I saw this on bsky a few days ago and was fascinated, so glad to see it made its way here! I had this question that went unanswered, so hopefully there's some experts/fellow musers here:
Why grow up if you don't need photosynthesis?
From my perusal of The Literature (AKA an amazing Wikipedia article + the paper discussed in this link), we have a few strong theories about the prototaxites:
1. They fed off decaying matter in the soil through a vast network of mycelia/roots, and didn't photosynthesize.
2. They grew large, trunk-like protrusions, but without any branches or leaves (that were fossilized, at least). Like, way, way taller than the bugs, moss, and short weird proto-grass around at the time.
3. These protrusions were regularly burrowed into by aforementioned bugs, which surely was a major health risk.
4. Even before this analysis, they've always been something of an oddball compared to contemporary life -- so everything's on the table, so to speak.
Given those facts, I'm pretty stumped as to what evolutionary pressures might have driven them to grow upwards. At first I considered spore (seed?) dispersal, but mushrooms seem to get along just fine without towering above everything else, and I don't think wind speeds were way lower or anything. Anyone here have any better guesses?
Why grow up if you don't need photosynthesis?
From my perusal of The Literature (AKA an amazing Wikipedia article + the paper discussed in this link), we have a few strong theories about the prototaxites:
1. They fed off decaying matter in the soil through a vast network of mycelia/roots, and didn't photosynthesize.
2. They grew large, trunk-like protrusions, but without any branches or leaves (that were fossilized, at least). Like, way, way taller than the bugs, moss, and short weird proto-grass around at the time.
3. These protrusions were regularly burrowed into by aforementioned bugs, which surely was a major health risk.
4. Even before this analysis, they've always been something of an oddball compared to contemporary life -- so everything's on the table, so to speak.
Given those facts, I'm pretty stumped as to what evolutionary pressures might have driven them to grow upwards. At first I considered spore (seed?) dispersal, but mushrooms seem to get along just fine without towering above everything else, and I don't think wind speeds were way lower or anything. Anyone here have any better guesses?