If that patch of skin wasn’t there between our "Digits" then we wouldn’t be able to open our fingers too well because that patch of skin allows you to spread your fingers easily. And, it also allows us to swim better with our hands as "Oars".

As I know only bats have skin between their phalanges. Others such as squirrels just have between front and hind legs. And no it does not show that we evolved from any of those groups. Neither from aquatic forms like Lutra (otter I think) or beaver although thay also have swiming skin between their phalanges.

It must be a coincidence, as bats evolved to fly, not glide. I’ve never seen a morphology of skin between the digits that would allow for gliding rather than flight, and no human forerunner could fly. It’s much more reasonable to think along beetle’s and zim’s lines.

You’re falling into the trap of homologous and analogous structures. Just because echidnas have spines, doesn’t mean they evolved from porcupines. Similarly, just because dolphins have dorsal fins, doesn’t mean they evolved from Tuna.
Some humans have genetic anomalies that cause their feet or hands to be webbed. That demonstrates that our genome has the capacity to cause that to happen, but not necessarily that we at one time had an ancestor with webbed feet and or hands.
I don’t want to discourage you from scientific inquiry, but perhaps next time you have a hypothesis, you can do a little research before posting.

Speaking of bats does anyone knows what animals were the ancestors of them? And when did thay evolved and become true (todays) bats? I never thoght about it.

That’s still a pretty big mystery. The fossil record doesn’t really have much information on that point. In fact, the evolution of flight as a whole is still quite a mystery.
There are different hypotheses:

1. They were arboreal gliders that evolved powered flight
2. They were terrestrial and used a patagium for intimidation and escape.
3. They evolved independently from a flying proto-mammal

we really don’t know though. So if you’re looking for something to dedicate your life’s research to, there you go!

Amazing. I never thought of that but there definitely does seem to be a family resemblance.

Bats have incredibly diverse pheonotypes and karyotypes. There are bats with faces very similar to canids (flying fox) and those with faces more resembling mice (vespertilionids). The shape and appearance of their face is mostly just convergence. A detailed study of their skulls will reveal many differences.
Interestingly, most bats have the same teeth as insectivores (shrews, voles, moles, etc).

David I’d like to see some documentation on the relationship between lemurs and bats. Could you post that? There is a very large taxonomic gap between bats and lemurs (Chiroptera and Primate). I get the feeling that people may say their related just because of the convergent petagium, so could you please post a link to your source?

Thank you David. How embarassing, you’re right the flying lemurs are dermoptera. I should have remembered that, as I took mammology just a few weeks ago 😳 .
Flying lemurs are interesting, as are sugar gliders and flying squirrels. But do they really show a transitional morphology? What would it take to evolve from a glider to a flyer? The fact that there are several extant species of gliders, across several orders, but only one extant order of flying mammals, indicates to me that that transition is very difficult, rare, and imporobable.
Anyhow, the fossil record is still sadly lacking in transitional fossils for the evolution of flight. Archaeopteryx is the closest one that I know of, and it didn’t fly.
I think it’s really interesting that flight evolved independently in pterodactyls and was lost to their lineage when they went extinct. For me that kind of puts flight into perspective, as a biological characteristic rather than a fanciful idea. Flight was around long before birds or bats evolved, and WAY before humans. I think humans have a very romanticized view of flight (at least I do) and as a result, may look at the evolution of flight through that same lense.
I think that the lack of transitional fossils is an indication that the evolution from non-flying to flying occured very rapidly (relatively). I’ve heard of studies that supposedly showed that the alteration of one gene could account for the transition in petagium structure to allow flight, but I don’t really buy that. If that were the case, we’d have multiple extant lineages of flying mammals.

Just out of curiosity, does anyone know anything about the evolution of flight in insects? They were the first lifeforms to evolve flight, weren’t they? There’s also countless insect lineages to study, though I’m not sure how common enough insect fossils are to make serious investigation worthwhile.

Thank you for the reply about bats David. Interesting. Are you trying to say that higher primates evolved from Tarsiers?

I didnt get this about Plecoptera and insect flight. Can you explain it little more. Are you saying that they evolved flight under water and that wings derived from legs?

I have read about several theories. The one I was refering to when said that wings are derived from leg is "leg exsite theory". It also looks probable to me. But haven`t Plecoptera appeared later, after the Odonatas and Ephemeroptera? So we should be looking for first wing insects among them, I think Ephemeroptera ancestors.

Sorry if i am butting into the discussion, i just wondered, aren’t most modern animals related if you follow their ancestory back far enough? It’s just a thought. For example, taking the echidna idea: Echidna and porcupines are both mammals, so if you followe their ancestory back far enough then might they have a comman ancestor?