Latest news with #Mesozoic
Yahoo
6 days ago
- Science
- Yahoo
'Statistically, that shouldn't have happened': Something very weird occurred in the ocean after the dinosaur-killing asteroid hit
When you buy through links on our articles, Future and its syndication partners may earn a commission. About 66 million years ago — perhaps on a downright unlucky day in May — an asteroid smashed into our planet. The fallout was immediate and severe. Evidence shows that about 70% of species went extinct in a geological instant, and not just those famous dinosaurs that once stalked the land. Masters of the Mesozoic oceans were also wiped out, from mosasaurs — a group of aquatic reptiles topping the food chain — to exquisitely shelled squid relatives known as ammonites. Even groups that weathered the catastrophe, such as mammals, fishes and flowering plants, suffered severe population declines and species loss. Invertebrate life in the oceans didn't fare much better. But bubbling away on the seafloor was a stolid group of animals that has left a fantastic fossil record and continues to thrive today: bivalves — clams, cockles, mussels, oysters and more. What happened to these creatures during the extinction event and how they rebounded tells an important story, both about the past and the future of biodiversity. Marine bivalves lost around three-quarters of their species during this mass extinction, which marked the end of the Cretaceous Period. My colleagues and I — each of us paleobiologists studying biodiversity — expected that losing so many species would have severely cut down the variety of roles that bivalves play within their environments, what we call their "modes of life." But, as we explain in a study published in the journal Sciences Advances, that wasn't the case. In assessing the fossils of thousands of bivalve species, we found that at least one species from nearly all their modes of life, no matter how rare or specialized, squeaked through the extinction event. Statistically, that shouldn't have happened. Kill 70% of bivalve species, even at random, and some modes of life should disappear. Related: The 5 mass extinction events that shaped the history of Earth — and the 6th that's happening now Most bivalves happily burrow into the sand and mud, feeding on phytoplankton they strain from the water. But others have adopted chemosymbionts and photosymbionts — bacteria and algae that produce nutrients for the bivalves from chemicals or sunlight in exchange for housing. A few have even become carnivorous. Some groups, including the oysters, can lay down a tough cement that hardens underwater, and mussels hold onto rocks by spinning silken threads. We thought surely these more specialized modes of life would have been snuffed out by the effects of the asteroid's impact, including dust and debris likely blocking sunlight and disrupting a huge part of the bivalves' food chain: photosynthetic algae and bacteria. Instead, most persisted, although biodiversity was forever scrambled as a new ecological landscape emerged. Species that were once dominant struggled, while evolutionary newcomers rose in their place. The reasons some species survived and others didn't leave many questions to explore. Those that filtered phytoplankton from the water column suffered some of the highest species losses, but so did species that fed on organic scraps and didn't rely as much on the Sun's energy. Narrow geographic distributions and different metabolisms may have contributed to these extinction patterns. Life rebounded from each of the Big Five mass extinctions throughout Earth's history, eventually punching through past diversity highs. The rich fossil record and spectacular ecological diversity of bivalves gives us a terrific opportunity to study these rebounds to understand how ecosystems and global biodiversity rebuild in the wake of extinctions. The extinction caused by the asteroid strike knocked down some thriving modes of life and opened the door for others to dominate the new landscape. While many people lament the loss of the dinosaurs, we malacologists miss the rudists. These bizarrely shaped bivalves resembled giant ice cream cones, sometimes reaching more than 3 feet (1 meter) in size, and they dominated the shallow, tropical Mesozoic seas as massive aggregations of contorted individuals, similar to today's coral reefs. At least a few harbored photosymbiotic algae, which provided them with nutrients and spurred their growth, much like modern corals. Today, giant clams (Tridacna) and their relatives fill parts of these unique photosymbiotic lifestyles once occupied by the rudists, but they lack the rudists' astonishing species diversity. Mass extinctions clearly upend the status quo. Now, our ocean floors are dominated by clams burrowed into sand and mud, the quahogs, cockles and their relatives — a scene far different from that of the seafloor 66 million years ago. Ecological traits alone didn't fully predict extinction patterns, nor do they entirely explain the rebound. We also see that simply surviving a mass extinction didn't necessarily provide a leg up as species diversified within their old and sometimes new modes of life — and few of those new