Dinosaurs became extinct, deep-sea animals survived

This 2015 video from Canada says about itself:

Cretaceous Seas Exhibit at Mount Royal University

Cretaceous Seas is the largest marine vertebrate exhibit in Calgary. Installed from the atrium ceilings in Mount Royal’s East Gate and B-Wing, Cretaceous Seas provides students and the public the opportunity to view life-sized specimens of extinct marine reptiles and fishes that swam or flew the seas of western North America during the Cretaceous Period, more than 65 million years ago. The casts on display were constructed from molds produced from bones of marine reptiles, pterosaurs and fishes unearthed from sea bottom muds deposited in the Western Interior Seaway.

From the Geological Society of America:

Evolution after Chicxulub asteroid impact: Rapid response of life to end-cretaceous mass extinction

July 14, 2020

The impact event that formed the Chicxulub crater (Yucatán Peninsula, México) caused the extinction of 75% of species on Earth 66 million years ago, including non-avian dinosaurs. One place that did not experience much extinction was the deep, as organisms living in the abyss made it through the mass extinction event with just some changes to community structure.

New evidence from International Ocean Discovery Program (IODP) Expedition 364 of trace fossils of burrowing organisms that lived in the seafloor of the Chicxulub Crater beginning a few years after the impact shows just how quick the recovery of the seafloor ecosystem was, with the establishment of a well-developed tiered community within approximately 700,000 years after the event.

In April and May 2016, a team of international scientists drilled into the Chicxulub impact crater. This joint expedition, organized by the International Ocean Discovery Program (IODP) and International Continental Scientific Drilling Program (ICDP) recovered an extended syn- and post-impact set of rock cores, allowing study of the effects of the impact on life and its recovery after the mass extinction event. The end-Cretaceous (K-Pg) event has been profusely studied and its effect on biota are relatively well-known. However, the effect of these changes on the macrobenthic community, the community of organisms living on and in the seafloor that do not leave body fossils, is poorly known.

The investigators concluded that the diversity and abundance of trace fossils responded primarily to variations in the flux of organic matter (i.e., food) sinking to the seafloor during the early Paleocene. Local and regional-scale effects of the K-Pg impact included earthquakes of magnitude 10-11, causing continental and marine landslides, tsunamis hundreds of meters in height that swept more than 300 km onshore, shock waves and air blasts, and the ignition of wildfires. Global phenomena included acid rain, injection of aerosols, dust, and soot into the atmosphere, brief intense cooling followed by slight warming, and destruction of the stratospheric ozone layer, followed by a longer-term greenhouse effect.

Mass extinction events have punctuated the past 500 million years of Earth’s history, and studying them helps geoscientists understand how organisms respond to stress in their environment and how ecosystems recover from the loss of biodiversity. Although the K-Pg mass extinction was caused by an asteroid impact, previous ones were caused by slower processes, like massive volcanism, which caused ocean acidification and deoxygenation and had environmental effects that lasted millions of years.

By comparing the K-Pg record to earlier events like the end Permian mass extinction (the so-called “Great Dying” when 90% of life on Earth went extinct), geoscientists can determine how different environmental changes affect life. There are similar overall patterns of recovery after both events with distinct phases of stabilization and diversification, but with very different time frames. The initial recovery after the K-Pg, even at ground zero of the impact, lasted just a few years; this same phase lasted tens of thousands of years after the end Permian mass extinction. The overall recovery of seafloor burrowing organisms after the K-Pg took ~700,000 years, but it took several million years after the end Permian.

Dinosaurs became extinct, penguins survived

This 14 August 2019 video says about itself:

Researchers at Canterbury Museum in New Zealand say they found the fossils of a penguin that stood more than five feet tall.

That was then. And now …

From Flinders University in Australia:

When penguins ruled after dinosaurs died

Chatham Island provides missing link in evolution

December 9, 2019

What waddled on land but swam supremely in subtropical seas more than 60 million years ago, after the dinosaurs were wiped out on sea and land?

Fossil records show giant human-sized penguins flew through Southern Hemisphere waters — along side smaller forms, similar in size to some species that live in Antarctica today.

Now the newly described Kupoupou stilwelli has been found on the geographically remote Chatham Islands in the southern Pacific near New Zealand’s South Island. It appears to be the oldest penguin known with proportions close to its modern relatives.

It lived between 62.5 million and 60 million years ago at a time when there was no ice cap at the South Pole and the seas around New Zealand were tropical or subtropical.

Flinders University PhD palaeontology candidate and University of Canterbury graduate Jacob Blokland made the discovery after studying fossil skeletons collected from Chatham Island between 2006 and 2011.

He helped build a picture of an ancient penguin that bridges a gap between extinct giant penguins and their modern relatives.

“Next to its colossal human-sized cousins, including the recently described monster penguin Crossvallia waiparensis, Kupoupou was comparatively small — no bigger than modern King Penguins which stand just under 1.1 metres tall,” says Mr Blokland, who worked with Professor Paul Scofield and Associate Professor Catherine Reid, as well as Flinders palaeontologist Associate Professor Trevor Worthy on the discovery.

“Kupoupou also had proportionally shorter legs than some other early fossil penguins. In this respect, it was more like the penguins of today, meaning it would have waddled on land.

“This penguin is the first that has modern proportions both in terms of its size and in its hind limb and foot bones (the tarsometatarsus) or foot shape.”

As published in the US journal Palaeontologica Electronica, the animal’s scientific name acknowledges the Indigenous Moriori people of the Chatham Island (Rēkohu), with Kupoupou meaning ‘diving bird’ in Te Re Moriori.

