Giant, fungus-like organism may be a completely unknown branch of life

https://www.livescience.com/animals/giant-fungus-like-organism-may-be-a-completely-unknown-branch-of-life

by wglb • 1 year ago

312 129 1 year ago

Prototaxites, an ancient treetrunk-mushroom-like organism that preceded land plants about 400M yr ago. Its fossils contained plantlike lignin instead of funguslike chitin or chitosan.

https://www.biorxiv.org/content/10.1101/2025.03.14.643340v1

https://en.wikipedia.org/wiki/Prototaxites

Liquix• 1 year ago

hilarious:

John William Dawson, a Canadian scientist, studied Prototaxites fossils, which he described as partially rotten giant conifers, containing the remains of the fungi which had been decomposing them. This concept was not disputed until 1872, when the rival scientist William Carruthers poured ridicule on the idea. ... Dawson fought adamantly to defend his original interpretation until studies of the microstructure made it clear that his position was untenable, whence he promptly attempted to rename the genus himself, calling it Nematophyton ("stringy plant"), and denying with great vehemence that he had ever considered it to be a tree.

qbxk• 1 year ago

Prototaxites did not contain chitin, a major building block of fungal cell walls and a hallmark of the fungal kingdom. The Prototaxites fossils instead appeared to contain chemicals similar to lignin, which is found in the wood and bark of plants. ... best considered a member of a previously undescribed, entirely extinct group of eukaryotes

So these are the ancestors of Groot? or Ents? and all manner of "animated trees"?

sshine• 1 year ago

Protogroots

a3w• 1 year ago

Protomolecule.

Allows for Protozombies [as seen on TV]?

guerrilla• 1 year ago

I am Groot. I am Groot? I am Groot.

N_A_T_E• 1 year ago

Pretty sure this was a major plot point of the latest resident evil game.

andrewstuart• 1 year ago

There’s one of them at the back of my fridge.

mfdoom13• 1 year ago

Common Side Effects, here we come.

chasil• 1 year ago

I'm still trying to wrap my head around nitroplasts, another newfound plastid.

deadbabe• 1 year ago

Is there a point in Earth’s history where if you were to visit you’d find it was just a fungus planet, with no other form of life? Could there have been fungal type creatures that lived, died, and left no trace?

doctoboggan• 1 year ago

No, non-fungi single celled organisms have existed at all times that fungi have existed on earth.

adrian_b3• 1 year ago

Blue-green algae have colonized fresh water and all moist spaces on the continents billions of years before the appearance of fungi and of the terrestrial green plants. They were accompanied by the ancestors of several groups of heterotrophic bacteria, e.g. Firmicutes and Actinobacteria (the Gram-positive bacteria), which had developed abilities like making spores that could survive dryness and be spread by wind, like also fungi would do later.

In fact, it is likely that blue-green algae have appeared for the first time on continents, either in fresh water or moist rocks, and only much later they have spread into marine environments, which had been previously dominated by anoxygenic phototrophic bacteria, which were oxidizing sulfur, iron or manganese, not water. The transition to oxidizing water is likely to have been necessary for the spreading of the blue-green algae on continents, where the fresh water had only a very small content of substances that could be oxidized unlike seawater, which at that time was rich in hydrogen sulfide and in Fe(II) and Mn(II) ions. When the blue-green algae have expanded back into the oceans, that must have been after the oxygenation of the atmosphere has modified the composition of the oceans, by precipitating most of the iron and manganese and oxidizing sulfide to sulfate, which would have deprived the anoxygenic phototrophic bacteria of their food.

Then, in the oceans, at some point in time a blue-green alga has become symbiotic with the ancestor of red algae and green algae, which have then dominated for many hundred million years the oceans, before the much later appearance of other phototrophic groups, like diatoms and brown algae. Multicellular red algae and green algae already existed in the oceans around one billion years ago, when no other multicellular eukaryotes existed.

When the fungi have appeared through a transition to a terrestrial lifestyle, that could happen only if on land they could find great amounts of dead living matter, which had been produced by blue-green algae. It is not known for sure whether fungi have appeared a long time before the first terrestrial green plants or about the same time, but it seems that already for the most ancient terrestrial green plants, symbioses with fungi that enhanced the absorptive capabilities of their roots have been important. For aquatic plants, roots had only a fixation function, not the function of absorbing nutrients, so perhaps symbiosis with some already existing terrestrial fungi might have been necessary, not optional, for the first terrestrial green plants, until better absorbing roots have evolved.

So for a long time in the history of the planet, the drier parts of the land would be barren, but wherever there was moisture you would find mats or crusts of blue-green algae, with associated heterotrophic bacteria and viruses.