modes dominate the ecological landscape today. Like the rudists, trigoniid bivalves had lots of different species prior to the extinction event. These highly ornamented clams built parts of their shells with a super strong biomaterial called nacre — think iridescent pearls — and had fractally interlocking hinges holding their two valves together. But despite surviving the extinction, which should have placed them in a prime position to accumulate species again, their diversification sputtered. Other types of bivalves that made a living in the same way proliferated instead, relegating this once mighty and global group to a handful of species now found only off the coast of Australia. These unexpected patterns of extinction and survival may offer lessons for the future. The fossil record shows us that biodiversity has definite breaking points, usually during a perfect storm of climatic and environmental upheaval. It's not just that species are lost, but the ecological landscape is overturned. Many scientists believe the current biodiversity crisis may cascade into a sixth mass extinction, this one driven by human activities that are changing ecosystems and the global climate. Corals, whose reefs are home to nearly a quarter of known marine species, have faced mass bleaching events as warming ocean water puts their future at risk. Acidification as the oceans absorb more carbon dioxide can also weaken the shells of organisms crucial to the ocean food web. Findings like ours suggest that, in the future, the rebound from extinction events will likely result in very different mixes of species and their modes of life in the oceans. And the result may not align with human needs if species providing the bulk of ecosystem services are driven genetically or functionally extinct. RELATED STORIES —Are we in a 6th mass extinction? —After the 'Great Dying,' life on Earth took millions of years to recover. Now, scientists know why. —Refuge from the worst mass extinction in Earth's history discovered fossilized in China The global oceans and their inhabitants are complex, and, as our team's latest research shows, it is difficult to predict the trajectory of biodiversity as it rebounds — even when extinction pressures are reduced. Billions of people depend on the ocean for food. As the history recorded by the world's bivalves shows, the upending of the pecking order — the number of species in each mode of life — won't necessarily settle into an arrangement that can feed as many people the next time around. This edited article is republished from The Conversation under a Creative Commons license. Read the original article.
Yahoo
10-06-2025
- Science
- Yahoo
Ancient fossils show how the last mass extinction forever scrambled the ocean's biodiversity
About 66 million years ago – perhaps on a downright unlucky day in May – an asteroid smashed into our planet. The fallout was immediate and severe. Evidence shows that about 70% of species went extinct in a geological instant, and not just those famous dinosaurs that once stalked the land. Masters of the Mesozoic oceans were also wiped out, from mosasaurs – a group of aquatic reptiles topping the food chain – to exquisitely shelled squid relatives known as ammonites. Even groups that weathered the catastrophe, such as mammals, fishes and flowering plants, suffered severe population declines and species loss. Invertebrate life in the oceans didn't fare much better. But bubbling away on the seafloor was a stolid group of animals that has left a fantastic fossil record and continues to thrive today: bivalves – clams, cockles, mussels, oysters and more. What happened to these creatures during the extinction event and how they rebounded tells an important story, both about the past and the future of biodiversity. Marine bivalves lost around three-quarters of their species during this mass extinction, which marked the end of the Cretaceous Period. My colleagues and I – each of us paleobiologists studying biodiversity – expected that losing so many species would have severely cut down the variety of roles that bivalves play within their environments, what we call their 'modes of life.' But, as we explain in a study published in the journal Sciences Advances, that wasn't the case. In assessing the fossils of thousands of bivalve species, we found that at least one species from nearly all their modes of life, no matter how rare or specialized, squeaked through the extinction event. Statistically, that shouldn't have happened. Kill 70% of bivalve species, even at random, and some modes of life should disappear. Most bivalves happily burrow into the sand and mud, feeding on phytoplankton they strain from the water. But others have adopted chemosymbionts and photosymbionts – bacteria and algae that produce nutrients for the bivalves from chemicals or sunlight in exchange for housing. A few have even become carnivorous. Some groups, including the oysters, can lay down a tough cement that hardens underwater, and mussels hold onto rocks by spinning silken threads. We thought surely these more specialized modes of life would have been snuffed out by the effects of the asteroid's impact, including dust and debris likely blocking