Permian-Triassic mass extinction and volcanoes, new research

This 2017 video is called Fireball Earth: The Permian Extinction – History Documentary.

From Tohoku University in Japan:

Large volcanic eruption caused the largest mass extinction

November 10, 2020

Researchers in Japan, the US and China say they have found more concrete evidence of the volcanic cause of the largest mass extinction of life. Their research looked at two discrete eruption events: one that was previously unknown to researchers, and the other that resulted in large swaths of terrestrial and marine life going extinct.

There have been five mass extinctions since the divergent evolution of early animals 450 — 600 million years ago. The third was the largest one and is thought to have been triggered by the eruption of the Siberian Traps — a large region of volcanic rock known as a large igneous province. But the correlation between the eruption and mass extinction has not yet been clarified.

Sedimentary mercury enrichments, proxies for massive volcanic events, have been detected in dozens of sedimentary rocks from the end of the Permian. These rocks have been found deposited inland, in shallow seas and central oceans, but uncertainty remains as to their interpretation. Mercury can be sourced from either direct atmospheric deposition from volcanic emissions and riverine inputs from terrestrial organic matter oxidation when land/plant devastation — referred to as terrestrial ecological disturbance — occurs.

The largest mass extinction occurred at the end of the Permian — roughly 252 million years ago. This mass extinction was marked by the transition from the divergence of the Paleozoic reptiles and marine animals like brachiopods and trilobites to Mesozoic dinosaurs and marine animals such as mollusks. Approximately 90% of species disappeared at the end of the Permian.

Current professor emeritus at Tohoku University, Kunio Kaiho led a team that looked into possible triggers of the largest mass extinction. They took sedimentary rock samples from two places — southern China and Italy — and analyzed the organic molecules and mercury (Hg) in them. They found two discrete coronene-Hg enrichments coinciding with the first terrestrial ecological disturbance and the following mass extinction in both areas.

“We believe this to be the product of large volcanic eruptions because the coronene anomaly was formed by abnormally high temperature combustion,” says professor Kaiho. “High temperature magma or asteroid/comet impacts can make such a coronene enrichment.

From the volcanic aspect, this could have occurred because of the higher temperature combustion of living and fossil organic matter from lava flows and horizontally intruded magma (sill) into the sedimentary coal and oil. The different magnitude of the two coronene-mercury enrichments shows that the terrestrial ecosystem was disrupted by smaller global environmental changes than the marine ecosystem. The duration between the two volcanic events is tens of thousands of years.”

Huge volcanic eruptions can produce sulfuric acid aerosols in the stratosphere and carbon dioxide in the atmosphere, which causes global climate changes. This rapid climate change is believed to be behind the loss of land and marine creatures.

Coronene is a highly condensed six-ring polycyclic aromatic hydrocarbon, which requires significantly higher energy to form as compared to smaller PAHs. Therefore, high temperature volcanic combustion can cause the coronene enrichments. This means that high temperature combustion of hydrocarbons in the sedimentary rocks by lateral intrusion of magmas formed CO2 and CH4 causing high pressure and eruption to induce global warming and the mass extinction. The coronene-mercury concentration firstly evidenced that volcanic hydrocarbon combustion helped contribute to the extinction through global warming.

Kaiho’s team is now studying other mass extinctions in the hopes of further understanding the cause and processes behind them.

Diplocaulus, prehistoric Permian ‘hammerhead salamanders’

This 22 May 2020 video about Diplocaulus says about itself:

The Hammerheaded Salamander

This boomerang head has been a part of every prehistoric background scene. Why is this, and what did it do with those horns?

Permian-Triassic mass extinction, new research

This 2017 video says about itself:

Dr. John Geissman gives a talk on the Permian-Triassic Extinction Event & what has been learned about it in South Africa’s Karoo Basin. This was the greatest extinction event, the one sometimes characterized as “When Life Nearly Died”. John provides cutting edge insights into evidence from the Karoo Basin about what is being learned about the “P-T Event”.

From the University of California – Berkeley in the USA:

In Earth’s largest extinction, land animal die-offs began long before marine extinction

New dates for fossils indicate land animal turnover extended for hundreds of thousands of years

March 27, 2020

Summary: Because of poor dates for land fossils laid down before and after the mass extinction at the end of the Permian, paleontologists assumed that the terrestrial extinctions from Gondwana occurred at the same time as the better-documented marine extinctions. But a new study provides more precise dates for South African fossils and points to a long, perhaps 400,000-year period of extinction on land before the rapid marine extinction 252 million years ago.