Then, probably not earlier than the Cambrian, there would be also fungi, and even later the first moss-like terrestrial green plants would appear.

calibas3• 1 year ago

with eukarya containing all multicellular organisms within the four kingdoms of fungi, animals, plants and protists.

This bugs me so much. The four-kingdom system should have died out decades ago, it's absurdly wrong. For one thing, fungi and animals should be together (opisthokonts) if you're dividing eukaryotes into the major groups. If you consider genetics, there's no such thing as "protists", they're just a whole bunch of small things that were grouped together because we didn't know otherwise.

It's more like, Archaeplastida, Excavata, SAR supergroup, Amoebozoa, and Opisthokonta at the moment. The exact list is up for debate, and currently undergoing change. There's plenty of weird things like Hemimastigophora and we're not really sure where they fit yet.

mmooss8• 1 year ago

The exact list is up for debate, and currently undergoing change.

My strong impression is that even the roots of the tree are debated, with competing models that often change.

The four-kingdom system should have died out decades ago

First, hopefully not! :) Second, I think it's used because it's the last stable model. Third, it's a model that the public can understand - theres no point in even trying to use "Archaeplastida, Excavata, SAR supergroup, Amoebozoa, and Opisthokonta" unless you are an expert in phylogenics or evolution. Who can understand and remember that?

calibas3• 1 year ago

Children can memorize all 50 US state capitals, they can memorize a handful of scientific names. If we really wanted to, we could teach them a much more accurate view of the tree of life. Also, I don't think the four-kingdom system has been taught in schools for a while? I went to high school in the late 90s and it wasn't taught then.

It's strange to see people promoting it online in 2025. If adults want to remain ignorant, so be it, but at least teach children the truth. Let them know that life is incredibly complicated, it's a mystery we're still solving, and they could be the ones to help figure it out. Don't overly simplify things for small minds, it creates a false picture and it kills the imagination.

mjan22640• 1 year ago

Who can understand and remember that?

Anybody who is interested in it

f1shy• 1 year ago

At which point started to be important in science that “public can understand”? I think if something is a better explanation for the reality, we ahould go for it, even if it is difficult for the public.

Disclaimer: in this case I have absolutely no idea what is better. But the rationale seems wrong.

idiotsecant• 1 year ago

Yes I agree. 4 humors were enough for medieval europe, they're good enough for me!! Who can remember all this complicated 'germ theory of disease' liberal junk?! There must be hundreds of these supposed 'germs' out there! No sir, no thank you!

dreamcompiler2• 1 year ago

And then there are viruses, which don't show up on the tree of life at all because there's no consensus that they even constitute "life."

Ultimatt2• 1 year ago

Pretty sure anyone who knows anything about viruses would say they are alive. Or at least as alive as parasitic nano archaea with genomes smaller than the viruses living right next to them... The philosophical way to look at it is humans aren't alive in the space between planets they live inside these little hard shells, then when they get to a planet they go wild using all the other resources around them made of biomass. Viruses are just this, their biome isn't the wider one you participate in instead they are sub-cellular life, in the same way you are sub-planetary life. Humans don't make the oxygen atmosphere on the planet themselves, they parasitize this feature of planets from other life. In the same way viruses use cellular machinery.

GioM• 1 year ago

I feel like what trips people up is the abstraction layer.

Viruses are abstracted on top of other living things in the same way that animals are abstracted on top of plants, in that they both require the lower layer of abstraction for their basic survival.

renewiltord• 1 year ago

One of the great wonders of clustering algorithms is that no matter what k > n you choose, you can construct k clusters. Then we can argue about the clusters and about k. It is said that when Humanity discovers the One True K, the taxonomy will disappear and be replaced by a different one.

boxed2• 1 year ago

From what I've gathered it's been pretty clear for a while now that archea is basal to eucarya, meaning humans are archea.

adrian_b3• 1 year ago

When classifying living beings, a single classification criterion is not good enough.

One classification criterion is descendance from a common ancestor, i.e. cladistic classification.

In many cases this is the most useful classification criterion, because the living beings grouped in a class defined by having a common ancestor share a lot of characteristics inherited from their common ancestor, so when using a name that is applied to that class of living beings, the name provides a lot of information about any member.

However there are at least 2 reasons which complicate such a cladistic classification.

One is that the graph of the evolution of living beings is not strictly a tree, because there are hybridization events that merge branches.

Sometimes the branches that are merged are closely related, e.g. between different species of felids, so they do not change the overall aspect of the tree. However there are also merges between extremely distant branches, like the symbiosis event between some blue-green alga (Cyanobacteria) and some unicellular eukaryote, which has created the ancestors of all eukaryotes that are oxygenic phototrophs, including the green plants.

