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Paleontologists Discover Complete Saurornitholestes langstoni Specimen

Saturday, October 19, 2019

Saurornitholestes langstoni. Image credit: Jan Sovak.

A fossil site in Canada has yielded the best-preserved specimen of the dromaeosaurid dinosaur Saurornitholestes langstoni ever found.

First scientifically described in 1978, Saurornitholestes langstoni is a carnivorous feathered dinosaur within the family Dromaeosauridae (also known as raptors).

It lived approximately 76 million years ago (Cretaceous period) in what is now North America.

The species was previously known from fragmentary remains and was long thought to be so closely related to Velociraptor from Mongolia that some paleontologists called it Velociraptor langstoni.

The new, almost complete skeleton of Saurornitholestes langstoni was discovered by Clive Coy from the University of Alberta in Dinosaur Provincial Park in 2014.

The specimen was remarkably complete and exquisitely preserved, with all the bones (except for the tail) preserved in life position.

“Because of their small size and delicate bones, small meat-eating dinosaur skeletons are exceptionally rare in the fossil record,” said Dr. David Evans, a researcher in the Department of Natural History at the Royal Ontario Museum and the Department of Ecology & Evolutionary Biology at the University of Toronto.

“The new skeleton is by far the most complete and best-preserved raptor skeleton ever found in North America. It’s a scientific goldmine.”

Dr. Evans and his colleague, University of Alberta’s Professor Philip Currie, analyzed the new specimen and found that Saurornitholestes langstoni had a shorter and deeper skull than Velociraptor.

At the front of the skull’s mouth, they also discovered a flat tooth with long ridges, which was likely used for preening feathers. The same tooth has since been identified in Velociraptor and other dromaeosaurids.

The team also established a distinction between dromaeosaurids in North America and Asia.

“The new anatomical information we have clearly shows that the North American dromaeosaurids are a separate lineage from the Asian dromaeosaurids, although they do have a common ancestor,” Professor Currie said.

“This changes our understanding of intercontinental movements of these animals and ultimately will help us understand their evolution.”

The team’s paper was published in the journal Anatomical Record.

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Philip J. Currie & David C. Evans. Cranial Anatomy of New Specimens of Saurornitholestes langstoni (Dinosauria, Theropoda, Dromaeosauridae) from the Dinosaur Park Formation (Campanian) of Alberta. Anatomical Record, published online September 9, 2019; doi: 10.1002/ar.24241

Source: www.sci-news.com

Giant Dinosaurs Evolved Various Brain-Cooling Mechanisms: Study

Friday, October 18, 2019

Gigantic dinosaurs like the sauropod Diplodocus, which weighed over 15 tons and was longer than an 18-wheeler truck, would have had problems with potentially lethal overheating. Hot blood from the body core would have been pumped to the head, damaging the delicate brain. The new study shows that in sauropods, evaporation of moisture in the nose and mouth would have cooled extensive networks of venous blood destined for the brain. Other large dinosaurs evolved different brain-cooling mechanisms, but all involving evaporative cooling of blood in different regions of the head. Image credit: Michael Skrepnick / WitmerLab, Ohio University.

Different groups of gigantic dinosaurs had different thermoregulatory strategies to help moderate brain temperatures in the face of high heat loads, according to new research from the Ohio University’s Heritage College of Osteopathic Medicine.

“Small dinosaurs could have just run into the shade to cool off, but for giant dinosaurs, the potential for overheating was literally inescapable,” said Professor Lawrence Witmer, co-author of the study.

“They must have had special mechanisms to control brain temperature, but what were they?”

Professor Witmer and his colleague, Dr. Ruger Porter, looked to the modern-day relatives of dinosaurs, birds and reptiles, where studies indeed showed that evaporation of moisture in the nose, mouth, and eyes cooled the blood on its way to the brain.

Using a technique that allows arteries and veins to show up in CT scans, they were able to trace blood flow from the sites of evaporative cooling to the brain. They also precisely measured the bony canals and grooves that conveyed the blood vessels.