The mass extinction at the end of the Permian Period 252 million years ago — one of the great turnovers of life on Earth — appears to have played out differently and at different times on land and in the sea, according to newly redated fossils beds from South Africa and Australia.

New ages for fossilized vertebrates that lived just after the demise of the fauna that dominated the late Permian show that the ecosystem changes began hundreds of thousands of years earlier on land than in the sea, eventually resulting in the demise of up to 70% of terrestrial vertebrate species. The later marine extinction, in which nearly 95% of ocean species disappeared, may have occurred over the time span of tens of thousands of years.

Though most scientists believe that a series of volcanic eruptions, occurring in large pulses over a period of a million years in what is now Siberia, were the primary cause of the end-Permian extinction, the lag between the land extinction in the Southern Hemisphere and the marine extinction in the Northern Hemisphere suggests different immediate causes.

“Most people thought that the terrestrial collapse started at the same time as the marine collapse, and that it happened at the same time in the Southern Hemisphere and in the Northern Hemisphere,” said paleobotanist Cindy Looy, University of California, Berkeley, associate professor of integrative biology. “The fact that the big changes were not synchronous in the Northern and Southern hemispheres has a big effect on hypotheses for what caused the extinction. An extinction in the ocean does not, per se, have to have the same cause or mechanism as an extinction that happened on land.”

Members of Looy’s lab have conducted experiments on living plants to determine whether a collapse of Earth’s protective ozone layer may have irradiated and wiped out plant species. Other global changes — a warming climate, a rise in carbon dioxide in the atmosphere and an increase in ocean acidification — also occurred around the end of the Permian period and the beginning of the Triassic and likely contributed.

On land, the end-Permian extinction of vertebrates is best documented in Gondwana, the southern half of the supercontinent known as Pangea that eventually separated into the continents we know today as Antarctica, Africa, South America and Australia. There, in the South African Karoo Basin, populations of large herbivores, or plant eaters, shifted from the Daptocephalus assemblage to the Lystrosaurus assemblage. These groups are now extinct.

In the ocean, the extinction is best documented in the Northern Hemisphere, in particular by Chinese fossils. The end-Permian extinction is perhaps best associated with the demise of trilobites.

To improve on previous dates for the land extinction, an international team of scientists, including Looy, conducted uranium-lead dating of zircon crystals in a well-preserved volcanic ash deposit from the Karoo Basin. Looy, who is also a curator of paleobotany at the campus’s Museum of Paleontology and curator of gymnosperms at the University and Jepson Herbaria, confirmed that sediments from several meters above the dated layer were devoid of Glossopteris pollen, evidence that these seed ferns, which used to dominate late Permian Gondwanan floras, became extinct around that time.

At 252.24 million years old, the zircons — microscopic silicate crystals that form in rising magma inside volcanoes and are spewed into the atmosphere during eruptions — are 300,000 years older than dates obtained for the confirmed Permian-Triassic (P-T) boundary in China. This means that the sediment layer assumed to contain the P-T boundary in South Africa was actually at least 300,000 years too old.

Dates for an ash deposit in Australia, just above the layers that document the initial plant extinction, similarly came in almost 400,000 years older than thought. That work was published in January by Christopher Fielding and colleagues at the University of Nebraska in Lincoln.

“The Karoo Basin is the poster child for the end-Permian vertebrate turnover, but until recently, it was not well-dated,” Looy said. “Our new zircon date shows that the base of the Lystrosaurus zone predates the marine extinction with several hundred thousand years, similar to the pattern in Australia. This means that both the floral and faunal turnover in Gondwana is out of sync with the Northern Hemisphere marine biotic crisis.

“For some years now, we have known that — in contrast to the marine mass extinction — the pulses of disturbance of life on land continued deep into the Triassic Period. But that the start of the terrestrial turnover happened so long before the marine extinction was a surprise.”

In their paper, Looy and an international team of colleagues concluded “that greater consideration should be given to a more gradual, complex, and nuanced transition of terrestrial ecosystems during the Changhsingian (the last part of the Permian) and, possibly, the early Triassic.”

