Giant prehistoric seabirds discovery in Antarctica

This 2016 video says about itself:

How the Largest Flying Bird of All Time Stayed Airborne

With a 24-foot wingspan, how did the prehistoric Pelagornis sandersi, the largest known flying bird of all time, manage to fly so well? It relied on two key factors: a light frame and an ability to soar with the ocean currents.

From the University of California – Berkeley in the USA:

Antarctica yields oldest fossils of giant birds with 21-foot wingspans

Two fossils from a group of extinct seabirds represent the largest individuals ever found

October 27, 2020

Summary: Some of the largest birds in history, called pelagornithids, arose a few million years after the mass extinction that killed off the dinosaurs and patrolled the oceans with giant wingspans for some 60 million years. A team of paleontologists has found two fossils — each from individual pelagornithids with wingspans of 20 feet or more — that show this gigantism arose at least 50 million years ago and lasted at least 10 million years.

Fossils recovered from Antarctica in the 1980s represent the oldest giant members of an extinct group of birds that patrolled the southern oceans with wingspans of up to 21 feet that would dwarf the 11½-foot wingspan of today’s largest bird, the wandering albatross.

Called pelagornithids, the birds filled a niche much like that of today’s albatrosses and traveled widely over Earth’s oceans for at least 60 million years. Though a much smaller pelagornithid fossil dates from 62 million years ago, one of the newly described fossils — a 50 million-year-old portion of a bird’s foot — shows that the larger pelagornithids arose just after life rebounded from the mass extinction 65 million years ago, when the relatives of birds, the dinosaurs, went extinct. A second pelagornithid fossil, part of a jaw bone, dates from about 40 million years ago.

“Our fossil discovery, with its estimate of a 5-to-6-meter wingspan — nearly 20 feet — shows that birds evolved to a truly gigantic size relatively quickly after the extinction of the dinosaurs and ruled over the oceans for millions of years,” said Peter Kloess, a graduate student at the University of California, Berkeley.

The last known pelagornithid is from 2.5 million years ago, a time of changing climate as Earth cooled, and the ice ages began.

Kloess is the lead author of a paper describing the fossil that appears this week in the open-access journal Scientific Reports. His co-authors are Ashley Poust of the San Diego Natural History Museum and Thomas Stidham of the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences in Beijing. Both Poust and Stidham received their Ph.Ds from UC Berkeley.

Birds with pseudoteeth

Pelagornithids are known as ‘bony-toothed’ birds because of the bony projections, or struts, on their jaws that resemble sharp-pointed teeth, though they are not true teeth, like those of humans and other mammals. The bony protrusions were covered by a horny material, keratin, which is like our fingernails. Called pseudoteeth, the struts helped the birds snag squid and fish from the sea as they soared for perhaps weeks at a time over much of Earth’s oceans.

Large flying animals have periodically appeared on Earth, starting with the pterosaurs that flapped their leathery wings during the dinosaur era and reached wingspans of 33 feet. The pelagornithids came along to claim the wingspan record in the Cenozoic, after the mass extinction, and lived until about 2.5 million years ago. Around that same time, teratorns, now extinct, ruled the skies.

The birds, related to vultures, “evolved wingspans close to what we see in these bony-toothed birds (pelagornithids),” said Poust. “However, in terms of time, teratorns come in second place with their giant size, having evolved 40 million years after these pelagornithids lived. The extreme, giant size of these extinct birds is unsurpassed in ocean habitats.”

The fossils that the paleontologists describe are among many collected in the mid-1980s from Seymour Island, off the northernmost tip of the Antarctic Peninsula, by teams led by UC Riverside paleontologists. These finds were subsequently moved to the UC Museum of Paleontology at UC Berkeley.

Kloess stumbled across the specimens while poking around the collections as a newly arrived graduate student in 2015. He had obtained his master’s degree from Cal State-Fullerton with a thesis on coastal marine birds of the Miocene era, between 17 million and 5 million years ago, that was based on specimens he found in museum collections, including those in the UCMP.

“I love going to collections and just finding treasures there,” he said. “Somebody has called me a museum rat, and I take that as a badge of honor. I love scurrying around, finding things that people overlook.”

