Paleontology

Ancient amphibian had mouthful of teeth ready to grab you: �鶹��Ƶ research

rasbachn — Thu, 14 Sep 2017 16:33:59 +0000

Ancient amphibian had mouthful of teeth ready to grab you: �鶹��Ƶ research

rasbachn Thu, 09/14/2017 - 12:33

Cutline

The Early Permian dissorophid Cacops displays its fearsome dentition as it preys on the hapless reptile Captorhinus (illustration by Brian Engh)

Elaine Smith

Author legacy

Elaine Smith

Topic

Global Lens

University of Toronto Mississauga

Department of Biology

Paleontology

The idea of being bitten by a nearly toothless modern frog or salamander sounds laughable, but their ancient ancestors had a full array of teeth, large fangs and thousands of tiny hook-like structures called denticles on the roofs of their mouths that would snare prey, according to new research by paleontologists at the University of Toronto.

In research published online in a recent issue of PeerJ, an open access journal, Robert Reisz, distinguished professor of paleontology at University of Toronto Mississauga, explains that the presence of such an extensive field of teeth provides clues to how the intriguing feeding mechanism seen in modern amphibians was also likely used by their ancient ancestors.

The researchers believe that the tooth-bearing plates “were ideally suited for holding on to prey, such as insects or smaller tetrapods, may have facilitated a method of swallowing prey items via retraction of the eyeballs into the mouth, as some amphibians do today."

In many vertebrates, ranging from fish to early synapsids (ancestors of mammals), denticles are commonly found in dense concentrations on the bones of the hard palate (roof of the mouth). However, in one group of tetrapods, temnospondyls (which are thought to be the ancestors of modern amphibians), these denticles were also found on small, bony plates that filled the large soft part of the palate. The entire roof of the mouth was covered with literally thousands of these tiny teeth that they used to grab prey. Since these toothy plates were suspended in soft tissue, they are often lost or scattered during fossilization.

Denticles are significantly smaller than the teeth around the margin of the mouth – on the order of dozens to a couple hundred microns in length. They are actually true teeth, rather than just protrusions in the mouths of these tetrapods, says Reisz and his colleagues, Bryan Gee and Yara Haridy, both graduate students in paleontology.

“Denticles have all of the features of the large teeth that are found on the margin of the mouth,” says Reisz. “In examining tetrapod specimens dating back (approximately) 289 million years, we discovered that the denticles display essentially all of the main features that are considered to define teeth, including enamel and dentine, pulp cavity and peridontia.”

A look at the skull of a small amphibamid dissorophid called Passawioops, with the tiny palatal plates in place in the roof of the mouth, with two close-ups to the right.

In reaching these conclusions, the researchers analyzed specimens unearthed from the fossil-rich Dolese Brothers Limestone Quarry near Richards Spur, Okla. They were extraordinarily well preserved, making them ideal candidates for study.

The researchers extracted and isolated the denticle-bearing plates, created thin section slides and examined them under the microscope – no small feat since denticles on this animal were only about 100 microns long.

Reisz and his graduate students suggest that the next big question relates to evolutionary changes to the overall abundance of teeth: If these ancient amphibians had an astonishing number of teeth, why have most modern amphibians reduced or entirely lost their teeth?

The research was supported by the Natural Sciences and Engineering Research Council of Canada.

�鶹��Ƶ paleontologists uncover 76-million-year-old armoured dinosaur skull

ullahnor — Thu, 10 Aug 2017 17:58:19 +0000

�鶹��Ƶ paleontologists uncover 76-million-year-old armoured dinosaur skull

ullahnor Thu, 08/10/2017 - 13:58

Cutline

From left to right, postdoctoral researcher Victoria Arbour, PhD student Cary Woodruff and Associate Professor David Evans with the newly discovered dinosaur skull (photos courtesy of Mary Paquet/Royal Ontario Museum)

Topic

Global Lens

Paleontology

Faculty of Arts & Science

Dinosaur

A team of paleontologists affiliated with the University of Toronto and the Royal Ontario Museum (ROM) discovered a 76-million-year-old armoured dinosaur skull over the weekend in Southern Alberta.