The discovery may even link the origins of penguins themselves to the eastern region of New Zealand — from the Chatham Island archipelago to the eastern coast of the South Island, where other most ancient penguin fossils have been found, 800km away.

University of Canterbury adjunct Professor Scofield, Senior Curator of Natural History at the Canterbury Museum in Christchurch, says the paper provides further support for the theory that penguins rapidly evolved shortly after the period when dinosaurs still walked the land and giant marine reptiles swam in the sea.

“We think it’s likely that the ancestors of penguins diverged from the lineage leading to their closest living relatives — such as albatross and petrels — during the Late Cretaceous period, and then many different species sprang up after the dinosaurs were wiped out,” Professor Scofield says

“It’s not impossible that penguins lost the ability to fly and gained the ability to swim after the extinction event of 66 million years ago, implying the birds underwent huge changes in a very short time. If we ever find a penguin fossil from the Cretaceous period, we’ll know for sure.”

BACKGROUND: The new species is based on the fossilised bones of five partial skeletons. Another two specimens showed a second larger penguin species was also present on the main Chatham Island but there was not enough material to formally name it. All of the described skeletons were collected between 2006 and 2011 by a group led by Monash University palaeontologist Jeffrey Stilwell. Dr Alan Tennyson from Te Papa Tongarewa the Museum of New Zealand and Professor Julia Clark from University of Texas at Austin were in the group and are also-coauthors of the paper. The species is named after Associate Professor Stilwell with all specimens now cared for by Te Papa.

I visited the Chatham islands. But I did not know about that fossil penguin then.

How mammals recovered after dinosaur extinction

This 2017 video is about Paleogene animals.

By John Pickrell in Science News, October 24, 2019 at 2:00 pm:

Remarkable fossils capture mammals’ recovery after the dino-killing asteroid

Survivors grew from the size of a rat to that of a wolf within 700,000 years of the impact

Understanding how life rebounded after an asteroid strike 66 million years ago, which wiped out up to 75 percent of Earth’s species and ended the dinosaurs’ reign, has been hard. Fossils from the immediate aftermath are exceedingly rare (SN: 4/2/19). Now, though, a fossil-rich deposit in Colorado’s Denver Basin is offering paleontologists a window into how mammals, plants and reptiles recovered and flourished following the impact.

The find has allowed the scientists to piece together a detailed timeline of how mammals quickly diversified and grew in size once nonavian dinosaurs were out of the way. Within 700,000 years after the impact, for instance, some mammals had grown to be 100 times as heavy as the original survivors, researchers report online October 24 in Science.

“This is one of those discoveries all paleontologists dream of,” says Steve Brusatte, a paleontologist at the University of Edinburgh who was not involved in the research. “With a snap of a finger, mammals took over from the dinosaurs. More than 150 million years of dinosaur dominance was ended, just like that, and our ancestors took over.”

The Corral Bluffs site in the Denver Basin is the only known locality in the world to have numerous fossils of animals and plants representing a whole series of time slices in the 1 million years following the Cretaceous–Paleogene, or K–Pg, extinction.

Over the last three years, a team led by researchers at the Denver Museum of Nature and Science has uncovered more than 7,000 fossils there. These include 233 kinds of plants and 16 species of mammals — among which are the earliest known mammals to reach relatively large sizes as they evolved and filled ecological roles previously occupied by dinosaurs (SN: 1/25/17).

Despite a century of searching, the site had previously yielded few fossils — until paleontologist Tyler Lyson realized in 2016 that bones were preserved inside nodules of rock called concretions, rather than visible among the surface rocks.

That eureka moment allowed his team to “crack the code” of discovery there, Lyson says. “That was the real game-changing moment when I broke open the first concretion and saw a mammal skull staring back at me.”

By comparing plant and animal fossils with data on precise dates, the researchers have puzzled together the story of what happened at Corral Bluffs 65 million to 66 million years ago. Following the global devastation wrought by the asteroid impact, ferns and palms dominated, but were slowly replaced by forests with a much greater diversity of trees.

Mammals took a little while to recover, but then swiftly diversified into a variety of forms and body sizes. The biggest initial survivors of the impact weighed just 500 grams, about the size of a rat. But in layers of rock dated to just 100,000 years later, raccoon-sized mammals weighing up to six kilograms appear, Lyson says, not too far off from the maximum size mammals had reached before the mass extinction.

A lack of large predators in the post-impact world — as well as an explosion in plant diversity, offering a wider variety of better food sources — may be what allowed some mammals to reach 25 to 30 kilograms, such as beaver-sized Carsioptychus, by 300,000 years after the impact.

By 700,000 years in the same rocks that the earliest known members of the legume, or bean, family of plants are found, mammals of nearly 50 kilograms appear, such as wolf-sized Eoconodon.

Aside from the sheer number of fossils and different time slices revealed at Corral Bluffs, it was the number of mammal skulls — at least 40 so far, Lyson says — that astounded Brusatte. Skulls are usually very rare and mammals from around this time are typically “known just from teeth, and maybe a few bones here and there,” he says.

Brusatte is working on a site in New Mexico that is one of very few others with similarly aged vertebrate fossils. Though those fossils are less complete, they also point to a rapid recovery and diversification of mammals after the impact. “Different areas are giving the same signal; that tells us that it’s probably true,” he says.