Looy and colleagues published their findings March 19 in the open-access journal Nature Communications. Her co-authors are Robert Gastaldo of Colby College in Maine; Sandra Kamo of the University of Toronto in Ontario; Johann Neveling of the Council for Geosciences in Pretoria, South Africa; John Geissman of the University of Texas in Dallas and Anna Martini of Amherst College in Massachusetts. The research was funded by the National Science Foundation.

The Permian-Triassic extinction, also known as the Great Dying, took place roughly 252 million years ago. It saw the loss of an estimated 90% of marine species, 70% of land species, widespread loss of plant diversity and extreme soil erosion. While the exact cause of the terrestrial mass extinction is still debated, it is becoming apparent that the terrestrial ecosystems were wiped out prior to the marine ecosystems. However, until now it was unclear if or how the terrestrial extinction consequently impacted the chemistry of Earth’s ancient oceans: here.

Permian age marine predator Helicoprion

This 13 December 2019 video says about itself:

The sharklike Helicoprion lived 275 million years ago and could slice its prey in two with its buzz saw jaw.

‘New’ Permian mass extinction discovered

This 23 August 2019 video says about itself:

Here Dr. Mike Day talks to us about the Guadalupian extinction event that occurred about 8 million years before the End of the Permian mass extinction event.

From New York University in the USA:

Researchers unearth ‘new’ mass-extinction

New analysis brings total of species extinctions to six

September 9, 2019

A team of scientists has concluded that earth experienced a previously underestimated severe mass-extinction event, which occurred about 260 million years ago, raising the total of major mass extinctions in the geologic record to six.

“It is crucial that we know the number of severe mass extinctions and their timing in order to investigate their causes,” explains Michael Rampino, a professor in New York University’s Department of Biology and a co-author of the analysis, which appears in the journal Historical Biology. “Notably, all six major mass extinctions are correlated with devastating environmental upheavals — specifically, massive flood-basalt eruptions, each covering more than a million square kilometers with thick lava flows.”

Scientists had previously determined that there were five major mass-extinction events, wiping out large numbers of species and defining the ends of geological periods: the end of the Ordovician (443 million years ago), the Late Devonian (372 million years ago), the Permian (252 million years ago), the Triassic (201 million years ago), and the Cretaceous (66 million years ago). And, in fact, many researchers have raised concerns about the contemporary, ongoing loss of species diversity — a development that might be labeled a “seventh extinction” because such a modern mass extinction, scientists have predicted, could end up being as severe as these past events.

The Historical Biology work, which also included Nanjing University’s Shu-zhong Shen, focused on the Guadalupian, or Middle Permian period, which lasted from 272 to about 260 million years ago.

Here, the researchers observe, the end-Guadalupian extinction event — which affected life on land and in the seas — occurred at the same time as the Emeishan flood-basalt eruption that produced the Emeishan Traps, an extensive rock formation, found today in southern China. The eruption’s impact was akin to those causing other known severe mass extinctions, Rampino says.

“Massive eruptions such as this one release large amounts of greenhouse gases, specifically carbon dioxide and methane, that cause severe global warming, with warm, oxygen-poor oceans that are not conducive to marine life,” he notes.

“In terms of both losses in the number of species and overall ecological damage, the end-Guadalupian event now ranks as a major mass extinction, similar to the other five,” the authors write.

Sick Permian reptile discovery

This May 2015 video says about itself:

Ancestral Evolution – Ichthyostega to Varanops

It takes over 3 billion years for our ancestor to evolve from a single cell to a foot-long armoured fish. Our future looks bleak but natural selection throws us a lifeline. Over millions of years and thousands of generations, our body adapts until we do something no fish has done before, breathe air! The air travels into a new organ, a lung. Take a breath and remember it’s because a monster fish chased our ancestor into stagnant water forcing them to breathe air. We’re Ichthyostega, we can breathe air or water, closing off our windpipe to switch between lungs and gills. Today our gills are gone but the mechanism remains and sometimes it spasms giving us the hiccups. 365 million years ago we stick our head out of the water, there’s a swamp behind us, paradise ahead, the choice is simple but the consequences are immense. We pull ourselves out of the water and change the course of history.

From PLOS:

Permian lizard-like animal suffered from a bone condition similar to Paget’s disease

Susceptibility to this type of disease may extend back to the Early Permian

August 7, 2019

A lizard-like animal that lived 289 million years ago suffered from a bone condition similar to Paget’s disease, according to a study published August 7, 2019 in the open-access journal PLOS ONE by Yara Haridy of the Museum für Naturkunde in Berlin and colleagues. This is the most ancient known case of such a disease.

