Dinosaurs weren't going extinct before the asteroid strike
When you buy through links on our articles, Future and its syndication partners may earn a commission.
Dinosaurs weren't in decline when an asteroid smashed into Earth and wiped them out, scientists say. Instead, the idea that dinosaur diversity was declining before the asteroid struck 66 million years ago is likely based on faulty fossil data, according to a study that looked at nearly 18 million years of fossil evidence.
Fossil discoveries have long indicated that dinosaurs were shrinking in numbers and diversity prior to the asteroid impact at the end of the Cretaceous period. Previously, some researchers believed this was a sign that dinosaurs were already on the road toward extinction even before the cataclysmic encounter with a space rock. However, this idea has long been controversial, with other researchers arguing that dinosaur diversity was doing just fine at the time of their demise.
"It's been a subject of debate for more than 30 years — were dinosaurs doomed and already on their way out before the asteroid hit?" study lead author Chris Dean, a paleontologist at University College London, said in a statement.
Now, new research published Tuesday (April 8) in the journal Current Biology suggests that the apparent rarity of dinosaurs before their extinction may simply be due to a poor fossil record.
The scientists studied records of around 8,000 fossils from North America dating to the Campanian age (83.6 million to 72.1 million years ago) and Maastrichtian age (72.1 million to 66 million years ago), focusing on four families: the Ankylosauridae, Ceratopsidae, Hadrosauridae and Tyrannosauridae.
At face value, their analysis showed that dinosaur diversity peaked around 76 million years ago, then shrank until the asteroid strike wiped out the nonavian dinosaurs. This trend was even more pronounced in the 6 million years before the mass extinction, with the number of fossils from all four families decreasing in the geological record.
However, there is no indication of environmental conditions or other factors that would explain this decline, the researchers found. All of the dinosaur families were widespread and common, according to models developed by the researchers — and thus at low risk for extinction, barring a catastrophic event such as the asteroid impact.
Rather, the Maastrichtian may have had poorer geological conditions for fossilization, the researchers suggested. Events such as the retreat of the Western Interior Seaway, which once ran from the Gulf of Mexico up through the Arctic, and the rise of the Rocky Mountains starting around 75 million years ago, may have impeded or disrupted fossilization, making it appear as if there were fewer dinosaurs and less diversity during that time.
The team also found that geological outcrops from the Maastrichtian of North America were not exposed, or were covered by vegetation. In other words, rock from this time that might hold dinosaur fossils was not readily accessible to researchers who were searching for the remains. Because half of the known fossils from this period are from North America, the study's findings may have global implications as well.
RELATED STORIES
—Dinosaurs dominated our planet not because of their massive size or fearsome teeth — but thanks to the way they walked
—'Exquisitely preserved' ginormous claws from Mongolia reveal strange evolution in dinosaurs
—166 million-year-old fossil found on Isle of Skye belongs to pony-size dinosaur from Jurassic
Among the 8,000 fossil records examined, the team found that Ceratopsians — a group that includes horned dinosaurs like Triceratops and its relatives — were the most common, probably because they inhabited plain regions that were most conducive to preservation during the Maastrichtian. Hadrosaurians — duck-billed dinosaurs — were the least common, possibly due to their preference for rivers. Reductions in river flow may have led to fewer depositions of sediment that could have preserved these dinosaurs, the researchers wrote in the study.
"Dinosaurs were probably not inevitably doomed to extinction at the end of the Mesozoic [252 million to 66 million years ago]," study co-author Alfio Alessandro Chiarenza, a paleontologist at University College London, said in a statement. "If it weren't for that asteroid, they might still share this planet with mammals, lizards, and their surviving descendants: birds."