While many mammals before the impact were from long-extinct subgroups, placental mammals, the young of which develop in a womb, came to dominate afterward, making up 95 percent of the roughly 6,500 mammal species alive today. “This is the best record to my knowledge on Earth that shows the recovery of terrestrial biotas after the K–Pg extinction,” says Jin Meng, a paleontologist and expert on dinosaur-era mammals at the American Museum of Natural History in New York City. “The study shows at least part of the earliest record, part of the trunk, of the placental mammal tree of life.”

Ancient fossil bird discovery in New Zealand

This 18 September 2019 video from New Zealand says about itself:

Fossil of ancient bony-toothed bird found in Canterbury

One of world’s oldest bird species has been found in North Canterbury.

Bony-toothed birds, an ancient family of huge seafaring birds, were thought to have evolved in the Northern Hemisphere – but that theory has been upended by the discovery of the family’s oldest, but smallest member in New Zealand.

At 62 million-years-old, the newly-found Protodontopteryx ruthae is rewriting the history of the seabird family.

And as Eleisha Foon reports, while the discovery was made last year, it’s taken until now for experts to determine exactly what it was.

From the Canterbury Museum in New Zealand:

One of world’s oldest bird species found in Waipara, New Zealand

September 17, 2019

The ancestor of some of the largest flying birds ever has been found in Waipara, North Canterbury. …

It lived in New Zealand soon after the dinosaurs died out.

While its descendants were some of the biggest flying birds ever, with wingspans of more than 5 metres, ‘Protodontopteryx’ was only the size of an average gull. Like other members of its family, the seabird had bony, tooth-like projections on the edge of its beak.

The seabird fossil was identified by the same team that recently announced the discovery of a 1.6 metre-high giant penguin from the same site.

Amateur palaeontologist Leigh Love found the partial ‘Protodontopteryx’ skeleton last year at the Waipara Greensand fossil site. The bird was named ‘Protodontopteryx ruthae’ after Love’s wife Ruth. Love wanted to thank her for tolerating his decades-long passion for palaeontology.

Fellow amateur Alan Mannering prepared the bones, and a team comprising Love, Mannering, Canterbury Museum Curators Dr Paul Scofield and Dr Vanesa De Pietri and Dr Gerald Mayr of Senckenberg Research Institute and Natural History Museum in Frankfurt, Germany, described ‘Protodontopteryx’.

Dr Scofield says the age of the fossilised bones suggests pelagornithids evolved in the Southern Hemisphere. “While this bird was relatively small, the impact of its discovery is hugely significant in our understanding of this family. Until we found this skeleton, all the really old pelagornithids had been found in the Northern Hemisphere, so everyone thought they’d evolved up there.”

“New Zealand was a very different place when ‘Protodontoperyx’ were in the skies. It had a tropical climate — the sea temperature was about 25 degrees so we had corals and giant turtles”, he adds.

Dr Mayr says the discovery of ‘Protodontopteryx’ was “truly amazing and unexpected. Not only is the fossil one of the most complete specimens of a pseudotoothed bird, but it also shows a number of unexpected skeletal features that contribute to a better understanding of the evolution of these enigmatic birds.”

Later pelagornithid species evolved to soar over oceans with some species measuring up to 6.4 metres across the wings. ‘Protodontopteryx’s’ skeleton suggests it was less suited for long-distance soaring than later pelagornithids and probably covered much shorter ranges. Its short, broad pseudoteeth were likely designed for catching fish. Later species had needle-like pseudoteeth which were likely used to catch soft-bodied prey like squid.

Dr De Pietri says “because ‘Protodontopteryx’ was less adapted to sustained soaring than other known pelagornithids, we can now say that pseudoteeth evolved before these birds became highly specialised gliders.”

The last pelagornithid species died out around 2.5 million years ago, just before modern humans evolved.

The Waipara Greensand site where the ‘Protodontopteryx’ skeleton was found has yielded several important scientific discoveries in recent years, including ancient penguins and the world’s oldest tropicbird fossil.

Some of these discoveries, including the ‘Protodontopteryx’ fossil, will be displayed in an exhibition about ancient New Zealand at the Museum later this year.

This research was funded by the Royal Society of New Zealand’s Marsden Fund.

First day of dinosaur extinction, new research

This July 2016 video says about itself:

Experience the Disaster that Wiped Out Dinosaurs

When the dinosaur-killing asteroid struck Earth, most of the impact energy was directed outwards and upwards into space. Only 1% of the force traveled down into the ground, but it was enough to ring the planet like a bell and wipeout species around the globe. Only those creatures able to seek shelter from the intense heat on the surface survived.

From the University of Texas at Austin in the USA:

Rocks at asteroid impact site record first day of dinosaur extinction

September 9, 2019

Summary: The research centers on the asteroid impact that wiped out non-avian dinosaurs, with the researchers getting the most detailed look yet of the aftermath that followed by examining the rocks and debris that filled the crater within the first 24 hours after impact.

When the asteroid that wiped out the dinosaurs slammed into the planet, the impact set wildfires, triggered tsunamis and blasted so much sulfur into the atmosphere that it blocked the sun, which caused the global cooling that ultimately doomed the dinos.

That’s the scenario scientists have hypothesized. Now, a new study led by The University of Texas at Austin has confirmed it by finding hard evidence in the hundreds of feet of rocks that filled the impact crater within the first 24 hours after impact.

The evidence includes bits of charcoal, jumbles of rock brought in by the tsunami‘s backflow and conspicuously absent sulfur. They are all part of a rock record that offers the most detailed look yet into the aftermath of the catastrophe that ended the Age of Dinosaurs, said Sean Gulick, a research professor at the University of Texas Institute for Geophysics (UTIG) at the Jackson School of Geosciences.

