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Behold Thylacoleo, Australia’s Extinct Giant Marsupial “Lion”

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An artist's rendering of Thylacoleo carnifex, Australia's massive marsupial "lion," based on earlier fossil evidence. A new, nearly complete skeleton of the animal, announced today, refines our understanding of its body plan and biomechanics. (Credit: Wikimedia/Jose Manuel Canete)

An artist’s rendering of Thylacoleo carnifex, Australia’s massive marsupial “lion,” based on earlier fossil evidence. A complete skeletal reconstruction, announced today, refines our understanding of its body plan and biomechanics. (Credit: Wikimedia/Jose Manuel Canete)

Multiple recently discovered specimens of Thylacoleo carnifex have allowed researchers to reconstruct the extinct animal’s entire skeleton for the first time, revising what we know about how Australia’s largest-ever carnivorous mammal moved. Spoiler alert: It appears that, despite weighing in excess of 200 pounds, the animal was an adept climber. Add that skill to the list of traits, including unique flesh-shearing teeth and a lethal thumb claw, that make Thylacoleo so fascinating.

Nicknamed the marsupial lion for its size and formidable teeth, T. carnifex roamed Australia for roughly 2 million years, going extinct only about 40,000 years ago. Thylacoleo was first described in the mid-19th century, based on a skull and jaw fragments that suggested it was a ferocious predator. Paleontologists have debated its actual ecological niche for decades, however, in part because subsequent finds were mostly fragmentary and it was difficult to reconstruct what the animal might have been like in life.

Fortunately, thanks to a series of finds in caves along the southern Australian coast over the last decade, including virtually complete T. carnifex individuals, researchers are finally able to piece together Thylacoleo in all its glory. The recent fossils unearthed include the first known tail and collarbone of the animal — both of which played key roles in its biomechanics.

Apex Predator Or Supreme Scavenger? Or Both?

After reconstructing the animal’s complete skeleton, the authors compared it with those of living Australian marsupials to better understand how it might have moved and, by extension, how it hunted. The researchers confirmed that Thylacoleo would have been a lousy pursuit hunter. It simply wasn’t built for chasing prey at speed. It may, however, have been a skilled ambush hunter. It’s also almost certain that it scavenged.

However it acquired its prey, Thylacoleo’s unusual dentition allowed the animal to make short work of it. Those big pointy teeth you see in renderings of its skull are not canines. Rather, they’re incisors that, unique among carnivorous mammals, evolved into large, serrated steak knives. Meanwhile, the predator’s third molar, along the cheek, is a long shearing blade.

Thylacoleo also had a large claw on its first digit, which it may have used to gut prey. At over 200 pounds (some individuals may have weighed closer to 300 pounds), it must have been an impressive animal.

Perhaps even more intriguing, we now know that T. carnifex had a heavily-muscled and fairly stiff tail, a rigid lower back and powerful forelimbs. These traits suggest the large animal was an excellent climber, able to use its tail and hindlimbs like a tripod to support its weight as it climbed.

Fig 11. Thylacoleo carnifex reconstructions. (A) Reconstruction of the skeleton of T. carnifex. (B) Body outline based on examination of musculature evident in x-ray imaging of marsupials Vogelnest and Allen. CREDIT Wells et al., 2018

A reconstruction of T. carnifex‘s skeleton (A) and body outline (B) based on multiple recent fossil finds that allowed researchers to recreate the predator’s biomechanics. (Credit: Wells et al., 2018)

Exactly what Thylacoleo climbed, however, is unclear. There may have been few if any trees able to support its weight in some of the areas in which fossil remains have been unearthed.

However, the authors point to previous analysis of claw marks on steep cave and pit walls where multiple T. carnifex individuals have been found. The marks have been interpreted as evidence of skillful wall-climbing by the large animals. In addition, multiple juvenile T. carnifex individuals found in several caves across Australia suggest that the animals may have lived socially and used the caverns as communal dens.

Although not related to T. carnifex, the Tasmanian devil, an ambush predator/scavenger, may be its closest living analog in terms of body plan — but not in size. Tasmanian devils are about as big as a small-to-medium-size dog, while Thylacoleo was at least ten times as large.

The open-access study appears today in PLOS One.

Tasmanian devils like this li'l fella, a resident at the Devils@Cradle Sanctuary in Tasmania, are the nearest living relatives of newly described carnivorous marsupial Whollydooleya. Credit: G. Tarlach.

Tasmanian devils like this li’l fella are not related to T. carnifex, though the authors behind today’s study note that the devils provide the best modern analog for Thylacoleo’s body plan, with one significant exception: size. Today’s Tassies weigh roughly 8-25 pounds, but Thylacoleo tipped the scales at more than 200. (Credit: G. Tarlach)

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Ecology

Today’s letters: ‘Visionary’ plans don’t always work in Ottawa

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The opinion piece written by Tobi Nussbaum, CEO of the NCC, declares that a “bold, visionary transit plan” would showcase the capital.