The skull belongs to Euoplocephalus – one of the largest plant-eating armoured dinosaurs in Canada. The largely complete skull, found in the heart of Alberta's Badlands, has a broad, rounded snout and is covered with blocky ornamental plates.

A large horn projects down from its cheek, and there's a blunt horn above the eye, writes David Evans, associate professor of ecology & evolutionary biology at �鶹��Ƶ and the ROM, via email from the area.

“This is an exciting find for our team,” he adds. “Fossil of armoured dinosaurs are very rare, even in places like Alberta where fossils form the Age of Dinosaurs are relatively common. This is the first good skull of an ankylosaur that my team has collected in the last 15 years of digging in southern Alberta, and it is an important find for helping us understand the dinosaur ecosystem at the time, about 75 million years ago.”

Evans says the skull was found Aug. 5 by Wendy Sloboda, a renowned Alberta fossil hunter who works with the team.

Ouch! �鶹��Ƶ paleontologists identify 508-million-year-old sea creature with can opener-like pincers

ullahnor — Wed, 26 Apr 2017 15:39:11 +0000

Ouch! �鶹��Ƶ paleontologists identify 508-million-year-old sea creature with can opener-like pincers

ullahnor Wed, 04/26/2017 - 11:39

Cutline

Reconstruction of “Tokummia katalepsis” showing a pair of large pincers at the front for capturing prey with much of the multi-segmented body protected by a hardened shell (illustration by Lars Fields)

Sean Bettam

Author legacy

Sean Bettam

Topic

Breaking Research

Fossils

Marine

Faculty of Arts & Science

Paleontology

Ecology & Evolutionary Biology

Earth Sciences

Subheadline

Discovery points to origin of millipedes, crabs and insects among other species

Paleontologists at the University of Toronto and the Royal Ontario Museum (ROM) have uncovered a new fossil species that sheds light on the origin of mandibulates, the most abundant and diverse group of organisms on Earth, to which belong familiar animals such as flies, ants, crayfish and centipedes.

The finding was announced in a study published today in Nature.

Early Career Teaching Awards spotlight: Q&A with ornithologist Sanja Hinić-Frlog

geoff.vendeville — Thu, 16 Mar 2017 18:40:48 +0000

Early Career Teaching Awards spotlight: Q&A with ornithologist Sanja Hinić-Frlog

geoff.vendeville Thu, 03/16/2017 - 14:40

Cutline

Sanja Hinić-Frlog takes her students on nature walks to teach them how to identify birds by their song. The assistant professor, teaching stream in biology at �鶹��Ƶ Mississauga won an Early Career Teaching Award (photo courtesy of Hinić-Frlog)

Geoffrey Vendeville

Author legacy

Geoffrey Vendeville

Topic

Subheadline

Assistant professor Sanja Hinić-Frlog at �鶹��Ƶ Mississauga takes her students on nature walks to teach them how to identify birdsongs

Although it was two decades ago, Sanja Hinić-Frlog clearly remembers the early morning walk when she first recognized a bird by its song. The songbird in question was the northern parula, a warbler with a yellow breast and orange throat that is about the length of an iPhone 5.

Hinić-Frlog’s ears have perked up at the sound of chirping ever since.

The �鶹��Ƶ Mississauga assistant professor now teaches her own undergraduate students how to listen for birdsongs on walks along �鶹��Ƶ Mississauga’s Nature Trail. She is one of four winners of this year's Early Career Teaching Award. She spoke with �鶹��Ƶ News, describing her teaching habits and her all-time favourite birds.

This is the third story in a series casting a spotlight on the Early Career Teaching Award winners. This year's other winners are:

Dawn Kilkenny, assistant professor, teaching stream in the Institute of Biomaterials & Biomedical Engineering at the Faculty of Applied Science & Engineering
David Roberts, assistant professor, teaching stream, Innis College urban studies program, Faculty of Arts & Science
Ashley Stirling, assistant professor, teaching stream in the Faculty of Kinesiology & Physical Education

What do you enjoy most about teaching?

The thing I love the most about teaching about birds is that once you hear the birds, you are never the same.

We hear all these urban noises around us and don't pay attention to them. I remember the moment someone pointed out a bird song to me, and I never forgot that bird song. I heard birds all the time from that moment on. It doesn't matter if you're a little kid or if you're 50, and you learn about this. It opens up a world you're not really attuned to. It helps you realize you're a part of something bigger.