“It’s an expanded record of events that we were able to recover from within ground zero,” said Gulick, who led the study and co-led the 2016 International Ocean Discovery Program scientific drilling mission that retrieved the rocks from the impact site offshore of the Yucatan Peninsula. “It tells us about impact processes from an eyewitness location.”

The research was published in the Proceedings of the National Academy of Sciences on Sept. 9 and builds on earlier work co-led and led by the Jackson School that described how the crater formed and how life quickly recovered at the impact site. An international team of more than two dozen scientists contributed to this study.

Most of the material that filled the crater within hours of impact was produced at the impact site or was swept in by seawater pouring back into the crater from the surrounding Gulf of Mexico. Just one day deposited about 425 feet of material — a rate that’s among the highest ever encountered in the geologic record. This breakneck rate of accumulation means that the rocks record what was happening in the environment within and around the crater in the minutes and hours after impact and give clues about the longer-lasting effects of the impact that wiped out 75% of life on the planet.

Gulick described it as a short-lived inferno at the regional level, followed by a long period of global cooling.

“We fried them and then we froze them,” Gulick said. “Not all the dinosaurs died that day, but many dinosaurs did.”

Researchers estimate the asteroid hit with the equivalent power of 10 billion atomic bombs of the size used in World War II. The blast ignited trees and plants that were thousands of miles away and triggered a massive tsunami that reached as far inland as Illinois. Inside the crater, researchers found charcoal and a chemical biomarker associated with soil fungi within or just above layers of sand that shows signs of being deposited by resurging waters. This suggests that the charred landscape was pulled into the crater with the receding waters of the tsunami.

Jay Melosh, a Purdue University professor and expert on impact cratering, said that finding evidence for wildfire helps scientists know that their understanding of the asteroid impact is on the right track.

“It was a momentous day in the history of life, and this is a very clear documentation of what happened at ground zero,” said Melosh, who was not involved with this study.

However, one of the most important takeaways from the research is what was missing from the core samples. The area surrounding the impact crater is full of sulfur-rich rocks. But there was no sulfur in the core.

That finding supports a theory that the asteroid impact vaporized the sulfur-bearing minerals present at the impact site and released it into the atmosphere, where it wreaked havoc on the Earth’s climate, reflecting sunlight away from the planet and causing global cooling. Researchers estimate that at least 325 billion metric tons would have been released by the impact. To put that in perspective, that’s about four orders of magnitude greater than the sulfur that was spewed during the 1883 eruption of Krakatoa — which cooled the Earth’s climate by an average of 2.2 degrees Fahrenheit for five years.

Although the asteroid impact created mass destruction at the regional level, it was this global climate change that caused a mass extinction, killing off the dinosaurs along with most other life on the planet at the time.

“The real killer has got to be atmospheric”, Gulick said. “The only way you get a global mass extinction like this is an atmospheric effect.”

The research was funded by a number of international and national support organizations, including the National Science Foundation.

Giant Paleocene penguin discovery in New Zealand

From the Canterbury Museum in New Zealand:

Monster penguin find in Waipara, New Zealand

August 14, 2019

A new species of giant penguin — about 1.6 metres tall — has been identified from fossils found in Waipara, North Canterbury.

The discovery of Crossvallia waiparensis, a monster penguin from the Paleocene Epoch (between 66 and 56 million years ago), adds to the list of gigantic, but extinct, New Zealand fauna. These include the world’s largest parrot, a giant eagle, giant burrowing bat, the moa and other giant penguins.

C. waiparensis is one of the world’s oldest known penguin species and also one of the largest — taller even than today’s 1.2 metre Emperor Penguin — and weighing up to 70 to 80 kg.

A team comprising Canterbury Museum curators Dr Paul Scofield and Dr Vanesa De Pietri, and Dr Gerald Mayr of Senckenberg Natural History Museum in Frankfurt, Germany, analysed the bones and concluded they belonged to a previously unknown penguin species.

In a paper published this week in Alcheringa: An Australasian Journal of Palaeontology, the team concluded that the closest known relative of C. waiparensis is a fellow Paleocene species Crossvallia unienwillia, which was identified from a fossilised partial skeleton found in the Cross Valley in Antarctica in 2000.

Canterbury Museum Senior Curator Natural History Dr Paul Scofield says finding closely related birds in New Zealand and Antarctica shows our close connection to the icy continent.

“When the Crossvallia species were alive, New Zealand and Antarctica were very different from today — Antarctica was covered in forest and both had much warmer climates,” he says.

The leg bones of both Crossvallia penguins suggest their feet played a greater role in swimming than those of modern penguins, or that they hadn’t yet adapted to standing upright like modern penguins.

C. waiparensis is the fifth ancient penguin species described from fossils uncovered at the Waipara Greensand site.

Dr Gerald Mayr says the Waipara Greensand is arguably the world’s most significant site for penguin fossils from the Paleocene Epoch. “The fossils discovered there have made our understanding of penguin evolution a whole lot clearer,” he says. “There’s more to come, too — more fossils which we think represent new species are still awaiting description.”

Dr Vanesa De Pietri, Canterbury Museum Research Curator Natural History, says discovering a second giant penguin from the Paleocene Epoch is further evidence that early penguins were huge. “It further reinforces our theory that penguins attained a giant size very early in their evolution,” she says.

The fossils of several giant species, including C. waiparensis, will be displayed in a new exhibition about prehistoric New Zealand at Canterbury Museum later this year.

