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In what may be the most dramatic mass extinction in Earth’s history, an asteroid impacted our planet 66 million years ago near what is now Chicxulub on the Yucatan Peninsula. The resulting hellscape extinguished 75 percent of then living species – including all non-avian dinosaurs. Over the last few years, scientists have discovered many more traces of this cataclysmic impact, providing us with ever greater details of its extreme aftermath – from world-encircling dust to wildfires up to 1,500 kilometers (930 miles) from the impact site. In 2019, a team found fossil records of the immediate hours after, including evidence of debris swept up by the resulting tsunami. Now, researchers have discovered enormous megaripples engraved by the tsunami in sediments 1,500 meters (5,000 feet) below what is now central Louisiana. By analyzing seismic imaging data for central Louisiana, gained from a fossil fuel company., the team determined the imprinted ripple crests form a straight line right back to the Chicxulub crater and their orientation is consistent with the impact. These megaripple features have average wavelengths of 600 meters and average wave heights of 16 meters making them the largest ripples documented on Earth. Compare that to the largest Camas Prairie megaripple at 289m x 17m. Modelling of this monstrous tsunami suggests its waves would have reached a staggering 1,500 meters high (nearly 1 mile) after the Richter scale 11 megaearthquake triggered by the collision. The aftereffects would have been particularly devastating in the regions surrounding the impact site, sweeping sea life onto land and land life into the sea. “Tsunami continued for hours to days as they reflected multiple times within the Gulf of Mexico while diminishing in amplitude,” the team wrote. What carved out the ripples we can still detect today were the forces from the massive walls of water smashing into the shallow shelf near the shores, and reflecting back towards their source. Excerpted from: sciencealert.com/tsunami-megaripples-from-the-dinosaur-killing-asteroid-impact-discovered-in-louisiana Read another article at: https://www.sciencetimes.com/articles/32252/20210713/dino-killer-space-rock-left-fossilized-megaripples-mile-high-giant.htm

Using detailed fossil comparison techniques, scientists have been able to identify a giant new saber-toothed cat species, Machairodus lahayishupup, which would have prowled around the open spaces of North America between 5 and 9 million years ago. One of the biggest cats ever discovered, M. lahayishupup is estimated in this new study to have a body mass of some 274 kilograms (604 pounds) or so, and possibly even bigger. It’s an ancient relative of the well-known Smilodon, the so-called saber-toothed tiger. A total of seven M. lahayishupup fossil specimens, including upper arms and teeth, were analyzed and compared with other species to identify the new felid, with the fossils collected from museum collections in Oregon, Idaho, Texas, and California. Upper arms are crucial in these cats for killing prey, and the largest upper arm or humerus fossil discovered in the study was about 1.4 times the size of the same bone in a modern-day lion. That gives you an idea of just how hefty and powerful M. lahayishupup would have been. “We believe these were animals that were routinely taking down bison-sized animals,” says paleontologist Jonathan Calede from Ohio State University. “This was by far the largest cat alive at that time.” Rhinoceroses would have been abundant at the same and may have been animals that M. lahayishupup preyed on, alongside camels and sloths significantly bigger than the ones we’re used to today. Peering back so many millions of years into the past isn’t easy, and the researchers say that a more detailed saber-tooth cat family tree is going to be needed to work out exactly where this species fits in. The findings also open up some interesting evolutionary questions about these giant cats. “It’s been known that there were giant cats in Europe, Asia, and Africa, and now we have our own giant saber-toothed cat in North America during this period as well,” says Calede. “There’s a very interesting pattern of either repeated independent evolution on every continent of this giant body size in what remains a pretty hyper-specialized way of hunting, or we have this ancestral giant saber-toothed cat that dispersed to all of those continents. It’s an interesting paleontological question.” Excerpted from SCIENCE ALERT article by DAVID NIELD8 MAY 2021