sunlight and disrupting a huge part of the bivalves' food chain: photosynthetic algae and bacteria. Instead, most persisted, although biodiversity was forever scrambled as a new ecological landscape emerged. Species that were once dominant struggled, while evolutionary newcomers rose in their place. The reasons some species survived and others didn't leave many questions to explore. Those that filtered phytoplankton from the water column suffered some of the highest species losses, but so did species that fed on organic scraps and didn't rely as much on the Sun's energy. Narrow geographic distributions and different metabolisms may have contributed to these extinction patterns. Life rebounded from each of the Big Five mass extinctions throughout Earth's history, eventually punching through past diversity highs. The rich fossil record and spectacular ecological diversity of bivalves gives us a terrific opportunity to study these rebounds to understand how ecosystems and global biodiversity rebuild in the wake of extinctions. The extinction caused by the asteroid strike knocked down some thriving modes of life and opened the door for others to dominate the new landscape. While many people lament the loss of the dinosaurs, we malacologists miss the rudists. These bizarrely shaped bivalves resembled giant ice cream cones, sometimes reaching more than 3 feet (1 meter) in size, and they dominated the shallow, tropical Mesozoic seas as massive aggregations of contorted individuals, similar to today's coral reefs. At least a few harbored photosymbiotic algae, which provided them with nutrients and spurred their growth, much like modern corals. Today, giant clams (Tridacna) and their relatives fill parts of these unique photosymbiotic lifestyles once occupied by the rudists, but they lack the rudists' astonishing species diversity. Mass extinctions clearly upend the status quo. Now, our ocean floors are dominated by clams burrowed into sand and mud, the quahogs, cockles and their relatives – a scene far different from that of the seafloor 66 million years ago. Ecological traits alone didn't fully predict extinction patterns, nor do they entirely explain the rebound. We also see that simply surviving a mass extinction didn't necessarily provide a leg up as species diversified within their old and sometimes new modes of life – and few of those new modes dominate the ecological landscape today. Like the rudists, trigoniid bivalves had lots of different species prior to the extinction event. These highly ornamented clams built parts of their shells with a super strong biomaterial called nacre – think iridescent pearls – and had fractally interlocking hinges holding their two valves together. But despite surviving the extinction, which should have placed them in a prime position to accumulate species again, their diversification sputtered. Other types of bivalves that made a living in the same way proliferated instead, relegating this once mighty and global group to a handful of species now found only off the coast of Australia. These unexpected patterns of extinction and survival may offer lessons for the future. The fossil record shows us that biodiversity has definite breaking points, usually during a perfect storm of climatic and environmental upheaval. It's not just that species are lost, but the ecological landscape is overturned. Many scientists believe the current biodiversity crisis may cascade into a sixth mass extinction, this one driven by human activities that are changing ecosystems and the global climate. Corals, whose reefs are home to nearly a quarter of known marine species, have faced mass bleaching events as warming ocean water puts their future at risk. Acidification as the oceans absorb more carbon dioxide can also weaken the shells of organisms crucial to the ocean food web. Findings like ours suggest that, in the future, the rebound from extinction events will likely result in very different mixes of species and their modes of life in the oceans. And the result may not align with human needs if species providing the bulk of ecosystem services are driven genetically or functionally extinct. The global oceans and their inhabitants are complex, and, as our team's latest research shows, it is difficult to predict the trajectory of biodiversity as it rebounds – even when extinction pressures are reduced. Billions of people depend on the ocean for food. As the history recorded by the world's bivalves shows, the upending of the pecking order – the number of species in each mode of life – won't necessarily settle into an arrangement that can feed as many people the next time around. This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Stewart Edie, Smithsonian Institution Read more: Megalodon sharks ruled the oceans millions of years ago – new analyses of giant fossilized teeth are helping scientists unravel the mystery of their extinction As climate change and pollution imperil coral reefs, scientists are deep-freezing corals to repopulate future oceans Growing quickly helped the earliest dinosaurs and other ancient reptiles flourish in the aftermath of mass extinction Stewart Edie receives funding from the Smithsonian Institution.