The animal in question belonged to an extinct group of lizard-like creatures called varanopids, relatives of the earliest ancestors of mammals or reptiles.

It is still uncertain whether varanopids were ‘mammal-like reptiles’, ancestral to mammals, or rather diapsids, ancestral to lizards, dinosaurs, etc.

The authors identified the disease in an isolated pair of tail vertebrae discovered in an Early Permian cave at Richards Spur, Oklahoma. Micro-CT scanning allowed examination of both the external and internal structure of the elements, revealing that in some places the bone had been thinned by abnormally high levels of reabsorption, while in other areas excessive bone growth had resulted in abnormal bone thickening and the ultimate fusion of the two vertebrae.

According to the researchers, this condition is most similar to Paget’s disease, a bone metabolic disorder marked by a breakdown in communication between bone building cells and bone destroying cells. Paget’s disease is commonly seen today in the hips and vertebrae of humans and has been diagnosed in other living mammals and reptiles as well as one Early Jurassic dinosaur fossil. The disease has been linked to both genetic and viral factors, though its precise cause remains controversial.

With only two vertebrae preserved, it is impossible to say how widespread the disease was in this animal’s body. If it was restricted to the tail, the animal may only have suffered minor pain and stiffness. This discovery marks the oldest known occurrence of a Paget-like disease and suggests that susceptibility to such disorders was already present in our early Permian cousins.

Haridy adds: “Paleopathology is the study of ancient diseases, here we scanned a pair of fused tail bones from a permian (280 million years ago) Varanopid (a superficially-lizard like animal), what we found was evidence of a bone disease similar to modern day Paget’s disease. This enigmatic disease is still not well understood in humans, however finding something similar in an ancient animal likely links it to something deep in our bone biology. This study is a great example of how when palaeontologists have well preserved fossils we can tell a lot more than just what animals were present, we can explore their biology, physiology and even what diseases ailed them!”

Permian-Triassic mass extinction, 250,000,000 years ago

This 18 July 2019 video says about itself:

The Siberian Traps: A 250 Million Year Old Crime Scene

The event that killed the dinosaurs 66 million years ago might be the most famous mass extinction ever, but it’s not the only one in Earth’s history, nor is it the worst… not by a long shot.

Permian-Triassic mass extinction, caused by volcanoes?

This 15 September 2015 video from the USA says about itself:

Around 252 millions years ago life on Earth collapsed in a unprecedented fashion as more than 96 percent of marine species and 70 percent of land species disappeared.

The cause of this severe extinction has been a mystery, until now. (Learn more here. MIT researchers have now determined the Siberian Traps erupted at the right time and for the right duration to have been a likely trigger for the end-Permian extinction.

Video produced and edited by Melanie Gonick/MIT

Additional footage and stills: Henrik Svensen, Scott Simper and Seth Burgess

Music sampled from “Out” by Ryan Cross

From the University of Cincinnati in the USA:

New evidence suggests volcanoes caused biggest mass extinction ever

Mercury found in ancient rock around the world supports theory that eruptions caused ‘Great Dying’ 252 million years ago.

April 15, 2019

Researchers say mercury buried in ancient rock provides the strongest evidence yet that volcanoes caused the biggest mass extinction in the history of the Earth.

The extinction 252 million years ago was so dramatic and widespread that scientists call it “the Great Dying.” The catastrophe killed off more than 95 percent of life on Earth over the course of hundreds of thousands of years.

Paleontologists with the University of Cincinnati and the China University of Geosciences said they found a spike in mercury in the geologic record at nearly a dozen sites around the world, which provides persuasive evidence that volcanic eruptions were to blame for this global cataclysm.

The study was published this month in the journal Nature Communications.

The eruptions ignited vast deposits of coal, releasing mercury vapor high into the atmosphere. Eventually, it rained down into the marine sediment around the planet, creating an elemental signature of a catastrophe that would herald the age of dinosaurs.

“Volcanic activities, including emissions of volcanic gases and combustion of organic matter, released abundant mercury to the surface of the Earth,” said lead author Jun Shen, an associate professor at the China University of Geosciences.

The mass extinction occurred at what scientists call the Permian-Triassic Boundary. The mass extinction killed off much of the terrestrial and marine life before the rise of dinosaurs. Some were prehistoric monsters in their own right, such as the ferocious gorgonopsids that looked like a cross between a sabre-toothed tiger and a Komodo dragon.

