Oldest Big Cat: Fossil of Four-Plus Million-Year-Old Big Cat Species Discovered
Researchers on an expedition in Tibet recently discovered the oldest big cat fossil ever found, filling a significant gap in the fossil record.
The skull from the new species, named Panthera blytheae, is described today in the Proceedings of the Royal Society B: Biological Sciences. The research, led by Jack Tseng, a Ph.D. student at the University of Southern California at the time of the discovery and now a postdoctoral fellow at the Museum, suggests that big cats have a deeper evolutionary origin than previously expected based on the existing fossil record.
DNA evidence and “molecular clock” age estimation techniques had suggested that “big cats”—the Pantherinae subfamily, including lions, jaguars, tigers, leopards, snow leopards, and clouded leopards—diverged from their nearest evolutionary cousins, Felinae (which includes cougars, lynxes, and domestic cats), about 10.8 million years ago.
However, the oldest fossils of big cats previously found are tooth fragments uncovered at Laetoli in Tanzania, dating to just 3.6 million years ago.
Using magnetostratigraphy—dating fossils based on the distinctive patterns of reversals in the Earth’s magnetic field, which are recorded in layers of rock—Tseng and his team were able to estimate the age of the new fossil skull at around 4.4 million years old.
The find not only challenges previous suppositions about the origins of big cats, it also helps place that evolution in a geographical context. The discovery occurred in a region that overlaps the majority of current big cat habitats, and suggests that the group evolved in central Asia and spread outward, rather than originating in Africa as previously inferred from the known fossil record.
Eerie, beautiful, captivating images of sea urchins mating and being born (that little triangle guy is a baby sea urchin).
These are a glimpse of how life begins in the deep ocean — and there’s a lot of life down there. The oceans provide about 190 times as much living space as every other space on Earth — soil, air and fresh water — put together. A vast array of amazing creatures live in the depths of this watery world. Squid, jellyfish, and plankton are just a few of our favorites (all shown as tiny babies in that last gif).
Crabs sop up microplastic pollution via their food and gills, researchers have found in a laboratory study. The tiny particles can lodge in the crustaceans’ bodies for weeks. Crabs become the first marine creature known to trap microplastics in their respiratory systems.
Previous studies had looked at how plastics affect marine organisms through their diet but not through what they breathe. “For a marine crustacean to actually uptake microplastics through respiration and then retain them in the gills — that’s groundbreaking,” says environmental marine biologist Phillip Cowie of the University of Glasgow.
Crabs are central players in the marine food web. They consume other seafloor dwellers, including mollusks, while crabmeat often forms meals for large predators like octopuses, otters and humans. Studies have found that many animals’ bodies hang on to plastic particles, but questions remain over whether those particles persist in the food chain and for how long.
Microplastics, any plastic particles smaller than 5 millimeters across, are pervasive aquatic pollutants. They can result from the breakdown of larger plastic chunks and also feature in personal care products. “Toothpastes, deodorants, hand cleanser, makeup — most consumer products with a powdery feel have them, and wastewater treatment facilities do not have the means to capture these microplastics,”says marine geochemist Tracy Mincer of the Woods Hole Oceanographic Institution in Massachusetts. “This careful study begins drawing the links between microplastics and the food chain.”
To find out how crabs handle the plastics in their diet, marine ecologist and biochemist Andrew Watts and colleagues at the University of Exeter in England started by feeding mussels fluorescent microplastics. The researchers then fed those mollusks to shore crabs,Carcinus maenas.Normal food passes through a crab’s digestive tract within two days, but the fluorescent microplastics took as many as 14 days to emerge in the crabs’ feces, the researchers report June 27 in Environmental Science & Technology.
To find out whether respiration also filled the crabs with plastic particles, the team fitted shore crabs with masks that flushed high concentrations of microplastic beads over the animals’ gills for 16 hours. On each subsequent day, the researchers changed the water in the crabs’ tanks, putting in fresh seawater and measuring microplastics in the used water. The crabs took up to three weeks to expel the pollutants.
Clinging upside down to polished surfaces is simple for geckos, but scientists’ grasp of the underlying forces behind this phenomenal adherence just became murkier. Researchers report that the adhesiveness of gecko feet is aided by static electricity, contrary to long-held beliefs.
The misconception over gecko adhesion dates back to 1934, says Yale University chemical engineer and study coauthor Hadi Izadi. A German scientist named W.D. Dellit wondered whether gecko adhesion was explainable by electrostatic forces, the differences in electric charge that build up between any two surfaces. Dellit used X-rays on the air surrounding the reptile’s toes as they stuck to a metal wall. The X-rays ionized the air, neutralizing any charge on the wall’s surface, Izadi explains. Anything attached to the wall via electrostatic forces should have fallen, yet the lizards remained. So researchers ruled out electrostatic forces and moved on to other ideas. But scientists may have been too hasty in ruling out electrostatic forces, Izadi says. The gap between a smooth surface and a gecko’s setae is too small for destabilizing air ions to pass through, which wasn’t known in Dellit’s era. So his X-ray experiment probably didn’t counteract electrostatic forces that may have helped the geckos stick.
As a graduate student at Canada’s University of Waterloo, Izadi compared how the footpads of tokay geckos (Gekko gecko) stuck to two polymer surfaces. One surface consisted of Teflon AF, a material related to the nonstick cookware coating, while the other was made from a silicone rubber dubbed polydimethylsiloxane. Because of their chemical makeup, both substances should have had similar degrees of van der Waals interactions with the geckos’ setae, and therefore the animals should have clung equally to both surfaces. But when the researchers gently pulled a lizard’s foot away, the footpads stuck to Teflon AF with twice as much strength as they did to polydimethylsiloxane, Izadi and his colleagues report July 9 in the Journal of the Royal Society Interface. Because the adhesions were very different, the team concluded that van der Waals forces don’t fully explain how geckos stick to walls.
Next, the researchers examined whether electrostatic forces could account for this discrepancy by measuring the charge between each polymer surface and the gecko’s feet. The geckos’ toe pads and the polymer surfaces were electrically neutral before touching. But when they came in contact, electrons jumped from the gecko foot to the polymers, leaving the foot positively charged and the polymers negatively charged. The team also ruled out water-governed capillary forces, leading to the conclusion: “Electrostatic interactions are the dominant forces, and they are not something that scientists can ignore,” Izadi says.