As a long-term resident of Ottawa, I’ve had it with visionary plans. In the 1950s, the streetcars serving Ottawa so well were sent to the scrapyards. In the early ’60s, Queensway construction bulldozed established neighbourhoods and ripped the city apart. Later in the decade, the downtown railway station, which could have formed the hub of a commuter network, was relocated to the suburbs. These actions, in the name of “progress,” were undertaken with the “vision” to make Ottawa a car-reliant city.

Now we have an LRT, built just in time for most people to realize that they do not have to go downtown as they can work from home.

Current thinking is pushing a new “link” between Ottawa and Gatineau, with yet more expensive and disruptive infrastructure projects being touted, including a tramway or another tunnel under the downtown core.

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Ecology

That was then: Biggest earthquake since 1653 rocked Ottawa in 1925

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A regular weekly look-back at some offbeat or interesting stories that have appeared in the Ottawa Citizen over its 175-year history. Today: The big one hits.

The Ottawa Senators were playing a Saturday night game against the Montreal Canadiens at the Auditorium, the score tied 0-0 halfway through the second period. Sens’ rookie Ed Gorman and the Habs’ Billy Boucher had just served penalties for a dustup when the building began to make “ominous creaking sounds.” A window crashed to the ground.

Nearby, at Lisgar Collegiate, all eyes were on teenager Roxie Carrier, in the role of Donna Cyrilla in the musical comedy El Bandido. She had the stage to herself and was singing “Sometime” when the building rocked, the spotlight went out, and someone in the audience yelled “Fire!”

At a home on Carey Avenue, one woman’s normally relaxed cat suddenly arched its back, rushed around the room two or three times, spitting angrily, and climbed up the front-window curtains.

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Ecology

Ottawa delays small nuclear reactor plan as critics decry push for new reactors

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TORONTO — Canadians will have to wait a little while longer to see the federal government’s plan for the development of small nuclear reactors, seen by proponents as critical to the country’s fight against global warming.

Speaking at the opening of a two-day virtual international conference on Wednesday, the parliamentary secretary to the minister of natural resources said the plan will lay out key actions regarding the reactors. Its launch, Paul Lefebvre said, would come in the next few weeks.

“We’re still putting the finishing touches on it,” Lefebvre said. “The action plan is too important to be rushed.”

Small modular reactors — SMRs — are smaller in size and energy output than traditional nuclear power units, and more flexible in their deployment. While conventional reactors produce around 800 megawatts of power, SMRs can deliver up to 300 megawatts.

Proponents consider them ideal as both part of the regular electricity grid as well as for use in remote locations, including industrial sites and isolated northern communities. They could also play a role in the production of hydrogen and local heating.

“SMRs will allow us to take a bold step of meeting our goal of net-zero (emissions) by 2050 while creating good, middle class jobs and strengthening our competitive advantage,” said Lefebvre.

Natural Resources Minister Seamus O’Regan had been scheduled to speak at the conference but did not due to a family emergency.

Industry critics were quick to pounce on the government’s expected SMR announcement. They called on Ottawa to halt its plans to fund the experimental technology.

While nuclear power generation produces no greenhouse gas emissions, a major problem facing the industry is its growing mound of radioactive waste. This week, the government embarked on a round of consultations about what do with the dangerous material.

Dozens of groups, including the NDP, Bloc Quebecois, Green Party and some Indigenous organizations, oppose the plan for developing small modular reactors. They want the government to fight climate change by investing more in renewable energy and energy efficiency.

“We have options that are cheaper and safer and will be available quicker,” Richard Cannings, the NDP natural resources critic, said in a statement.

Lefebvre, however, said the global market for SMRs is expected to be worth between $150 billion and $300 billion a year by 2040. As one of the world’s largest producers of uranium, Canada has to be part of the wave both for economic and environmental reasons, he said.

“There’s a growing demand for smaller, simpler and affordable nuclear technology energy,” Lefebvre said.

Joe McBrearty, head of Canadian Nuclear Laboratories, told the conference the company had signed a host agreement this week with Ottawa-based Global First Power for a demonstration SMR at its Chalk River campus in eastern Ontario. A demonstration reactor will allow for the assessment of the technology’s overall viability, he said.

“When talking about deploying a new technology like an SMR, building a demonstration unit is vital to the success of that process,” McBrearty said. “Most importantly, it allows the public to see the reactor, to kick the tires so to speak, and to have confidence in the safety of its operation.”

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