Reviewing the original notes by former UC Riverside student Judd Case, now a professor at Eastern Washington University near Spokane, Kloess realized that the fossil foot bone — a so-called tarsometatarsus — came from an older geological formation than originally thought. That meant that the fossil was about 50 million years old instead of 40 million years old. It is the largest specimen known for the entire extinct group of pelagornithids.

The other rediscovered fossil, the middle portion of the lower jaw, has parts of its pseudoteeth preserved; they would have been up to 3 cm (1 inch) tall when the bird was alive. The approximately 12-cm (5-inch-) long preserved section of jaw came from a very large skull that would have been up to 60 cm (2 feet) long. Using measurements of the size and spacing of those teeth and analytical comparisons to other fossils of pelagornithids, the authors are able to show that this fragment came from an individual bird as big, if not bigger, than the largest known skeletons of the bony-toothed bird group.

A warm Antarctica was a bird playground

Fifty million years ago, Antarctica had a much warmer climate during the time known as the Eocene and was not the forbidding, icy continent we know today, Stidham noted. Alongside extinct land mammals, like marsupials and distant relatives of sloths and anteaters, a diversity of Antarctic birds occupied the land, sea and air.

The southern oceans were the playground for early penguin species, as well as extinct relatives of living ducks, ostriches, petrels and other bird groups, many of which lived on the islands of the Antarctic Peninsula. The new research documents that these extinct, predatory, large- and giant-sized bony-toothed birds were part of the Antarctic ecosystem for over 10 million years, flying side-by-side over the heads of swimming penguins.

“In a lifestyle likely similar to living albatrosses, the giant extinct pelagornithids, with their very long-pointed wings, would have flown widely over the ancient open seas, which had yet to be dominated by whales and seals, in search of squid, fish and other seafood to catch with their beaks lined with sharp pseudoteeth,” said Stidham. “The big ones are nearly twice the size of albatrosses, and these bony-toothed birds would have been formidable predators that evolved to be at the top of their ecosystem.”

Museum collections like those in the UCMP, and the people like Kloess, Poust and Stidham to mine them, are key to reconstructing these ancient habitats.

“Collections are vastly important, so making discoveries like this pelagornithid wouldn’t have happened if we didn’t have these specimens in the public trust, whether at UC Riverside or now at Berkeley,” Kloess said. “The fact that they exist for researchers to look at and study has incredible value.”

Antarctic Peninsula wildlife conservation needed

This 14 October 2020 video says about itself:

“The Antarctic Peninsula” showcases the breathtaking beauty and biodiversity hidden at the end of the Earth. Following the binational expedition conducted by the governments of Argentina and Chile in collaboration with National Geographic Pristine Seas, “The Antarctic Peninsula” documents the work and findings of the team of scientists and conservationists who explored the incredible ecosystem above and below the waters of Antarctica. With stunning underwater footage captured by diving in sub-zero temperatures, learn about one of the most unknown and fragile marine ecosystems which is home to incredible sea creatures that are facing the challenges of climate change and fishing pressure.

Introduced by National Geographic Pristine Seas Director for Latin America Alex Muñoz, dive into this unique ecosystem and learn about the international efforts to protect one of the most spectacular wild places on Earth.

From the University of Sydney in Australia:

Marine protected area urged for Antarctica Peninsula

October 18, 2020

Summary: Species on the Antarctic Peninsula are threatened by climate change and human activities including commercial fishing, tourism, and research infrastructure.

The Western Antarctic Peninsula is one of the fastest-warming places on earth. It is also home to threatened humpback and minke whales, chinstrap, Adélie and gentoo penguin colonies, leopard seals, killer whales, seabirds like skuas and giant petrels, and krill — the bedrock of the Antarctic food chain.

With sea ice covering ever-smaller areas and melting more rapidly due to climate change, many species’ habitats have decreased. The ecosystem’s delicate balance is consequently tilted, leaving species in danger of extinction.

Cumulative threats from a range of human activities including commercial fishing, research activities and tourism combined with climate change is exacerbating this imbalance, and a tipping point is fast approaching.

Dr Carolyn Hogg, from the University of Sydney School of Life and Environmental Sciences, was part of the largest ever all-female expedition to the Antarctic Peninsula, with the women in STEMM initiative, Homeward Bound, in late 2019. There, she witnessed the beauty and fragility of the area, and the negative impacts of climate change and human activity on native species, first-hand. As part of the Homeward Bound program she learnt about the science, conservation and governance of Antarctica.

