Warming in the Arctic shrank the ice covering the polar ocean this year to its second-lowest extent in four decades, scientists announced Monday, yet another sign of how climate change is rapidly transforming the region.
Satellites recorded this year’s sea ice minimum at 3.74 million square kilometres on Sept. 15, only the second time the ice has been measured below 4 million square kilometres in 40 years of record keeping, said researchers at the National Snow and Ice Data Center.
“It’s fairly devastating that we’ve had such consistently low sea ice. But unfortunately, it’s not surprising,” said Twila Moon, a glaciologist at the research centre in Boulder, Colorado.
The record low of 3.41 million square kilometres, reached in 2012 after a late-season cyclonic storm broke up the remaining ice, is not much below what researchers see today.
This year’s decline was especially fast between Aug. 31 and Sept. 5, thanks to pulses of warm air coming off a heat wave in Siberia, according to the NSIDC. The rate of ice loss during those six days was faster than during any other year on record. Another team of scientists found in July that the Siberian heat wave would have been all but impossible without human-caused climate change.
As the Arctic sea ice vanishes, it leaves patches of dark water open. Those dark waters absorb solar radiation rather than reflecting it back out of the atmosphere, a process that amplifies warming and helps to explain why Arctic temperatures have risen more than twice as fast as the rest of the world over the last 30 years.
The loss of sea ice also threatens Arctic wildlife, from polar bears and seals to plankton and algae, said Tom Foreman, a polar wildlife expert and Arctic guide.
“The numbers that we’re getting in terms of extent of sea ice decrease each year put us pretty much on red alert in terms of the level of worry that we have, our concern for the stability of this environment,” Foreman said.
The same warming that is opening summertime Arctic waters is also eating away at the ice sheets covering Arctic lands in Canada and Greenland. The faster those ice sheets melt into surrounding ocean, the faster sea levels will rise worldwide.
Given that a warmer Arctic could impact weather patterns worldwide, Moon said the world should not wait for another new record sea ice low before taking action to limit climate change.
“We should work very hard to make differences in our emissions of polluting gases so that we do not see so many records created in the future,” Moon said.
These Tiny, Little-Winged Dinosaurs Were Probably Worse at Flying Than Chickens – ScienceAlert
The discovery of two small dinosaurs with bat-like wings a few years ago was a palaeontologist’s dream. Just how flight evolved in birds is something we’re still trying to nail down, and looking at this early evolution of bat-like wings in dinosaurs could give us a clue.
But a team of researchers has now pointed out that just because you have wings, it doesn’t necessarily mean you’re actually any good at flying.
Yi qi and Ambopteryx longibrachium are two species of theropod dinosaurs that lived around 160 million years ago, both of which had unusually elongated fingers, and a skin membrane stretching between them, similar to a bat’s wing.
This is an entirely different kind of wing to the one theropod dinosaurs evolved to fly with – the dinosaurs that eventually became birds. And, unlike them, after only a few million years, Yi and Ambopteryx became extinct, which is the first hint that these unusual wings could not match those birds-to-be.
However, weird wings on extinct critters mean it’s likely multiple types of wings (and therefore flight) evolved over the years, and that Yi and Ambopteryx’s attempts were not the winning strategy.
But before you can write off Yi and Ambopteryx as complete evolutionary flight failures, you have to know how good (or bad, as the case may be) the two species were at flight.
In 2015, when Yi was found, that team of researchers suggested that the size of its wings and other flight characteristics could mean it was a gliding creature – however it’s unlike any other glider we know of, and its centre of mass might have made even gliding difficult. We just weren’t sure.
A new study, by researchers in the US and China, has now looked into the flight potential of Yi and Ambopteryx in a lot more detail, and come to the conclusion that they really weren’t good at getting their little feet off the trees they lived in.
“Using laser-stimulated fluorescence imaging, we re-evaluate their anatomy and perform aerodynamic calculations covering flight potential, other wing-based behaviours, and gliding capabilities,” the team writes.
“We find that Yi and Ambopteryx were likely arboreal, highly unlikely to have any form of powered flight, and had significant deficiencies in flapping-based locomotion and limited gliding abilities.”
The team’s analysis of the fossils (Yi pictured below) was able to pick up tiny details in soft-tissue that you can’t see with normal light.
Then the team modelled how the dinosaurs might have flown, adjusting for things such as weight, wingspan, and muscle placement (all stuff we can’t tell just from the fossils).
The results were… underwhelming.
“They really can’t do powered flight,” says first author, biologist Thomas Dececchi from Mount Marty University.
“You have to give them extremely generous assumptions in how they can flap their wings. You basically have to model them as the biggest bat, make them the lightest weight, make them flap as fast as a really fast bird, and give them muscles higher than they were likely to have had to cross that threshold. They could glide, but even their gliding wasn’t great.”
So, according to Dececchi and his team’s model, we’re looking at flying capabilities considerably worse than a chicken, perhaps worse than the flightless New Zealand parrot, the kakapo, which is also mostly limited to gliding from trees, but can at least flap to control descent.
But although it’s a bit sad for the Yi and Ambopteryx, it’s good news for us – the findings give even more evidence that dinosaurs evolved flight (or at least tried to) multiple times.
“We propose that this clade was an independent colonisation of the aerial realm for non-avialan theropods. If true, this would represent at least two, but more likely three or more attempts at flight (both powered and gliding) by small pennaraptoran theropods during the Mesozoic,” the team writes in their paper.
“Given the large number of independent occurrences of gliding flight within crown mammals, this should perhaps be unsurprising, but it does create a more complex picture of the aerial ecosystem.”
