Over in talk.origins, there was a brief discussion of some fascinating fossils of first rate importance. Except for stromatolites, they are one of only a handful of fossil organisms from a gigayear or more ago. Named *Bicellum* *brasieri,* it possesses two distinct cell types, and AFAIK this sets it apart from all fossil species from more than 600 million years ago.

It was described scientifically here:

"A possible billion-year-old holozoan with differentiated multicellularity,"
by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
Martin Saunders, Charles H. Wellman,
Current Biology 31, 1--8 June 21, 2021

https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3

The article is free access. It includes many detailed photographs of a high magnification.

The title is guardedly optimistic about it being an animal. It does try to narrow it down somewhat:

"It seems reasonable to assume that Bicellum falls within one of
the lineages leading to one of the six clades that possess complex multicellularity today: animals, plants, florideophyte algae,
brown algae, ascomycete fungi, and basidiomycete fungi."

The words "of eukaryotes" should have been inserted after "six clades". They do try to rule out prokaryotes with:

"... these cells probably lacked rigid cell walls. This eliminates both cyanobacteria and the eukaryotic chlorophyte algae as likely homologs, because multicellular form in these taxa is strongly influenced by their
possession of rigid cell walls."

This reliance on a single feature of *extant* cyanobacteria (some of which do have two very distinct kinds of cells)
is a weakness which calls for independent corroboration, provided by more characteristically
eukaryotic features.

Here is why. Between their time and ours, there occurred the Cryogenic Period of geological history,
a time of several "snowball earths" when the entire earth (except for some high mountains) was covered by thick ice.
In between the successive ones, there are hypothesized to have been warm periods relatively free of ice.
The cyanobacteria of today may only represent the hardiest kinds that survived this ordeal by ice.

Heedless of such considerations, the popularization of these discoveries
puts two pieces of speculation in its title, reflected in the url:

https://www.sheffield.ac.uk/news/billion-year-old-fossil-reveals-missing-link-evolution-animals#

However, the article is nicely illustrated and is a good read, as long as
one is willing to suspend disbelief, like we all do when watching an engrossing movie.

Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
University of South Carolina
http://people.math.sc.edu/nyikos

On 5/28/21 7:07 PM, Peter Nyikos wrote:
> Over in talk.origins, there was a brief discussion of some fascinating fossils of first rate importance. Except for stromatolites, they are one of only a handful of fossil organisms from a gigayear or more ago. Named *Bicellum* *brasieri,* it possesses two distinct cell types, and AFAIK this sets it apart from all fossil species from more than 600 million years ago.
>
> It was described scientifically here:
>
> "A possible billion-year-old holozoan with differentiated multicellularity,"
> by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
> Martin Saunders, Charles H. Wellman,
> Current Biology 31, 1--8 June 21, 2021
>
> https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3
>
> The article is free access. It includes many detailed photographs of a high magnification.
>
> The title is guardedly optimistic about it being an animal. It does try to narrow it down somewhat:
>
> "It seems reasonable to assume that Bicellum falls within one of
> the lineages leading to one of the six clades that possess complex multicellularity today: animals, plants, florideophyte algae,
> brown algae, ascomycete fungi, and basidiomycete fungi."
>
> The words "of eukaryotes" should have been inserted after "six clades".

"complex" would seem to rule out any of the various multicellular
prokaryotes.

> They do try to rule out prokaryotes with:
>
> "... these cells probably lacked rigid cell walls. This eliminates both cyanobacteria and the eukaryotic chlorophyte algae as likely homologs, because multicellular form in these taxa is strongly influenced by their
> possession of rigid cell walls."
>
> This reliance on a single feature of *extant* cyanobacteria (some of which do have two very distinct kinds of cells)
> is a weakness which calls for independent corroboration, provided by more characteristically
> eukaryotic features.

How big are these cells? That could be a good clue. Of course one might
postulate giant cyanobacteria, I suppose. Of course what they would need
would be some character or other unique to animals. Perhaps something
molecular, if they can find any traces. Or it would be nice to find
collar cells or something similar.

> Here is why. Between their time and ours, there occurred the Cryogenic Period of geological history,
> a time of several "snowball earths" when the entire earth (except for some high mountains) was covered by thick ice.
> In between the successive ones, there are hypothesized to have been warm periods relatively free of ice.
> The cyanobacteria of today may only represent the hardiest kinds that survived this ordeal by ice.

Still, cells similar to the cyanobacteria of today are the only ones we
have fossil evidence of before or after the Cryogenian.