“The handy thing about blood vessels is that they basically write their presence into the bones,” said Dr. Porter, lead author of the study.

“The bony canals and grooves that we see in modern-day birds and reptiles are our link to the dinosaur fossils.”

“We can use this bony evidence to restore the patterns of blood flow in extinct dinosaurs and hopefully get a glimpse into their thermal physiology and how they dealt with heat.”

The researchers looked at bony canal sizes in the dinosaurs to assess the relative importance of the different sites of evaporative cooling based on how much blood was flowing through them.

A key factor turned out to be body size. Smaller dinosaurs such as the goat-sized pachycephalosaur Stegoceras had a very balanced vascular pattern with no single cooling region being particularly emphasized.

“That makes physiological sense because smaller dinosaurs have less of a problem with overheating,” Dr. Porter said.

“But giants like sauropods and ankylosaurs increased blood flow to particular cooling regions of the head far beyond what was necessary to simply nourish the tissues.”

This unbalanced vascular pattern allowed the thermal strategies of large dinosaurs to be more focused, emphasizing one or more cooling regions.

But although sauropods like Diplodocus and Camarasaurus and ankylosaurs like Euoplocephalus all had unbalanced vascular patterns emphasizing certain cooling regions, they still differed.

Sauropods emphasized both the nasal cavity and mouth as cooling regions whereas ankylosaurs only emphasized the nose.

“It’s possible that sauropods were so large — often weighing dozens of tons — that they needed to recruit the mouth as a cooling region in times of heat stress. Panting sauropods may have been a common sight,” Dr. Porter said.

One problem that the scientists encountered was that many of the theropod dinosaurs — such as the 10-ton T. rex — were also gigantic, but the quantitative analysis showed that they had a balanced vascular pattern, like the small-bodied dinosaurs.

“This finding had us scratching our heads until we noticed the obvious difference — theropods like Majungasaurus and T. rex had a huge air sinus in their snouts,” Professor Witmer said.

Looking closer, the team discovered bony evidence that this antorbital air sinus was richly supplied with blood vessels.

Profeesor Witmer had previously shown that air circulated through the antorbital air sinus like a bellows pump every time the animal opened and closed its mouth.

“Boom! An actively ventilated, highly vascular sinus meant that we had another potential cooling region. Theropod dinosaurs solved the same problem… but in a different way,” he said.

The findings appear in the journal Anatomical Record.

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Wm. Ruger Porter & Lawrence M. Witmer. Vascular Patterns in the Heads of Dinosaurs: Evidence for Blood Vessels, Sites of Thermal Exchange, and Their Role in Physiological Thermoregulatory Strategies. Anatomical Record, published online October 16, 2019; doi: 10.1002/ar.24234

Source: www.sci-news.com

480-Million-Year-Old Arthropods Formed Orderly Queues

Friday, October 18, 2019

JEAN VANNIER

Fossils of ancient arthropods discovered in linear formation may indicate a collective behaviour either in response to environmental cues or as part of seasonal reproductive migration. The findings, which are published in Scientific Reports, suggest that group behaviours comparable to those of modern animals existed as early as 480 million years ago.

Collective and social behaviour is known to have evolved through natural selection over millions of years and modern arthropods provide numerous examples, such as the migratory chains of caterpillars, ants or spiny lobsters. Yet, the origins and early history of collective behaviour has remained largely unknown.

Jean Vannier and colleagues described several linear clusters of Ampyx priscus, a trilobite arthropod from the lower Ordovician period (ca 480 Million years ago) of Morocco. The trilobites, which were between 16 and 22 millimetres long, had a stout spine at the front of their bodies and a pair of very long spines at the back. In each cluster of trilobite fossils examined by the authors, individuals were arranged in a line, with the front of their bodies facing in the same direction, maintaining contact via their spines. The authors suggest that, given the scale of the patterns seen, this consistent linearity and directionality is unlikely to be the result of passive transportation or accumulation by currents. Instead, it is more likely that Ampyx was killed suddenly while travelling, for example by being buried rapidly by sediment during a storm.