Time of India
09-06-2025
- Science
- Time of India
160-million-year-old blue-stain fungi in China found to be harmful to trees
Source: In a groundbreaking discovery, researchers have uncovered 160-million-year-old blue-stain fungi fossils from the Jurassic Tiaojishan Formation in China. The new findings offer fresh insights into the ecological relationships between blue-stain fungi, plants, and insects during the Jurassic period. These fungi are generally nonfatal to their hosts but often accelerate tree mortality when associated with wood-boring insects . According to ScienceDaily, a Chinese team of scientists highlights the discovery of well-preserved blue-stain fungal hyphae within Jurassic fossil wood from northeastern China, pushing back the earliest known fossil record of this fungal group by approximately 80 million years. Know about the blue-stain fungi, deadly to trees Blue-stain fungi are known for their ability to colonize wood, particularly in conifer trees, causing characteristic discoloration in the sapwood. While these fungi do not decompose wood, they often cause considerable damage when associated with wood-boring insects. Their role in accelerating tree mortality is significant, yet their evolutionary origins have long remained a mystery. Molecular phylogenetic analyses suggest that blue-stain fungi are an ancient fungal group, possibly originating during the Late Paleozoic or early Mesozoic. by Taboola by Taboola Sponsored Links Sponsored Links Promoted Links Promoted Links You May Like 夢の農場を作り上げよう アドベンチャーゲーム ゲームをプレイ Undo This recent discovery in China revises our understanding of blue-stain fungi's history, suggesting their origins trace much further back into Earth's past. Dr. Ning Tian, a paleontologist at Shenyang Normal University, explained the rarity of such findings: 'Not until 2022 was the first credible fossil record of blue-stain fungi reported from the Cretaceous in South Africa, with an age of approximately 80 million years.' Discovery of the fossils of the blue-stain fungus The fossils were found inside the petrified wood of Xenoxylon phyllocladoides, a type of conifer tree from the Jurassic period in western Liaoning province, China. Researchers discovered dark-colored fungal threads called hyphae, which are typical of blue-stain fungi. 'Under the microscope, the fossil hyphae appear dark, showing pigmentation that is a key feature of modern blue-stain fungi, which cause wood to change color,' the team explained. This shows that these fungi have existed for millions of years and are connected to fungi we see today. The researchers also found a special structure the fungi use to enter the wood. 'When the fungi penetrate the wood's cell walls, the hyphae often form a structure called a penetration peg,' they said. This peg helps the fungi break through the tough wood cells by mechanical force, which is different from other fungi that use enzymes to break down wood. A major leap in the fossil record of blue-stain fungi The discovery of the blue-stain fungi found in China not only fills a gap in the fossil record but also provides critical evidence for understanding the early evolution of blue-stain fungi and their ecological interactions. The fact that these fungi were already established in the Jurassic period suggests that their relationship with wood-boring insects, which are likely the main agents for spore dispersal, was already in place long before the advent of modern insect species The fossilized blue-stain fungi represent a significant milestone in paleontological research. 'The finding of Jurassic blue-stain fungi from China represents the second report of the blue-stain fungi and the earliest fossil record of this fungal group in the world, pushing back the earliest known fossil record of this fungal group by approximately 80 million years,' said Dr. Yongdong Wang, a paleontologist at the Nanjing Institute of Geology and Paleontology.