> Heedless of such considerations, the popularization of these discoveries
> puts two pieces of speculation in its title, reflected in the url:
>
> https://www.sheffield.ac.uk/news/billion-year-old-fossil-reveals-missing-link-evolution-animals#
>
> However, the article is nicely illustrated and is a good read, as long as
> one is willing to suspend disbelief, like we all do when watching an engrossing movie.
>
>
> Peter Nyikos
> Professor, Dept. of Mathematics -- standard disclaimer--
> University of South Carolina
> http://people.math.sc.edu/nyikos
>
>
>
>

On Saturday, May 29, 2021 at 9:16:28 AM UTC-4, John Harshman wrote:
> On 5/28/21 7:07 PM, Peter Nyikos wrote:
> > Over in talk.origins, there was a brief discussion of some fascinating fossils of first rate importance. Except for stromatolites, they are one of only a handful of fossil organisms from a gigayear or more ago. Named *Bicellum* *brasieri,* it possesses two distinct cell types, and AFAIK this sets it apart from all fossil species from more than 600 million years ago.
> >
> > It was described scientifically here:
> >
> > "A possible billion-year-old holozoan with differentiated multicellularity,"
> > by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
> > Martin Saunders, Charles H. Wellman,
> > Current Biology 31, 1--8 June 21, 2021
> >
> > https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3
> >
> > The article is free access. It includes many detailed photographs of a high magnification.
> >
> > The title is guardedly optimistic about it being an animal. It does try to narrow it down somewhat:
> >
> > "It seems reasonable to assume that Bicellum falls within one of the lineages leading
> > to one of the six clades that possess complex multicellularity today: animals, plants, florideophyte algae,
> > brown algae, ascomycete fungi, and basidiomycete fungi."
> >
> > The words "of eukaryotes" should have been inserted after "six clades".

> "complex" would seem to rule out any of the various multicellular
> prokaryotes.

It also rules out these cells. The quoted "complex multicellularity" is pure gravy.

By the way, I saw no argument in the paper that they ought to be on the stem of one of the six clades; why not
a clade that includes two or three of them, eh?

Remember all the different ways of rooting the tree Eukaria, that could not be ruled out? We took a
good long look at them on the talk.origins thread where the mysteries of meiosis were the topic.

> > They do try to rule out prokaryotes with:
> >
> > "... these cells probably lacked rigid cell walls. This eliminates both cyanobacteria and the eukaryotic chlorophyte algae as likely homologs, because multicellular form in these taxa is strongly influenced by their
> > possession of rigid cell walls."
> >
> > This reliance on a single feature of *extant* cyanobacteria (some of which do have two very distinct kinds of cells)
> > is a weakness which calls for independent corroboration, provided by more characteristically
> > eukaryotic features.

> How big are these cells?

Haven't you looked at the paper yet? They are quite small: the whole organism is less than 50 microns in diameter,
and the individual cells less than 5 microns.

> That could be a good clue.

Size is not a useful character at these scales. At one extreme is a giant spherical bacterium that gets to over 500 microns,
and thus visible to the naked eye:

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

Another of the same order of magnitude typically has an internal cell mass consisting of offspring
at some point in its life cycle:

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

It's doubtful, though, that the internal cells of *Bicellum* *brasieri* serve the same function; even
if they do, this is almost surely due to evolutionary convergence (homoplasy).

To be continued, hopefully today; if not, certainly tomorrow.

Peter Nyikos
Professor, Dept. of Mathematics . . -- standard disclaimer--
Univ. of South Carolina
http://people.math.sc.edu/nyikos

On 5/31/21 3:15 PM, Peter Nyikos wrote:
> On Saturday, May 29, 2021 at 9:16:28 AM UTC-4, John Harshman wrote:
>> On 5/28/21 7:07 PM, Peter Nyikos wrote:
>>> Over in talk.origins, there was a brief discussion of some fascinating fossils of first rate importance. Except for stromatolites, they are one of only a handful of fossil organisms from a gigayear or more ago. Named *Bicellum* *brasieri,* it possesses two distinct cell types, and AFAIK this sets it apart from all fossil species from more than 600 million years ago.
>>>
>>> It was described scientifically here:
>>>
>>> "A possible billion-year-old holozoan with differentiated multicellularity,"
>>> by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
>>> Martin Saunders, Charles H. Wellman,
>>> Current Biology 31, 1--8 June 21, 2021
>>>
>>> https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3
>>>
>>> The article is free access. It includes many detailed photographs of a high magnification.
>>>
>>> The title is guardedly optimistic about it being an animal. It does try to narrow it down somewhat:
>>>
>>> "It seems reasonable to assume that Bicellum falls within one of the lineages leading
>>> to one of the six clades that possess complex multicellularity today: animals, plants, florideophyte algae,
>>> brown algae, ascomycete fungi, and basidiomycete fungi."
>>>
>>> The words "of eukaryotes" should have been inserted after "six clades".
>
>> "complex" would seem to rule out any of the various multicellular
>> prokaryotes.
>
> It also rules out these cells. The quoted "complex multicellularity" is pure gravy.

If that's pure gravy, how much more gravious would addding "eukaryote" be?

> By the way, I saw no argument in the paper that they ought to be on the stem of one of the six clades; why not
> a clade that includes two or three of them, eh?

Because multicellularity arose independently within each of those six
clades and can't parsimoniously be attributed to the common ancestor of
any two of them.

> Remember all the different ways of rooting the tree Eukaria, that could not be ruled out? We took a
> good long look at them on the talk.origins thread where the mysteries of meiosis were the topic.

Yes, and none of those ways changes the number of independent origins of
multicellularity.