The authors suggest that Ampyx probably migrated in groups and used their long projecting spines to maintain a single-row formation by physical contact, as they moved along the seafloor. This may have been a stress response to disturbance of their environment by storms, detected by motion and touch sensors, which motivated Ampyx to migrate to quieter and deeper waters. A comparable behaviour is seen in present-day spiny lobsters. Alternatively, the pattern may have been the result of a seasonal reproductive behaviour involving the migration of sexually mature individuals to spawning grounds. Knowing that Ampyx was blind, the authors hypothesize that the trilobites may have coordinated using sensory stimulation via spines and chemicals.

The discovery shows that a 480-million-year-old arthropod may have used its neural complexity to develop a temporary collective behaviour.

###

Article and author details

Collective behaviour in 480-million-year-old trilobite arthropods from Morocco

Corresponding authors:

Jean Vannier
The University of Lyon, Lyon, France

DOI

10.1038/s41598-019-51012-3

Online paper

https://www.nature.com/articles/s41598-019-51012-3

Source: www.eurekalert.org

‘Jurassic World 3’ Filming Date Revealed

Thursday, October 17, 2019

Image via Universal Pictures and Amblin Entertainment

The third installment in the blockbuster Jurassic World franchise is set to begin shooting in February of next year, with a projected release date of June, 2021, according to a recent Forbes interview with producer Frank Marshall. According to Marshall, the untitled Jurassic World 3 is already in pre-production in London’s famous Pinewood Studios.

Marshall’s wife and longtime collaborator, Lucasfilm president Kathleen Kennedy, produced the original Jurassic Park series with Steven Spielberg. Marshall himself joined the series on Jurassic World. Altogether, the Jurassic films have grossed just a shade under $5 billion dollars since the original was released in 1993.

The third film will see the return of original Jurassic World director Colin Trevorrow, who recently surprised Jurassic World fans with an eight-minute short film titled Battle at Big Rock. The short, which takes place one year after the events of Jurassic World: Fallen Kingdom, depicts a family doing battle with a bunch of wild dinosaurs, and was largely well-received. If the short was any indication of what Jurassic World 3 is going to be like, it stands to be the most interesting addition to the Jurassic franchise since the shirtless Jeff Goldblum scene.

Recently, Collider revealed that Goldblum would be appearing in the third Jurassic World film, alongside his original Jurassic Park costars Sam Neill and Laura Dern.

If 2021 is too long to wait for your dinosaur fix, you can catch the Jurassic World Live Tour, an arena show boasting an original story and impressive special effects, as it travels through major cities for the next several months.

Source: https://collider.com

Laura Dern Teases Jurassic World 3: “Being Back with Sam Neill and Jeff Goldblum Sounds Like a Dream”

Thursday, October 17, 2019

"I’m very excited to see how it will all weave together," the actress adds.

Laura Dern's had an amazing year. Not only has the actress attracted Oscar buzz for a phenomenal performance in Marriage Story, but her forthcoming movie Little Women has the internet excited to see Greta Gerwig's follow-up to Lady Bird. Also on Dern's horizon is the recently announced Jurassic World 3.

Dern will reprise her most famous character, Jurassic Park’s paleobotanist Dr. Ellie Sattler, in the movie, which is due to begin filming next year. Sitting down with our sister publication Total Film, Dern spoke about the sequel. "I’m very excited to see how it will all weave together," she says, "but I know it’s a deep intent both of [director] Colin [Trevorrow] and the entire tribe, including Steven Spielberg, to pay homage to the original and where the franchise has gone from there. The idea of bringing back the original cast, in a really beautiful way, it sounds amazing… the idea of being back with Sam [Neill] and Jeff [Goldblum] sounds like a dream."