The first birdsong that Hinić-Frlog learned to identify was that of the northern parula (audio courtesy of the Cornell Lab of Ornithology)

Is there a particular bird that fascinates you?

My students make fun of me because I always say “That's my favourite bird!” and then the next day I say “That's my favourite bird!”

I think I'll just stick with my fossil bird. It's called Hesperornis, and it's not around anymore. [She did her PhD dissertation on Hesperornis regalis, an aquatic and carnivorous bird that lived about 80 million years ago]. It lived in Kansas when Kansas was all covered by ocean. There's a lot of fascinating things we still don't know about these birds. And they lived in water and swam very fast. They spent most of their time in water. They’re fascinating.

Any bird that's really good at flying and moving in both air and water is interesting to me because those are two very different mediums with different mechanical and physical pressures.

An illustration of Hesperornis from student Chi-Chun Liu's master's research project in biomedical communications at �鶹��Ƶ Mississauga (photo courtesy of Chi-Chun Liu)

How do we know they could swim?

There are certain characteristics of the toe bones that can help you decide whether or not there was webbing between the toes, which is an indication that a bird lived in close association with an aquatic environment.

How would you describe your teaching method?

I use different methods in different classes, but I always incorporate an active learning approach. Although this approach may look very different in my small and large classes, it is essentially providing an opportunity for students to learn by doing.

In my large classes, I use classroom response systems to break up the lecture and allow for in-class problem solving through content-related questions, case-studies or small discussions.
In a small classroom, like ornithology, it comes more naturally. When we're outdoors, we're learning by doing right away.

Students learn through peer discussion in active classrooms, or by looking for and learning to identify birds by sight and sound through walks on the nature trail.

How do you keep students engaged?

In addition to getting students engaged by using the active-learning approach mentioned above, I use case studies, animations, videos and common misconceptions to introduce topics in lecture.

When we are preparing for a test, I also often use popular-game structures such as Jeopardy or Pictionary to design a review session. I also like to provide students with time to reflect on their learning both inside and outside of the class and at least some choice in both the topics we cover and the assessment weights.

What do you hope students take away from your courses?

If I had to pick one thing – it's going to sound very non-academic, but I think it's important – I want them to learn something about themselves.

If they’re new to the university, many of them can feel quite lost. If I can help them figure out at least what they don't want to do, I think that's useful for them. Using the content outside the classroom to formulate arguments, that is also something that's also very useful.

�鶹��Ƶ researchers and science illustrator bring fossilized creatures to life

geoff.vendeville — Mon, 27 Feb 2017 16:06:28 +0000

�鶹��Ƶ researchers and science illustrator bring fossilized creatures to life

geoff.vendeville Mon, 02/27/2017 - 11:06

Cutline

A scientific illustration of Ovatiovermis cribratus shows how this legged worm-like creature would have looked like with its front-feeding limbs extended (illustration by Danielle Dufault ©Royal Ontario Museum)

Geoffrey Vendeville

Author legacy

Geoffrey Vendeville

Topic

�鶹��Ƶ researchers – some of whom are students – have uncovered fossils of creatures that roamed the earth or swam in its waters millions of years ago.

But it’s only with the help of science illustrators like Danielle Dufault at the Royal Ontario Museum that they are able to bring these long-extinct species back to life.

After many hours of research and consultation with experts, she depicts ancient creatures using traditional and digital media.

“Being able to work and collaborate with scientists gives you the opportunity to learn every day,” she told �鶹��Ƶ News. “This is honestly my dream job.”

On Tuesday, Dufault will be speaking at the annual ROM Research Colloquium and Vaughan Lecture, about her work with researchers.

Read about Moysiuk in The New York Times

Moysiuk said the process can help researchers refine their hypotheses.

“If something doesn’t make sense in the reconstruction, you have a chance to go back and look at the fossils to see why,” he said.

“For our project, it was particularly difficult to determine how the helens (curving spines) would have been positioned relative to the body in the living hyolith.”

