Were dinosaurs headed for extinction even before massive asteroid strike? Scientists offer new clues
Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more.
It's a long-standing debate in paleontology: Were dinosaurs thriving when an asteroid hit Earth one fateful spring day 66 million years ago, or were they already on their way out, and the space rock delivered a final, devastating blow?
To find answers, a team of researchers studied North America's fossil record, focusing on the 18 million years before the mass extinction at the end of the Cretaceous period. The new analysis, published Tuesday in the journal Current Biology, adds to a growing body of evidence that the dinosaurs were doing just fine before the asteroid's deadly impact.
However, at face value, the fossils available for study from this time — more than 8,000 — suggest the number of dinosaur species peaked about 75 million years ago and then declined in the 9 million years leading up to the asteroid strike.
'It comes down to the fossil record and its fidelity, or its quality. And so there's been an awareness since the 1970s that the fossil record is not accurate, but it is a biased reflection in the past,' said lead study author Chris Dean, a research fellow in paleontology at University College London.
'It's only in very recent years that we've started to see the full extent of (the bias issue), when using these large databases of fossil occurrences,' he said.
To understand better what was going on at the time of the dinosaurs' demise, Dean and his colleagues turned to a statistical approach called occupancy modeling to estimate the probability of a dinosaur being present at a site. Used in present-day ecology and conservation, occupancy modeling aims to account for the fact that a species may be overlooked or not detected even when present in a particular area. This study marks the first time the approach has been used to look at dinosaurs and over a large scale, Dean said.
'Applying a new technique is really hard,' Dean noted. 'I don't think it will be the last word. I'm sure there's a lot more to be said.'
For the new study, the researchers looked at four main dinosaur families: Ankylosauridae (armored plant-eating dinosaurs such as the club-tailed Ankylosaurus), Ceratopsidae (large three-horned herbivores including Triceratops), Hadrosauridae (duck-billed dinosaurs), and Tyrannosauridae (carnivores such as Tyrannosaurus rex).
'We looked at these bigger groupings so we could have more data, effectively,' Dean said. 'We gridded up North America into a big spatial grid (and determined) the places where we can find fossils, (the places where we) have physically found fossils and how many times people have gone to look for fossils (in these places).'
The information was fed into a computer model, and Dean and his colleagues compared the physical fossil record with that proposed by the model and found a mismatch.
The model suggested that, during the 18 million-year time period in question, the proportion of land the four dinosaur clades likely occupied remained constant overall, suggesting their potential habitat area remained stable, and the risk of extinction stayed low.
One of the factors that could have clouded the true diversity patterns of dinosaurs was the lack of rock exposed at the Earth's surface during that window of time — and thus available for fossil hunters today to scrutinize.
'In this study, we show that this apparent decline is more likely a result of a reduced sampling window, caused by geological changes in these terminal Mesozoic fossil-bearing layers — driven by processes such as tectonics, mountain uplift, and sea-level retreat — rather than genuine fluctuations in biodiversity,' said study coauthor Alfio Alessandro Chiarenza, a Royal Society Newton International Fellow at University College London's department of Earth sciences, in a statement.
'Dinosaurs were probably not inevitably doomed to extinction at the end of the Mesozoic,' Chiarenza said. 'If it weren't for that asteroid, they might still share this planet with mammals, lizards, and their surviving descendants: birds.'
The study helped to highlight what biases may affect scientists' understanding of the true pattern of dinosaur diversity leading up to the extinction event, said Darla Zelenitsky, a paleontologist at the University of Calgary in Alberta who wasn't involved in the research.
'Because of the nature of the rock record, (paleontologists have) found it was more difficult to detect dinosaurs and thus understand their diversity patterns in that window of time just before the mass extinction,' she said.
'It certainly makes sense as we know there are biases related to the rock record that can obscure true biological patterns. The more rock that is exposed at the surface (today), the better our chance of finding dinosaurs in that rock, which in turn leads to a better understanding of their diversity patterns.'
Mike Benton, a professor of vertebrate paleontology at the UK's University of Bristol, called the paper 'thorough and detailed' but said it doesn't prove there was no reduction in dinosaur diversity ahead of the extinction event. Benton's work has suggested that dinosaurs were in decline before the asteroid wiped them out. He wasn't involved in the new study.