Moreover, there have been additional symbiosis events that have merged additional eukaryote branches and which have created the ancestors of other eukaryote phototrophs, e.g. the ancestor of brown algae.

After any such hybridization event, there is the question how you should classify the descendants of the hybrid ancestor, as belonging to one branch or to the other branch that have been merged.

For some purposes it is more useful to classify all eukaryote phototrophs based on the branch that has provided the main nucleus of the hybrid cell, and this is the most frequently used classification.

For other purposes it is more useful to group together all the living beings that are oxygenic phototrophs, including various kinds of eukaryotes and also the blue-green algae, and divide them based on the evolution tree of their light-capturing organelles, i.e. the chloroplasts.

This is also a valid cladistic classification, because all oxygenic phototrophs, both eukaryotes and prokaryotes, are the descendants of a single common ancestor, some ancient phototrophic bacteria that has switched from oxidizing manganese using light energy, to oxidizing water, which releases free dioxygen.

Even when there are no branch merges due to hybridization, there remains the problem that in the set of descendants from a single ancestor there are some that are conservative, so they still resemble a lot with their ancestor, and some that are progressive, which may have changed a lot, so they no longer resemble with their ancestor.

In this case, using the name of the entire group provides very little information, because most characteristics that were valid for the ancestor may be completely inapplicable to the subgroups that have become different. In such a case, defining and using a name for the paraphiletic set of subgroups that remains after excluding the subgroups that have evolved divergently may be more useful in practice than using only names based on a cladistic classification. For instance the use of the word "fish" with its traditional paraphiletic meaning, i.e. "vertebrate that is not a tetrapod", is very useful and including tetrapods in "fishes" is stupid, because that would make "fish" and "vertebrate" synonymous and it would require the frequent use of the expression "fishes that are not tetrapods", whenever something is said that is correct only for vertebrates that are not tetrapods, or of the expression "bony fishes that are not tetrapods", for things valid for bony fishes, but not for tetrapods.

While in many contexts it is very useful to know that both fungi and animals are opisthokonts, and there are a few facts that apply to all opisthokonts, regardless whether they are fungi, animals or other opisthokonts more closely related to fungi or more closely related to animals, the number of cases when it is much more important to distinguish fungi from animals is much greater than the number of cases when their common ancestry is relevant.

Animals are multicellular eukaryotes that have retained the primitive lifestyle of the eukaryotes, i.e. feeding by ingesting other living beings, which is made possible by cell motility.

Fungi are multicellular eukaryotes that have abandoned the primitive lifestyle of the eukaryotes, and which have reverted to a lifestyle similar to that of heterotrophic bacteria, just with a different topology of the interface between cells and environment (i.e. with a branched multicellular mycelium instead of multiple small separate cells).

This change in lifestyle has been caused by the transition to a terrestrial life, which has been accomplished with a thick cell wall (of chitin) for avoiding dehydration, which has suppressed cell motility, making impossible the ingestion of other living beings, the same as for bacteria. Moreover the transition to a bacterial lifestyle has also been enabled by several lateral gene transfers from some bacteria, which have provided some additional metabolic pathways that enable fungi to survive when feeding with simpler substances than required by most eukaryotes, including animals.

So even from a cladistic point of view, fungi have some additional bacterial ancestors for their DNA, besides the common opisthokont ancestor that they share with the animals.

Animals are unique among eukaryotes, because all other multicellular eukaryotes have abandoned the primitive lifestyle of eukaryotes, by taking the lifestyles of either heterotrophic or phototrophic bacteria. However for both other kinds of lifestyle changes there are multiple examples, i.e. besides true fungi that are opisthokonts there are several other groups of fungous eukaryotes that are not opisthokonts, the best known being the Oomycetes. There are also bacteria with fungal lifestyle and topology, e.g. actinomycetes a.k.a. Actinobacteria.

If we will ever explore other planets with life, those living beings will not have a common ancestor with the living beings from our planet, but nevertheless it will still be possible to classify them based on their lifestyle in about a half of dozen groups that would be analogous to animals (multicellular living beings that feed by ingestion, so they must be mobile or they must have at least some mobile parts), fungi (multicellular beings that grow into their food, absorbing it after external digestion), oxygenic phototrophs, anoxygenic phototrophs, chemoautotrophs, unicellular equivalents of animals and fungi, like protozoa and heterotrophic bacteria, viruses.

These differences in lifestyles are more important in most contexts than the descendance from a common ancestor.