The eruptions occurred in a volcanic system called the Siberian Traps in what is now central Russia. Many of the eruptions occurred not in cone-shaped volcanoes but through gaping fissures in the ground. The eruptions were frequent and long-lasting and their fury spanned a period of hundreds of thousands of years.

“Typically, when you have large, explosive volcanic eruptions, a lot of mercury is released into the atmosphere,” said Thomas Algeo, a professor of geology in UC’s McMicken College of Arts and Sciences.

“Mercury is a relatively new indicator for researchers. It has become a hot topic for investigating volcanic influences on major events in Earth’s history,” Algeo said.

Researchers use the sharp fossilized teeth of lamprey-like creatures called conodonts to date the rock in which the mercury was deposited. Like most other creatures on the planet, conodonts were decimated by the catastrophe.

The eruptions propelled as much as 3 million cubic kilometers of ash high into the air over this extended period. To put that in perspective, the 1980 eruption of Mount St. Helens in Washington sent just 1 cubic kilometer of ash into the atmosphere, even though ash fell on car windshields as far away as Oklahoma.

In fact, Algeo said, the Siberian Traps eruptions spewed so much material in the air, particularly greenhouse gases, that it warmed the planet by an average of about 10 degrees centigrade.

The warming climate likely would have been one of the biggest culprits in the mass extinction, he said. But acid rain would have spoiled many bodies of water and raised the acidity of the global oceans. And the warmer water would have had more dead zones from a lack of dissolved oxygen.

“We’re often left scratching our heads about what exactly was most harmful. Creatures adapted to colder environments would have been out of luck,” Algeo said. “So my guess is temperature change would be the No. 1 killer. Effects would exacerbated by acidification and other toxins in the environment.”

Stretching over an extended period, eruption after eruption prevented the Earth’s food chain from recovering.

“It’s not necessarily the intensity but the duration that matters,” Algeo said. “The longer this went on, the more pressure was placed on the environment.”

Likewise, the Earth was slow to recover from the disaster because the ongoing disturbances continued to wipe out biodiversity, he said.

Earth has witnessed five known mass extinctions over its 4.5 billion years.

Scientists used another elemental signature — iridium — to pin down the likely cause of the global mass extinction that wiped out the dinosaurs 65 million years ago. They believe an enormous meteor struck what is now Mexico.

The resulting plume of superheated earth blown into the atmosphere rained down material containing iridium that is found in the geologic record around the world.

Shen said the mercury signature provides convincing evidence that the Siberian Traps eruptions were responsible for the catastrophe. Now researchers are trying to pin down the extent of the eruptions and which environmental effects in particular were most responsible for the mass die-off, particularly for land animals and plants.

Shen said the Permian extinction could shed light on how global warming today might lead to the next mass extinction. If global warming, indeed, was responsible for the Permian die-off, what does warming portend for humans and wildlife today?

“The release of carbon into the atmosphere by human beings is similar to the situation in the Late Permian, where abundant carbon was released by the Siberian eruptions,” Shen said.

Algeo said it is cause for concern.

“A majority of biologists believe we’re at the cusp of another mass extinction — the sixth big one. I share that view, too,” Algeo said. “What we should learn is this will be serious business that will harm human interests so we should work to minimize the damage.”

People living in marginal environments such as arid deserts will suffer first. This will lead to more climate refugees around the world.

“We’re likely to see more famine and mass migration in the hardest hit places. It’s a global issue and one we should recognize and proactively deal with. It’s much easier to address these problems before they reach a crisis.”

‘Permian-Triassic extinction killed plants first’

This March 2018 video says about itself:

‘The Great Dying’ Was Our Worst Extinction Ever, And It Could Happen Again

What exactly caused the greatest extinction on earth? New research may finally hold the answer to this long time mystery.

From the University of Nebraska-Lincoln in the USA:

Earth’s largest extinction event likely took plants first

January 31, 2019

Summary: New evidence from the cliffsides of Australia suggests that Earth’s largest extinction event — a volcanic cataclysm occurring roughly 252 million years ago — extinguished plant life long before many animal counterparts.

Little life could endure the Earth-spanning cataclysm known as the Great Dying, but plants may have suffered its wrath long before many animal counterparts, says new research led by the University of Nebraska-Lincoln.

