A world without flying animals is possible

Possible cause of a world without flying animals

The following extends what you mean by "earth-like" to the edge of our world, but might be doable.

We know that some birds - penguins - became flightless in order to better swim and eat fish near Antarctica. It is plausible that an ice planet, most of whose behavior takes place in the oceans, punishes flying beasts too severely in proportion to the amount of extra food they can receive. The only organisms that survive outside the ocean are those that live in burrows and hunt in the ocean, which makes flying terribly inefficient.

The magnetic field is weaker, the planet is heavier and drier, and the sun may be bigger and bluer, and we're a little further out to make up for this. This is a very speculative way of tweaking many different parameters a bit to get a similar but very different earth.

The idea is that the candidate atmosphere has a much weaker ozone layer and is more transparent to cancer-causing light - UV, X, and gamma rays all have photon energies that can break typical chemical bonds. However, there is a chance that this is mediated near the oceans and the surface of the planet, as the surface is warmed up a little more than the Earth normally does (which requires a little more gravity), which makes the air currents much stronger and storms over the Planets are raging.

The idea is that the "on the ground" experience is one of a perpetual smoggy haze mixed between fog and dust, obscuring something from direct sunlight; The hope is that this will provide protection from the cancer-causing radiation near the planet's surface. There would still be protected places - caves, ravines - where escape developed, but it would no longer be a global phenomenon.

So this idea is to hit the birds and insects with a triple or quadruple strike: yes, you can hypothetically fly, but (a) you are more likely to get cancer and (b) you will not be able to see your prey and (c ) You need to hide yourself anyway when the daily hurricane blows, and (d) your bones need to be even lighter and more frail to withstand the extra gravity.

In response, this is flying per se maybe no longer a common design goal, but maybe sliding is more common. One can imagine membranes like sugar gliders, or one can imagine lighter insects throwing a "kite" out of spider silk and "sailing" to distant places like spores and the like.


As much as I appreciate every other answer, I think this best fits what I was looking for ... Also, how could I not reward "Penguin Planet" !?