'The current paper suggests that the 'reduction' can be explained as a statistical artefact,' Benton said via email. 'What it shows is … simply that the reduction could be real or could be explained by reduced sampling, in my opinion.'
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Yahoo
8 hours ago
- Yahoo
The science of sleep paralysis, a brain-body glitch making people see demons and witches
Sign up for CNN's Sleep, But Better newsletter series. Our seven-part guide has helpful hints to achieve better sleep. Baland Jalal lay in bed terrified, experiencing his own real-life horror film. Newly awake, the 19-year-old could see his surroundings but couldn't move or speak, and he didn't know why. He thought, ''My God, what do I do?'' Jalal, now 39, said of that moment in 2005. 'I tried to call my mom (and) dad, but no words would emerge from my throat. … I had this ominous presence of a monster, and it lifted my legs up and down. 'It strangled me, trying to kill me. And I was 100% sure that I was going to die,' Jalal added. 'It literally feels like all the evil of the universe is condensed into a bubble, and it's in your bedroom.' This type of hallucination is a hallmark for many people with sleep paralysis. It occurs during transitions into or out of rapid eye movement, or REM, sleep, similar to a traffic jam at a busy intersection — your brain, awake and alert, and body, still asleep and immobilized, collide momentarily, said Dr. Matthew P. Walker, director of the Center for Human Sleep Science at the University of California, Berkeley, via email. Following deep sleep, REM sleep is the next critical phase of sleep cycles, characterized by more dreaming that's also extra vivid and lifelike, and by faster heart rate and breathing. It's essential for memory, concentration, mood regulation and immune function. Jalal's experiences propelled him to study this phenomenon around the world. He aimed to discover the cause of sleep paralysis, he said, and why some people with the diagnosis 'have these powerful encounters where it feels like evil of epic proportions.' He has since earned a doctorate in psychiatry and is now a researcher in Harvard University's psychology department and a leading expert on sleep paralysis. He also treats patients struggling with it. An estimated 30% of people worldwide experience at least one episode of sleep paralysis in their lifetime, according to the Cleveland Clinic. How many of those people have recurring and impairing sleep paralysis isn't clear, but the percentage is likely low, Jalal said. Here's what else you should know about sleep paralysis and how it can be managed. In REM sleep, our bodies are paralyzed so we don't act out our dreams and risk hurting ourselves or others, Jalal said. Sleep paralysis episodes are usually only a few minutes long but can last up to 20 minutes, according to the Cleveland Clinic. During sleep paralysis, however, 'we regain consciousness before the muscles regain their freedom from REM-induced paralysis,' said Walker, who is also a professor of neuroscience and psychology at the University of California, Berkeley About 40% of people with sleep paralysis have visual, auditory or tactile hallucinations, such as pressure on one's chest or feeling out of body, Jalal said. For about 90% of those individuals, the illusions are terrifying. They can include ghosts or cat- or alien-like creatures, and their actions can be as innocuous as simply approaching them or as nefarious as molesting or trying to kill them. In Jalal's academic travels, he discovered the contents and interpretations of hallucinations, views on what causes sleep paralysis, and episode frequency and duration can all also have a cultural basis. People living in Egypt and Italy, for example, would often see witches and evil genies, hold them responsible and think they could die from sleep paralysis, Jalal said. People in Denmark, Poland and parts of the United States, on the other hand, have less supernatural or exotic explanations and less fear. 'Why do we see these monsters? Is it the dreaming imagery … that's spilling over into conscious awareness?' Jalal said. 