�鶹��Ƶ Associate Professor Jean-Bernard Caron and researcher Cédric Aria, who recently completed a PhD in �鶹��Ƶ's department of ecology and evolutionary biology, have worked with Dufault to illustrate a new species, Ovatiovermis cribratus, a 500-million-year-old worm-like creature said to be no longer than a thumb.

Aria said he had also worked with Dufault to animate a fossil called Yawunik, a lobster-like, Cambrian-age predator which is an ancestor of butterflies and spiders.

The pictures, which end up in studies, textbooks and museums, help communicate research findings to a wide audience, Aria said. In fact, the depictions are partly what drew him to the field.

“If I am a paleontologist today, it is because some reconstructions of prehistoric animals have managed to capture both the novelty and the reality of extinct life,” he said.

Good ribbance: �鶹��Ƶ researcher finds dino rib bones reveal remnants of 195-million-year-old protein

ullahnor — Wed, 01 Feb 2017 15:02:00 +0000

Good ribbance: �鶹��Ƶ researcher finds dino rib bones reveal remnants of 195-million-year-old protein

ullahnor Wed, 02/01/2017 - 10:02

Cutline

Skeleton of the 195-million-year-old dinosaur “Lufengosaurus” preserved as found in the ground in Yunnan Province, China. (photo courtesy of Robert Reisz)

Nicolle Wahl

Author legacy

Nicolle Wahl

Topic

Is fossilized rock all that remains when a dinosaur decomposes?

New research from scientists at the University of Toronto and researchers in China and Taiwan provides the first evidence that proteins have been preserved within the 195-million-year-old rib of the sauropodomorph dinosaur Lufengosaurus.

The study appears in the Jan. 31 issue of the journal Nature Communications and the news is already making headlines around the world.

Read The Washington Post story

“These dinosaur proteins are more than 100 million years older than anything previously discovered,” says Professor Robert Reisz, a specialist in vertebrate paleontology in the department of biology at �鶹��Ƶ Mississauga. “These proteins are the building blocks of animal soft tissues, and it’s exciting to understand how they have been preserved.”

Close up of a cross section of the “Lufengosaurus” rib, showing how the bone was organized around vascular canals that contained blood vessels in the living dinosaur, and ran along the length of the rib (photo courtesy of Robert Reisz)

The Canada-Taiwan research team, led by Reisz, used the synchrotron at the Taiwanese National Synchrotron Radiation Research Centre to find the substance in place, known as collagen type I, preserved within the tiny vascular canals of the rib where blood vessels and blood would be in the living dinosaur.

Read the Agence-France Presse story

300 teeth? Duck-billed dinosaurs would have been dentist’s dream

lavende4 — Tue, 16 Aug 2016 14:03:50 +0000

300 teeth? Duck-billed dinosaurs would have been dentist’s dream

lavende4 Tue, 08/16/2016 - 10:03

Cutline

Artist depiction of hadrosaurs (image copyright Danielle Dufault)

Elaine Smith

Author legacy

Elaine Smith

Topic

Breaking Research

Dinosaurs

University of Toronto Mississauga

Paleontology

Robert Reisz

Imagine how much dental care you’d need if you had 300 or more teeth packed together on each side of your mouth.

Duck-billed dinosaurs (hadrosaurs), who lived in the Cretaceous period between 90 million and 65 million years ago, sported this unique dental system, which had never been fully understood until it was examined at the microscopic level through recent research conducted by Aaron LeBlanc, a University of Toronto Mississauga PhD candidate; his supervisor, Professor Robert Reisz (University of Toronto Mississauga vice-dean, graduate), and colleagues at the Royal Ontario Museum and the Museum of the Rockies.

Rather than shedding teeth and replacing them with new ones like other reptiles, hadrosaurs’ mouths contain several parallel stacks of six or more teeth apiece, forming a “highly dynamic network” of teeth that was used to grind and shear tough plant material. Although hadrosaur teeth appear to be fused in place, LeBlanc and his colleagues show that the newest teeth were constantly pushed towards the chewing surface by a complex set of ligaments. When viewed under the microscope, the columns of teeth are not physically touching and are held together by the sand and mud that can get in between the teeth following the decay of the soft ligaments after the animals died.

