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
Yahoo
4 hours ago
- Yahoo
Why Elon Musk's satellites are 'dropping like flies'
When you buy through links on our articles, Future and its syndication partners may earn a commission. Elon Musk has no shortage of targets for his animosity: the media, "woke" progressives, the trans "agenda" and, most recently, his former best buddy Donald Trump. But one less expected Musk adversary is more powerful than them all: the Sun. SpaceX's vast network of Starlink internet service satellites are "dropping like flies", due to an extraterrestrial weather phenomenon caused by the Sun, said Futurism. And it's only set to get worse. The thousands of Starlink satellites orbiting our planet have given space scientists a "golden opportunity to study the effects" of the Sun's activity on the lifespan of these "minimalist, constellation-based spacecraft", said Futurism. And it appears that Musk's "space internet constellation" is "particularly prone to the effect of geomagnetic storms", triggered by eruptions from the Sun, said The Independent. These "ferocious solar storms", Nasa scientists have found, are causing many of Musk's low-orbit satellites to fall to Earth "faster than expected". The impact is particularly significant at the moment because the Sun is approaching the peak of an 11-year activity cycle, "known as the solar maximum", which provokes "large amounts of extreme space weather". The earlier than predicted satellite "re-entries" could "increase the chances of them not burning up properly in the Earth's atmosphere". and debris reaching the Earth. However, so far, the "only known instance" of this happening was in August 2024, when a piece of a Starlink satellite was discovered on a farm in Canada. The solar storm problem threatens one of Musk's biggest power grabs to date. When his engineers "bundled a batch of prototype satellites into a rocket's nose cone six years ago, there were fewer than 2,000 functional satellites in Earth's orbit". Now more than 7,000 of his satellites now surround Earth, "like a cloud of gnats", said The Atlantic. This is the most dominant any individual has been in the "orbital realm" since the late 1950s, when Sergei Pavlovich Korolev, the Soviet engineer who developed Sputnik and its launch vehicle, was "the only guy in town" as far as satellites were concerned, space historian Jonathan McDowell told the magazine. But the Sun is an adversary not even Musk can overcome. Solar storm forecasting "has significantly improved over the past few years", Piyush Mehta, a US professor of aerospace engineering, wrote on The Conversation in 2022 but "there is only so much shielding that can be done in the face of a powerful geomagnetic storm". The Sun is "essential for life to go on," he said, but, like a child who often throws tantrums, "its ever-changing disposition make things challenging".
Yahoo
10 hours ago
- Yahoo
How to see the 'Horse and Rider' in the Big Dipper's handle this summer
When you buy through links on our articles, Future and its syndication partners may earn a commission. At around 10 p.m. local daylight time on these warm June evenings, face north and look overhead to see the seven stars that compose the famous Big Dipper. At this time of the year, the handle appears to stand almost straight up while the bowl appears tilted down; draining its unknown contents toward the right. The Dipper is not a constellation in of itself, but an asterism, a prominent pattern or group of stars, typically having a popular name, belonging to a specific constellation. For most sky gazers, the Big Dipper is probably the most important group of stars in the sky. For anyone in the latitude of New York (41 degrees North) or points northward, it never goes below the horizon. It is one of the most recognizable patterns in the sky and thus one of the easiest for the novice to find. Of greatest importance is the ability to utilize the Big Dipper to locate Polaris, the North Star. This is made possible by the two bright stars that mark the outer edge of the bowl of the Big Dipper. These two stars — Dubhe and Merak — are known as the Pointers, because they always point to Polaris. Just draw a line, in your imagination, between these two stars and prolong this line about 5 times, the way our map shows; this line will ultimately hit a moderately bright star. That will be Polaris. Even those who live well south of the equator can see the Big Dipper now. During autumn in the Southern Hemisphere, it appears to hover upside-down above the northern horizon for those down to about latitude 30-degrees south. That includes the northern two-thirds of South America and virtually all of Africa. In his classic constellation guide, "The Stars — A New Way to See Them," author H.A. Rey sketched a cute cartoon on page 24 of a mother kangaroo and its joey above the caption: "The Dipper? Never seen it ..." And yet for the northern two-thirds of Australia, during April, May and June, the Dipper is