Time of India
02-06-2025
- Science
- Time of India
Shocking! 183-million-year-old Dinosaur-era sea creature found with skin and scales intact
In a discovery that's catching the attention of scientists, researchers have found a remarkably well-preserved fossil of a marine reptile that's challenging what we thought we knew about how these creatures lived. The fossil, identified as Plesiopterys wildi, is around 183 million years old and was uncovered in southern Germany. What makes it especially rare is the presence of preserved soft tissues, like skin, scales, and keratin, which are almost never found in marine reptiles from the Jurassic period. The findings, published in Current Biology, offer a rare and detailed look at the texture, colouring, and movement of plesiosaurs– long-necked marine reptiles that lived during the Mesozoic era. Until now, scientists had to rely mostly on bones to imagine what these animals looked like, but this discovery gives a much clearer picture. Fossil found in 1940, but only studied recently The fossil specimen, labelled MH 7, was originally discovered in 1940 near Holzmaden, a region known for its fossil-rich Posidonia Shale. However, the specimen remained unprepared for decades. It was only in 2020 that researchers began to remove the surrounding limestone carefully and realised the fossil contained patches of soft tissue. by Taboola by Taboola Sponsored Links Sponsored Links Promoted Links Promoted Links You May Like American Investor Warren Buffett Recommends: 5 Books For Turning Your Life Around Blinkist: Warren Buffett's Reading List Undo 'Fossilized soft tissue, such as skin and internal organs, is exceptionally rare. We used a broad range of techniques to identify smooth skin in the tail region as well as scales along the rear edge of the flippers. This provided us with unparalleled insights into the appearance and biology of these long-extinct reptiles,' says Miguel Marx, a PhD student at Lund University and the study's lead author, as quoted by Lund University. Flippers show signs of specialised movement When researchers examined the fossil under a microscope, they found that the flippers were covered with tiny, triangular scales made of beta-keratin—a tough protein found in reptiles. These sturdy flippers likely helped the animal move with precision and control underwater. On the other hand, the skin on the tail was smoother and made of alpha-keratin, suggesting it had a different function. This difference in texture shows that various parts of the body were specially adapted for different roles in swimming and steering. 'Apart from the mosaic of smooth skin and scales, it was an incredible moment to visualize the cells in thin sections of the fossilized plesiosaur's skin. I was shocked when I saw skin cells that had been preserved for 183 million years. It was almost like looking at modern skin,' says Marx, as quoted by Lund University. Traces of pigment suggest patterned colouring One of the more unexpected findings was the discovery of melanosomes– tiny structures that carry pigment– in the skin of the tail. This suggests that the animal may have had patterns or variations in skin colour, instead of the plain or pale look that scientists usually imagine for marine reptiles. The researchers noted that this pigmentation could have played a role in camouflage or communication, though further analysis would be needed to confirm such functions. Discovery of a tail fin adds new clues Along with the preserved skin and scales, researchers also found a soft-tissue tail fin– something rarely seen in plesiosaur fossils. This broad and flexible structure suggests the tail may have helped the animal steer more effectively or even boosted its speed while swimming. Exceptional preservation thanks to Posidonia Shale The exceptional condition of the fossil is thanks to the unique environment where it was preserved. The Posidonia Shale– an ancient seabed with very low oxygen levels– slows down the process of decay, sometimes allowing soft tissues to fossilise along with bones. This kind of preservation is extremely rare in marine reptiles, which makes MH 7 a remarkable find and an important discovery for paleontologists. Adding detail to the story of Plesiosaur evolution Most studies on plesiosaurs have focused only on their bones, but this fossil gives a much fuller picture of the animal's biology. The preserved soft tissues offer new insights into how different parts of its body worked and how these features may have evolved over time. According to the research team, these findings may also contribute to understanding how plesiosaurs adapted to specific environments over time. 'Our findings help us create more accurate life reconstructions of plesiosaurs, something that has been extremely difficult since they were first studied over 200 years ago. Also, the well-preserved German fossil really highlights the potential for soft tissue in providing valuable insights into the biology of these long-extinct animals,' explains Marx, as quoted by Lund University. After sitting untouched for nearly 80 years, this discovery is now offering one of the most detailed views yet into the biology of a creature that swam the Earth's oceans almost 200 million years ago. The MH 7 fossil not only deepens our understanding of plesiosaurs but also highlights how valuable it can be to revisit and study old, forgotten specimens. Thumb image credit: X/@JoschuaKnuppe (Illustration of "Skin, scales, and cells in a Jurassic plesiosaur")