“Hadrosaur teeth are actually similar to what we have because our teeth are not solidly attached to our jaws. Like us, hadrosaur teeth would have had some fine-scale mobility as they chewed thanks to this ligament system that suspended the teeth in place,” says Reisz.

As they reached the grinding surface, hadrosaur teeth were essentially dead, filled with hard tissue – unlike humans, whose teeth have an inner core filled with blood vessels and nerves.

“Since the teeth were already dead, they could be ground down to little nubbins,” Reisz says.

LeBlanc says this tooth structure – with its tough grinding surface – was “well-adapted to break down tough plant material for digestion,” through both shearing and grinding. This adaptation may have contributed to the hadrosaurs’ longevity and proliferation.

Reisz says that hadrosaurs had “probably the most complex dental system ever made.”

“It’s very elegant – not a single brick of teeth working as a solid unit,” he says. “It’s more like chain mail, providing flexibility as well as strength.”

LeBlanc notes that the duck-billed dinosaur has been known for over 150 years and its dental system has long been recognized as unique, but no one had taken a look inside it at the microscopic level previously. He created thin sections of entire dental assemblies from the upper and lower jaws, that he then ground down, polished and examined under a powerful microscope. Working with their museum colleagues, he and Reisz were also able to explore how hadrosaur teeth form in embryos and hatchlings, providing a more complete picture of this unique model of dental evolution and development.

“The amazing thing is how consistently these dental assemblies conform to our hypothesis of how the system works,” LeBlanc says. “Even in the youngest specimens, the same processes that maintained dental assemblies in the adults were visible.”

The paper, published online in BMC Evolutionary Biology, is part of LeBlanc’s PhD research into the evolution and development of teeth in reptiles and mammals.

When snakes had legs: New look at rare fossil reveals clues about early reptiles

krisha — Mon, 27 Jun 2016 13:49:28 +0000

When snakes had legs: New look at rare fossil reveals clues about early reptiles

krisha Mon, 06/27/2016 - 09:49

Cutline

The fossil snake Tetrapodophis, as preserved (composite image of part and counterpart) and as reconstructed in life (image by: Alessandro Palci, Michael Caldwell & Michael Lee - Flinders University, University of Alberta and South Australian Museum)

Blake Eligh

Author legacy

Blake Eligh

Topic

Close examination of a rare Brazilian fossil is shedding new light on an enduring controversy in evolutionary thought – why snakes evolved their long, limbless bodies.

At the heart of the controversy is a tiny fossil discovered in Brazil. Known as a squamate, Tetrapdophis amplectus was a snakelike creature that lived about 110 million years ago during the early Cretaceous period. It is is considered one of the oldest snakes and is notable for having four small, paddle-like legs.

Previous research described the creature as a primitive snake and worm-like burrower, suggesting that snakes originally evolved to live underground. However, new findings by a Canadian-Australian research team reveal that the creature was more closely related to aquatic lizards, suggesting that snakes evolved their long bodies for eel-like swimming.

Professor Robert Reisz of �鶹��Ƶ Mississauga’s department of biology studied the 20-centimetre-long juvenile specimen first-hand.

“This exquisite tiny fossil is very slender, with limbs that are certainly not suited for burrowing,” Reisz says. “Instead, it shares features with aquatic lizards from the Late Cretaceous. Tetrapodophis may be closely related to snakes and resembles a snake, but probably is not a snake proper.”

Did dinosaurs have lips? Ask this University of Toronto paleontologist

lanthierj — Thu, 19 May 2016 20:08:17 +0000

Did dinosaurs have lips? Ask this University of Toronto paleontologist

lanthierj Thu, 05/19/2016 - 16:08

Cutline

Artist interpretation shows 190-million-year-old nests, eggs, hatchlings and adults of the prosauropod dinosaur Massospondylus in Golden Gate Highlands National Park, South Africa (image credit: Julius Csotonyi)

Blake Eligh

Author legacy

Blake Eligh

Topic

Subheadline

“In popular culture, we imagine dinosaurs as more ferocious-looking, but that is not the case”

Can a crocodile’s smile reveal whether dinosaurs had lips? What if lips and gums hid most of dinosaur's teeth?

New findings from University of Toronto vertebrate palaeontologist Robert Reisz challenge the idea of what therapods might have looked like when dinosaurs roamed the earth.

