Are any of these species likely to evolve the ability for true “powered flight”, like birds, bats, or winged insects? I dunno if there is actually a factual answer for this query, since it would involve speculation, but I’m certainly willing to be educated on the subject.
(There are probably other gliding animals that in my ignorance I might have overlooked. If anyone wants to speculate about any of the critters that I have missed, please feel free to chime in.)
It’s possible but very unlikely. We’re talking some major biological changes for this kind of thing to happen. One of the key reasons for any animal to evolve is to fit a certain niche to adapt and survive. Animals like the flying squirrel really face no biological pressure to evolve flight. So while it is possible, I wouldn’t bet on it.
That’s true of anything we might now call a transitional form. It has to work in its own right - so somewhere along the way, there must have been sort-of-birds and nearly-bats that could only glide or make short flights, and were just fine in their niches at that time.
You’re right of course that it’s impossible to predict, and also unlikely.
The flying frog’s advantage is that webbed hands look a lot like the other powered flyers we know about. If you connected a flap of skin from one finger to the body and extend the other fingers, you’d have almost the same wing structure a bat has. Extend the finger and you’re a lot like a pteranodon. The flying frogs are at least following a successful model used by other vertebrates with powered flight.
Flying squirrels and colugos rely on a different arrangement for their flaps of skin. It’s not impossible to envision extending the front arms and changing the attachment points for the flap of skin to look more like a bat or pteranodon, but you need multiple changes to get there. Colugos already have webbed toes, so that gives them a little head start on this transition, but they’re not really using those toes to fly.
Snakes… we should probably do some computer simulations on this method of flying to see how viable it is. I’m not sure they have a good path to powered flight, but maybe I ought to rank them higher than the squirrels.
My guess is that we can rule out flying fish. Without the ability to breathe air, flight time is limited by more than just wings. Gliding is sufficient to escape predators while they hold their breath. They don’t really have a winning bone structure for powered flight either.
The squid doesn’t have lungs or a good bone structure. They are fairly smart and have manipulative tentacles, though… These guys are more likely to fly by becoming intelligent and building airplanes.
In this case it probably matters whether humans survive long enough. Because if snakes start showing any signs of being able to fly, I’m pretty sure half of humanity will join forces to exterminate them.
I don’t know about likely, but evolution could bring us another flying animal. It could be descended from one of the ones that are gliding now. I’ll get back to you in a few hundred million years with details.
Might they? Sure. But the nature of evolution is such that we can’t actually know. Evolution has no goal. Flying animals aren’t “trying for flight”, and just partway there. They evolved that way because their ancestors had some lucky mutation that happened to work for something (getting away from predators, maybe), and so it stuck around. Now, maybe a flying squirrel will have another mutation that makes it better at gliding, and that becomes the new standard, and maybe one if its descendants will become so good at it that they can use their muscles to extend their glide, and maybe one of its descendants will become good enough at powered gliding to continue it for an extended time and become a true flyer. Or maybe that mutation will just happen to never occur, or maybe it will occur and it’ll turn out that it’s more trouble than it’s worth, or maybe it’ll occur and it really would be a big advantage and that squirrel just has the dumb luck to be eaten by a cat anyway.
The question is ongoing of how birds evolved flight: whether it was “top down”- their ancestors climbed trees and became gliders; or whether flight evolved from the ground up- think of a protobird that mostly walked but could briefly flutter like a chicken. One school of thought is that true flight always evolves from the ground up, and that therefore gliders are usually dead ends.
It’s not impossible, but I think it’s less likely, since all the good jobs for flying animals are already taken. If there were no other flying animals, a small fox that could sort-of fly hypothetically might have a huge advantage in catching slow insects near but above the ground. Enough of an advantage to survive and get more advantage by developing better and better flying abilities.
But now, a sort-of flyer would be competing against swifts and other really good flying birds in the day and really good flying bats at night.
This would be a big part of it, opening up the niche for a new flying animal to thrive.
I saw a doc on the bluefin tuna the other day that showed seabirds diving as far as 50 ft. underwater to feed on baitballs of fish herded up by dolphins. The birds and bluefin were possibly cooperating by coming in from above and below. I can see the way that led to penguins adapting to the water, giving up flight, and become marine creatures. It seems bit more difficult for gliders to compete against powered flyers that way but things do change over time. Something that caused a great reduction in the existing flying animals could open up that niche someday, but who knows if the current gliders would even be the ones to take advantage of that.
There’s definitely some truth to this, but if we’re talking about the likelihood of new flying species, we probably have to assume they’re taking advantage of some kind of disruption. Climate change, extinction, disease, local isolation, etc. For example, if a newly evolved rat manages to eat every bird egg in the Amazon, flying frogs only have to compete with bats.
I don’t know the answer to the OP, but it seems to me that most flight involves getting away from predators. Flying fish fly (up to 100 meters) to get away from predators. Birds on an island without predators seem to lose flight presumably because it is costly and not needed. That to me seems to mean that the selective pressure has to be high before flight will evolve. If gliding suffices to avoid predation, there is no reason to expect it to evolve further.
Just to be clear, everything “evolves further”, it’s just that things don’t evolve in a particular direction. As noted, it would be a mistake to think that the evolution of gliding is a half-way measure and that these species are “trying” to evolve towards powered flight.
Insects achieved flight without being warm-blooded, but they are tiny. A larger, exothermal gliding animal could evolve true flight by simultaneously evolving warm-bloodedness.
I think it likely that bats and birds both evolved flight as a way to catch flying insects: the run-and-jump hypothesis. They were evolving the power and the flight at the same time. Existing gliding animals have probably all gotten that way as a way of surviving falls; thus there was little pressure to evolve the the skeletal and muscular structures that would be needed to add power to the flight surfaces.
Bird fossils date back to about 125MYA. Although we don’t have a lot of good bat fossils, we pretty much expect that bats first showed up on the scene about 50-60 MYA.
Heck, “birds” predate much of the branching out of the placental mammals. None of the orders we recognize today (carnivores, rodents, etc) would have been around when birds were first taking off (pun intended). So birds are 2-3x older than bats.