Alright, so let's see what we have. Here's my response to the first thought about birds.
Regarding the question of bird bones potentially not fossilizing, I should just start by saying that I believe anything is possible. God can truly do anything. But on the question specifically, I think it is very unlikely to find Paleozoic bird fossils. As in, more unlikely than both of us winning the lottery or getting struck by lightening.
I say that for a few reasons. Consider that fossils have been being uncovered by tens or hundreds of thousands of people over the past 200 to 300 years, all around the world. We might expect that such a thing had been found by now.
The second reason being that, at this stage in the game, we are pretty confident in our succession. At some point in time, people just have to come to terms with what exists. And I know it's challenging for people to accept, but it just is what it is. This succession of fossils is confirmed and re affirmed pretty much every day by paleontologists worldwide who continue to dig up fossils, including myself.
And the thing that is also good to know, is that you, as an individual, can confirm or deny the fossil record in your own back yard. As long as you have a hammer from a toolbox, a geologic map (which can easily be found through google or cool geology apps like "rockd", and maybe some safety glasses, you have the power in your own hands to go out to any rock outcrop that is anywhere around you, and you can look at it with your own eyes if you do not believe. If you don't believe, look for yourself.
And on the question of hollow bone fossilization, laagerstaaten have been found as far back as the Cambrian and the ediacaran (some 2-3 times older than birds), laagerstaaten being preservation of structures of soft bodied organisms. Basically the permineralizatiom of soft bodied animals. So there isn't any logical reason to believe that bird bones might not be able to be preserved, as softer structures much older have been preserved (or permineralized) on numerous occasions.
But also, back on the succession, we have theropod dinosaurs that honestly look a lot like birds. Some dinosaurs were literally indistinguishable from birds in a lay practical sense. Protoavis, archaeopteryx, confuciusornis etc. These are theropod/bird hybrids.
Archaeopteryx for example...going in:
Somewhere around 170–140 million years ago, bird-like theropods and theropod-like birds appear in the fossil record, and somewhat prior to that going back some 200 million years ago, bird-like traits appear in reptiles in the fossil succession.
Cladistically, birds are descended from reptiles and this evolution unfolded sometime between the Triassic to Jurassic periods of the mesozoic.
Some young earthers attempt to critique the idea that birds evolved from reptiles by citing research from scientists arguing in favor of birds not descending from dinosaurs. However, suggesting that birds did not evolve from dinosaurs, is not equivelant to suggesting that birds did not evolve from mesozoic reptiles (which all paleontologists agree on). Typically in these cases, the research cited by young earthers is simply suggesting that birds descended from other dinosaur-like reptiles, but not dinosaurs themselves.
To add to the above, note the below figure:
Late theropod dinosaurs of course are feathered. Birds have genes for sharp teeth and are on rare occasions born with them.
Surprise: Chickens Can Grow Teeth
They possess similar morphological traits, such as the direction and lenghts of the bones of their hands and feet.
Notice archaeopteryx has lenghtened forelimbs like a birds wings. The pubis transitions from front to back, then in archaeopteryx the first toe is on the back of the foot, much like a bird. And theropod dinosaurs that are derived and look much like birds have feathers and scales. Yet, archaeopteryx still has a long bony tail, much like the theropod on the left.
So, ultimately, what we see in the fossil record is the initial appearance of reptiles some 300 million years ago, but somewhere around the middle of the mesozoic, reptiles become more and more bird like. Until ultimately it becomes challenging to differentiate between birds and dinosaurs. The closer we look at the fossil record with more and more precision, the more blurred the lines become between one type of animal and another.
So the point of the above tirade is just to point out that, not only could Paleozoic bird fossils hypothetically be preserved if they lived at earlier times, but we are confident in the succession and know why they don't exist. And we have had 2-300 years to find such and haven't and all others are also welcome to look for themselves if they don't believe.
And I would recommend review of the geologic column if any of the terms aren't making sense.