>>> They do try to rule out prokaryotes with:
>>>
>>> "... these cells probably lacked rigid cell walls. This eliminates both cyanobacteria and the eukaryotic chlorophyte algae as likely homologs, because multicellular form in these taxa is strongly influenced by their
>>> possession of rigid cell walls."
>>>
>>> This reliance on a single feature of *extant* cyanobacteria (some of which do have two very distinct kinds of cells)
>>> is a weakness which calls for independent corroboration, provided by more characteristically
>>> eukaryotic features.
>
>
>> How big are these cells?
>
> Haven't you looked at the paper yet? They are quite small: the whole organism is less than 50 microns in diameter,
> and the individual cells less than 5 microns.

That seems quite small for a eukaryotic cell, doesn't it? It's large for
a prokaryote, but not unreasonably large. The average size is 2.5
microns. There are eukaryotes with cells less than 1 micron in diameter.
Still, if we consider size alone these are more within the prokaryote
than the eukaryote size distribution.

>> That could be a good clue.
>
> Size is not a useful character at these scales. At one extreme is a giant spherical bacterium that gets to over 500 microns,
> and thus visible to the naked eye:
>
> https://en.wikipedia.org/wiki/Thiomargarita_namibiensis
>
> Another of the same order of magnitude typically has an internal cell mass consisting of offspring
> at some point in its life cycle:
>
> https://en.wikipedia.org/wiki/Epulopiscium
>
> It's doubtful, though, that the internal cells of *Bicellum* *brasieri* serve the same function; even
> if they do, this is almost surely due to evolutionary convergence (homoplasy).
>
>
> To be continued, hopefully today; if not, certainly tomorrow.
>
>
> Peter Nyikos
> Professor, Dept. of Mathematics . . -- standard disclaimer--
> Univ. of South Carolina
> http://people.math.sc.edu/nyikos
>

On Saturday, May 29, 2021 at 9:16:28 AM UTC-4, John Harshman wrote:
> On 5/28/21 7:07 PM, Peter Nyikos wrote:
> > Over in talk.origins, there was a brief discussion of some fascinating fossils of first rate importance. Except for stromatolites, they are one of only a handful of fossil organisms from a gigayear or more ago. Named *Bicellum* *brasieri,* it possesses two distinct cell types, and AFAIK this sets it apart from all fossil species from more than 600 million years ago.
> >
> > It was described scientifically here:
> >
> > "A possible billion-year-old holozoan with differentiated multicellularity,"
> > by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
> > Martin Saunders, Charles H. Wellman,
> > Current Biology 31, 1--8 June 21, 2021
> >
> > https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3
> >
> > The article is free access. It includes many detailed photographs of a high magnification.
> >
> > The title is guardedly optimistic about it being an animal. It does try to narrow it down somewhat:
> >
> > "It seems reasonable to assume that Bicellum falls within one of
> > the lineages leading to one of the six clades that possess complex multicellularity today: animals, plants, florideophyte algae,
> > brown algae, ascomycete fungi, and basidiomycete fungi."
> >
> > The words "of eukaryotes" should have been inserted after "six clades".
> "complex" would seem to rule out any of the various multicellular
> prokaryotes.
> > They do try to rule out prokaryotes with:
> >
> > "... these cells probably lacked rigid cell walls. This eliminates both cyanobacteria and the eukaryotic chlorophyte algae as likely homologs, because multicellular form in these taxa is strongly influenced by their
> > possession of rigid cell walls."
> >
> > This reliance on a single feature of *extant* cyanobacteria (some of which do have two very distinct kinds of cells)
> > is a weakness which calls for independent corroboration, provided by more characteristically
> > eukaryotic features.

My first response to this post ended with my answer to the following question:

> How big are these cells?

I looked up a cyanobacterium with two very different kinds of cells, one with which I have an intimate acquaintance: *Anabaena*.
Its cells are just about the same size as the ones of *Bicellum* *brasieri.* So the following was a false lead:

> That could be a good clue. Of course one might
> postulate giant cyanobacteria, I suppose.

We are in full agreement about the following:

> Of course what they would need
> would be some character or other unique to animals. Perhaps something
> molecular, if they can find any traces. Or it would be nice to find
> collar cells or something similar.

No such luck as collar cells with these organisms . Haven't you looked at the paper yet?
You did not answer this question in your reply to my first reply.

> > Here is why. Between their time and ours, there occurred the Cryogenic Period of geological history,
> > a time of several "snowball earths" when the entire earth (except for some high mountains) was covered by thick ice.
> > In between the successive ones, there are hypothesized to have been warm periods relatively free of ice.
> > The cyanobacteria of today may only represent the hardiest kinds that survived this ordeal by ice.

> Still, cells similar to the cyanobacteria of today are the only ones we
> have fossil evidence of before or after the Cryogenian.

Can you give me a good source for them, apart from the ones (if any) found in stromatolites?

> > Heedless of such considerations, the popularization of these discoveries
> > puts two pieces of speculation in its title, reflected in the url:
> >
> > https://www.sheffield.ac.uk/news/billion-year-old-fossil-reveals-missing-link-evolution-animals#
> >
> > However, the article is nicely illustrated and is a good read, as long as
> > one is willing to suspend disbelief, like we all do when watching an engrossing movie.

And who knows, they might be right! But you've come up with reasons yourself about why "missing link"
is very unlikely.