'My answer to that is, according to my research, no, not exactly. But it's part of it.' When you're aware yet paralyzed and confused, your natural reaction is to escape that situation. Your brain is bombarding your body with signals to move, but your body can't return any feedback. Jalal's theory, in short, is that your brain says, 'to hell with it' and concocts a story it thinks your body must be facing to be experiencing such bizarre symptoms. The reduced activity in your prefrontal cortex — responsible for reason and logic — also contributes to hallucinations becoming 'extremely realistic and emotionally charged, amplified by an overly active amygdala, the brain's emotional alarm center,' Walker said. Though scientists know that wake-sleep glitch is what's happening during a sleep paralysis episode, they're not entirely sure why. But there are several factors that can increase the risk of fragmented sleep and sleep paralysis. Those factors include stress and related conditions such as anxiety, post-traumatic stress disorder (PTSD), bipolar disorder and panic disorder, experts said. Much of Jalal's sleep paralysis occurred when he was in school. Now when he has an episode once or twice per year, it's usually during a high-stress period, he said. (Once you've experienced sleep paralysis, you can be conscious of that during an episode but still feel afraid.) Other common contributors are sleep deprivation, jet lag, an irregular sleep schedule, sleep disorders such as narcolepsy, and genetic factors, Walker and Jalal said. Obstructive sleep apnea, substance use disorder and some medications — such as those for attention deficit hyperactivity disorder — can also raise risk, according to the Cleveland Clinic. As scary as sleep paralysis may sound, it's not actually dangerous, experts said. But depending on how recurring it is, sleep paralysis can be a sign of an underlying sleep disorder, Jalal said. Regular episodes can also lead to anxiety around sleep and then avoidance of sleep, Jalal said. This pattern can interfere with your daily energy and ability to function. And if you often have frightening hallucinations, that can lead to anxiety or trauma-like symptoms. Sleep paralysis can be significantly alleviated with several practices or treatments, Walker said — starting with healthy sleep habits, for one. That includes seven to nine hours of restful sleep nightly. Maintaining a sleep schedule consistent in quality and quantity 'acts like tuning your internal clock, reducing the chance of disruptive wake-sleep overlaps — much like ensuring all parts of an orchestra are synchronized for perfect harmony,' Walker said. Also prioritize stress management, by using, for example, mindfulness and relaxation exercises, Walker said. Therapies can relieve certain underlying issues triggering sleep paralysis, including cognitive behavioral therapy, especially the version for people with insomnia. In more serious situations, medications are sometimes used, Walker said. Those include SSRI (selective serotonin reuptake inhibitor) or tricyclic antidepressants that can help manage a smooth flow between sleep stages or even reduce the REM phase of sleep. Generally, boosting the brain's serotonin levels somehow compensates for the loss of the REM phase, Jalal said. But rarely, long-term antidepressant use has been linked with REM sleep behavior disorder. While the aforementioned treatments can help reduce the frequency or length of sleep paralysis episodes, there isn't yet a gold-standard treatment that can stop an episode once it's happening. Jalal has been trying to officially create one over the past decade, though, and it's self-inspired. Called meditation relaxation therapy, the treatment reduced sleep paralysis by 50% after eight weeks for six people with narcolepsy, compared with a control group of four participants, found a small pilot study Jalal published in 2020. He currently has another study of the same treatment with more participants underway at Harvard. And the steps of Jalal's therapy are as follows: Cognitively reappraise the meaning of the attack. Close your eyes and remind yourself that your experience is common and you won't die from it. Emotionally distance yourself from it. Tell yourself that since your brain is just playing tricks on you, there's no reason for you to be scared or risk the situation getting worse because of your own negative expectations. Focus on something positive. Whether it's praying or imagining a loved one's face, this refocusing can make thoughts more pleasant rather than monstrous. Relax your muscles and don't move. Some experts say trying to slightly move your fingers or toes one by one may help you come out of an episode sooner. But Jalal's fourth step advises against this movement since you'd still be sending signals to paralyzed muscles and maybe triggering hallucinations. Viewing your own biology in a more objective way by learning more about the scientific basis of sleep paralysis is also helpful, Jalal said.