Hashtags

Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles


Associated Press
42 minutes ago
- Associated Press
Peanuts or almonds? Rice or millet? Planet-friendly grocery shopping choices go beyond cutting meat
It's one of the most impactful climate decisions we make, and we make it multiple times a day. The U.N. estimates about a third of the world's greenhouse gas emissions, the main driver of climate change, come from food. That pollution can come from several links in the food supply chain: how farmland is treated, how crops are grown, how food is processed and how it's ultimately transported. Maybe you've already heard the short answer to minimizing your diet's impact on the planet: eat more plants and fewer animals. The data backs up that suggestion. Emissions from meat-rich diets are four times higher than that of vegan diets. But so much focus on meats overshadows many other food choices that also impact the environment and can contribute to global warming. Here is a look at other important grocery store decisions: Proteins Swapping one serving of chicken per day for beef cuts a diet's emissions nearly in half. Ruminant animals such as cows, sheep and goats are the top drivers of emissions. Those animals 'are associated not only with nitrous oxide emissions, but they're also related to direct methane emissions because they burp them up while they digest food,' said Marco Springmann, professorial research fellow in climate change, food systems and health at University College London. Springmann said processed animal products have a higher impact on the planet, too: 'You need 10 times the amount of milk to make one unit of cheese.' So — and this is true of most food groups — the less processed the food, the smaller the environmental impact. Plant-based proteins like legumes, beans and nuts all boast a much lower climate impact. Grains The standout here is rice, and not in a good way. 'Rice uses a ton of water. It uses gobs of fertilizer. There's flooded rice paddy fields, and that water actually breeds all kinds of bacteria, and those bacteria produce methane gas,' said eco-dietitian nutritionist Mary Purdy. Purdy said the most planet-friendly alternative is just eating a bunch of different grains. 'The wheat, corn and soy world is very, very familiar to us because we've been seeing it. It's been heavily marketed. When was the last time you saw a commercial for millet or buckwheat?' she asked. Diverse diets, Purdy said, incentivize biodiverse agriculture, which is more resilient to erratic weather — a hallmark of climate change — and makes healthier soil. Fruits and vegetables When it comes to produce, minimizing impact is less about choosing between foods and more about buying based on the way that food was grown. Conventionally grown produce 'very likely is using pesticides, fertilizer, and maybe more water because the soil isn't healthy,' said Purdy. Purdy said organic labels, such as Regenerative Organic Certified, indicate those foods had a smaller climate impact when they were grown. The tradeoff is that organic food has a lower yield, so it requires more land use and is often more expensive. Local and 'in season' foods also have a smaller climate impact, but not just for one of the reasons you may be thinking of: emissions from international shipping. Every day, thousands of large ships transport goods, including produce, around the world, and the fuel they use is heavily polluting. However, 'it's mostly those local emissions on trucks that are actually impactful, not the international shipping emissions,' Springmann said. Also, food grown nearby tends to be grown in a way that fits with the local climate and is less harmful to the environment. 'We're not trying to grow oranges in some place in a greenhouse,' Purdy said. Butter and oil Plants win out over animals, again. Vegetable oils are less impactful than butter or lard. Springmann also said tropical oils are healthiest in moderation, such as those from coconuts or palms, because they have a higher fat content. Plus, palm oil is associated with deforestation. As for nut butters, almonds might be a great option for limiting carbon emissions, but they require a lot of water. One study out of Tulane University found that a serving of peanuts has an emissions footprint similar to almonds but 30% less impact on water use. Don't waste food Throwing less food away might sound obvious, but roughly a third of food grown in the U.S. is wasted. Meal planning, freezing leftovers and checking the fridge before heading to the grocery store all help cut waste. 'The climate impact, the embedded water use, all of the labor and different aspects that went into producing that food, that all gets wasted if we don't eat it,' Blackstone said. ___ The Associated Press' climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP's standards for working with philanthropies, a list of supporters and funded coverage areas at
Yahoo
4 hours ago
- Yahoo
'This felt like fishing.' A NASA astronaut winds up with a spectacular glimpse of the aurora during his first-ever attempt at a time-lapse
When you buy through links on our articles, Future and its syndication partners may earn a commission. I remember the first time I ever caught the Northern Lights on camera – I was photographing the night sky when I was startled to see a pale green 'cloud' on the back of the camera that I couldn't see with my eyes. But NASA astronaut Jonny Kim recently shared his first-ever attempt at taking a time-lapse – and it's quite impressive. The timelapse, shared on the astronaut's social media pages, shows a time-lapse of Earth taken from the International Space Station. The sped-up video starts with city lights and even some flashes of lightning seen from space, but ends with colorful wisps dancing over Southeast Asia and Australia as the Aurora Australis or Southern Lights makes an appearance at the end of the timelapse. Kim notes in the post that he's never shot a time-lapse before, but took some tips from 'Vapor,' Nichole Ayes, a fellow NASA astronaut also aboard the ISS. 'After seeing the result, I told her this felt like fishing,' Kim wrote. 'Prepping the camera, the angle, the settings, the mount, then setting your timer and coming back to hope you got a catch. And after catching my first fish, I think I'm hooked.' As someone who has spent many sleepless nights trying to catch the aurora on camera, I agree with the comparison. Sometimes, I leave with nothing but a few photos of stars. Other times, I leave with some of my favorite landscape images that I've ever taken (plus an adrenaline rush from the chase). Kim arrived on the ISS on April 8 and is expected to spend around eight months aboard. A time-lapse is a series of still images taken at regular intervals, stitched together into a video. The result is a sped-up video, sort of like the opposite of a slow-motion video. (A few commenters missed this fact; the Earth actually isn't spinning as fast as it appears to be in the video.) One of the most common mistakes creatives make when taking their first time lapse is not taking enough shots and ending up with a too short video. A tripod is also a must. For more insight into creating timelapses, read DCW's guide on how to create time-lapses. Or, read about how to photograph the northern lights or what night sky events to photograph this June.