Peter Nyikos
Professor, Dept. of Mathematics
University of South Carolina
-- standard disclaimer--
http://people.math.sc.edu/nyikos

On 6/1/21 10:12 AM, Peter Nyikos wrote:
> On Saturday, May 29, 2021 at 9:16:28 AM UTC-4, John Harshman wrote:
>> On 5/28/21 7:07 PM, Peter Nyikos wrote:
>>> Over in talk.origins, there was a brief discussion of some fascinating fossils of first rate importance. Except for stromatolites, they are one of only a handful of fossil organisms from a gigayear or more ago. Named *Bicellum* *brasieri,* it possesses two distinct cell types, and AFAIK this sets it apart from all fossil species from more than 600 million years ago.
>>>
>>> It was described scientifically here:
>>>
>>> "A possible billion-year-old holozoan with differentiated multicellularity,"
>>> by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
>>> Martin Saunders, Charles H. Wellman,
>>> Current Biology 31, 1--8 June 21, 2021
>>>
>>> https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3
>>>
>>> The article is free access. It includes many detailed photographs of a high magnification.
>>>
>>> The title is guardedly optimistic about it being an animal. It does try to narrow it down somewhat:
>>>
>>> "It seems reasonable to assume that Bicellum falls within one of
>>> the lineages leading to one of the six clades that possess complex multicellularity today: animals, plants, florideophyte algae,
>>> brown algae, ascomycete fungi, and basidiomycete fungi."
>>>
>>> The words "of eukaryotes" should have been inserted after "six clades".
>> "complex" would seem to rule out any of the various multicellular
>> prokaryotes.
>>> They do try to rule out prokaryotes with:
>>>
>>> "... these cells probably lacked rigid cell walls. This eliminates both cyanobacteria and the eukaryotic chlorophyte algae as likely homologs, because multicellular form in these taxa is strongly influenced by their
>>> possession of rigid cell walls."
>>>
>>> This reliance on a single feature of *extant* cyanobacteria (some of which do have two very distinct kinds of cells)
>>> is a weakness which calls for independent corroboration, provided by more characteristically
>>> eukaryotic features.
>
> My first response to this post ended with my answer to the following question:
>
>> How big are these cells?
>
> I looked up a cyanobacterium with two very different kinds of cells, one with which I have an intimate acquaintance: *Anabaena*.
> Its cells are just about the same size as the ones of *Bicellum* *brasieri.* So the following was a false lead:
>
>> That could be a good clue. Of course one might
>> postulate giant cyanobacteria, I suppose.
>
>
> We are in full agreement about the following:
>
>> Of course what they would need
>> would be some character or other unique to animals. Perhaps something
>> molecular, if they can find any traces. Or it would be nice to find
>> collar cells or something similar.
>
> No such luck as collar cells with these organisms . Haven't you looked at the paper yet?
> You did not answer this question in your reply to my first reply.
>
>>> Here is why. Between their time and ours, there occurred the Cryogenic Period of geological history,
>>> a time of several "snowball earths" when the entire earth (except for some high mountains) was covered by thick ice.
>>> In between the successive ones, there are hypothesized to have been warm periods relatively free of ice.
>>> The cyanobacteria of today may only represent the hardiest kinds that survived this ordeal by ice.
>
>> Still, cells similar to the cyanobacteria of today are the only ones we
>> have fossil evidence of before or after the Cryogenian.
>
> Can you give me a good source for them, apart from the ones (if any) found in stromatolites?

Those are the ones.

>>> Heedless of such considerations, the popularization of these discoveries
>>> puts two pieces of speculation in its title, reflected in the url:
>>>
>>> https://www.sheffield.ac.uk/news/billion-year-old-fossil-reveals-missing-link-evolution-animals#
>>>
>>> However, the article is nicely illustrated and is a good read, as long as
>>> one is willing to suspend disbelief, like we all do when watching an engrossing movie.
>
> And who knows, they might be right! But you've come up with reasons yourself about why "missing link"
> is very unlikely.
>
>
> Peter Nyikos
> Professor, Dept. of Mathematics
> University of South Carolina
> -- standard disclaimer--
> http://people.math.sc.edu/nyikos
>