plainly visible hanging low above the northern horizon. The middle star in the Dipper's handle is Zeta Ursae Majoris; the Greek letter is the given name, and the possessive of the Latin name of its constellation. In this case Ursa Major, the Great Bear — is its family name. But this particular star is far better known as "Mizar," derived from the Arabic meaning for "wrapping" or "cover." With just your eyes alone, if you look carefully, you'll notice that Mizar appears to have a fainter companion by the name of Alcor, also derived from the Arabic, meaning "faint one." The Persian Al Kazwini stated during the 13th century that people "tested their eyesight by this star." TOP TELESCOPE PICK: Want to see Alcor and the other stars of the Big Dipper? The Celestron NexStar 4SE is ideal for beginners wanting quality, reliable and quick views of celestial objects. For a more in-depth look at our Celestron NexStar 4SE review. Mizar and Alcor were known as the "Horse and Rider" to the ancient Arabs and the Arabian writer Al Firuzabadi, in the 14th century referred to Alcor as Al Sadak, "The Test" or "The Riddle." So, when the ancient Arabs remarked: "He can see Alcor," they were alluding to someone who had normal vision. Why not test your own eyesight by looking for Alcor tonight? Alcor is one-fifth as bright as Mizar and the two stars are separated by roughly one-third of the apparent diameter of the moon. Both stars are located about 83 light-years away and recent observations suggest that Alcor is traveling around Mizar in a wide orbit that takes 750,000 years to complete. Binoculars provide a better view of this pair, but there's more to see here than many skywatchers realize. As an example, Mizar, is in itself a true binary star; one of the first to be observed and identified as a binary pair by astronomers in the 17th century. A binary star is two or more stars that are physically connected with each other and are "locked" or connected together by gravity. They actually orbit each other in a fashion similar to the Earth and the planets orbiting the sun or the moon orbiting the Earth. To see the companion of Mizar you'll need a small telescope and an eyepiece providing a magnification of at least 50-power. Between Mizar and Alcor and a little to their south is an 8th-magnitude star that was once mistaken for a new planet. In December 1722, the German professor Johann Georg Liebknecht announced that this object had just moved into its present position. He christened his "planet" Sidus Ludoviciana — Ludwig's Star — to flatter his local sovereign Ludwig V of Hesse-Darmstadt in hopes of being granted money. The object never moved again. Liebknecht disappeared in a hail of ridicule, but amazingly the name of the "faux" or "ersatz" planet remains to this very day! If you draw a line east from Mizar through Alcor, you'll come across a 5th-magnitude star, glowing with a distinct ruddy hue. That's 83 Ursae Majoris, a red giant star roughly 80 times larger and about 1,300 times more luminous than the sun. It's located at a distance of 580 light-years from us. If you continue onward along the same line at about twice the distance past 83, you'll come to the big, but dim galaxy M101. Under a dark sky M101 appears in 7 x 50 and larger binoculars in much the same way that its discoverer Pierre Méchain described it in 1781: "very obscure and pretty large." It is popularly known as the "Pinwheel Galaxy," and at 21 million light years, it is one of the closer spiral galaxies to our Milky Way. But in order to perceive its spiral structure, you'll need a rather large telescope, very dark skies and a low-power eyepiece. Finally, our familiar Dipper will not last forever. Of the seven stars that make up this pattern, five apparently belong to a loosely joined swarm of stars, all hurtling through space at roughly the same speed and the same direction. These five range in distances from 78 to 84 light-years from Earth. Two of the stars, however — Dubhe (the northern Pointer) and Alkaid (the star at the end of the handle) — are not part of the swarm and appear to be rushing at even greater speeds in the opposite direction. Alkaid is 101 light-years away, while Dubhe is 124 light-years distant. These opposing motions will slowly alter the form of the Big Dipper. In short, the Dipper is slowly going to pieces. The bent handle will bend still more as time wears on, while the bowl will spread. Granted, it will still remain a fairly convincing dipper for about the next 25,000 years, but 50,000 years (or 2,000 generations) from now it will be hopelessly out of shape. If you're looking for a telescope or binoculars to observe the night sky, our guides for the best binoculars deals and the best telescope deals now can help. Our guides on the best cameras for astrophotography and best lenses for astrophotography can also help you prepare to capture the next skywatching sight. Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, Sky and Telescope and other publications.
