Illustration shows the Permian Period tiger-sized saber-toothed protomammal Inostrancevia atop its dicynodont prey
By Will Dunham
Mon, May 22, 2023
Unlike the asteroid 66 million years ago that ravaged the dinosaurs, this extinction event unfolded over a protracted time span, with species perishing one by one as conditions worsened. Scientists said on Monday fossils unearthed in South Africa provide a peek into this drama, telling the tale of an apex predator that over multiple generations migrated halfway around the world in a desperate, and ultimately failed, bid to survive.
This beast, a tiger-sized, saber-toothed mammal forerunner called Inostrancevia, had been known only from fossils excavated in Russia's northwestern corner bordering the Arctic Sea until new remains were discovered at a farm in central South Africa.
The fossils suggest that Inostrancevia left its place of origin and trekked over time - maybe hundreds or thousands of years - about 7,000 miles (12,000 km) across Earth's ancient supercontinent Pangaea at a time when today's continents were united. Inostrancevia filled the ecological niche of top predator in South Africa left vacant after four other species already had vanished.
"However, it did not survive there long," said paleontologist Christian Kammerer of the North Carolina Museum of Natural Sciences, lead author of the research published in the journal Current Biology, noting that Inostrancevia and all of its closest relatives disappeared in the mass extinction called "the Great Dying."
"So, they have no living descendants, but they are a member of the larger group called synapsids, which includes mammals as living representatives," Kammerer added.
Inostrancevia is part of an assemblage of animals called protomammals that combined reptile-like and mammal-like features. It was 10-13 feet (3-4 meters) long, roughly the size of a Siberian tiger, but with a proportionally larger and elongated skull as well as enormous, blade-like canine teeth.
"I suspect these animals primarily killed prey with their saber-like canine fangs and either carved out chunks of meat with the serrated incisors or, if it was small enough, swallowed the prey whole," Kammerer said.
Inostrancevia's body had an unusual posture typical of protomammals, not quite sprawling like a reptile or erect like a mammal but something in between, with sprawled forelimbs and mostly erect hind limbs. It also lacked the mammalian facial musculature and would not have produced milk.
"Whether these animals were furry or not remains an open question," Kammerer said.
The mass extinction, occurring over a span of a million years or so, set the stage for the rise of the dinosaurs in the subsequent Triassic Period. Massive volcanism unleashed lava flows across large portions of Eurasia and pumped carbon dioxide into the atmosphere for thousands of years. This caused a spike in worldwide temperatures, depletion of oxygen in the seas and atmosphere, ocean acidification and global desertification.
Top predators were especially vulnerable to extinction because they required the most food and space.
"They tend to take a relatively long time to mature and have few offspring. When ecosystems are disrupted and prey supplies are reduced or available habitat is limited, top predators are disproportionately affected," Kammerer said.
The researchers see parallels between the Permian crisis and today's human-induced climate change.
"The hardship these species faced was as a direct result of a global-warming climate crisis, so they really had no choice but to adapt to it or go extinct. This is clear by evidence of their brief perseverance in spite of these conditions, but eventually they disappeared one by one," said paleontologist and study co-author Pia Viglietti of the Field Museum in Chicago.
"Unlike our Permian predecessors," Viglietti added, "we actually have the ability to do something to prevent this kind of ecosystem crisis from happening again."
(Reporting by Will Dunham, Editing by Rosalba O'Brien)
Fossils of a saber-toothed top predator reveal a scramble for dominance leading up to “the Great Dying”
IMAGE: GIANT GORGONOPSIAN INOSTRANCEVIA WITH ITS DICYNODONT PREY, SCARING OFF THE MUCH SMALLER AFRICAN SPECIES CYONOSAURUS. view more
CREDIT: ART BY MATT CELESKEY.
Two hundred and fifty-two million years ago, Earth experienced a mass extinction so devastating that it’s become known as “the Great Dying.” Massive volcanic eruptions triggered catastrophic climate change, killing off nine out of every ten species and eventually setting the stage for the dinosaurs. But the Great Dying was a long goodbye-- the extinction event took place over the course of up to a million years at the end of the Permian period. During that time, the fossil record shows drama and upheaval as species fought to get a foothold in their changing environments. One animal that exemplifies this instability was a tiger-sized, saber-toothed creature called Inostrancevia: a new fossil discovery suggests that Inostrancevia migrated 7,000 miles across the supercontinent Pangaea, filling a gap in a faraway ecosystem that had lost its top predators, before going extinct itself.