In a new commentary piece published in Nature, Dr Hogg and her colleagues from the expedition outline these threats, and importantly, offer ways to counter them. More than 280 women in STEMM who have participated in the Homeward Bound initiative are co-signatories to the piece.

A global initiative, Homeward Bound ‘aims to elevate the voices of women in science, technology, engineering mathematics and medicine in leading for positive outcomes for our planet’.

Women are noticeably absent in Antarctica’s human history, which is steeped in tales of male heroism. Female scientists are still a minority in the region’s research stations.

“Now, more than ever, a broad range of perspectives is essential in global decision-making, if we are to mitigate the many threats our planet faces,” said Dr Hogg.

“Solutions include the ratification of a Marine Protected Area around the Peninsula, set to be discussed on 19 October, at a meeting of a group of governments that collectively manage the Southern Ocean’s resources,” said Dr Hogg. “The region is impacted by a number of threats, each potentially problematic in their own right, but cumulated together they will be catastrophic.”

Decreasing krill affects whole ecosystem

The Peninsula’s waters are home to 70 percent of Antarctic krill. In addition to climate change, these krill populations are threatened by commercial fishing. Last year marked the third-largest krill catch on record. Nearly 400,000 tonnes of this animal were harvested, to be used for omega-3 dietary supplements and fishmeal.

“Even relatively small krill catches can be harmful if they occur in a particular region, at a sensitive time for the species that live there,” said Dr Cassandra Brooks, a co-author on the comment from the University of Colorado, Boulder. “For example, fishing when penguins are breeding lowers their food intake, and affects their subsequent breeding success. A Marine Protected Area will conserve and protect this unique ecosystem and its wildlife, and we need to implement it now.”

Climate change is fundamentally altering the Western Antarctic Peninsula:

• temperatures reached a record 20.75°C in February 2020
• the average daily temperature that month was two degrees higher than the mean over the past 70 years
• almost 90 percent of the region’s glaciers are receding rapidly
• in spring 2016, sea-ice levels reached their lowest since records began
• if carbon emissions keep climbing, within 50 years the area of sea-ice will almost halve, and the volume of ice-shelves will decrease by one quarter

As sea ice recedes, populations of larval and juvenile krill, which use the ice for shelter and to feed off the algae it attracts, decline.

A warmer climate and less sea-ice cover will also give opportunities to invasive species, which can enter the territory via international ships, including those carrying tourists.

The lasting tourism and research footprint

Tourism’s footprint is growing. The Peninsula is the most-visited region in Antarctica, owing to its proximity to South America, dramatic beauty and rich marine ecosystem.

Tourist numbers have more than doubled in the past decade, with 74,000 visiting last year compared to 33,000 in 2009.

“Ships can pollute the ocean with micro-plastics, oils and ship noise,” said Dr Justine Shaw, another co-author from the University of Queensland.

While the International Association of Antarctica Tour Operators (IAATO), a self-regulating association that advocates for safe and environmentally responsible travel, provides guidelines for cruise ships and tourists, “an increasing number of vessels that are not IAATO members and that carry up to about 500 passengers have begun visiting the region, and this is concerning as it adds greater pressure,” Dr Shaw said.

While the collection of data and knowledge is important, research activities can also potentially damage the Antarctic Peninsula’s sensitive environment, the team stated.

The Peninsula hosts science facilities belonging to 18 nations — the highest concentration on the continent. New stations and expansions are ever-present.

While these scientific endeavours can increase our understanding of native species’, there can be negative impacts on the region if not properly managed. Dr Shaw explained: “Buildings and infrastructure displace wildlife and vegetation.”

Three ways to protect the Peninsula

1. A Marine Protected Area (MPA) designation for the watersThe authors endorse a proposed MPA for the western Antarctic Peninsula. Led by Chile and Argentina, this is due to be discussed during a two-week meeting commencing 19 October by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), a group of governments that collectively manage the Southern Ocean’s resources.

The MPA would reduce commercial fishing in ecologically sensitive areas, helping preserve the food chain and ensuring greater sustainability for the future in surrounding areas.

A comparable MPA for the Ross Sea, in southern Antarctica, was agreed to in October 2016 to global celebration.

