>>16921889
The exact "how" of flight evolution will likely always be a mystery. It evolved independently multiple times so it could be a different pathway each time. One famous demonstration by Richard Dawkins showed that even tiny outward projections acting as a source of drag could reduce injury from falling from trees immensely.

>why don't kangaroos have wings?
They never developed them. There's nothing saying the same adaptations must arise from similar behaviors.

they are also very heavy, not many birds weight as much as a kangaroo

File: evolution.jpg (258.9 KB)

258.9 KB JPG

>>16921889
this handy dandy flow chart explains evolution.

>>16921889
So many misconceptions in one post. First off evolution doesn't work by doing something and then evolving it. There needs to be selective pressure and for something as significant as heavier-than air flight, that pressure needs to be there for a long time. So it will go from lighter mass to gliding then flying over many generations. Also heavier-than air flight evolved multiple times independently so it must be naturally beneficial to have. And you need the right skeleton and body structure, so a species like kangaroo can never have wings. In fact when man made heavier-than air flight was researched in the 1800s we used a lot of the design and biology from birds.

IMO The strange thing is that no creature ever evolved lighter-than air flight, despite being much more simpler than heavier-than air flight. Kind of like in real life history where it took until the Montgolfier Brothers in the French Revolution to invent hot air balloons when Ancient Civilizations could easily make a vehicle like that thousands of years earlier.

File: flight.jpg (125 KB)

125 KB JPG

>>16921889
>I read that some animals used to run and jump a lot and because of all the jumping they evolved wings and started flying
That’s a really old idea that nobody really takes seriously nowadays. Early feathered wings in flightless dinosaurs would’ve been used to create downforce rather than lift while flapping to help them climb steep surfaces as well as slow their descent while jumping to the ground. We know that’s the most likely case because modern birds still do it

>>16921889
It's not jumping as a means of travel that leads to wings, it's jumping for predation, safe landing from trees, climbing and other maneuvering or escaping from predators that does.