This research was partly supported by the Royal Society of New Zealand’s Marsden Fund.

Dinosaurs extinct, lichens survived

This 25 January 2018 video says about itself:

What’s in a Lichen? How Scientists Got It Wrong for 150 Years | Short Film Showcase

For 150 years, scientists believed lichen were defined by a symbiotic relationship between a fungus and algae. Meet the team of researchers who upended this belief in this short film by Andy Johnson, Talia Yuki Moore, Chris A. Johns, and Kate Furby.

From the Field Museum in the USA:

When the dinosaurs died, lichens thrived

Mass extinction hurt land plants, but DNA shows that some fungus/plant combo organisms rose up

June 28, 2019

Summary: When the asteroid hit, dinosaurs weren’t the only ones that suffered. Clouds of ash blocked the sun and cooled the planet’s temperature, devastating plant life. But fungi, which decompose dead stuff, did well. So what happened to the lichens, which are made of a plant and fungus living together as one organism?

When an asteroid smacked into the Earth 66 million years ago, it triggered mass extinctions all over the planet. The most famous victims were the dinosaurs, but early birds, insects, and other life forms took a hit too. The collision caused clouds of ash to block the sun and cool the planet’s temperature, devastating plant life. But a new study in Scientific Reports shows that while land plants struggled, some kinds of lichens — organisms made of fungi and algae living together — seized the moment and evolved into new forms to take up plants’ role in the ecosystem.

“We thought that lichens would be affected negatively, but in the three groups we looked at, they seized the chance and diversified rapidly,” says Jen-Pang Huang, the paper’s first author, a former postdoctoral researcher at the Field Museum now at Academia Sinica in Taipei. “Some lichens grow sophisticated 3D structures like plant leaves, and these ones filled the niches of plants that died out.”

The researchers got interested in studying the effects of the mass extinction on lichens after reading a paper about how the asteroid strike also caused many species of early birds to go extinct. “I read it on the train, and I thought, ‘My god, the poor lichens, they must have suffered too, how can we trace what happened to them?'” says Thorsten Lumbsch, senior author on the study and the Field Museum’s curator of lichenized fungi.

You’ve seen lichens a million times, even if you didn’t realize it. “Lichens are everywhere,” says Huang. “If you go on a walk in the city, the rough spots or gray spots you see on rocks or walls or trees, those are common crust lichens. On the ground, they sometimes look like chewing gum. And if you go into a more pristine forest, you can find orange, yellow, and vivid violet colors — lichens are really pretty.” They’re what scientists call “symbiotic organisms” — they’re made up of two different life forms sharing one body and working together. They’re a partnership between a fungus and an organism that can perform photosynthesis, making energy from sunlight — either a tiny algae plant, or a special kind of blue-green bacterium. Fungi, which include mushrooms and molds, are on their own branch on the tree of life, separate from plants and animals (and actually more closely related to us than to plants). The main role of fungi is to break down decomposing material.

During the mass extinction 66 million years ago, plants suffered since ash from the asteroid blocked out sunlight and lowered temperatures. But the mass extinction seemed to be a good thing for fungi — they don’t rely on sunlight for food and just need lots of dead stuff, and the fossil record shows an increase in fungal spores at this time. Since lichens contain a plant and a fungus, scientists wondered whether they were affected negatively like a plant or positively like a fungus.

“We originally expected lichens to be affected in a negative way, since they contain green things that need light,” says Huang.

To see how lichens were affected by the mass extinction, the scientists had to get creative — there aren’t many fossil lichens from that time frame. But while the researchers didn’t have lichen fossils, they did have lots of modern lichen DNA.

From observing fungi growing in lab settings, scientists know generally how often genetic mutations show up in fungal DNA — how frequently a letter in the DNA sequence accidentally gets switched during the DNA copying process. That’s called the mutation rate. And if you know the mutation rate, if you compare the DNA sequences of two different species, you can generally extrapolate how long ago they must have had a common ancestor with the same DNA.

The researchers fed DNA sequences of three families of lichens into a software program that compared their DNA and figured out what their family tree must look like, including estimates of how long ago it branched into the groups we see today. They bolstered this information with the few lichen fossils they did have, from 100 and 400 million years ago. And the results pointed to a lichen boom after 66 million years ago, at least for some of the leafier lichen families.

“Some groups don’t show a change, so they didn’t suffer or benefit from the changes to the environment,” says Lumbsch, who in addition to his work on lichens is the Vice President of Science and Education at the Field. “Some lichens went extinct, and the leafy macrolichens filled those niches. I was really happy when I saw that not all the lichens suffered.”

The results underline how profoundly the natural world we know today was shaped by this mass extinction. “If you could go back 40 million years, the most prominent groups in vegetation, birds, fungi — they’d be more similar to what you see now than what you’d see 70 million years ago,” says Lumbsch. “Most of what we see around us nowadays in nature originated after the dinosaurs.”

And since this study shows how lichens responded to mass extinction 66 million years ago, it could shed light on how species will respond to the mass extinction the planet is currently undergoing. “Before we lose the world’s biodiversity, we should document it, because we don’t know when we’ll need it,” says Huang. “Lichens are environmental indicators — by simply doing a biodiversity study, we can infer air quality and pollution levels.”

Beyond the potential implications in understanding environmental impacts and mass extinctions, the researchers point to the ways the study deepens our understanding of the world around us.

“For me, it’s fascinating because you would not be able to do this without large molecular datasets. This would have been impossible ten years ago,” says Lumbsch. “It’s another piece to the puzzle to understanding what’s around us in nature.”

