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Humans evolved from animals that can glide

Discussion of everything related to the Theory of Evolution.

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Postby AstusAleator » Mon Mar 06, 2006 7:30 pm

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 :oops: .
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.
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Postby alextemplet » Mon Mar 06, 2006 11:28 pm

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.
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Postby David George » Tue Mar 07, 2006 5:32 am

Astus as I told you before bats evolved from genus Purgatorius at about 65 million years.After few million years in the Paleocene epoch Plesiadapiformes evolved. This genus is the ancestor of the rodents along their side the flying lemurs evolved[They had their own genus].The bats evolved a patagium not to glide but to fly in the earlier times to provide lift.The first formed bats were the megabats which donot use echolocation to find food.They evolved larger wings to fly and for balance.Genus Petrolemuridae evolved during the paleocene epoch but only after the evolution of flying lemurs.This genus consists of animals resembling lemurs.It divided into genus Adapidae and genus Omomyidae.Adapidae consists of lemurs and lorises while omomyidae consists of tarsiers only here the cranial size of primates started to rapidly evolve.Any further doubts Please ask.

Alex my Friend there are lot of theories for the evolution of flight of Insects the order Plecoptera has many members that tell us about the evolution of flight in insects.The first formed members of this genus were only insects dwelling in water they started to move faster in water and at one point they started to skim in the water with only four legs then with two legs gradually developing flight as they found water provide more resistance than air.
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Postby Beetle » Wed Mar 08, 2006 10:39 am

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?
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Postby David George » Thu Mar 09, 2006 6:30 am

Yes Beetle higher primates evolved from tarsiers but not lorises and lemurs.Plecoptera have the ability to skim on water.Modern stoneflies walk on the surface of water, and raise their rudimentary wings if they feel a puff of air. They then get propelled across the water by the breeze .The ancestors of stone flies didnot have wings they skimmed on water with the whole body.Later they skimmed on water with four legs then with two legs by this time they could fly for short distances if there was a breeze eventually evolving to fly.The wings themselves are by many thought to be highly modified (tracheal) gills. And there is no doubt that the tracheal gills of the mayfly nymph in many species looks like wings.Wings were not derived fron legs.
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Postby Beetle » Thu Mar 09, 2006 10:38 am

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.
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Postby David George » Fri Mar 10, 2006 7:11 am

Great news Beetle I forgot about the evolution about insects.Did you know Plecoptera,Odonatas,Ephemeroptera[Mayflies] all belong to a mainly aquatic taxa.And ephemeropterais supposed to be the first evolved flying insect order.The first stage of the life of a mayfly is the nymph (larva), which not only looks very different from the adult, but lives in the water. When the nymphs hatch from the eggs, they are less than 1 mm long. They have no gills at first, and their body shape varies according to habitat.In older nymphs, gills are found in pairs on each segment of the abdomen (see pictures below). The gills extend from the sides of the body and are oval-shaped. These gills beat to control the flow of water through the body, which also controls the amount of oxygen and salt that flows through the body. Nymphs in still waters generally have larger gills, and those in running water have smaller gills; this allows the nymphs of each habitat to get their optimum flow of water. Not only do the gills function in uptake of water, salt, and oxygen, but they also send water off at right angles to the body. This is used to mislead predators. If the water simply flowed out the back of the nymph's body, predators would know that the nymph was sitting at the beginning of the stream.This is where the gills evolved to wings remember may flies nymphs need water.Hope that is good enough.
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Postby Georgie » Fri Mar 24, 2006 8:31 am

AstusAleator wrote: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.


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?
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Postby David George » Fri Mar 24, 2006 12:30 pm

Offcourse you are right Georgie but we were telling about the closest relative.
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