2. Protect land areas

Only 1.5 percent of Antarctica’s ice-free terrain enjoys formal protected status. Much unprotected land is adjacent to research and tourist areas and is therefore vulnerable to human-generated risks like pollution and invasive species.

The authors call for a greater extent and variety of landscapes to be protected.

“Globally, parties to the Convention on Biological Diversity have agreed that 17 percent of land should be protected to ensure conservation of biodiversity. This is a good starting point for Antarctica,” Dr Hogg said.

3. Integrate conservation efforts

For conservation efforts to be effective, they have to be collaborative. Dr Shaw furnished examples: “The Council of Managers of National Antarctic Programs (COMNAP) must work to limit the expansion of research infrastructure. Tour operators’ body IAATO and parties to the Antarctic Treaty System should cooperate to better manage tourist activity — ensuring all tour operators abide by IAATO regulations regardless of whether they are IAATO members.”

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Mosasaur egg discovery in Antarctica?

This October 2018 video says about itself:

Mosasaurs were Earth’s last great marine reptiles. Learn about the surprising places they’d hunt, how some species dwarfed even the Tyrannosaurus rex, and how key physical adaptations allowed these reptiles to become a prehistoric apex predator.

From the University of Texas at Austin in the USA:

First egg from Antarctica is big and might belong to an extinct sea lizard

June 17, 2020

In 2011, Chilean scientists discovered a mysterious fossil in Antarctica that looked like a deflated football. For nearly a decade, the specimen sat unlabeled and unstudied in the collections of Chile’s National Museum of Natural History, with scientists identifying it only by its sci-fi movie-inspired nickname — “The Thing.”

An analysis led by researchers at The University of Texas at Austin has found that the fossil is a giant, soft-shell egg from about 66 million years ago. Measuring in at more than 11 by 7 inches, the egg is the largest soft-shell egg ever discovered and the second-largest egg of any known animal.

The specimen is the first fossil egg found in Antarctica and pushes the limits of how big scientists thought soft-shell eggs could grow. Aside from its astounding size, the fossil is significant because scientists think it was laid by an extinct, giant marine reptile, such as a mosasaur — a discovery that challenges the prevailing thought that such creatures did not lay eggs.

“It is from an animal the size of a large dinosaur, but it is completely unlike a dinosaur egg,” said lead author Lucas Legendre, a postdoctoral researcher at UT Austin’s Jackson School of Geosciences. “It is most similar to the eggs of lizards and snakes, but it is from a truly giant relative of these animals.”

A study describing the fossil egg was published in Nature on June 17.

Co-author David Rubilar-Rogers of Chile’s National Museum of Natural History was one of the scientists who discovered the fossil in 2011. He showed it to every geologist who came to the museum, hoping somebody had an idea, but he didn’t find anyone until Julia Clarke, a professor in the Jackson School’s Department of Geological Sciences, visited in 2018.

“I showed it to her and, after a few minutes, Julia told me it could be a deflated egg!” Rubilar-Rogers said.

Using a suite of microscopes to study samples, Legendre found several layers of membrane that confirmed that the fossil was indeed an egg. The structure is very similar to transparent, quick-hatching eggs laid by some snakes and lizards today, he said. However, because the fossil egg is hatched and contains no skeleton, Legendre had to use other means to zero in on the type of reptile that laid it.

He compiled a data set to compare the body size of 259 living reptiles to the size of their eggs, and he found that the reptile that laid the egg would have been more than 20 feet long from the tip of its snout to the end of its body, not counting a tail. In both size and living reptile relations, an ancient marine reptile fits the bill.

Adding to that evidence, the rock formation where the egg was discovered also hosts skeletons from baby mosasaurs and plesiosaurs, along with adult specimens.

“Many authors have hypothesized that this was sort of a nursery site with shallow protected water, a cove environment where the young ones would have had a quiet setting to grow up,” Legendre said.

The paper does not discuss how the ancient reptile might have laid the eggs. But the researchers have two competing ideas.

One involves the egg hatching in the open water, which is how some species of sea snakes give birth. The other involves the reptile depositing the eggs on a beach and hatchlings scuttling into the ocean like baby sea turtles. The researchers say that this approach would depend on some fancy maneuvering by the mother because giant marine reptiles were too heavy to support their body weight on land. Laying the eggs would require the reptile to wriggle its tail onshore while staying mostly submerged, and supported, by water.