“We expect a lot of patterns from studying other organisms, but fungi don’t follow the pattern. Fungi are weird,” says Huang. “They’re really unpredictable, really diverse, really fun.”

This study was contributed to by researchers from the Field Museum, Kasetsart University, Brigham Young University, and Academia Sinica.

Antarctic marine life recovery after dinosaurs’ extinction

This August 2016 video says about itself:

Fossil hunters want to know what life was like when dinosaurs became extinct 66 million years ago. We join an Aussie [Australian] palaeontologist on a US expedition searching for dinosaur fossils in Antarctica, the most challenging place to explore the end of their ancient world.

From the British Antarctic Survey:

Antarctic marine life recovery following the dinosaurs’ extinction

June 19, 2019

A new study shows how marine life around Antarctica returned after the extinction event that wiped out the dinosaurs.

A team led by British Antarctic Survey studied just under 3000 marine fossils collected from Antarctica to understand how life on the sea floor recovered after the Cretaceous-Paleogene (K-Pg) mass extinction 66 million years ago. They reveal it took one million years for the marine ecosystem to return to pre-extinction levels. The results are published today (19 June 2019) in the journal Palaeontology.

The K-Pg extinction wiped out around 60% of the marine species around Antarctica, and 75% of species around the world. Victims of the extinction included the dinosaurs and the ammonites. It was caused by the impact of a 10 km asteroid on the Yucatán Peninsula, Mexico, and occurred during a time period when the Earth was experiencing environmental instability from a major volcanic episode. Rapid climate change, global darkness, and the collapse of food chains affected life all over the globe.

The K-Pg extinction fundamentally changed the evolutionary history of life on Earth. Most groups of animals that dominate modern ecosystems today, such as mammals, can trace the roots of their current success back to the aftermath of this extinction event.

A team of scientists from British Antarctic Survey, the University of New Mexico and the Geological Survey of Denmark & Greenland show that in Antarctica, for over 320,000 years after the extinction, only burrowing clams and snails dominated the Antarctic sea floor environment. It then took up to one million years for the number of species to recover to pre-extinction levels.

Author Dr Rowan Whittle, a palaeontologist at British Antarctic Survey says:

“This study gives us further evidence of how rapid environmental change can affect the evolution of life. Our results show a clear link in the timing of animal recovery and the recovery of Earth systems.”

Author Dr James Witts, a palaeontologist at University of New Mexico says:

“Our discovery shows the effects of the K-Pg extinction were truly global, and that even Antarctic ecosystems, where animals were adapted to environmental changes at high latitudes like seasonal changes in light and food supply, were affected for hundreds of thousands of years after the extinction event.”

Life recoveries after mass extinctions

This 2014 video says about itself:

Evolution of Life After the Dinosaur Extinction

Paleontologist Richard Smith explains the unusual life that evolved on this isolated continent [Australia] during the Paleocene Age 65 million years ago.

From the University of Texas at Austin in the USA:

Evolution imposes ‘speed limit’ on recovery after mass extinctions

April 8, 2019

It takes at least 10 million years for life to fully recover after a mass extinction, a speed limit for the recovery of species diversity that is well known among scientists. Explanations for this apparent rule have usually invoked environmental factors, but research led by The University of Texas at Austin links the lag to something different: evolution.

The recovery speed limit has been observed across the fossil record, from the “Great Dying” that wiped out nearly all ocean life 252 million years ago to the massive asteroid strike that killed all nonavian dinosaurs. The study, published April 8 in the journal Nature Ecology & Evolution, focused on the later example. It looks at how life recovered after Earth’s most recent mass extinction, which snuffed out most dinosaurs 66 million years ago. The asteroid impact that triggered the extinction is the only event in Earth’s history that brought about global change faster than present-day climate change, so the authors said the study could offer important insight on recovery from ongoing, human-caused extinction events.

The idea that evolution — specifically, how long it takes surviving species to evolve traits that help them fill open ecological niches or create new ones — could be behind the extinction recovery speed limit is a theory proposed 20 years ago. This study is the first to find evidence for it in the fossil record, the researchers said.

The team tracked recovery over time using fossils from a type of plankton called foraminifera, or forams. The researchers compared foram diversity with their physical complexity. They found that total complexity recovered before the number of species — a finding that suggests that a certain level of ecological complexity is needed before diversification can take off.

In other words, mass extinctions wipe out a storehouse of evolutionary innovations from eons past. The speed limit is related to the time it takes to build up a new inventory of traits that can produce new species at a rate comparable to before the extinction event.

Lead author Christopher Lowery, a research associate at the University of Texas Institute for Geophysics (UTIG), said that the close association of foram complexity with the recovery speed limit points to evolution as the speed control.

“We see this in our study, but the implication should be that these same processes would be active in all other extinctions,” Lowery said. “I think this is the likely explanation for the speed limit of recovery for everything.”

Lowery co-authored the paper with Andrew Fraass, a research associate at the University of Bristol who did the research while at Sam Houston State University. UTIG is a research unit of the UT Jackson School of Geosciences.

The researchers were inspired to look into the link between recovery and evolution because of earlier research that found recovery took millions of years despite many areas being habitable soon after Earth’s most recent mass extinction. This suggested a control factor other than the environment alone.