At least she won’t have to keep as many secrets as she did two years ago, when she appeared in Star Wars: The Last Jedi. "I was shooting Big Little Lies, but couldn’t say anything about it; I was doing Star Wars and couldn’t tell anyone I was in it; and I was shooting Twin Peaks and I couldn’t couldn’t tell anyone I was in it… I had to be very careful even with my own children at the very beginning, with Star Wars." She was the "most boring interview ever", at least for a while. "I’m sure I’m about to be boring again. At least people know I might be working with dinosaurs in the future, but I’m sure I won’t be able to say anything more than that!"

Source: www.gamesradar.com

Lessiniabatis aenigmatica: Eocene-Epoch Stingray Had Unique Body Plan

Wednesday, October 16, 2019

Lessiniabatis aenigmatica from the Eocene of Bolca Lagerstätte. Scale bars – 10 cm. Image credit: Marrama et al, doi: 10.1038/s41598-019-50544-y.

A new species of prehistoric stingray with an exceptional anatomy, which greatly differs from living species, has been identified from fossils found in Italy.

“Stingrays (order Myliobatiformes) are a very diverse group of cartilaginous fishes comprising more than 360 extant species arranged in 11 families,” explained Dr. Giuseppe Marrama, a paleontologist with the Institute of Paleontology at the University of Vienna, and colleagues.

“They are known for their venomous and serrated tail stings, which they use against other predatory fish, and occasionally against humans. They have a rounded or wing-like pectoral disc and a long, whip-like tail that carries one or more serrated and venomous stings.”

“Fossil remains of stingrays are very common, especially their isolated teeth. Complete skeletons, however, exist only from a few extinct species coming from particular fossil sites.”

“Among these, the rich fossil site near Bolca in northeastern Italy is one of the best known.”

Silhouettes of selected living and fossil species as representatives for the modern stingray families and holomorphic fossil species: (a) Hexatrygon bickelli, (b) Dasyatis marmorata, (c) Potamotrygon tigrina, (d) Urobatis halleri, (e) Plesiobatis daviesi, (f) Urolophus kapalensis, (g) Lessiniabatis aenigmatica, (h) Asterotrygon maloneyi, (i) Heliobatis radians, (j) Gymnura altavela, (k) Promyliobatis gazolai, (l) Myliobatis hamlyni, (m) Aetobatus laticeps, (n) Rhinoptera bonasus, (o) Mobula mobular. Image credit: Marrama et al, doi: 10.1038/s41598-019-50544-y.

Dr. Marrama and co-authors found three nearly complete specimens of a previously unknown stingray species at the Bolca site.

Named Lessiniabatis aenigmatica, the creature lived some 50 million years ago (Eocene epoch) in the waters of the western Tethys Ocean.

It had a flattened body and a pectoral disc ovoid in shape. What is striking is the absence of sting and the extremely short tail, which was not long as in the other stingrays and didn’t protrude posteriorly to the disc.

This unique body plan is unknown in other extinct or living species of stingrays.

“More than 70% of the organisms, such as dinosaurs, marine reptiles, several mammal groups, numerous birds, fish and invertebrates, disappeared during the fifth largest extinction event in the Earth’s history that occurred about 66 million years ago at the end of the Cretaceous period,” the researchers said.

“In marine environments, the time after this event is characterized by the emergence and diversification of new species and entire groups of bony and cartilaginous fishes (sharks and rays), which reoccupied the ecological niches left vacant by the extinction’s victims.”

“From this perspective, the emergence of a new body plan in a 50-million-year-old stingray such as Lessiniabatis aenigmatica is particularly intriguing when viewed in the context of simultaneous, extensive diversification and emergence of new anatomical features within several fish groups, during the recovery of the life after the end-Cretaceous extinction event,” Dr. Marrama said.

paper on the discovery is published in the journal Scientific Reports.

