estimating the magnitude of the Signor–Lipps effect, which is the incorrect assignment of extinctions that occurred during a crisis to an interval preceding the crisis because of the incompleteness of the fossil record.

Estimates for the magnitudes of mass extinctions presented here are in most cases lower than those previously published. They indicate that only ∼81% of marine species died out in the great terminal Permian crisis, whereas levels of 90–96% have frequently been quoted in the literature. Calculations of the latter numbers were incorrectly based on combined data for the Middle and Late Permian mass extinctions. About 90 orders and more than 220 families of marine animals survived the terminal Permian crisis, and they embodied an enormous amount of morphological, physiological, and ecological diversity. Life did not nearly disappear at the end of the Permian, as has often been claimed.

Mid-Permian extinction of animals, new study


This 2013 video says about itself:

Animal Armageddon The Great Dying – Episode 5

The Permian-Triassic extinction event, informally known as the Great Dying, was an extinction event that occurred 252 million years ago, forming the boundary between the Permian and Triassic geologic periods, as well as the Paleozoic and Mesozoic eras. It is the Earth’s most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It is the only known mass extinction of insects. Some 57% of all families and 83% of all genera became extinct. Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after any other extinction event, possibly up to 10 million years.

Researchers have variously suggested that there were from one to three distinct pulses, or phases, of extinction. There are several proposed mechanisms for the extinctions; the earlier phase was likely due to gradual environmental change, while the latter phase has been argued to be due to a catastrophic event. Suggested mechanisms for the latter include large or multiple impact events, increased volcanism, coal/gas fires and explosions from the Siberian Traps, and sudden release of methane from the sea floor; gradual changes include sea-level change, increasing aridity, and a shift in ocean circulation driven by climate change.

From the Geological Society of America:

15 April 2015

New evidence adds the Capitanian extinction to the list of major extinction crises

Boulder, Colo., USA – Since the Cambrian Explosion, ecosystems have suffered repeated mass extinctions, with the “Big 5” crises being the most prominent. Twenty years ago, a sixth major extinction was recognized in the Middle Permian (262 million years ago) of China, when paleontologists teased apart losses from the “Great Dying” at the end of the period. Until now, this Capitanian extinction was known only from equatorial settings, and its status as a global crisis was controversial.

David P.G. Bond and colleagues provide the first evidence for severe Middle Permian losses amongst brachiopods in northern paleolatitudes (Spitsbergen). Their study shows that the Boreal crisis coincided with an intensification of marine oxygen depletion, implicating this killer in the extinction scenario.

The widespread loss of carbonates across the Boreal Realm also suggests a role for acidification. The new data cements the Middle Permian crisis’s status as a true “mass extinction.” Thus the “Big 5” extinctions should now be considered the “Big 6.”

An abrupt extinction in the Middle Permian (Capitanian) of the Boreal Realm (Spitsbergen) and its link to anoxia and acidification: David P.G. Bond et al., University of Hull, Hull, UK. Published online ahead of print on 14 Apr. 2015; http://dx.doi.org/10.1130/B31216.1. This article is OPEN ACCESS (available for free online).

Ancient tree rings from the Permian period record a roughly 11-year cycle of wet and dry periods, climate fluctuations caused by the ebbing and flowing of solar activity, researchers propose January 9 in Geology. The discovery would push back the earliest evidence of today’s 11-year solar cycle by tens of millions of years: here.

Dimetrodon ancient reptile, new discoveries


This dimetrodon video is called Paleoworld– Tale Of A Sail (Part 1).

From Sci-News.com:

Dimetrodon Had Steak-Knife Teeth, Scientists Say

Feb 10, 2014

An international team of paleontologists suggests dimetrodon – a 4-m-long prehistoric reptile that lived during the early Permian period, between 295 million and 272 million years ago, and went extinct about 40 million years before the appearance of first dinosaurs – was the first terrestrial vertebrate to develop serrated ziphodont teeth.

Dimetrodon was the top of the terrestrial food chain in the early Permian and is considered to be the forerunner of mammals.

According to a new study reported in the journal Nature Communications, dimetrodons had a diversity of previously unknown tooth structures and were also the first terrestrial vertebrate to develop cusps – teeth with raised points on the crown, which are dominant in mammals.

The study also suggests ziphodont teeth were confined to later species of dimetrodon, indicating a gradual change in feeding habits.

“This research is an important step in reconstructing the structure of ancient complex communities,” said senior author Prof Robert Reisz from the University of Toronto Mississauga.

“Teeth tell us a lot more about the ecology of animals than just looking at the skeleton.”

“We already know from fossil evidence which animals existed at that time but now with this type of research we are starting to piece together how the members of these communities interacted.”

Prof Reisz and his co-author, Kirstin Brink from the University of Toronto Mississauga, studied the changes in dimetrodon teeth across 25 million years of evolution.

The analysis indicated the changes in tooth structure occurred in the absence of any significant evolution in skull morphology. This indicates a change in feeding style and trophic interactions.

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