Yahoo
30-05-2025
- General
- Yahoo
Birds have been nesting in the Arctic Circle for almost 73 million years, newly discovered fossils reveal
When you buy through links on our articles, Future and its syndication partners may earn a commission. Birds have been nesting in rugged Arctic environments for almost 73 million years, new research finds — more than 25 million years longer than was previously thought. A collection of more than 50 fossils found in northern Alaska, which include embryos and hatchlings, suggest some of the early ancestors of modern birds either migrated or adapted to the harsh polar environment in the Mesozoic era, the age of dinosaurs. "The common conception is they're too primitive to be exhibiting this advanced behavior," Lauren Wilson, lead author of the study and a doctoral student of paleontology at Princeton University, told Live Science. "So you're either dealing with [Arctic winters] as an itty-bitty, freshly hatched bird, or you're 3 months old, and having to fly about 2,000 kilometers [1,240 miles] to get to a point where it makes sense to even migrate," Wilson explained. "I don't think we would expect either of those things from these birds that don't belong to that modern lineage of birds." Whether the birds migrated south or hunkered down for the winter, the research provides the earliest known evidence of either behavior in birds. And while some modern birds, like the ivory gull (Pagophila eburnea) and snowy owl (Bubo scandiacus) are known to nest in the frigid Arctic, there is now evidence that this behavior started millions of years before the meteor that wiped out non-avian dinosaurs crashed into Earth, if not earlier. "Many birds nest in the Arctic today, and they are key parts of Arctic communities and ecosystems and food webs," Steve Brusatte, a professor of paleontology and evolution at the University of Edinburgh who peer-reviewed the study but was not involved in it, told Live Science in an email. "These fossils show that birds were already integral parts of these high latitude communities many tens of millions of years ago, and thus that these communities are a long-term norm of Earth history, not a recent ecological innovation of modern times." The fossils in the collection come from at least three different families of bird: the extinct, loon-like hesperornithes; ichthyornithes, an extinct bird that resembled seagulls; and several species resembling ducks that are within or very similar to neornithes, the group containing all modern birds. Related: Hoatzin: The strange 'stinkbird' born with clawed wings that appears to be an evolutionary 'orphan' Notably, the researchers did not find any fossils of the dominant bird group of the Cretaceous period (145 million to 66 million years ago) — enantiornithes, now-extinct birds that typically had teeth in their beaks and claws on their wings. But a few factors reveal why they likely didn't live in the Arctic. They likely took longer than other birds to incubate their eggs, they took several years to reach full adult size (where most modern birds grow to adult size within weeks) and they "may have had a period where they're almost naked because they molted their feathers simultaneously," which is not helpful during an Arctic winter, said study co-author Daniel Ksepka, a paleontologist and curator of the Bruce Museum in Connecticut. The world was warmer in the Late Cretaceous than it is today, but the region the birds were found in likely experienced freezing temperatures, snow and roughly four straight months of winter darkness. Growing to adulthood so quickly allowed modern birds to practice long-range migration and prosper during those ancient Arctic summers, which boasted around six months of 24-hour daylight and a burst in insect populations. But the weather wasn't the only challenge. They lived alongside "probably about 12 or 13 different kinds of typical dinosaurs," like the Pachyrhinosaurus, a relative of Triceratops that was about 16 feet (5 meters) long and weighed 2 tons (1,800 kilograms). Other dinosaurs like Troodon, an 11-foot tall meat-eater with short, serrated teeth, "would have happily taken advantage of a bunch of these little cute little chicks for dinner," said Patrick Druckenmiller, director of the University of Alaska Museum of the North and advising author of the study. RELATED STORIES —Chickens sprouted dino-like feathers when scientists messed with the Sonic Hedgehog gene —Why don't all birds fly? —Ancient duck-like creature discovered in Antarctica may be the oldest modern bird ever discovered To get to the fossil sites in the Prince Creek Formation in Northern Alaska, the researchers drove 500 miles (800 km) from Fairbanks, chartered a small aircraft to fly to the Colville River, then took inflatable motorboats up the river before setting up camp, Druckenmiller said. There they would look for an "orangey, pebbly, sandy" layer of sediment that contains small bones and teeth, and often lay on the permafrost to "excavate with little dental picks and small tools" from the layer itself. Now that the Prince Creek Formation is "one of the major North American Cretaceous bird sites," according to the researchers, Wilson says the next step is simply to find more fossils. "The more bones we find, the more confident we can be in exactly what types of birds we have," she said. "We might even still find a random bone that's from a bird we didn't know was there."