On Tuesday, June 1, 2021 at 2:02:59 PM UTC-4, John Harshman wrote:
> On 6/1/21 10:12 AM, Peter Nyikos wrote:
> > On Saturday, May 29, 2021 at 9:16:28 AM UTC-4, John Harshman wrote:
> >> On 5/28/21 7:07 PM, Peter Nyikos wrote:
> >>> Over in talk.origins, there was a brief discussion of some fascinating fossils of first rate importance. Except for stromatolites, they are one of only a handful of fossil organisms from a gigayear or more ago. Named *Bicellum* *brasieri,* it possesses two distinct cell types, and AFAIK this sets it apart from all fossil species from more than 600 million years ago.
> >>>
> >>> It was described scientifically here:
> >>>
> >>> "A possible billion-year-old holozoan with differentiated multicellularity,"
> >>> by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
> >>> Martin Saunders, Charles H. Wellman,
> >>> Current Biology 31, 1--8 June 21, 2021
> >>>
> >>> https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3
> >>>
> >>> The article is free access. It includes many detailed photographs of a high magnification.
> >>>
> >>> The title is guardedly optimistic about it being an animal. It does try to narrow it down somewhat:
> >>>
> >>> "It seems reasonable to assume that Bicellum falls within one of
> >>> the lineages leading to one of the six clades that possess complex multicellularity today: animals, plants, florideophyte algae,
> >>> brown algae, ascomycete fungi, and basidiomycete fungi."
> >>>
> >>> The words "of eukaryotes" should have been inserted after "six clades".
> >> "complex" would seem to rule out any of the various multicellular
> >> prokaryotes.
> >>> They do try to rule out prokaryotes with:
> >>>
> >>> "... these cells probably lacked rigid cell walls. This eliminates both cyanobacteria and the eukaryotic chlorophyte algae as likely homologs, because multicellular form in these taxa is strongly influenced by their
> >>> possession of rigid cell walls."
> >>>
> >>> This reliance on a single feature of *extant* cyanobacteria (some of which do have two very distinct kinds of cells)
> >>> is a weakness which calls for independent corroboration, provided by more characteristically
> >>> eukaryotic features.
> >
> > My first response to this post ended with my answer to the following question:
> >
> >> How big are these cells?
> >
> > I looked up a cyanobacterium with two very different kinds of cells, one with which I have an intimate acquaintance: *Anabaena*.
> > Its cells are just about the same size as the ones of *Bicellum* *brasieri.* So the following was a false lead:
> >
> >> That could be a good clue. Of course one might
> >> postulate giant cyanobacteria, I suppose.
> >
> >
> > We are in full agreement about the following:
> >
> >> Of course what they would need
> >> would be some character or other unique to animals. Perhaps something
> >> molecular, if they can find any traces. Or it would be nice to find
> >> collar cells or something similar.
> >
> > No such luck as collar cells with these organisms . Haven't you looked at the paper yet?
> > You did not answer this question in your reply to my first reply.

You seem uninterested in this whole discovery, John. This is the second time you've failed
to answer this simple question.

<snip for focus>

> >>> The cyanobacteria of today may only represent the hardiest kinds that survived this ordeal by ice.
> >
> >> Still, cells similar to the cyanobacteria of today are the only ones we
> >> have fossil evidence of before or after the Cryogenian.
> >
> > Can you give me a good source for them, apart from the ones (if any) found in stromatolites?

> Those are the ones.

Do you know of any articles or books that go into the exterior covering? Do we have any evidence that they
were made of peptidoglycan, as is the case with modern cyanobacteria?

Peter Nyikos
Dept. of Mathematics -- standard disclaimer--
University of South Carolina
http://people.math.sc.edu/nyikos

On Tuesday, June 1, 2021 at 3:52:28 PM UTC-7, nyik...@gmail.com wrote:
> On Tuesday, June 1, 2021 at 2:02:59 PM UTC-4, John Harshman wrote:
> > On 6/1/21 10:12 AM, Peter Nyikos wrote:
> > > On Saturday, May 29, 2021 at 9:16:28 AM UTC-4, John Harshman wrote:
> > >> On 5/28/21 7:07 PM, Peter Nyikos wrote:
> > >>> Over in talk.origins, there was a brief discussion of some fascinating fossils of first rate importance. Except for stromatolites, they are one of only a handful of fossil organisms from a gigayear or more ago. Named *Bicellum* *brasieri,* it possesses two distinct cell types, and AFAIK this sets it apart from all fossil species from more than 600 million years ago..
> > >>>
> > >>> It was described scientifically here:
> > >>>
> > >>> "A possible billion-year-old holozoan with differentiated multicellularity,"
> > >>> by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
> > >>> Martin Saunders, Charles H. Wellman,
> > >>> Current Biology 31, 1--8 June 21, 2021
> > >>>
> > >>> https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3
> > >>>
> > >>> The article is free access. It includes many detailed photographs of a high magnification.
> > >>>
> > >>> The title is guardedly optimistic about it being an animal. It does try to narrow it down somewhat:
> > >>>
> > >>> "It seems reasonable to assume that Bicellum falls within one of
> > >>> the lineages leading to one of the six clades that possess complex multicellularity today: animals, plants, florideophyte algae,
> > >>> brown algae, ascomycete fungi, and basidiomycete fungi."
> > >>>
> > >>> The words "of eukaryotes" should have been inserted after "six clades".
> > >> "complex" would seem to rule out any of the various multicellular
> > >> prokaryotes.
> > >>> They do try to rule out prokaryotes with:
> > >>>
> > >>> "... these cells probably lacked rigid cell walls. This eliminates both cyanobacteria and the eukaryotic chlorophyte algae as likely homologs, because multicellular form in these taxa is strongly influenced by their
> > >>> possession of rigid cell walls."
> > >>>
> > >>> This reliance on a single feature of *extant* cyanobacteria (some of which do have two very distinct kinds of cells)
> > >>> is a weakness which calls for independent corroboration, provided by more characteristically
> > >>> eukaryotic features.
> > >
> > > My first response to this post ended with my answer to the following question:
> > >
> > >> How big are these cells?
> > >
> > > I looked up a cyanobacterium with two very different kinds of cells, one with which I have an intimate acquaintance: *Anabaena*.
> > > Its cells are just about the same size as the ones of *Bicellum* *brasieri.* So the following was a false lead:
> > >
> > >> That could be a good clue. Of course one might
> > >> postulate giant cyanobacteria, I suppose.
> > >
> > >
> > > We are in full agreement about the following:
> > >
> > >> Of course what they would need
> > >> would be some character or other unique to animals. Perhaps something
> > >> molecular, if they can find any traces. Or it would be nice to find
> > >> collar cells or something similar.
> > >
> > > No such luck as collar cells with these organisms . Haven't you looked at the paper yet?
> > > You did not answer this question in your reply to my first reply.
> You seem uninterested in this whole discovery, John. This is the second time you've failed
> to answer this simple question.
>
> <snip for focus>
> > >>> The cyanobacteria of today may only represent the hardiest kinds that survived this ordeal by ice.
> > >
> > >> Still, cells similar to the cyanobacteria of today are the only ones we
> > >> have fossil evidence of before or after the Cryogenian.
> > >
> > > Can you give me a good source for them, apart from the ones (if any) found in stromatolites?
>
> > Those are the ones.
> Do you know of any articles or books that go into the exterior covering? Do we have any evidence that they
> were made of peptidoglycan, as is the case with modern cyanobacteria?
>
>
> Peter Nyikos
> Dept. of Mathematics -- standard disclaimer--
> University of South Carolina
> http://people.math.sc.edu/nyikos