His research will be presented today at a conference at �鶹��Ƶ Mississauga – and it's already making headlines.

Read the Globe and Mail story

Read the Vice story

Read the BBC story

Read the Guardian story

“When we see dinosaurs in popular culture, such as in the movie Jurassic Park, we see them depicted with big teeth sticking out of their mouths,” Reisz says. Large dinosaurs, such as Tyrannosaurus rex, bare a ferocious grin, while smaller creatures such as velociraptors are shown with scaly lips covering their teeth.

The �鶹��Ƶ Mississauga expert was curious about which version might be most accurate. “We have very little information about dinosaurs’ soft tissue,” he says.

For clues about how therapods might have appeared, he looked to modern-day reptilian predators like crocodiles and monitor lizards. According to Reisz, lipless crocodiles have exposed teeth, much like a Jurassic Park predator, while monitor lizards conceal teeth behind scaly lips that are similar to the movie version of velociraptors.

Lips help to protect teeth, in part by helping to enclose them in a moist environment where they won’t dry out, Reisz says. Crocodiles, which spend their time submerged in water, don’t need lips for protection. “Their teeth are kept hydrated by an aquatic environment,” Reisz says.

Reptiles with lips, such as monitor lizards, typically live on land (much like their movie counterparts) where their teeth require different protection. From this, Reisz concludes that dinosaur teeth would likely have been covered by scaly lips.

“It’s also important to remember that teeth would have been partially covered by gums. If we look at where the enamel stops, we can see that a substantial portion of the teeth would be hidden in the gums. The teeth would have appeared much smaller on a living animal.

“In popular culture, we imagine dinosaurs as more ferocious-looking, but that is not the case.”

(Below: Gorgosaurus using its specialized teeth for feeding on a young Corythosaurus/image credit: Danielle Default)

Reisz presents his findings on May 20 at the annual meeting of the Canadian Society of Vertebrate Palaeontolgy at UTM. The two-day conference, which began on May 19, brings together 60 Canadian researchers working in Canada and around the globe.

“Canada has some very significant locations for understanding vertebrate evolution, ranging from the late Cretaceous in Alberta to the Pleistocene in the Arctic and the early stages of terrestrial vertebrate evolution in the Atlantic region,” says Reisz, who helped to organized the conference.

“There are about 1,000 people worldwide who study vertebrate fossils. It’s important to come together and exchange ideas and unite a community that is so widespread geographically.”

The conference features presentations on the latest research in palaeontology, including a crocodile-like creature from Sudan discovered by �鶹��Ƶ researcher David Evans; a talk on the evolution of how birds hear; what a recently discovered ceratops from Montana tells us about horned dinosaurs; and deciphering the social behaviour of oviraptorsaurs found in Mongolia.

See the complete schedule

�鶹��Ƶ prof unlocks mystery of an ancient mass extinction

sgupta — Thu, 01 Oct 2015 16:03:47 +0000

�鶹��Ƶ prof unlocks mystery of an ancient mass extinction sgupta Thu, 10/01/2015 - 12:03

Cutline

(all photos via Marc Laflamme)

Blake Eligh

Author legacy

Blake Eligh

Topic

University of Toronto Mississauga paleontologist Marc Laflamme spends his summers exploring the rocky red canyons of Namibia, searching for the faint fossilized remains of a long-extinct and very unusual creature.

Neither animal nor vegetable, the biotas of the Ediacaran period were the earliest large, complex life forms on the planet, dominating salt oceans for nearly 40 million years. Very little is known about the soft-bodied creatures, except that they mysteriously disappeared about 500 million years ago, and have no living relatives today.

While the life of the creatures remains something of a mystery, Laflamme and his colleagues may have unlocked the secret of how and why the Ediacarans died out at the beginning of the Cambrian period. Ecosystem engineering by newly-evolving animals radically changed the Ediacaran environmen, causing the demise of the unusual organisms. The team’s research is published in the September edition of the Proceedings of the Royal Society B.

The researchers examined three theories about why the Ediacaran creatures disappeared.

“We theorized that the disappearance of Ediacarans could be due to a lack of (fossil) preservation, a catastrophic mass extinction due to climate change, or something else,” Laflamme says. The answer, to the team’s surprise, turned out to be the third option.

