The evolution of bats, even with ever-emerging research and fossil records, remains a mysterious one. Most evolution scientists agree that bats must have evolved from mammals, but unfortunately they can not find strong enough evidence as to which common ancestor bats splintered off from.
Scientists now theorize that bats, the only mammal known to have developed flight, evolved from small rodent-like animals, which now include rats, etc.
A discovery in 2008 did fill in a piece of this evolutionary puzzle with an exciting find. The oldest fossilized bat, dated to be over 52 million years old, put to rest another long standing argument in the scientific community as to whether flight or echolocation, the bat’s flight system, developed at different times or in congruency with each other. It turns out that this animal was able to fly but could not boast the use of echolocation. Dr. Nancy Simmons of the American Museum of Natural History in New York, who was part of the archeological find, says, “It’s clearly a bat, but unlike any previously known. In many respects it is a missing link between bats and their non-flying ancestors.”
This creature is theorized to have been a day flyer until it’s species was forced to become nocturnal to avoid new flying predators. But still this discovery does not prove from which animal family bats evolved. Even though gliding has evolved in mammals multiple times it is very clear that actual, familiar flying only developed once. And how excesses of skin found in gliding mammals developed into short, skinny flapping wings which give bats almost no resemblance to their original ancestor, still confuses every scientist to date.
The wings of bats are now highly advanced from over millions of years of evolution. They have developed hyper-sensitive wings with almost two dozen joints just within the wing membrane. This membrane is also suited to give the bat advantage over it’s flying counterparts; while birds and insects can change the angle of attack or fold in their winds to increase aerodynamic efficiency, bats have a much more flexible wing. This allows them to curve the bottom of the wing inward during their downstroke, generating greater lift for much less energy. Similarly, bats can fold in their wings closer to their bodies for each upstroke and they experience less drag. In fact, the wing is so flexible that bats can make a 180 degree turn in a matter of half a downstroke. This allows mass amounts of bats to fly very fast, in very close proximity to one another, and almost never crash.
Researchers have only recently begun to discover the remarkable ways in which bats developed a highly advanced and remarkable new style of flight. These specialized wing strokes do not only make the animal more aerodynamic, but they also allow the bat to hover, almost like an insect or hummingbird. The only problem with this is that theoretically, bats should be to large to be able to hover because flying animals over a certain weight can not beat their wings fast enough to maintain a steady state. However in the downstroke a remarkable phenomenon occurs; a tiny vortex is created at the tip of the bats wing. The vortex then swirls around the wing on the upstroke, creating a pressurized air bubble below the wing, giving the creature extra lift by lowering air pressure above.
The result is amazing; “Even as gravity plucks at its heels, the bat’s homegrown tornadoes suck it back up toward Oz.” The vortexes were discovered and retested by a number of different groups, all which came to the same conclusion. When putting a bat in a wind tunnel and sending colored streaks of smoke towards it, they can see plainly that tiny swirls appear at the tip of the bat’s wing while it is attempting to hover, and the bat flaps it’s wing three times per second, which is even more remarkable for such a large animal.
Engineers are now trying to design and manufacture a type of flying robot that can mirror the skills that bats possess. However, they are wary of simply making the robot look like a bat, but rather they want to design something that is more practical for human use while still maintaining the bat-like flight.