Seems like some things don’t change much, even in a hundred million years.
The research has been published in iScience.
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SHOP WITH SCOUTED
SHOP WITH SCOUTED
'Weird bat-winged' dinosaurs glided through treetops in attempt at flight: study – CTV News
A new study investigating the flight capabilities of two tiny dinosaurs with thin, bat-like wings is shedding light on the evolution of avian flight itself — an evolution that, it turns out, had a lot of dead ends and false starts along the way.
Published in the journal iScience earlier this week, the study looked at Yi and Ambopteryx, two dinosaurs who lived around 160 million years ago in the Late Jurassic era of China. Both were believed to have the potential for flight due to the thin membranes stretched between their arms and their bodies.
However, when researchers applied mathematical modelling to these prehistoric creatures, they found that they were nowhere near capable of propelling themselves through the air like birds, and instead would’ve used their small wings only to glide.
“We know some dinosaurs could fly before they evolved into birds,” Hans Larsson, a professor at McGill University and Director of McGill’s Redpath Museum, said in a press release. “What this shows us is that at least one lineage of dinosaurs experimented with a completely different mode of aerial locomotion.”
A ‘WEIRD BAT-WINGED’ PAIR
Researchers scanned fossils of Yi and Ambopteryx with lasers to pick out where the soft tissue would fall on their wings, details that couldn’t be seen under regular light.
Then they reconstructed the dinosaurs’ morphology with computer modelling to see whether they could power themselves to flight, whether by leaping from trees or from the ground. They also changed important variables like wingspan and body weight to assess different scenarios on how they might have flown.
In order to flap their wings with enough force to support their own body, the dinosaurs would’ve needed strong pectoral muscles, which were absent. Ambopteryx could only take off in flight at the lowest estimated body size and highest estimated power level, and Yi could not obtain any lift-off except at body weights researchers said were likely too small to be accurate. In almost all scenarios, the dinosaurs could not get off the ground under their own power.
Even with a running start to help them, the minimum take off speed for Yi would be between 1.1 and three times the maximum possible speed Yi would have been capable of. For Ambopteryx, the minimum take-off speed was even more out of reach, needing to be at least 2.3 to four times their top sprinting speed.
The two dinosaurs were capable of gliding if they leaped from trees — but not well. The research found that compared to other dinosaurs capable of gliding or flying, these two “show poorly developed gliding abilities.”
Both Yi and Ambopteryx would have to launch from higher points in trees at higher speeds than other creatures that glide, and they would be less precise when they landed.
They are thought to have spent most of their lives in trees, eating insects, seeds and plants.
AVIALANS AND THE EVOLUTION OF FLIGHT
Many modern creatures can glide, but only pterosaurs, bats and birds developed the structures necessary to fly by flapping their wings.
It’s well known that modern day birds are descendants of dinosaurs, but this new research adds a complication to the predominant theory of how avian flight came about.
The majority of dinosaurs with flying capabilities — called avialans — have had very similar characteristics and body types, and different families of dinosaurs who have evolved towards flight have started as ground-dwelling creatures and gone through similar body changes — such as a reduction in body size, getting an increased shoulder mobility and developing feathers on their four limbs — before gaining the ability to fly.
This has told a reasonably streamlined tale about the evolution of flight from dinosaurs to birds for the most part, the study explained.
But Yi and Ambopteryx are outliers, showing that dinosaur flight went through some bumps on the road.
Both are therapods, a categorization of carnivorous dinosaurs with hollow bones that includes the T-rex and birds, but they’re also part of a little-understood group called Scansoriopterygidae, which are climbing and gliding dinosaurs.
It’s been posited before that scansoriopterygids could represent an interim stage before avialans, an early model of bird flight that then evolved to support more powered flying. But researchers say this was far more likely an independent attempt at flight, a “failed experimental lineage of early arboreal gliders” unconnected to the evolution of avialan flight.
“Given the large number of independent occurrences of gliding flight within crown mammals, this should perhaps be unsurprising, but it does create a more complex picture of the aerial ecosystem,” the study stated.
“We used to think of birds evolving as a linear trend from their ground-dwelling dinosaur ancestry,” Larsson said in the release.
“We can [now] revise this textbook scenario to one that had an explosive diversity of experimentation, with dinosaurs evolving powered flight several times independently from birds, many having fully feathered wings but with bodies too heavy or wings too small to have gotten off the ground, and now, a weird bat-winged group of dinosaurs that were not only the first arboreal dinosaurs, but ones that glided.”
He added that he feels like researchers are “still just scratching the surface,” of dinosaur biodiversity.
Yi, Ambopteryx and others scansoriopterygids had a short-lived existence, unable to compete with the mammalian gliders and avialan fliers that were evolving around them.
Both dinosaurs went extinct after only a few million years, according to the press release.
“Once birds got into the air, these two species were so poorly capable of being in the air that they just got squeezed out,” lead author Thomas Dececchi, an assistant professor of biology at Mount Marty University, said in the release. “Maybe you can survive a few million years underperforming, but you have predators from the top, competition from the bottom, and even some small mammals adding into that, squeezing them out until they disappeared.”
Gliding isn’t an efficient way to get around, as you have to climb to a great height first to travel any sort of distance, he explained.
“It’s not efficient, but it can be used as an escape hatch. It’s not a great thing to do, but sometimes it’s a choice between losing a bit of energy and being eaten. Once they were put under pressure, they just lost their space.
“They couldn’t win on the ground,” he said. “They couldn’t win in the air. They were done.”
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