But before they could prove that theory, the team had to actually locate the fossils. The team looks for subtle tube-like impressions in the rocks by the soft-bodied organisms that lived on the floor of long-gone salt-water bodies.

“It’s a challenge to find fossilized records,” Laflamme says. There are about 50 sites around the world where Ediacaran fossils are found but, according to Laflamme, the Namibian site is a fossil bonanza.

“It marks the boundary of the Ediacaran world and the animal world, so we can study how ecosystems changed,” he says.

Geochemistry ruled out the catastrophic mass extinction theory. “Conducting tests on the chemical composition of the rocks tells us if we were dealing with environments that were oxygenated or undergoing a stressful change,” he says.

Positive results would have shown changes in ancient environments due to massive climate change, a volcanic activity or meteor impacts.

“We looked for evidence in the geochemistry, but our data didn’t show evidence of environmentally-driven extinction.”

But a different look at the fossil record revealed a surprising answer to their query, suggesting that “ecosystem engineering” caused the Ediacaran to disappear.

“Ecosystem engineers are organisms that significantly alter their environment,” Laflamme says. “Clams, for instance, can filter a lot of bacteria and nutrients out of the water, which causes problems for other creatures that need those resources.

“Something came in and shook up the Ediacaran system,” he adds. “We hypothesized that it had to do with the evolution of new life, and asked ourselves, ‘What happens when you introduce new biology to a system?’”

The researchers found fossil evidence of new animals – worms and worm-like animals – burrowing into sediment on the ocean floor.

“We can see trails all over the place, showing evidence of different behaviours like burrowing, feeding and den building,” Laflamme says. “We documented how new populations of Ediacaran biota responded to the presence of things that we knew, for sure, were animal fossils.”

“The new organisms would have disrupted the layer of bacteria along the sea floor that Ediacaran biota likely fed on,” Laflamme says. “It made it difficult for anything that didn’t move to survive.“

Delicate and sedentary, the Ediacarans couldn’t move or adapt, leaving them vulnerable to the effects of emerging new animals that disturbed the ocean environment. Unable to compete with the new animals for ecosystem space for nutrients, for space on the sea floor, and for food and oxygen, the biota were edged out by animals who were better adapted to use the available resources.

Laflamme’s research team included UTM graduate students Thomas Boag and Sara Mason. Funding was provided by Yale Peabody Museum of Natural History, NASA Astrobiology Institute, the Connaught Foundation, National Science and Engineering Research Council of Canada, National Science Foundation-Earth Sciences and the National Geographic Society.

Hear Marc Laflamme talk about his research on CBC Radio’s Quirks & Quarks program

See photos from the team's field research in Namibia

picpath

sites/default/files/2015-10-01-fossil.jpg

Paleontology

Ancient amphibian had mouthful of teeth ready to grab you: �鶹��Ƶ research

�鶹��Ƶ paleontologists uncover 76-million-year-old armoured dinosaur skull

Read more at CBC News

Read more about the research dig in the Badlands

Ouch! �鶹��Ƶ paleontologists identify 508-million-year-old sea creature with can opener-like pincers

Read more at the Globe and Mail

Read more at The Washington Post

Read more at The Guardian

Early Career Teaching Awards spotlight: Q&A with ornithologist Sanja Hinić-Frlog

�鶹��Ƶ researchers and science illustrator bring fossilized creatures to life

Read more about the event

Read more about the cone-shaped hyolith

Read about Moysiuk in The New York Times

Read more about the worm-like creature

Good ribbance: �鶹��Ƶ researcher finds dino rib bones reveal remnants of 195-million-year-old protein

Read The Washington Post story

Read more at the Globe and Mail

Read the Agence-France Presse story

Read more about the discovery at BBC News

300 teeth? Duck-billed dinosaurs would have been dentist’s dream

When snakes had legs: New look at rare fossil reveals clues about early reptiles

Read more about research by Robert Reisz

Did dinosaurs have lips? Ask this University of Toronto paleontologist

Read the Globe and Mail story

Read the Vice story

Read the BBC story

Read the Guardian story

See the complete schedule

�鶹��Ƶ prof unlocks mystery of an ancient mass extinction