Yahoo
10 hours ago
- Yahoo
NASA raises the odds that an asteroid could hit the moon in 2032
When you buy through links on our articles, Future and its syndication partners may earn a commission. Asteroid 2024 YR4, once considered the highest impact risk to Earth ever recorded, is back in the spotlight — this time due to a slight increase in the chance that it could impact the moon in 2032. Although now too distant to observe from Earth, the asteroid briefly came into view in May for the James Webb Space Telescope (JWST). Using data from the telescope's Near-Infrared Camera, a team led by Andy Rivkin of the Johns Hopkins Applied Physics Laboratory refined predictions of where 2024 YR4 will be on Dec. 22, 2032 by nearly 20%. That revised trajectory nudged the odds of a lunar impact from 3.8% to 4.3%, according to a NASA update. "As data comes in, it is normal for the impact probability to evolve," the statement read. Even if a collision occurs, "it would not alter the moon's orbit." Astronomer Pawan Kumar, a former researcher at the Indian Institute of Astrophysics in Bengaluru, agrees the moon is safe, noting a collision with the moon "won't be a cause for concern" because any moon debris blasted into space from the impact "blow up in Earth's atmosphere if any of it makes it to near-Earth space." First detected on Dec. 27 last year, 2024 YR4 is estimated to be about 174 to 220 feet long (53 to 67 meters), or about the size of a 10-story building. The asteroid quickly grabbed headlines for having more than a 1% chance of striking Earth, the highest recorded for any large asteroid. Follow-up observations in January and February saw the impact risk climb from 1.2% to a peak of 3.1%. The asteroid's projected trajectory at the time suggested it could cause blast damage across a wide potential impact zone, spanning the eastern Pacific, northern South America, Africa and southern Asia. If it enters Earth's atmosphere over the ocean, NASA estimated it would be unlikely to trigger significant tsunamis, but an airburst over a populated city could shatter windows and cause minor structural damage. However, the impact risk dropped sharply as additional orbital data came in. By Feb. 19, the probability had fallen to 1.5%, and then to 0.3% the next day. On Feb. 24, NASA announced an official "all clear" on social media, reporting the impact probability had dropped to just 0.004% and that the asteroid is "expected to safely pass by Earth in 2032." Further analysis has since allowed scientists to rule out any risk to Earth, not only in 2032 but from all future close approaches as well. Data from telescopes in Chile and Hawaii recently suggested the space rock originated in the central main belt between Mars and Jupiter and gradually shifted into a near-Earth orbit. Since mid-April, the asteroid has been too far away and too faint to be seen from Earth. It will swing back into view in 2028, giving scientists another chance to observe the asteroid and further refine its orbit using both JWST and ground-based telescopes. In particular, scientists will aim to gather more data on its shape and composition, which are key factors in understanding both its behavior and potential impact effects. RELATED STORIES — Odds of an asteroid impact in 2032 just went up. Here's why experts say you shouldn't worry — Asteroid apocalypse: How big must a space rock be to end human civilization? — Astronomers discover 196-foot asteroid with 1-in-83 chance of hitting Earth in 2032 While 2024 YR4 no longer poses any danger, it provided scientists with a rare, real-world opportunity to rehearse the full scope of planetary defense strategy, ranging from initial detection and risk analysis to public messaging. It was "an actual end-to-end exercise" for how we might respond to a potentially hazardous asteroid in the future, said Kumar. "2024 YR4 is a tailor-made asteroid for planetary defense efforts," he said. "It has everything it takes to get our attention."