“We can’t exclude the idea that they shoved their tail end up on shore because nothing like this has ever been discovered”, Clarke said.

First frog fossil from Antarctica discovered

This video says about itself:

Saturday, 25 April 2020

First frog fossil found on Antarctica

In 2015, Thomas Mörs reached for a frog in the sand — but the frog didn’t hop away. That’s because the frog had been fossilized 40 million years ago.

By Maria Temming, April 23, 2020 at 11:00 am:

The first frog fossil from Antarctica has been found

An ancient amphibian sheds light on when the continent iced over

The first fossil of a frog found in Antarctica gives new insight into the continent’s ancient climate.

Paleontologists uncovered fragments of the frog’s hip bone and skull in 40-million-year-old sediment collected from Seymour Island, near the tip of the Antarctic Peninsula.

Scientists have previously found evidence of giant amphibians that walked Antarctica during the Triassic Period, over 200 million years ago, but no traces on the continent of amphibians like those around today (SN: 3/23/15). The shape of the newly discovered bones indicates that this frog belonged to the family of Calyptocephalellidae, or helmeted frogs, found today in South America.

The fossilized frog’s modern relatives live exclusively in the warm, humid central Chilean Andes. This suggests that similar climate conditions existed on Antarctica around 40 million years ago, researchers report April 23 in Scientific Reports.

That offers a clue about how fast Antarctica switched from balmy to bitter cold (SN: 4/1/20). Antarctica quickly froze over after splitting from Australia and South America, which were once all part of the supercontinent Gondwana (SN: 10/10/19). But some geologic evidence suggests that ice sheets began forming on Antarctica before it fully separated from the other southern continents about 34 million years ago.

“The question is now, how cold was it, and what was living on the continent when these ice sheets started to form?” says study coauthor Thomas Mörs, a paleontologist at the Swedish Museum of Natural History in Stockholm. “This frog is one more indication that in [that] time, at least around the Peninsula, it was still a suitable habitat for cold-blooded animals like reptiles and amphibians.”

Antarctic penguins and climate change

This 8 April 2020 video says about itself:

Antarctica, climate change and a tale of two penguins

Jonathan Watts visits Antarctica with a team of scientists to look at how human activity and rising temperatures are creating winners and losers among penguins – and why this should be a warning to us all.

Food wrapping, fishing gear and plastic waste continue to reach the Antarctic. Two new studies detail how plastic debris is reaching sub-Antarctic islands: here.

Dinosaur age rainforest discovery in Antarctica

This 2016 video says about itself:

Discovery of fossil “voice box” of Antarctic bird suggests dinosaurs couldn’t sing.

Researchers have found the oldest known fossil vocal organ of a bird … in Antarctica. The voice box is from a species related to ducks and geese that lived during the age of dinosaurs more than 66 million years ago.

A National Science Foundation-funded team led by the University of Texas at Austin discovered the ancient vocal organ called a syrinx–and its apparent absence from non-bird dinosaur fossils of the same age. Researchers believe the organ may have originated late in the evolution of birds after the origin of flight. Drawing on their research, team leader Julia Clarke said that other dinosaurs may not have been able to make noises similar to modern bird calls, but most likely made closed-mouth sounds similar to ostrich booms that don’t require a syrinx.

The organ was found in a fossil species called Vegavis iaai. The fossil was discovered in 1992 on Vega Island in the Antarctic Peninsula by a team from the Argentine Antarctic Institute. It was named in 2005 by Clarke and Argentine colleagues. But, it wasn’t until 2013 Clarke discovered the fossil syrinx in the new specimen and began analysis. The international team may figure out what dinosaurs sounded like, gaining insight into the origins of bird song. The findings appear in the October 12 issue of “Nature”.

From Imperial College London in England:

Traces of ancient rainforest in Antarctica point to a warmer prehistoric world

April 1, 2020

Researchers have found evidence of rainforests near the South Pole 90 million years ago, suggesting the climate was exceptionally warm at the time.

A team from the UK and Germany discovered forest soil from the Cretaceous period within 900 km of the South Pole. Their analysis of the preserved roots, pollen and spores shows that the world at that time was a lot warmer than previously thought.

The discovery and analysis were carried out by an international team of researchers led by geoscientists from the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research in Germany and including Imperial College London researchers. Their findings are published today in Nature.