Yahoo
a day ago
- Yahoo
Authorities expose secret pipeline fueling endangered species trade: 'An important threat to the biodiversity ... and the wider region'
Protecting animal species from exploitation and extinction requires accurate information about the animals and how humans are interacting with them. Sometimes, that information is hard to get, as is the case for North Korea due to its lack of open communication with the rest of the world. However, a recent study published in the journal Biological Conservation sheds light on North Korea's wildlife — and, unfortunately, the situation is dire, University College London reported. The information in the report came from interviews with North Korean defectors directly involved in the illegal wildlife trade, including hunters, buyers, and middlemen, gathered between 2021 and 2022. This group revealed that despite North Korea's system of protected habitats and protected species, it is extremely common for endangered animals to be hunted for meat, skins, traditional medicine ingredients, and other resources. Some of the animals and parts are traded within North Korea, with the rest crossing the border to China. The North Korean government itself is involved in illegal wildlife trade, which violates both its own laws and international law regarding the treatment of endangered species. Lead author Dr Joshua Elves-Powell said in the UCL report: "The widespread harvesting of North Korea's wildlife, driven by the economic limitations of the North Korean state and the shortages of food, medicine, and basic goods experienced by many of its citizens, is an important threat to the biodiversity of North Korea and the wider region." Protected animals like Amur tigers, Amur leopards, Asiatic black bears, long-tailed gorals, and Eurasian otters are among the species of most concern in this report. But after an economic collapse and famine in the 1990s, it's likely that almost every mammal species heavier than half a kilogram (just over a pound) has been affected to some extent, UCL reported. As this data makes clear, many people in North Korea are relying on the animals in the country for food or their livelihoods. Unfortunately, wildlife is not an unlimited resource. The more those animal populations are pushed toward extinction, the more the people involved will suffer. Species that are lost can never be recovered, and populations that are damaged may take many years of conservation efforts to restore. It doesn't just impact the animals within North Korea's borders. Normally, animals should be able to cross the border freely, interbreeding and searching for food. Populations near the border will be impacted by the activities that happen on only one side, as there will be fewer individuals to maintain genetically diverse populations. The study authors called on China to crack down on buyers and put economic pressure on North Korea to stop the illegal wildlife trade. As the market for the majority of illegal animal parts that leave North Korea, China has the power to shut down demand. Do you think people should be allowed to keep exotic animals as pets? Yes No It depends on the animal It depends on the person Click your choice to see results and speak your mind. Join our free newsletter for good news and useful tips, and don't miss this cool list of easy ways to help yourself while helping the planet.
Yahoo
2 days ago
- Yahoo
Some Dead Sea Scrolls may be even older than archaeologists thought, new study finds
Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. Many of the Dead Sea Scrolls, some of the most widely known archaeological finds of all time, may be older than once thought, according to a new study. The fresh analysis, which paired radiocarbon dating with artificial intelligence, determined some of the biblical manuscripts date to about 2,300 years ago, when their presumed authors lived, said Mladen Popović, lead author of the report published Wednesday in the journal PLOS One. Bedouin shepherds first spotted the scrolls by chance in the Judaean Desert, near the Dead Sea, in 1947. Archaeologists then recovered thousands of fragments belonging to hundreds of manuscripts from 11 caves, all near the site of Khirbat Qumran in what is now the West Bank. 'The Dead Sea Scrolls were extremely important when they were discovered, because they completely changed the way we think about ancient Judaism and early Christianity,' said Popović, who is also dean of the Faculty of Religion, Culture and Society at the University of Groningen in the Netherlands. 'Out of around 1,000 manuscripts, a bit more than 200 are what we call biblical Old Testament, and they are the oldest copies we have of the Hebrew Bible. They gave us a lot of information about what the text looked like back then.' The scrolls are like a time machine, according to Popović, because they let scholars see what people were reading, writing and thinking at the time. 'They are physical, tangible evidence of a period of history that is crucial — whether you're Christian, Jewish or don't believe at all, because the Bible is one of the most influential books in the history of the world, so the scrolls allow us to study it as a form of cultural evolution,' he said. Almost none of the Dead Sea Scrolls — which were written mostly in Hebrew on parchment and papyrus — have dates on them. Based primarily on paleography, the study and deciphering of ancient writing and manuscripts, scholars have believed the manuscripts range from the third century BC to the second century AD. 'But now, with our project, we have to date some manuscripts already to the end of the fourth century BCE,' he said, meaning that the earliest scrolls could be up to 100 years older than previously thought. 