[HN Gopher] Prototaxites
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Prototaxites
Author : andsoitis
Score : 66 points
Date : 2025-12-20 00:22 UTC (5 days ago)
(HTM) web link (astrobiology.com)
(TXT) w3m dump (astrobiology.com)
| thatoneengineer wrote:
| https://en.wikipedia.org/wiki/Prototaxites has more context. Tree
| sized and shaped living thing that wasn't a plant, which probably
| fed and reproduced like a fungus but per this latest research
| wasn't a fungus either, by far the largest known organism on land
| up to that point, in a time when land animals barely existed.
| Unsettling!
| admissionsguy wrote:
| So is it the kind of thing that Voynich manuscript describes?
| simonh wrote:
| Well, that and lots of naked ladies having baths.
| jibal wrote:
| No.
| funerr wrote:
| ChatGPT summary:
|
| Prototaxites was a massive, trunk-like organism (up to ~8m tall,
| ~1m wide) that dominated land ~420-370 million years ago, long
| before trees or complex plants existed. It looked like a tree,
| but chemical evidence suggests it didn't photosynthesize.
| Internally it was made of interwoven microscopic tubes, unlike
| plant tissue. It's often described as a giant fungus, but it
| doesn't cleanly match modern fungi either, and some researchers
| think it may represent an entirely extinct branch of eukaryotic
| life. In other words, early "forests" may have been dominated by
| something we don't have a modern analog for.
| Gravityloss wrote:
| If no photosynthesis, where did it get energy? Modern fungi
| feed on plant remains.
| adrian_b wrote:
| That is a very good question.
|
| Plants grow tall to be able to gather light, instead of
| staying in a shadow.
|
| Fungi and many other terrestrial organisms that reproduce
| like fungi (e.g. slime molds and myxobacteria) grow above the
| ground only in order to be able to launch their spores into
| the wind.
|
| It does not seem possible to explain the size of Prototaxites
| by the need of launching spores in the wind.
|
| The only plausible explanation is that it was tall in order
| to ensure access to light.
|
| If it was not a plant, it might have had a symbiotic
| relationship with a phototrophic living being, which grew on
| the surface of Prototaxites, i.e. either a blue-green alga
| (Cyanobacteria) or a green alga, exactly like the present
| lichens. Prototaxites could have provided access to light,
| water and minerals, while the alga would have provided food.
| throw310822 wrote:
| > The only plausible explanation is that it was tall in
| order to ensure access to light.
|
| Thought the same, but that implies both that it grew in
| very dense "forests" (mono-species because there were no
| competitors) and probably that it had leaves (because
| otherwise trunks don't occlude much light).
|
| Although, counterexample: why do (some) cactuses grow tall?
| Claude provides these explanations that might apply:
|
| Water collection and storage -- Height means more volume
| for water storage. A large saguaro can hold thousands of
| liters of water in its stem, which is crucial for surviving
| long droughts.
|
| Temperature regulation -- Being taller gets the growing tip
| and flowers farther from the scorching ground surface,
| where temperatures can be extreme. The ground in deserts
| can reach 70degC (160degF), while air temperature a few
| meters up is significantly cooler.
| adrian_b wrote:
| The 2 explanations given for cactuses seem non-applicable
| to Prototaxites, as the fossils appear to have formed in
| some swamps with abundant water.
|
| According to the linked paper, the structure of the stem
| of Prototaxites contained several kinds of tubes, which
| might have formed some kind of simple vascular system,
| able to extract the water from the soil and circulate it
| through the body.
|
| You are right however that the plants among which
| Prototaxites was growing had a much smaller height so the
| competition with them would not have been a strong reason
| for its height and for the competition between
| Prototaxites individuals there is no evidence that they
| would occlude much light.
|
| Still, I am not aware of any better explanation for its
| height. At that time there were no flying insects. The
| terrestrial vertebrates and bigger arthropods were
| predatory. There were a few groups of non-predatory
| arthropods, i.e. millipedes, mites and springtails, some
| of which might have been able to feed on Prototaxites
| tissues, but such small arthropods are likely to have
| been able to easily climb its stem, so it seems unlikely
| that its height could have provided any protection for
| its reproductive parts.
|
| Besides avoiding shadows, there is another explanation
| for the great height, but that is also applicable only to
| organisms able to capture solar light. As there is
| evidence in its isotopic composition that Prototaxites
| was not phototrophic, any explanation based on capturing
| light must involve a symbiotic alga. A great height could
| have helped with the ascent of water through the stem of
| Prototaxites, due to capillarity and evaporation at its
| top. However this explanation requires for the pumped
| water to be useful somewhere high in the stem, which
| would be the case if the water were given to a symbiotic
| alga, which would provide food in return.
| binary132 wrote:
| "Peter Griffin here to explain the article!"
| hresvelgr wrote:
| ChatGPT copypasta isn't helpful, or interesting. If I wanted a
| ChatGPT explanation, I would have gone to ChatGPT.
| oofbey wrote:
| Is this distinct as in it branched super early from other earth
| life and died out? Or distinct as in maybe came from another
| planet and is completely distinct? Can we tell? The journal is
| astrobiology.
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