Yahoo
12 hours ago
- Yahoo
'We've got a new mystery on our hands': Titan's weird wobble just got even stranger
When you buy through links on our articles, Future and its syndication partners may earn a commission. For years, scientists have been intrigued by a weird "wobble" in the atmosphere of Titan, Saturn's largest moon. Now, new research is revealing clues about Titan's strange atmospheric tilt, but it's also raising new mysteries. Data from the Cassini mission to Saturn has shown that, unlike Earth's atmosphere, Titan's atmosphere doesn't rotate in sync with its surface. Instead, it tilts and shifts like a spinning top that changes its orientation with the seasons. "The behaviour of Titan's atmospheric tilt is very strange," Lucy Wright, lead author of the new research and a postdoctoral researcher in the School of Earth Sciences at the University of Bristol in the U.K., said in a statement. "We think some event in the past may have knocked the atmosphere off its spin axis, causing it to wobble." Scientists thought the direction of the tilt would be influenced by either Saturn's gravity or the position of the sun, as is often the case in planetary systems — meaning it would change as Titan orbited Saturn and the sun. But observations show that the tilt direction doesn't move. Instead, it stays pointed the same way in space, as if unaffected by those external forces. This finding was unexpected. If solar heating or Saturn's gravity were controlling the tilt, it should move over time. Instead, the tilt seems locked in place, suggesting that some other, still-unknown process is at work, the researchers reported in a study published May 20 in The Planetary Science Journal. "That would've given us clues to the cause," Nick Teanby, co-author of the study and a planetary scientist at the University of Bristol, said in the statement. "Instead, we've got a new mystery on our hands." Titan is the only moon in the solar system known to have a substantial atmosphere. It is composed primarily of nitrogen and contains complex organic molecules, making it a scientifically important object for studying things like atmospheric processes and prebiotic chemistry. RELATED STORIES —Saturn's moon Titan may have a 6-mile-thick crust of methane ice — could life be under there? —There's liquid on Titan, Saturn's largest moon. But something's missing and scientists are confused —Alien life could exist on Saturn's big moon Titan — but finding it will be tough From 2004 to 2017, NASA's Cassini spacecraft closely observed Titan, revealing important changes in its atmosphere, like a steady tilt in the middle layers and the appearance and disappearance of swirling winter polar vortices. This new understanding of Titan's atmospheric wobble is important for NASA's upcoming Dragonfly mission, which is set to arrive in the 2030s. Because Titan's winds are much faster than its surface rotation, knowing how the atmosphere shifts with the seasons will help engineers more accurately plan Dragonfly's descent and landing. "Our work shows that there are still remarkable discoveries to be made in Cassini's archive," study co-author Conor Nixon, a planetary scientist at NASA's Goddard Space Flight Center, said in the statement. "This instrument, partly built in the U.K., journeyed across the Solar System and continues to give us valuable scientific returns. "The fact that Titan's atmosphere behaves like a spinning top disconnected from its surface raises fascinating questions — not just for Titan, but for understanding atmospheric physics more broadly, including on Earth," Nixon added.