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Giuseppe Marramà et al. 2019. A bizarre Eocene dasyatoid batomorph (Elasmobranchii, Myliobatiformes) from the Bolca Lagerstätte (Italy) reveals a new, extinct body plan for stingrays. Scientific Reports 9, article number: 14087; doi: 10.1038/s41598-019-50544-y

Source: www.sci-news.com

"Trespasser: The Lost World": Jurassic Park's Forgotten Digital Sequel

Monday, October 14, 2019

Time to revive some good old memories of this glorious flawed game. It was ahead of its time and I wish we could one day either get a remastered or a remake of this game.

The story pretty much acts both a sequel and prequel to the rest of Jurassic Park as you play a native-american woman named Anne who was left stranded on Isla Sorna after surviving a plane crash and along your travels you discover the origins of Jurassic Park via Hammond's memoirs provided by the voice talent of the late Richard Attenborough. However the game's continuity is a blend of both Film canon and Novel canon 

Unlike many shooters, you control an awkwardly coded arm to pick up your weapons. It takes some time to master the control over Anne's arm.

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Source: /www.scified.com

How The Study Of Dinosaurs Could Help Us

Monday, October 14, 2019

Spinosaurus skeleton. Credit: AFP

China’s leading paleontologist on why the country has emerged as a dinosaur hub and how the discipline can help us navigate the climate crisis.

Before he became China’s best-known paleontologist Xu Xing had wanted to be many other things: an Einstein-inspired physicist and a Shaolin monk, a Karl Marx inspired economist, and a C++ programmer. His admission letter to Peking University (PKU) indicated paleontology as his major, the only option on offer. It was a rationed spot at the famed university that was offered to only a handful of students from his home province of Xinjiang. In Xu’s mind, however, thoughts about dinosaurs were as non-existent as real ones.

Today, at 50, Beijing-based Xu is the “go-to-man in China for anything people want to know about dinosaurs,” paleontologist Paul Barrett, from London’s Natural History Museum, once said. Xu is based in the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing under the Chinese Academy of Sciences and is credited with discovering over 70 new prehistoric species, the most for any verterbrate palaeontologist living today. One of Xu’s discoveries is the controversial four-winged Microraptor from Liaoning, discovered in 2003, which challenged the mainstream view that the ability to fly, as it developed in ground-dwelling dinosaurs, was powered to lift the reptiles off the ground. Xu’s Microraptor offered a different position: that flight developed with dinosaurs who were gliding down from trees. “Nearly 15-20 years later, we have new data and new analysis to support our hypothesis,” he says.

Outside the ninth floor window of Xu’s office, Beijing’s skies are hazy with pollution. Fossils from South Korea, part of his ongoing research, are lined neatly near a microscope. Xu agrees that paleontology research, unlike cutting edge communication technologies, is not going to boost the country’s GDP. “For the general public, the very first question would be: what’s the use of this? Science is basically about understanding the world we live in at a fundamental level, but also, in building a knowledge system. Paleontology is part of this big knowledge system. It can help human beings better survive in the future.”

The last two decades have witnessed active digging and excavating globally, says Xu, but China has somehow emerged as the hub for dinosaurs. “The reason that is China and some other countries were less explored previously, so the discoveries here are more likely to be new ones which also makes it scientifically more important,” he says.

Fossils have been discovered across 21 of China’s 34 provinces and autonomous regions. In a recent talk at the Polish Embassy in Beijing, Xu said the discoveries span periods of 200 to 66 million years ago, from the Early and Middle Jurassic hotbeds in Sichuan and Yunnan provinces, to the Cretaceous fossils at Liaoning. In fact, Zhucheng in Shandong province has the largest dinosaur fossil find where 7,600 fossils were recovered from a 300 m-long pit. The Zhucheng Geopark is currently closed for renovations till 2021 when it will be opened as a theme park and footprint museum.

“We were very lucky. When we started working we immediately found some new species,” he says. These discoveries are partly because of luck in spotting sedimentary rocks close to the surface. Fossils have also been uncovered at an astonishing rate as the ground gets dug up to accommodate more high-rises to meet the demands of China’s booming housing sector. Over the years, local people, too, have come forward to share their accidental finds, mostly for free.