They found that although foram diversity as a whole was decimated by the asteroid, the species that survived bounced back quickly to refill available niches. However, after this initial recovery, further spikes in species diversity had to wait for the evolution of new traits. As the speed limit would predict, 10 million years after extinction, the overall diversity of forams was nearly back to levels observed before the extinction event. Foram fossils are prolific in ocean sediments around the world, allowing the researchers to closely track species diversity without any large gaps in time.

Pincelli Hull, an assistant professor at Yale University, said the paper sheds light on factors driving recovery.

“Before this study, people could have told you about the basic patterns in diversity and complexity, but they wouldn’t have been able to answer how they relate to one another in a quantitative sense,” she said.

The authors said that recovery from past extinctions offers a road map for what might come after the modern ongoing extinction, which is driven by climate change, habitat loss, invasive species and other factors.

Which mammals survived dinosaurs?

This July 2013 video says about itself:

Why Did Mammals Survive Dinosaurs’ Extinction?

A new paper by William Lewis of the University of Colorado has strung together multiple lines of evidence to produce the first comprehensive theory of extinction survival.

From the Fundação de Amparo à Pesquisa do Estado de São Paulo in Brazil:

The idiosyncratic mammalian diversification after extinction of the dinosaurs

Researchers state that many mammals lineages coexisted with the dinosaurs before the end-Cretaceous mass extinction. Although many species of mammals also disappeared in the extinction event, several lineages survived.

December 20, 2018

Mass extinction typically conjures up a picture of a meteor falling to Earth and decimating the dinosaurs along with everything else. However, this is not exactly what happened. Different groups of living beings were affected differently by the various mass extinctions that have occurred during the planet’s history.

Consider mammals, a class of vertebrates that already existed during the dinosaur era and survived the mass extinction event in which almost all the dinosaurs were wiped out 66 million years ago, marking the end of the Cretaceous Period.

Four lineages of mammals were contemporaries of the giant reptiles. All four survived. Some were worse hit than others. In a study published in the journal Biology Letters, biologists Tiago Bosisio Quental of the University of São Paulo (USP) and Mathias Pires of the University of Campinas (UNICAMP), both from Brazil, set out to understand how the different groups of mammals made it through the end-Cretaceous mass extinction. Their research was supported by São Paulo Research Foundation — FAPESP.

“When people talk about a mass extinction, it’s assumed that they’re referring to a single extinction event of exceptional magnitude during which a large number of species became extinct in a relatively short time,” Pires said.

Another way of looking at mass extinctions consists of observing the number of species in the fossil record. It can be inferred that a mass extinction occurred in a given geological period when the total number of species that disappeared from the fossil record was much higher than the number of new species that emerged.

“In other words, the extinction rate — the speed at which species are lost — surpasses the speciation rate — the speed at which species are created. This makes the diversification rate negative, since the diversification rate is given by the difference between the extinction and speciation rates,” Pires said.

Five great mass extinctions have been identified in the fossil record in the last 500 million years (as well as many others on a smaller scale). They occurred for various reasons, such as magma spills lasting thousands or millions of years and releasing billions of tons of greenhouse gases that poisoned the atmosphere and blocked out the sun’s rays.

This is what caused the worst of all mass extinctions, in which over 90% of species vanished. It happened 252 million years ago, marking the boundary between the Permian and Triassic Periods (and between the Paleozoic and Mesozoic Eras).

Mass extinctions have also been caused by huge greenhouse effects due to the release of billions of tons of carbon gas (CO2) trapped under the seabed. One such episode is believed to have occurred at the end of the Triassic some 201 million years ago, killing 80% of all species.

The reverse has also happened, with billions of tons of CO2 being sequestered from the atmosphere and causing temperatures to crash and ice to cover the planet. This was the case 444 million years ago at the end of the Ordovician, when 86% of life forms disappeared.

The mass extinction that occurred 66 million years ago is known as the K-Pg event. The acronym refers to the end of the Cretaceous (Kreide in German) and the onset of the Paleogene (Pg).

On a larger time scale, the K-Pg event marks the boundary between the Mesozoic, the era dominated by dinosaurs, and the Cenozoic, the era extending from 66 million years ago to the present day during which mammals have been one of the dominant groups on the planet.

The K-Pg event was caused by a combination of two factors: devastating magma spills in what is now India and the impact of a comet or asteroid with a diameter of 10 km on the Yucatán peninsula in Mexico.

“All these mass extinction episodes are heterogeneous. They occurred for different reasons and unfolded in different ways. Their impact on life forms was not absolute but relative. Some groups suffered more, others less. Some disappeared, while others took advantage of the new environmental conditions after the catastrophe to diversify rapidly,” Pires said.

In the new study that was supported by FAPESP, the researchers set out to investigate how the different lineages of mammals that existed at the end of the Cretaceous succeeded in emerging from the biotic bottleneck represented by the K-Pg event. Daniele Silvestro of the University of Gothenburg (Sweden) and Brian Rankin of the University of California Berkeley (USA) also participated in the study.

The great class of mammals emerged in the Triassic at least 220 million years ago. This is the age of the oldest known fossil. At the end of the Cretaceous, mammalian species were highly diversified. There were the Eutheria or placental mammals, the clade to which Homo sapiens belongs, as do all primates, rodents, bats, cetaceans, and ungulates, among others.

In addition, there were Metatheria or marsupials, the clade to which today’s opossums, kangaroos, and koalas belong. They shared the planet with monotremes (egg-laying mammals) and multituberculates (an extinct taxon of rodent-like mammals named for the specific shape of their teeth, which had multiple tubercles).

The study by Pires and Quental stresses that mammals were particularly hard hit by the mass extinction in the Cretaceous. This does not mean that all four groups suffered equally. The mass extinction was more severe for some than for others.

