Prototaxites: the giant fungus-tree that wasn't?

[Halichoeres]

Prototaxites, whose name means something like "first yew," was originally thought to be an ancient conifer, but it's now pretty clear it was a fungus. It was possibly the largest lifeform of the Devonian, and its huge mycelia have been interpreted as being trunk-like columns for tree-sized fruiting bodies, perhaps with algal symbionts on the surface. A new paper concludes that it makes just as much sense horizontal as vertical, and may have been instead a great creeping fungal mass living at the soil-air interface. I imagine there will be a debate in the literature about this for a while.

Here's an illustration of a proposed growth habit for Prototaxites (uncredited, so presumably the work of one or more of the authors):


The paper is open access in the Canadian Journal of Microbiology: https://cdnsciencepub.com/doi/full/10.1139/cjm-2021-0358

[Newt]

It has also been accused of being a liverwort mat, rolled up like a bryophyte roulade by wind or water.

The paper is interesting, but it does not address just why a fungus would need meter-thick horizontal rhizomorphs; it's an awful lot of trouble to grow such a massive structure with little apparent benefit over a typical distributed network of relatively fine rhizomorphs, or a more laminar sheet of hyphae on or under the soil surface. The traditional hypothesis (also not addressed) that the massive "trunks" of Prototaxites gave it enough vertical height to greatly boost spore dispersal distance is at least a plausible reason for the tremendous investment of resources.

[Stuckasaurus (Dino Dad Reviews)]

I commented on Tom Holtz's feed when he shared this by saying "I guess my old meme is now inaccurate.."


(Original art by Hannah Bonner)

To which Fabio Alejandro replied with this edited version:

[Stuckasaurus (Dino Dad Reviews)]

"Prototaxites vented!"

[Faelrin]

I'm curious to see where this will go. Not favoring one interpretation or the other, because of my ignorance on the matter, but I do think the earlier one had this otherworldly charm to it, and is certainly more prevalent. But well I suppose there's always the giant termite mounds of today for similar vibes. I hope they can figure it out, and maybe find more specimens of this giant fungus someday.

@Stuckasaurus (Dino Dad Reviews) Never thought I'd see an Among Us meme with Prototaxites but here we are, lol. Glad I dabbled with it for a little bit to at least get your reference (in both posts).

[GojiraGuy1954]

cant believe the amogus virus has breached the DTF

[Stegotyranno420]

cant believe the amogus virus has breached the DTF

"Nothing gold can stay"-Robert Frost

[Stuckasaurus (Dino Dad Reviews)]

cant believe the amogus virus has breached the DTF

"Nothing gold can stay"-Robert Frost

There is an amogus meme among us...

[Halichoeres]

.

The paper is interesting, but it does not address just why a fungus would need meter-thick horizontal rhizomorphs; it's an awful lot of trouble to grow such a massive structure with little apparent benefit over a typical distributed network of relatively fine rhizomorphs, or a more laminar sheet of hyphae on or under the soil surface. The traditional hypothesis (also not addressed) that the massive "trunks" of Prototaxites gave it enough vertical height to greatly boost spore dispersal distance is at least a plausible reason for the tremendous investment of resources.

I don't know enough mycology to judge the strength of this hypothesis, but it does seem odd to have all that girth horizontal. I guess that would reduce its surface area relative to its volume, which could reduce desiccation risk?