By the mid-’90s, after a “typical” undergraduate life of not caring much for his subject, Xu developed a deep interest in paleontology. By 1999, he had co-authored a paper about the Beipiaosaurus, named after Beipiao in Liaoning province in northeast China and amongst the largest dinosaurs from the early Cretaceous period. During this time, he had learned how to camp out for 40 days in the Gobi desert, how to convert a makeshift kitchen into a portable case for fossils, and why summer is the best time to go digging. There was also a lot of luck.

“There was a time when a camera crew asked us to pretend to dig in the desert for good visuals, my colleague threw his hat in the wind to narrow down on a random spot. He started digging there and found a new species!” says Xu, with a laugh.

“The mid-90s was a very good time for doing science in China,” he says. The first big change was the internet. “If you wanted to contact people in those days outside China, the only way you can do so is by writing letters and the international post was very expensive. It was important for us to keep updated on new work in our field and the internet changed that.”

With that brought a network of the “best minds” in the field. “Paleontology is an international science and there are a lot of collaborations since you have to compare lots of different species from across the globe. For that reason you have more visitors from outside the country than other scientific disciplines in China,” says Xu.

As a climate crisis grips the world, Xu says there is much to learn from paleontology on the interactions between life and the environment. “Paleontology can do empirical study on extinction and that is really important for us to understand. Not just at an individual level but species and fossil records show multiple evidence of mass extinctions. Several palaeontologists are studying the fate of whole eco-systems. Those things without paleontology will be hard to understand,” he says.

Source: https://indianexpress.com

Dinosaur Discovery Sheds New Light On How Raptors Evolved

Saturday, October 12, 2019

A well-preserved fossil of a small, feathered “raptor” dinosaur called Saurornitholestes langstoni shows that North American raptors evolved separately from Asian raptors, including the famous Velociraptor. (Illustration: Jan Sovak)

Near-complete fossil found in Alberta reveals that North American and Asian raptors had distinct family trees.

The discovery of a nearly complete fossil of a small, feathered dinosaur in an Alberta provincial park sheds new light on how “raptor” dinosaurs evolved around the world, according to new research by University of Alberta paleontologists. 

The 76-million-year-old species, known as Saurornitholestes langstoni, was long thought to be so closely related to Velociraptor from Mongolia that some researchers called it Velociraptor langstoni

The new research, by world-renowned paleontologists Philip Currie and Clive Coy from the U of A and David Evans of the Royal Ontario Museum, illustrates how Saurornitholestes differs from Velociraptor. It also shows that Saurornitholestes had a specialized tooth for preening feathers and provides new evidence that the raptor lineage from North America that includes Saurornitholestes is distinct from an Asian lineage that includes the famous Velociraptor

“Paleontology in general is a gigantic puzzle where most of the pieces are missing. The discovery and description of this specimen represents the recovery of many pieces of the puzzle,” said Currie, who holds the Canada Research Chair in Dinosaur Paleobiology.

 “This ranks in the top discoveries of my career. It is pretty amazing.”

‘Scientific gold mine’ 

Saurornitholestes is a small, feathered carnivorous dinosaur within the dromaeosaurid family—also known as raptors—that was previously known from fragmentary remains. Discovered by Coy in Alberta’s Dinosaur Provincial Park in 2014, the new skeleton is remarkably complete and exquisitely preserved, with all the bones except for the tail preserved in life position. 

“Because of their small size and delicate bones, small meat-eating dinosaur skeletons are exceptionally rare in the fossil record. The new skeleton is by far the most complete and best-preserved raptor skeleton ever found in North America. It’s a scientific gold mine,” said Evans.

The research, which focuses on the skull, shows that the North American form has a shorter and deeper skull than the Velociraptor. At the front of the fossil's mouth, the researchers also discovered a flat tooth with long ridges, which was likely used for preening feathers. The same tooth has since been identified in Velociraptor and other dromaeosaurids.

“The new anatomical information we have clearly shows that the North American dromaeosaurids are a separate lineage from the Asian dromaeosaurids, although they do have a common ancestor,” said Currie. 