Co-author Professor Tina van de Flierdt, from the Department of Earth Science & Engineering at Imperial, said: “The preservation of this 90-million-year-old forest is exceptional, but even more surprising is the world it reveals. Even during months of darkness, swampy temperate rainforests were able to grow close to the South Pole, revealing an even warmer climate than we expected.”

The work also suggests that the carbon dioxide (CO2) levels in the atmosphere were higher than expected during the mid-Cretaceous period, 115-80 million years ago, challenging climate models of the period.

The mid-Cretaceous was the heyday of the dinosaurs but was also the warmest period in the past 140 million years, with temperatures in the tropics as high as 35 degrees Celsius and sea level 170 metres higher than today.

However, little was known about the environment south of the Antarctic Circle at this time. Now, researchers have discovered evidence of a temperate rainforest in the region, such as would be found in New Zealand today. This was despite a four-month polar night, meaning for a third of every year there was no life-giving sunlight at all.

The presence of the forest suggests average temperatures were around 12 degrees Celsius and that there was unlikely to be an ice cap at the South Pole at the time.

The evidence for the Antarctic forest comes from a core of sediment drilled into the seabed near the Pine Island and Thwaites glaciers in West Antarctica. One section of the core, that would have originally been deposited on land, caught the researchers’ attention with its strange colour.

The team CT-scanned the section of the core and discovered a dense network of fossil roots, which was so well preserved that they could make out individual cell structures. The sample also contained countless traces of pollen and spores from plants, including the first remnants of flowering plants ever found at these high Antarctic latitudes.

To reconstruct the environment of this preserved forest, the team assessed the climatic conditions under which the plants’ modern descendants live, as well as analysing temperature and precipitation indicators within the sample.

They found that the annual mean air temperature was around 12 degrees Celsius; roughly two degrees warmer than the mean temperature in Germany today. Average summer temperatures were around 19 degrees Celsius; water temperatures in the rivers and swamps reached up to 20 degrees; and the amount and intensity of rainfall in West Antarctica were similar to those in today’s Wales.

To get these conditions, the researchers conclude that 90 million years ago the Antarctic continent was covered with dense vegetation, there were no land-ice masses on the scale of an ice sheet in the South Pole region, and the carbon dioxide concentration in the atmosphere was far higher than previously assumed for the Cretaceous.

Lead author Dr Johann Klages, from the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, said: “Before our study, the general assumption was that the global carbon dioxide concentration in the Cretaceous was roughly 1000 ppm. But in our model-based experiments, it took concentration levels of 1120 to 1680 ppm to reach the average temperatures back then in the Antarctic.”

Visit to Dear Kitty blog from Antarctica

This October 2019 video says about itself:

Join a team of marine scientists as they embark on an unprecedented journey across the Great Southern Ocean and beyond to Antarctica.

Today, for the first time ever, WordPress stats recorded a visit to Dear Kitty. Some blog from Antarctica.

Welcome, visitor, like visitors from all continents are welcome here! This brings back fond memories from when I was in the Antarctic.

How emperor penguins stay warm by huddling

This 27 December 2019 video about emperor penguins says about itself:

How Does Huddling Help Penguins Stay Warm? | BBC Earth

The centre of a penguin huddle can reach temperatures of up to 37 degrees C! How exactly does piling in help these snow animals stay so warm?

Antarctic gentoo penguins build nests

This 16 December 2019 video says about itself:

Gentoo Penguins Build Love Nests! | Penguin Post Office | BBC Earth

Why have a rock on your finger when you can have them in a nice neat pile? These Gentoo penguins have the right idea.

On a tiny island in Antarctica, there’s a post office surrounded by jaw-dropping scenery and 4,000 Gentoo penguins… Every summer, as tourists turn up in their hundreds to see the penguins and to send a postcard, the birds rush to find a partner and raise their young. This extraordinary four-month drama starts when the first penguin hops onto the island and continues until the last one leaves and the post office closes its doors for winter.

I was privileged to see these Port Lockroy penguins.

Before dinosaur extinction, life in trouble

This 2018 BBC video is called How did an Asteroid Drive the Dinosaurs to Extinction? | Earth Unplugged.