'That's really exciting because it opens up new possibilities to think about how these texts were written and how they moved to other users and readers — outside of their original authors and their social circles,' Popović added. The findings will not only inspire further studies and affect historical reconstructions, according to the authors of the report, but will also unlock new prospects in the analysis of historical manuscripts. Earlier estimates of the manuscripts' age came from radiocarbon dating conducted in the 1990s. Chemist Willard Libby developed this method — used to ascertain the age of organic materials — in the late 1940s at the University of Chicago. Also known as carbon 14 dating, a chemical analysis of a sample, such as a fossil or manuscript, determines the quantity of carbon 14 atoms it contains. All living organisms absorb this element, but it starts to decay as soon as death occurs, so looking at how much is left can give a fairly accurate age of an organic specimen as old as about 60,000 years. Carbon dating has downsides, however. The analyzed sample is destroyed during the process, and some results can be misleading. 'The problem with earlier tests (on the scrolls) is that they didn't address the issue of castor oil,' Popović said. 'Castor oil is a modern invention, and it was used in the 1950s by the original scholars to make the text more legible. But it's a modern contaminant, and it skews the radiocarbon result to a much more modern date.' The study team first used new radiocarbon dating, applying more modern techniques, on 30 manuscripts, which revealed that most of them were older than previously thought. Only two were younger. The researchers then used high-resolution images of these newly dated documents to train an AI they developed, called Enoch after the Biblical figure who was the father of Methuselah. The scientists presented Enoch with more documents they had carbon-dated, but withheld the dating information, and the AI correctly guessed the age 85% of the time, according to Popović. 'In a number of cases, the AI even gave a narrower date range for the manuscripts than the carbon 14 did,' he said. Next, Popović and his colleagues fed Enoch more images from 135 different Dead Sea Scrolls that were not carbon-dated and asked the AI to estimate their age. The scientists rated the results as 'realistic' or 'unrealistic,' based on their own paleographic experience, and found that Enoch had given realistic results on 79% of the samples. Some of the manuscripts in the study were found to be 50 to 100 years older than formerly thought, Popović said. One sample from a scroll known to contain verse from the Book of Daniel was once believed to date to the second century BC. 'That was a generation after the original author,' Popović said, 'and now with the carbon 14, we securely move it (further back) to the time of the author.' Another manuscript, with verses from the Book of Ecclesiastes, also dates older, Popović added. 'The manuscript was previously dated on paleographic grounds to 175 to 125 BCE, but now Enoch suggests 300 to 240 BCE,' he said. Eventually, artificial intelligence could supplant carbon 14 as a method of dating manuscripts, Popović suggested. 'Carbon 14 is destructive,' he said, 'because you need to cut off a little piece of the Dead Sea Scroll, and then it's gone. It's only 7 milligrams, but it's still stuff that you lose. With Enoch, you don't have to do any of this. This a first step. There are all sorts of possibilities to improve Enoch further.' If the team pushes forward with Enoch's development, Popović believes it could be used to assess scripts such as Syriac, Arabic, Greek and Latin. Scholars who were not involved with the study were encouraged by the findings. Having both AI and an enhanced carbon 14 dating method allows a level of calibration across both methodologies that is helpful, according to Charlotte Hempel, a professor of Hebrew Bible and Second Temple Judaism at the University of Birmingham in the United Kingdom. 'The pronounced pattern seems to be that AI offers a narrower window within the Carbon 14 window,' she said via email. 'I wonder whether this suggests a higher level of precision, which would be extremely exciting.' The study represents a first attempt to harness AI technology to extend existing scientific knowledge from carbon 14 dating of certain manuscripts to other manuscripts, said Lawrence H. Schiffman, Global Distinguished Professor of Hebrew and Judaic Studies at New York University. 'To some extent, it is not yet clear whether or not the new method will provide us with reliable information on texts that have not yet been Carbon-14 dated,' he added via email. 'The interesting comments regarding revision of the dating of some manuscripts that may be expected through further development of this approach or new carbon-14 dating, while not new to this study, constitute a very important observation about the field of Dead Sea Scrolls in general.' Commenting on the computational aspects of the study, Brent Seales, the Alumni Professor of Computer Science at the University of Kentucky, said the approach taken by the authors seems rigorous even if the sample sizes are small. Using AI to completely replace carbon dating may be premature, however. '(AI) is a useful tool to incorporate into the broader picture, and to make estimates in the absence of Carbon-14 based on the witness of other similar fragments,' Seales wrote in an email. 'Like everything with machine learning, and like a fine wine, it should get better over time and with more samples. The dating of ancient manuscripts is an extremely difficult problem, with sparse data and heavy constraints on access and expertise. Bravo to the team for this data-driven contribution that takes a massive step forward.'