About 252 million years ago, with the planet’s continental crust mashed into the supercontinent called Pangaea, volcanoes in modern-day Siberia began erupting. Spewing carbon and methane into the atmosphere for roughly 2 million years, the eruption helped extinguish about 96 percent of oceanic life and 70 percent of land-based vertebrates — the largest extinction event in Earth’s history.

Yet the new study suggests that a byproduct of the eruption — nickel — may have driven some Australian plant life to extinction nearly 400,000 years before most marine species perished.

“That’s big news”, said lead author Christopher Fielding, professor of Earth and atmospheric sciences. “People have hinted at that, but nobody’s previously pinned it down. Now we have a timeline.”

The researchers reached the conclusion by studying fossilized pollen, the chemical composition and age of rock, and the layering of sediment on the southeastern cliffsides of Australia. There they discovered surprisingly high concentrations of nickel in the Sydney Basin’s mud-rock — surprising because there are no local sources of the element.

Tracy Frank, professor and chair of Earth and atmospheric sciences, said the finding points to the eruption of lava through nickel deposits in Siberia. That volcanism could have converted the nickel into an aerosol that drifted thousands of miles southward before descending on, and poisoning, much of the plant life there. Similar spikes in nickel have been recorded in other parts of the world, she said.

“So it was a combination of circumstances,” Fielding said. “And that’s a recurring theme through all five of the major mass extinctions in Earth’s history.”

If true, the phenomenon may have triggered a series of others: herbivores dying from the lack of plants, carnivores dying from a lack of herbivores, and toxic sediment eventually flushing into seas already reeling from rising carbon dioxide, acidification and temperatures.

‘It Lets Us See What’s Possible’

One of three married couples on the research team, Fielding and Frank also found evidence for another surprise. Much of the previous research into the Great Dying — often conducted at sites now near the equator — has unearthed abrupt coloration changes in sediment deposited during that span.

Shifts from grey to red sediment generally indicate that the volcanism’s ejection of ash and greenhouse gases altered the world’s climate in major ways, the researchers said. Yet that grey-red gradient is much more gradual at the Sydney Basin, Fielding said, suggesting that its distance from the eruption initially helped buffer it against the intense rises in temperature and aridity found elsewhere.

Though the time scale and magnitude of the Great Dying exceeded the planet’s current ecological crises, Frank said the emerging similarities — especially the spikes in greenhouse gases and continuous disappearance of species — make it a lesson worth studying.

“Looking back at these events in Earth’s history is useful because it lets us see what’s possible,” she said. “How has the Earth’s system been perturbed in the past? What happened where? How fast were the changes? It gives us a foundation to work from — a context for what’s happening now.”

The researchers detailed their findings in the journal Nature Communications. Fielding and Frank authored the study with Allen Tevyaw, graduate student in geosciences at Nebraska; Stephen McLoughlin, Vivi Vajda and Chris Mays from the Swedish Museum of Natural History; Arne Winguth and Cornelia Winguth from the University of Texas at Arlington; Robert Nicoll of Geoscience Australia; Malcolm Bocking of Bocking Associates; and James Crowley of Boise State University.

The National Science Foundation and the Swedish Research Council funded the team’s work.

Edaphosaurus, ancient sail-backed mammal-like reptile

This 28 January 2019 video says about itself:

Edaphosaurus, meaning “pavement lizard” for dense clusters of teeth) is a genus of extinct edaphosaurid synapsid. It lived in what is now North America and Europe around 300 to 280 million years ago, during the late Carboniferous to early Permian periods.

Edaphosaurus is important as one of the earliest known large plant-eating (herbivorous) amniote tetrapods (four-legged land-living vertebrates). In addition to the large tooth plates in its jaws, the most characteristic feature of Edaphosaurus is a sail on its back which is unique in shape and morphology. Edaphosaurus species measured from 0.5 metres (1.6 ft) to almost 3.5 metres (11.5 ft) in length and weighed over 300 kilograms (660 lb).

Like its more famous relative Dimetrodon, Edaphosaurus had a sail-like fin that was supported by bones of the vertebral column. Edaphosaurus differs from Dimetrodon in having cross-bars on the spines that supported its fin. Edaphosaurus and other members of the Edaphosauridae evolved tall dorsal sails independently of sail-back members of the Sphenacodontidae. Dimetrodon and Secodontosaurus that lived at the same time are an unusual example of parallel evolution.