“This changes our understanding of intercontinental movements of these animals and ultimately will help us understand their evolution.”

Future research will investigate the remainder of the skeleton as well as additional analyses on the relationships between dromaeosaurids.

The study, “Cranial Anatomy of New Specimens of Saurornitholestes langstoni (Dinosauria, Theropoda, Dromaeosauridae) From the Dinosaur Park Formation (Campanian) of Alberta,” was published in The Anatomical Record

Source: https://www.folio.ca

Giant Reptiles Once Ruled Australia. Their Loss Sparked An Ecological Disaster

Saturday, October 12, 2019

An enormous Komodo dragon relative, Megalania, stalks a herd of giant herbivorous marsupials. Credit: LAURIE BEIRNE

Saber-toothed cats, short-faced bears, and other ferocious mammals were the top predators of the ice age across most of the world. But not in Australia. Here, reptiles ruled: land-living crocs, monstrous snakes, and enormous relatives of the Komodo dragon, according to a study presented yesterday at the annual meeting of the Society of Vertebrate Paleontology here. The disappearance of these animals, the researchers argue, made room for mammalian predators to take over and set the stage for a massive extinction crisis that accelerated when Europeans arrived 200 years ago.

“Between the expansion of agriculture in Australia, which changed the landscape, and the predators that we brought in, there was no way for native animals to escape,” says Kenny Travouillon, a paleontologist at the Western Australian Museum in Perth who was not involved in the study.

The new picture emerged after Gilbert Price, a paleontologist at the University of Queensland in St. Lucia, Australia, and colleagues scoured the scientific literature on new fossil discoveries from the past 15 years or so. Added together, the finds showed that Australia had a much greater diversity of ice age reptiles than is widely accepted. These include 200-kilogram relatives of Komodo dragons, three to four times the size of those around today, and long-legged, land-living crocodiles. Price and others have also made new unpublished fossil discoveries that bolster the idea of a continent dominated by reptilian predators for much of the past 25 million years, up until at least 100,000 years ago.

“We think of the age of the dinosaurs as when reptiles like dinosaurs and crocs were dominant,” says Larisa DeSantis, a paleoecologist at Vanderbilt University in Nashville who was not involved with the research. “So, it’s exciting to think Australia was dominated by reptilian predators in its recent history.”

Travouillon says the idea that Australia was once dominated by reptiles was first proposed in the 1990s. But it fell out of favor as some research instead focused on native mammal predators, such as the marsupial lion, Thylacoleo. However, a better understanding of Australia’s fossil record is confirming “that originally the land predators were reptiles,” he says.

Most of these large reptiles, and the only large native mammal carnivores, had finally vanished by about 40,000 years ago along with Australia’s other megafauna, possibly because of changing climate. That left only small mammalian predators like the dog-size Tasmanian tiger and the even smaller Tasmanian devil to step into the role of apex predators across the continent. Price suggests these left ecosystems out of kilter.

Things got worse about 4000 years ago when people introduced the dingo, a placental mammal from Asia that was a more efficient hunter than the Tasmanian tiger or devil and quickly outcompeted them. But it was the European introduction of the cat and the red fox in the past 200 years that has caused the most damage. These animals devastated small marsupials, which had evolved alongside the reptiles but were not used to dealing with more intelligent and effective placental mammal predators.

“Our research demonstrates that it’s not normal for our continent to be dominated by placental mammals as top predators,” Price says, which have “reigned unchecked in the absence of the now-extinct ice age giants.”

The dingo was likely responsible for the loss of the Tasmanian devil and Tasmanian tiger. But cats and foxes have been implicated in the loss of 28 to 30 species and subspecies of Australian mammals in the past 200 years. “That represents 50% of global mammal extinctions over that time,” he says, “which is an absolute ecological disaster.”

And it all began with the disappearance of the ice age reptiles, Price argues. “We’re still facing the ecological fallout of their losses.”

Source: www.sciencemag.org

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