From Northwestern University in the USA:

Earth was stressed before dinosaur extinction

Fossilized seashells show signs of global warming, ocean acidification leading up to asteroid impact

December 11, 2019

Summary: By measuring the chemistry of fossilized seashells collected in Antarctica, researchers discovered that Earth was already experiencing carbon cycle instability before the asteroid impact that wiped out the dinosaurs.

New evidence gleaned from Antarctic seashells confirms that Earth was already unstable before the asteroid impact that wiped out the dinosaurs.

The study, led by researchers at Northwestern University, is the first to measure the calcium isotope composition of fossilized clam and snail shells, which date back to the Cretaceous-Paleogene mass extinction event. The researchers found that — in the run-up to the extinction event — the shells’ chemistry shifted in response to a surge of carbon in the oceans.

This carbon influx was likely due to long-term eruptions from the Deccan Traps, a 200,000-square-mile volcanic province located in modern India. During the years leading up to the asteroid impact, the Deccan Traps spewed massive amounts of carbon dioxide (CO2) into the atmosphere. The concentration of CO2 acidified the oceans, directly affecting the organisms living there.

“Our data suggest that the environment was changing before the asteroid impact,” said Benjamin Linzmeier, the study’s first author. “Those changes appear to correlate with the eruption of the Deccan Traps.”

“The Earth was clearly under stress before the major mass extinction event,” said Andrew D. Jacobson, a senior author of the paper. “The asteroid impact coincides with pre-existing carbon cycle instability. But that doesn’t mean we have answers to what actually caused the extinction.”

The study will be published in the January 2020 issue of the journal Geolology, which comes out later this month.

Jacobson is a professor of Earth and planetary sciences in Northwestern’s Weinberg College of Arts and Sciences. Linzmeier was a postdoctoral researcher with the Ubben Program for Climate and Carbon Science at the Institute for Sustainability and Energy at Northwestern when the research was conducted. He is now a postdoctoral fellow at the University of Wisconsin-Madison in the Department of Geoscience.

‘Each shell is a snapshot’

Previous studies have explored the potential effects of the Deccan Traps eruptions on the mass extinction event, but many have examined bulk sediments and used different chemical tracers. By focusing on a specific organism, the researchers gained a more precise, higher-resolution record of the ocean’s chemistry.

“Shells grow quickly and change with water chemistry,” Linzmeier said. “Because they live for such a short period of time, each shell is a short, preserved snapshot of the ocean’s chemistry.”

Seashells mostly are composed of calcium carbonate, the same mineral found in chalk, limestone and some antacid tablets. Carbon dioxide in water dissolves calcium carbonate. During the formation of the shells, CO2 likely affects shell composition even without dissolving them.

For this study, the researchers examined shells collected from the Lopez de Bertodano Formation, a well-preserved, fossil-rich area on the west side of Seymour Island in Antarctica. They analyzed the shells’ calcium isotope compositions using a state-of-the-art technique developed in Jacobson’s laboratory at Northwestern. The method involves dissolving shell samples to separate calcium from various other elements, followed by analysis with a mass spectrometer.

“We can measure calcium isotope variations with high precision,” Jacobson said. “And those isotope variations are like fingerprints to help us understand what happened.”

Using this method, the team found surprising information.

“We expected to see some changes in the shells’ composition, but we were surprised by how quickly the changes occurred,” Linzmeier said. “We also were surprised that we didn’t see more change associated with the extinction horizon itself.”

A future warning

The researchers said that understanding how the Earth responded to past extreme warming and CO2 input can help us prepare for how the planet will respond to current, human-caused climate change.

“To some degree, we think that ancient ocean acidification events are good analogs for what’s happening now with anthropogenic CO2 emissions,” Jacobson said. “Perhaps we can use this work as a tool to better predict what might happen in the future. We can’t ignore the rock record. The Earth system is sensitive to large and rapid additions of CO2. Current emissions will have environmental consequences.”

Brad Sageman and Matthew Hurtgen, both professors of Earth and planetary sciences at Northwestern, are co-senior authors of the paper.

The study, “Calcium isotope evidence for environmental variability before and across the Cretaceous-Paleogene mass extinction,” was supported by the Ubben Program for Climate and Carbon Science at Northwestern University, the David and Lucile Packard Foundation (award number 2007-31757) and the National Science Foundation (award numbers EAR-0723151, ANT-1341729, ANT-0739541 and ANT-0739432.