Science
New fossils shed light on evolution of insects – CTV News
Research based on a collection of fossils from the Burgess Shale shows a bizarre-looking animal with three eyes that sheds light on the evolution of the brain and head of insects and spiders.
The study, published in the journal Current Biology, looked at 268 specimens collected in the 1980s and 1990s from a site in Yoho National Park in British Columbia and stored at the Royal Ontario Museum in Toronto.
Dozens of those fossils contained the brain and nervous system of the half-billion-year-old Stanleycaris, which was part of an ancient, extinct offshoot of the arthropod evolutionary tree called Radiodonta, distantly related to modern insects and spiders.
“It’s a once-in-a-lifetime kind of discovery,” Joe Moysiuk, lead author of the study and a PhD candidate in ecology and evolutionary biology at the University of Toronto, said in an interview this week.
“We get so much information that we couldn’t get from the ordinary fossil record — things like features of the brain. We can see how many segments the brain of this animal is made up of. We can see the processing centres for visual information extending into the eyes of the animal, giving us all kinds of information about the neuroanatomy of this extinct organism.
“That, in turn, helps us to understand the evolution of the brain and nervous system of the group of modern animals we call the arthropods, so that includes things today like insects and spiders.”
The fossils show the brain was composed of two segments, which he said has deep roots in the arthropod lineage and that its evolution likely preceded the three-segmented brain that characterizes present-day insects.
“We think that third segment was added somewhere along that branch that is the tree of life between the divergency of the velvet worms and the modern arthropods,” explained Moysiuk.
Researchers, he said, were able to trace how the evolution of the brain segments occurred more than 500 million years ago.
“That’s pretty incredible when you think we are looking at these fossils. You think of fossils as being mostly things like shells and bones, not things like brains.”
Moysiuk said the right conditions were needed to preserve the small, compressed fossils of an animal that was about 20 centimetres in size.
“The organisms were preserved in these fast-flowing mudflows, so they were tumbling around and flattened in all kinds of orientations,” said Moysiuk, noting most of the specimens were five centimetres or less.
“So, when we looked at the different fossils that we find from these different orientations of preservation, we are able to piece back together what the whole creature looked like in three dimensions.”
Researchers found that the Stanleycaris, known as a predator in the Cambrian period, had an unexpected large central eye in front of its head in addition to its pair of stalked eyes.
“It emphasizes that these animals were even more bizarre-looking than we thought, but also shows us that the earliest arthropods had already evolved a variety of complex visual systems like many of their modern kin,” Jean-Bernard Caron, Moysiuk’s supervisor and curator of invertebrate paleontology at the Royal Ontario Museum, said in a news release.
“Since most radiodonts are only known from scattered bits and pieces, this discovery is a crucial jump forward in understanding what they looked like and how they lived.”
Moysiuk said the finding also shows the importance of fossil collections.
“There’s a lot of treasures that can be found by trolling through things that have been discovered a long time ago,” he said.
“We have this incredible collection of Burgess Shale fossils at the Royal Ontario Museum.”
This report by The Canadian Press was first published July 8, 2022.
Science
West Antarctica's ice sheet was smaller thousands of years ago – here's why this matters today – The Conversation
As the climate warms and Antarctica’s glaciers and ice sheets melt, the resulting rise in sea level has the potential to displace hundreds of millions of people around the world by the end of this century.
A key uncertainty in how much and how fast the seas will rise lies in whether currently “stable” parts of the West Antarctic Ice Sheet can become “unstable”.
One such region is West Antarctica’s Siple Coast, where rivers of ice flow off the continent and drain into the ocean.
This ice flow is slowed down by the Ross Ice Shelf, a floating mass of ice nearly the size of Spain, which holds back the land-based ice. Compared to other ice shelves in West Antarctica, the Ross Ice Shelf has little melting at its base because the ocean below it is very cold.
Although this region has been stable during the past few decades, recent research suggest this was not always the case. Radiocarbon dating of sediments from beneath the ice sheet tells us that it retreated hundreds of kilometres some 7,000 years ago, and then advanced again to its present position within the last 2,000 years.
Figuring out why this happened can help us better predict how the ice sheet will change in the future. In our new research, we test two main hypotheses.
Read more:
What an ocean hidden under Antarctic ice reveals about our planet’s future climate
Testing scenarios
Scientists have considered two possible explanations for this past ice sheet retreat and advance. The first is related to Earth’s crust below the ice sheet.
As an ice sheet shrinks, the change in ice mass causes the Earth’s crust to slowly uplift in response. At the same time, and counterintuitively, the sea level drops near the ice because of a weakening of the gravitational attraction between the ice sheet and the ocean water.
As the ice sheet thinned and retreated since the last ice age, crustal uplift and the fall in sea level in the region may have re-grounded floating ice, causing ice sheet advance.