“All the big top predators in the late Permian in South Africa went extinct well before the end-Permian mass extinction. We learned that this vacancy in the niche was occupied, for a brief period, by Inostrancevia,” says Pia Viglietti, a research scientist at the Field Museum in Chicago and a co-author of the new study in Current Biology.
The prehistoric creature looked the part of “top predator.” “Inostrancevia was a gorgonopsian, a group of proto-mammals that included the first saber-toothed predators on the planet,” says Viglietti. It was about the size of a tiger and likely had skin like an elephant or a rhino; while vaguely reptilian in appearance, it was part of the group of animals that includes modern mammals.
Prior to this new paper, Inostrancevia had only ever been found in Russia. But while examining the fossil record of South Africa’s Karoo Basin, Viglietti’s colleague Christian Kammerer identified the fossils of two large predatory animals that were different from those normally found in the region. “The fossils themselves were quite unexpected,” says Viglietti. It’s not clear how they made it from what’s now Russia, or how long it took them to cross Pangaea and arrive in what’s now South Africa. But being far from home was just one element of what made the fossils special.
“When we reviewed the ranges and ages of the other top predators normally found in the area, the rubidgeine gorgonopsians, with these Inostrancevia fossils, we found something quite exciting,” she says. “The local carnivores actually went extinct quite a bit before even the main extinction that we see in the Karoo-- by the time the extinction begins in other animals, they're gone.”
The arrival of Inostrancevia from 7,000 miles away and its subsequent extinction indicates that these top predators were “canaries in the coal mine” for the larger extinction event to come.
“This shows that the South African Karoo Basin continues to produce critical data for understanding the most catastrophic mass extinction in Earth’s history,” says co-author Jennifer Botha, director of GENUS Centre of Excellence in Palaeosciences and professor at the Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg.
“We have shown that the shift in which groups of animals occupied apex predator roles occurred four times over less than two million years around the Permian-Triassic mass extinction, which is unprecedented in the history of life on land. This underlines how extreme this crisis was, with even fundamental roles in ecosystems in extreme flux,” said Christian Kammerer, the study’s first author and a research curator of paleontology at the North Carolina Museum of Natural Sciences and research associate at the Field Museum.
The vulnerability of these top predators matches what we see today. “Apex predators in modern environments tend to show high extinction risk, and tend to be among the first species that are locally extirpated due to human-mediated activities such as hunting or habitat destruction,” says Kammerer. “Think about wolves in Europe or tigers in Asia, species which tend to be slow to reproduce and grow and require large geographic areas to roam and hunt prey, and which are now absent from most of their historic ranges. We should expect that ancient apex predators would have had similar vulnerabilities, and would be among the species that first go extinct during mass extinction events.”
In addition to shedding new light on the extinction event that helped lead to the rise of the dinosaurs, Viglietti says that the study is important for what it can teach us about the ecological disasters the planet is currently experiencing.
“It's always good to get a better understanding of how mass extinction events affect ecosystems, especially because the Permian is basically a parallel on what we’re going through now,” said Viglietti. “We don't really have any modern analogs of what to expect with the mass extinction happening today, and the Permo-Triassic mass extinction event represents one of the best examples of what we could experience with our climate crisis and extinctions. I guess the only difference is, we know what to do and how to stop it from happening.”
Inostrancevia fossils in the field.
Paul October, a now retired field technician from Iziko South African Museum, with Inostrancevia fossils in the field.
CREDIT
Photo by Jennifer Botha.
The field location where the Inostrancevia were found (a farm called Nooitgedacht in the Free State Province of South Africa's Karoo Basin).
CREDIT
Photo by Pia Viglietti.
JOURNAL
Current Biology
ARTICLE TITLE
Rapid turnover of top predators in African terrestrial faunas around the Permian-Triassic mass extinction
ARTICLE PUBLICATION DATE
22-May-2023
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