Here's the most recent comprehensive review of Cyanobacteria fossils:

https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub

Chemical remains are important information, but peptidoglycan (mentioned in the review) isn't discussed as
present in the fossils (no surprise there).

I haven't read all of it yet, but I intend to. Considerable info is new to me.

On Tuesday, June 1, 2021 at 8:04:07 PM UTC-4, erik simpson wrote:
> On Tuesday, June 1, 2021 at 3:52:28 PM UTC-7, nyik...@gmail.com wrote:
> > On Tuesday, June 1, 2021 at 2:02:59 PM UTC-4, John Harshman wrote:
> > > On 6/1/21 10:12 AM, Peter Nyikos wrote:
> > > > On Saturday, May 29, 2021 at 9:16:28 AM UTC-4, John Harshman wrote:
> > > >> On 5/28/21 7:07 PM, Peter Nyikos wrote:
> > > >>> Over in talk.origins, there was a brief discussion of some fascinating fossils of first rate importance. Except for stromatolites, they are one of only a handful of fossil organisms from a gigayear or more ago. Named *Bicellum* *brasieri,* it possesses two distinct cell types, and AFAIK this sets it apart from all fossil species from more than 600 million years ago.
> > > >>>
> > > >>> It was described scientifically here:
> > > >>>
> > > >>> "A possible billion-year-old holozoan with differentiated multicellularity,"
> > > >>> by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
> > > >>> Martin Saunders, Charles H. Wellman,
> > > >>> Current Biology 31, 1--8 June 21, 2021
> > > >>>
> > > >>> https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3
> > > >>>
> > > >>> The article is free access. It includes many detailed photographs of a high magnification.
> > > >>>
> > > >>> The title is guardedly optimistic about it being an animal. It does try to narrow it down somewhat:
> > > >>>
> > > >>> "It seems reasonable to assume that Bicellum falls within one of
> > > >>> the lineages leading to one of the six clades that possess complex multicellularity today: animals, plants, florideophyte algae,
> > > >>> brown algae, ascomycete fungi, and basidiomycete fungi."
> > > >>>
> > > >>> The words "of eukaryotes" should have been inserted after "six clades".
> > > >> "complex" would seem to rule out any of the various multicellular
> > > >> prokaryotes.
> > > >>> They do try to rule out prokaryotes with:
> > > >>>
> > > >>> "... these cells probably lacked rigid cell walls. This eliminates both cyanobacteria and the eukaryotic chlorophyte algae as likely homologs, because multicellular form in these taxa is strongly influenced by their
> > > >>> possession of rigid cell walls."
> > > >>>
> > > >>> This reliance on a single feature of *extant* cyanobacteria (some of which do have two very distinct kinds of cells)
> > > >>> is a weakness which calls for independent corroboration, provided by more characteristically
> > > >>> eukaryotic features.
> > > >
> > > > My first response to this post ended with my answer to the following question:
> > > >
> > > >> How big are these cells?
> > > >
> > > > I looked up a cyanobacterium with two very different kinds of cells, one with which I have an intimate acquaintance: *Anabaena*.
> > > > Its cells are just about the same size as the ones of *Bicellum* *brasieri.* So the following was a false lead:
> > > >
> > > >> That could be a good clue. Of course one might
> > > >> postulate giant cyanobacteria, I suppose.
> > > >
> > > >
> > > > We are in full agreement about the following:
> > > >
> > > >> Of course what they would need
> > > >> would be some character or other unique to animals. Perhaps something
> > > >> molecular, if they can find any traces. Or it would be nice to find
> > > >> collar cells or something similar.
> > > >
> > > > No such luck as collar cells with these organisms . Haven't you looked at the paper yet?
> > > > You did not answer this question in your reply to my first reply.
> > You seem uninterested in this whole discovery, John. This is the second time you've failed
> > to answer this simple question.
> >
> > <snip for focus>
> > > >>> The cyanobacteria of today may only represent the hardiest kinds that survived this ordeal by ice.
> > > >
> > > >> Still, cells similar to the cyanobacteria of today are the only ones we
> > > >> have fossil evidence of before or after the Cryogenian.
> > > >
> > > > Can you give me a good source for them, apart from the ones (if any) found in stromatolites?
> >
> > > Those are the ones.
> > Do you know of any articles or books that go into the exterior covering? Do we have any evidence that they
> > were made of peptidoglycan, as is the case with modern cyanobacteria?
> >
> >
> > Peter Nyikos
> > Dept. of Mathematics -- standard disclaimer--
> > University of South Carolina
> > http://people.math.sc.edu/nyikos
> Here's the most recent comprehensive review of Cyanobacteria fossils:
>
> https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub

Cyanobacteria evolution: Insight from the fossil record
Catherine F.Demoulin, Yannick J.Lara, Luc Cornet, CamilleFrançois, DenisBaurain, AnnickWilmotte, Emmanuelle J.Javaux,
Free Radical Biology and Medicine Volume 140, 20 August 2019, Pages 206-223

Thank you very much, Erik. It does look like a very valuable resource on the subject.
> Chemical remains are important information, but peptidoglycan (mentioned in the review) isn't discussed as
> present in the fossils (no surprise there).
>
> I haven't read all of it yet, but I intend to. Considerable info is new to me.

For me too. A quick skim fails to provide answers to the two questions that interest me most at the present time:
(1) are cyanobacteria fossils from a billion or more years ago exclusively from stromatolites and
(2) are they all thick-walled?

I'll be looking at it off and on for about a week before posting on it. Mostly off: for the better part
of this past academic year, my family has had to ration their time with me due to the tremendous burden
of online teaching -- almost three times as time-consuming as in-person teaching. I've decided to give
them some real quality and quantity time, so I'm going on a posting break until next Tuesday.

Meanwhile, here's something y'all might think about: how rare is it to have fossils of any organisms which,
like *Bicellum* *brasieri,* are from a billion or more years ago and are NOT from stromatolites?

Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
University of So. Carolina
http://people.math.sc.edu/nyikos

On Wednesday, June 2, 2021 at 3:01:16 PM UTC-7, Peter Nyikos wrote:
> On Tuesday, June 1, 2021 at 8:04:07 PM UTC-4, erik simpson wrote:
> > On Tuesday, June 1, 2021 at 3:52:28 PM UTC-7, nyik...@gmail.com wrote:
> > > On Tuesday, June 1, 2021 at 2:02:59 PM UTC-4, John Harshman wrote:
> > > > On 6/1/21 10:12 AM, Peter Nyikos wrote:
> > > > > On Saturday, May 29, 2021 at 9:16:28 AM UTC-4, John Harshman wrote:
> > > > >> On 5/28/21 7:07 PM, Peter Nyikos wrote:
> > > > >>> Over in talk.origins, there was a brief discussion of some fascinating fossils of first rate importance. Except for stromatolites, they are one of only a handful of fossil organisms from a gigayear or more ago. Named *Bicellum* *brasieri,* it possesses two distinct cell types, and AFAIK this sets it apart from all fossil species from more than 600 million years ago.
> > > > >>>
> > > > >>> It was described scientifically here:
> > > > >>>
> > > > >>> "A possible billion-year-old holozoan with differentiated multicellularity,"
> > > > >>> by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
> > > > >>> Martin Saunders, Charles H. Wellman,
> > > > >>> Current Biology 31, 1--8 June 21, 2021
> > > > >>>
> > > > >>> https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3
> > > > >>>
> > > > >>> The article is free access. It includes many detailed photographs of a high magnification.
> > > > >>>
> > > > >>> The title is guardedly optimistic about it being an animal. It does try to narrow it down somewhat:
> > > > >>>
> > > > >>> "It seems reasonable to assume that Bicellum falls within one of
> > > > >>> the lineages leading to one of the six clades that possess complex multicellularity today: animals, plants, florideophyte algae,
> > > > >>> brown algae, ascomycete fungi, and basidiomycete fungi."
> > > > >>>
> > > > >>> The words "of eukaryotes" should have been inserted after "six clades".
> > > > >> "complex" would seem to rule out any of the various multicellular
> > > > >> prokaryotes.
> > > > >>> They do try to rule out prokaryotes with:
> > > > >>>
> > > > >>> "... these cells probably lacked rigid cell walls. This eliminates both cyanobacteria and the eukaryotic chlorophyte algae as likely homologs, because multicellular form in these taxa is strongly influenced by their
> > > > >>> possession of rigid cell walls."
> > > > >>>
> > > > >>> This reliance on a single feature of *extant* cyanobacteria (some of which do have two very distinct kinds of cells)
> > > > >>> is a weakness which calls for independent corroboration, provided by more characteristically
> > > > >>> eukaryotic features.
> > > > >
> > > > > My first response to this post ended with my answer to the following question:
> > > > >
> > > > >> How big are these cells?
> > > > >
> > > > > I looked up a cyanobacterium with two very different kinds of cells, one with which I have an intimate acquaintance: *Anabaena*.
> > > > > Its cells are just about the same size as the ones of *Bicellum* *brasieri.* So the following was a false lead:
> > > > >
> > > > >> That could be a good clue. Of course one might
> > > > >> postulate giant cyanobacteria, I suppose.
> > > > >
> > > > >
> > > > > We are in full agreement about the following:
> > > > >
> > > > >> Of course what they would need
> > > > >> would be some character or other unique to animals. Perhaps something
> > > > >> molecular, if they can find any traces. Or it would be nice to find
> > > > >> collar cells or something similar.
> > > > >
> > > > > No such luck as collar cells with these organisms . Haven't you looked at the paper yet?
> > > > > You did not answer this question in your reply to my first reply.
> > > You seem uninterested in this whole discovery, John. This is the second time you've failed
> > > to answer this simple question.
> > >
> > > <snip for focus>
> > > > >>> The cyanobacteria of today may only represent the hardiest kinds that survived this ordeal by ice.
> > > > >
> > > > >> Still, cells similar to the cyanobacteria of today are the only ones we
> > > > >> have fossil evidence of before or after the Cryogenian.
> > > > >
> > > > > Can you give me a good source for them, apart from the ones (if any) found in stromatolites?
> > >
> > > > Those are the ones.
> > > Do you know of any articles or books that go into the exterior covering? Do we have any evidence that they
> > > were made of peptidoglycan, as is the case with modern cyanobacteria?
> > >
> > >
> > > Peter Nyikos
> > > Dept. of Mathematics -- standard disclaimer--
> > > University of South Carolina
> > > http://people.math.sc.edu/nyikos
> > Here's the most recent comprehensive review of Cyanobacteria fossils:
> >
> > https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub
> Cyanobacteria evolution: Insight from the fossil record
> Catherine F.Demoulin, Yannick J.Lara, Luc Cornet, CamilleFrançois, DenisBaurain, AnnickWilmotte, Emmanuelle J.Javaux,
> Free Radical Biology and Medicine Volume 140, 20 August 2019, Pages 206-223
>
> Thank you very much, Erik. It does look like a very valuable resource on the subject.
> > Chemical remains are important information, but peptidoglycan (mentioned in the review) isn't discussed as
> > present in the fossils (no surprise there).
> >
> > I haven't read all of it yet, but I intend to. Considerable info is new to me.
> For me too. A quick skim fails to provide answers to the two questions that interest me most at the present time:
> (1) are cyanobacteria fossils from a billion or more years ago exclusively from stromatolites and
> (2) are they all thick-walled?
>
>
> I'll be looking at it off and on for about a week before posting on it. Mostly off: for the better part
> of this past academic year, my family has had to ration their time with me due to the tremendous burden
> of online teaching -- almost three times as time-consuming as in-person teaching. I've decided to give
> them some real quality and quantity time, so I'm going on a posting break until next Tuesday.
>
> Meanwhile, here's something y'all might think about: how rare is it to have fossils of any organisms which,
> like *Bicellum* *brasieri,* are from a billion or more years ago and are NOT from stromatolites?
>
>
> Peter Nyikos
> Professor, Dept. of Mathematics -- standard disclaimer--
> University of So. Carolina
> http://people.math.sc.edu/nyikos