So while it is useful to have the name Opisthokonta for the contexts where fungi and animals and their close relatives must be included, it is much more frequent to need to speak separately about fungi and other fungous organisms on one hand, and animals on the other hand.

I agree that the term "kingdom" is obsolete when used in the context of a cladistic classification of the living beings.

Perhaps it should be retained for a non-cladistic classification of the living beings, based on the few fundamental lifestyles that are possible, and which would remain valid even for extraterrestrial living beings.

danmur• 1 year ago

Glad to see diamond inheritance being a problem in other fields

Ultimatt2• 1 year ago

I dunno you can mostly solve for this, look at the majority share of the genome in a compartment with a single membrane contained by the outer membrane (by definition for endosymbiogenesis), with the DNA molecules containing the highest quantity of coding gene content. That's the thing you do the cladistic descent on. Just because I'm carrying a load of bacterial symbionts that are better at digesting wheat doesn't make me a different species to humans who mostly eat rice. That I eventually carry those as an endosymbiont then eventually just a sack of genes doesn't really change who' was the boss in this situation, or who I'm able to reproduce with that entire time as a species either. Symbiogenesis is very much like this, look at Hatena arenicola if you want to see this emerging to see how it interacts with descent. This is really the difference between understanding reproductive relationships specifically, vs wider ecology. I agree that symbiogenesis is like this weird one where its both only going to happen through other ecological relationships and then reproduction. But there really is a clear cut time one turns into the other, with the fate of one of those organisms of the combination "winning" even though profoundly altered. Symbiodinium is probably another good example, it has loads of ecological partners and little remnants of all of those histories in its genetic material and organelle arrangement. But its still an obvious species, with all the other oddball dinoflagellates that act and look like it also appearing to have some common descent from something much simpler and eukaryotic.

As a programmer symbiogenesis is a mixin or interface not a class.

someone7x• 1 year ago

As an unscientific layperson this was a riveting analysis, thanks for interesting reading.

mmooss8• 1 year ago

All life on Earth is classified within three domains — bacteria, archaea and eukarya — with eukarya containing all multicellular organisms

Single cell eukaryotes also exist. Is it strictly true that there are no multicellular prokaryotes (what they call bacteria) or archaea? No exceptions at all?

dragonwriter• 1 year ago

Single cell eukaryotes also exist.

Yes, "with eukarya containing all multicellular organisms" does not mean "all eukarya are multicellular organisms" it means "multicellular organisms are a subset of eukarya".

Is it strictly true that there are no multicellular prokaryotes (what they call bacteria) or archaea?

First off, "prokaryotes (what they call bacteria)" is incorrect. Both archaea and bacteria, in the three-domain model referenced in the article, are prokaryotes.

Second, correct, everything understood as a multicellular organism -- as distinct from colonies of unicellular organisms -- is composed of cells with nuclei, classified in eukarya in the three-domain model.

(There is a newer proposed two-domain model which disposes with Eukarya as a top-level domain, folding it under Archaea; in that model, clearly, there are multicellular Archaea.)

mmooss8• 1 year ago

Both archaea and bacteria, in the three-domain model referenced in the article, are prokaryotes.

I suppose it depends on which model you use, and as discussed they seem to vary and be in flux right now, but the three domain model I learned was prokaryotes, archaea, and eukaryotes - the first two being different domains.

Yes, "with eukarya containing all multicellular organisms" does not mean "all eukarya are multicellular organisms" it means "multicellular organisms are a subset of eukarya".

We agree. I don't grasp your point?

zdragnar• 1 year ago

Cyanobacteria are an example of prokaryotes that, while not truly multicellular, may at times exhibit similar behavior.

They can form colonies and, within groups that share walls, specialize into different functions such as photosynthesis or nitrogen fixing behavior. This enables the colony to adapt to changing conditions that, while still made up of individual organisms, collectively appear to function similarly to a single multicellular one.

With that said, there aren't any examples of truly multicellular organisms within either domain. Just as an ant colony is not a single organism, cyanobacteria colony specializations are not examples of organs.

danwills• 1 year ago

I think prokaryotic bacteria can form biofilms which seems like one step on the road to multicellularity, but that's more like a community, and iiuc most biofilms these days at least contain eukaryotic yeasts. I don't know of any actually-properly-multicellular prokaryotes, but maybe I need to read up?