The other hypothesis is that the ice sheet behaviour may be due to changes in the ocean. When the surface of the ocean freezes, forming sea ice, it expels salt into the water layers below. This cold briny water is heavier and mixes deep into the ocean, including under the Ross Ice Shelf. This blocks warm ocean currents from melting the ice.
Seafloor sediments and ice cores tell us that this deep mixing was weaker in the past when the ice sheet was retreating. This means that warm ocean currents may have flowed underneath the ice shelf and melted the ice. Mixing increased when the ice sheet was advancing.
We test these two ideas with computer model simulations of ice sheet flow and Earth’s crustal and sea surface responses to changes in the ice sheet with varying ocean temperature.
Because the rate of crustal uplift depends on the viscosity (stickiness) of the underlying mantle, we ran simulations within ranges estimated for West Antarctica. A stickier mantle means slower crustal uplift as the ice sheet thins.
The simulations that best matched geological records had a stickier mantle and a warmer ocean as the ice sheet retreated. In these simulations, the ice sheet retreats more quickly as the ocean warms.
When the ocean cools, the simulated ice sheet readvances to its present-day position. This means that changes in ocean temperature best explain the past ice sheet behaviour, but the rate of crustal uplift also affects how sensitive the ice sheet is to the ocean.
What this means for climate policy today
Much attention has been paid to recent studies that show glacial melting may be irreversible in some parts of West Antarctica, such as the Amundsen Sea embayment.
In the context of such studies, policy debates hinge on whether we should focus on adapting to rising seas rather than cutting greenhouse gas emissions. If the ice sheet is already melting, are we too late for mitigation?
Our study suggests it is premature to give up on mitigation.
Global climate models run under high-emissions scenarios show less sea ice formation and deep ocean mixing. This could lead to the same cold-to-warm ocean switch that caused extensive ice sheet retreat thousands of years ago.
For West Antarctica’s Siple Coast, it is better if we prevent this ocean warming from occurring in the first place, which is still possible if we choose a low-emissions future.
Science
NASA's Voyager 1 resumes sending engineering updates to Earth – Phys.org
For the first time since November, NASA’s Voyager 1 spacecraft is returning usable data about the health and status of its onboard engineering systems. The next step is to enable the spacecraft to begin returning science data again. The probe and its twin, Voyager 2, are the only spacecraft to ever fly in interstellar space (the space between stars).
Voyager 1 stopped sending readable science and engineering data back to Earth on Nov. 14, 2023, even though mission controllers could tell the spacecraft was still receiving their commands and otherwise operating normally. In March, the Voyager engineering team at NASA’s Jet Propulsion Laboratory in Southern California confirmed that the issue was tied to one of the spacecraft’s three onboard computers, called the flight data subsystem (FDS). The FDS is responsible for packaging the science and engineering data before it’s sent to Earth.
The team discovered that a single chip responsible for storing a portion of the FDS memory—including some of the FDS computer’s software code—isn’t working. The loss of that code rendered the science and engineering data unusable. Unable to repair the chip, the team decided to place the affected code elsewhere in the FDS memory. But no single location is large enough to hold the section of code in its entirety.
So they devised a plan to divide affected the code into sections and store those sections in different places in the FDS. To make this plan work, they also needed to adjust those code sections to ensure, for example, that they all still function as a whole. Any references to the location of that code in other parts of the FDS memory needed to be updated as well.
The team started by singling out the code responsible for packaging the spacecraft’s engineering data. They sent it to its new location in the FDS memory on April 18. A radio signal takes about 22.5 hours to reach Voyager 1, which is over 15 billion miles (24 billion kilometers) from Earth, and another 22.5 hours for a signal to come back to Earth. When the mission flight team heard back from the spacecraft on April 20, they saw that the modification had worked: For the first time in five months, they have been able to check the health and status of the spacecraft.
During the coming weeks, the team will relocate and adjust the other affected portions of the FDS software. These include the portions that will start returning science data.
Voyager 2 continues to operate normally. Launched over 46 years ago, the twin Voyager spacecraft are the longest-running and most distant spacecraft in history. Before the start of their interstellar exploration, both probes flew by Saturn and Jupiter, and Voyager 2 flew by Uranus and Neptune.
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Science
Osoyoos commuters invited to celebrate Earth Day with the Leg Day challenge – Oliver/Osoyoos News – Castanet.net
Osoyoos commuters can celebrate Earth Day as the Town joins in on a national commuter challenge known as “Leg Day,” entering a chance to win sustainable transportation prizes.
The challenge, from Earth Day Canada, is to record 10 sustainable commutes taken without a car.
“Cars are one of the biggest contributors to gas emissions in Canada,” reads an Earth Day Canada statement. “That’s why, Earth Day Canada is launching the national Earth Day is Leg Day Challenge.”
So far, over 42.000 people have participated in the Leg Day challenge.
Participants could win an iGo electric bike, public transportation for a year, or a gym membership.
The Town of Osoyoos put out a message Monday promoting joining the national program.
For more information on the Leg Day challenge click here.
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