During the Cretaceous, between 145 million and 66 million years ago, the multituberculates were the dominant and most diversified group of mammals. We know this because multituberculates are the vast majority in the fossil record prior to the K-Pg event. Fossils of placentals and marsupials are less numerous but also plentiful.

Monotremes are the exception. Today, they are few and far between. Indeed, they are comprised of just two families: one includes the duck-billed platypus while the other regards echidnas. Monotremes are also rare in the fossil record both before and after the Cretaceous, suggesting that the group has always been relatively marginal among mammals. For this reason, the researchers did not include monotremes in their study.

Given the knowledge that there were multituberculates, placentals, and marsupials, which group of mammals was most severely affected by the K-Pg event? Which had the most surviving genera? Which displayed the largest increase in diversity (or highest speciation rate) in the millions of years that followed the biotic bottleneck? Which group failed to recover from the cataclysm?

The only way to find answers to these questions is by analyzing the fossil record in a specific region of the planet to try to ensure that all groups of mammals were affected more or less to the same extent by the catastrophe 66 million years ago and in that region.

Quental and Pires chose North America as the focus for their study. One hundred and fifty years of continuous paleontological prospecting in the region have created a detailed picture of mammalian diversity before, during and after the K-Pg event.

“North America has a fossil record of sufficient quality for this kind of study. Other studies have been conducted to analyze how mammals as a whole survived the Cretaceous extinction, but as far we know, this is one of the first studies to analyze the dynamics of diversification in the different groups of mammals,” Quental said.

Distinct diversification patterns

The scientists used a dataset containing 188 recent fossil assemblages from the Cretaceous and Paleocene (spanning from 69.9 million to 55 million years ago) located in the western interior of North America.

“The North American mammal fossil record has the richest and most extensively studied assemblages near the K-Pg event. Fossil occurrences are relatively well resolved, minimizing taxonomic uncertainty. This dataset includes information on nearly 290 genera of mammals, including multituberculates, eutherians, and metatherians,” Quental said.

Several advanced statistical methods were used to estimate origination, extinction and diversification patterns before, during and after the K-Pg event. The results showed that the three groups emerged very differently from the mass extinction.

The origination rate for Methateria (marsupials), for example, remained approximately constant throughout the studied interval. However, a clear peak in extinction was identified during the K-Pg, generating a pulse of negative net diversification. After the K-Pg, the extinction rate gradually diminished, but negative net diversification persisted for more than 2 million years until approximately 64 million years ago.

Multituberculates were diversifying toward the end of the Cretaceous prior to the K-Pg boundary, showing high origination rates and relatively low extinction rates. Near the K-Pg boundary, the extinction rate remained low, but a drop in origination reduced the diversification of multituberculates to near zero. In other words, during the K-Pg, the diversification rate was in balance, as roughly the same number of genera were being created and becoming extinct.

According to the study, after the K-Pg boundary, the extinction rate for multituberculates continued to fall; however, the decrease in multituberculates’ origination rate was even sharper, hence leading to negative diversification. Thus, the number of genera continued to diminish throughout the rest of the period analyzed, until 55 million years ago. The decline appears to have persisted for a long time, given that the multituberculates steadily disappear from the world fossil record. The clade ends approximately 35 million years ago.

Scientists believe the reason for the disappearance of the multituberculates may have been growing competition with rodents, a new eutherian lineage that originated shortly after the K-Pg in the Paleogene.

Eutherians (placentals) display high origination and high extinction near the K-Pg, resulting in high diversity turnover. Originations were higher than extinctions, except between 66 million and 64 million years ago.

Not long after this, there was a second origination pulse accompanied by a drop in the extinction rate, evidencing a short burst in diversification. Around 62 million years ago origination decreased and diversification remained around zero, suggesting diversity equilibrium.

“We found three diversification patterns among the mammalian groups. Metatheria (marsupials) conformed to the classic mass extinction response, with several temporally clustered extinctions leading to a sharp drop in diversification,” Quental said.

Multituberculates underwent a reduction in diversity, with a decrease in diversification and subsequent diversity loss driven by declining origination rates rather than extinction. In other words, their diversity diminished because the creation of new species took a long time.

“Among eutherians there was a more complex rise-and-fall pattern due to rapid fluctuations in the speciation rate during and just after the K-Pg, while the extinction rate rose but not enough to cause negative diversification for long,” Quental said.

According to Pires, the study shows that the K-Pg mass extinction was ecologically selective among mammalian lineages. “Extinctions were concentrated among the specialized carnivorous metatherians and insectivorous eutherians, whereas more generalized eutherians and multituberculates survived and maintained higher diversity,” he said.

Although the results suggest eutherians suffered substantial losses at the K-Pg boundary, these losses were offset by increased origination. Diversification may have occurred among the survivors as other groups of eutherians came to North America from other continents.

“The dietary plasticity of multituberculates may have enabled some species to persist, explaining the low extinction rates. The ecological and taxonomic diversity of multituberculates increased during the late Cretaceous. However, our analysis shows that the multituberculates failed to offset extinction losses because they created less and less diversity, unlike the eutherians, whose losses were offset by high origination rates,” Pires said.

In their conclusion, the authors note that when clades are assessed individually, mass extinction events may be seen as shifts in extinction, in origination, or in both regimes.

“This means that studies of macroevolutionary phenomena focusing on broad taxonomic groups may miss a much richer macroevolutionary history, which can be perceived only at finer taxonomic scales,” Pires said.