BrenBarn• 1 year ago

Upon examining the internal structure of the fossilized Prototaxites, the researchers found that its interior was made up of a series of tubes

Who knew the internet evolved millions of years ago?

exe342• 1 year ago

I love the idea that fungi house the Polises of Greg Egan.

culi• 1 year ago

it's called the wood wide web (seriously)

ddejohn• 1 year ago

Scientists are so adorable

amy214• 1 year ago

Who knews the scope and breadth of the reach of Al Gore, internet inventor, conceiver of the series of tubes paradaigm. Perhaps he has a tube all the way back 400 million years ago amongst his tube series

https://www.pellcenter.org/did-al-gore-invent-the-internet/

bbor3• 1 year ago

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?

clort• 1 year ago

When you feed off decaying matter, hosting a colony of bugs which go out daily, bring back food and leave waste all around your environment sounds like a pretty good strategy when you don't have any way to move to better pastures?

boxed2• 1 year ago

Isn't this a long time before insects and such though?

dwroberts• 1 year ago

One reason to grow upward is also just the need for oxygen. Mushrooms do this too - they tend to colonise and begin to fruit in high CO2 concentrations, but eventually want to escape it. And you can see the negative side effects of not being able to do this in mushrooms too (if the CO2 is too intense they grow too fast relative to their thickness [trying to reach air] and become nasty and stringy looking)

gg80• 1 year ago

If I remember correctly, there was this hypothesis that these things were covered by symbiotic algae so the idea is that they grew tall to increase the photosynthesis of their symbiotic organism (so kind of a giant lichen). But I can't find the source anymore, and I think that there isn't much evidence of any photobiont.

baalimago• 1 year ago

I wonder what it tastes like

intsunny• 1 year ago

The article about the study writes: `The study has not yet been peer-reviewed.`

We should just stop reading the article then and there. This is a major method of how a single study can perpetuate fake science and fake news.

verisimi• 1 year ago

This is a major method of how a single study can perpetuate fake science and fake news.

It's a feature, not a bug.

1970-01-01• 1 year ago

Clickbait is a bug tagged with WON'T FIX

jfengel• 1 year ago

We should, but we don't.

People want the news now. They don't want to wait for it to be peer reviewed, or even cursorily checked. There is an infinite maw for information, and it has already consumed every single known fact.

If you want science, you'll wait a month, because it's not actually urgent. These species waited hundreds of millions of years and it'll still be there in a few weeks.

If you want entertainment, you want it right this instant. And that's what LiveScience exists to do.

So you really should have stopped reading as soon as you saw the URL.

countWSS• 1 year ago

Perhaps its a Ediacaran biota remnant, that had very diverse groups some of which could be misclassified because the consensus is against Ediacaran relics existing past their period.

neuroelectron• 1 year ago

It's likely simply a fungus that used lignin instead of chitin. It went instinct when fungus learned to attack lignin.

hydrogen78002• 1 year ago

Discussions about classifying the domains of life aside, this article implies that there was, or could have been entire domains that are now extinct. Is this the case?

andrewflnr2• 1 year ago

That's really hard to answer without tackling the classification question head on. Do you mean groups that "would have" been considered a domain if humans had been around at the time? Or groups that are in some sense different from other domains to the same degree those domains are from each other?

Whether we tag something as a domain also depends on its abundance and/or visibility. I bet if you take dug into microorganisms, you'd find tons that are as different from plants and animals as plants and animals are fun each other. But they all tend to get lumped in as "protists" or something because... we kinda don't care. I wouldn't be surprised if we somehow found out there were a lot of extinct critters in equivalent situations.

hydrogen78002• 1 year ago

In my draft reply, I was going to add "is this even the right question", meaning "is the taxonomy more of a human construct than a natural one". It seems the answer is yes.

Or groups that are in some sense different from other domains to the same degree those domains are from each other?

This.

tremon2• 1 year ago

Depends on how wide your definition on "domain" is. Most of the dinosaur lineages have gone extinct, it's not too wild an assumption to assume the same is true for entire lineages of other species. So the safe answer to your question is "probably, yes".

damnitbuilds• 1 year ago

You never did like my mother.

riwsky• 1 year ago

Oh, that? That’s just Bob. He helps out around the busy season sometimes. Didn’t know this much about his family, though—neat!

roughly• 1 year ago

Acknowledging this is a pre-print, but it is _wild_ that we can do this kind of analysis on a species that went extinct nearly a third of a billion years before the first hominids emerged. Every now and again I'm reminded of just how far we've extended our sensorium as a species.

ChuckMcM• 1 year ago

This was an interesting read, and reminded me how paleo-biology is the closest thing to exobiology we've got. Looking at the different biomes that emerged on planet earth over a billion years feels equivalent to looking at a thousand different planets at the same time. Basically a thousand chance to see what that 'megayear' produced, life wise.

Giant, fungus-like organism may be a completely unknown branch of life

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