I believe most of the cyanobacterial fossils are derived from stromatolites, but some are found in other
"microbially induced sedimentary structures (MISS)".

Unsheathed cyanobacteria are known in the fossil record, but the majority of fossils are thick-walled, probably
due to tophonomy favoring the thick-walled specimens.

On Wednesday, June 2, 2021 at 7:13:58 PM UTC-4, erik simpson wrote:
> On Wednesday, June 2, 2021 at 3:01:16 PM UTC-7, Peter Nyikos wrote:
> > On Tuesday, June 1, 2021 at 8:04:07 PM UTC-4, erik simpson wrote:
> > > On Tuesday, June 1, 2021 at 3:52:28 PM UTC-7, nyik...@gmail.com wrote:
> > > > On Tuesday, June 1, 2021 at 2:02:59 PM UTC-4, John Harshman wrote:
> > > > > On 6/1/21 10:12 AM, Peter Nyikos wrote:
> > > > > > On Saturday, May 29, 2021 at 9:16:28 AM UTC-4, John Harshman wrote:
> > > > > >> On 5/28/21 7:07 PM, Peter Nyikos wrote:
> > > > > >>> Over in talk.origins, there was a brief discussion of some fascinating fossils of first rate importance. Except for stromatolites, they are one of only a handful of fossil organisms from a gigayear or more ago. Named *Bicellum* *brasieri,* it possesses two distinct cell types, and AFAIK this sets it apart from all fossil species from more than 600 million years ago.
> > > > > >>>
> > > > > >>> It was described scientifically here:
> > > > > >>>
> > > > > >>> "A possible billion-year-old holozoan with differentiated multicellularity,"
> > > > > >>> by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
> > > > > >>> Martin Saunders, Charles H. Wellman,
> > > > > >>> Current Biology 31, 1--8 June 21, 2021
> > > > > >>>
> > > > > >>> https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3
> > > > > >>>
> > > > > >>> The article is free access. It includes many detailed photographs of a high magnification.
> > > > > >>>
> > > > > >>> The title is guardedly optimistic about it being an animal. It does try to narrow it down somewhat:
> > > > > >>>
> > > > > >>> "It seems reasonable to assume that Bicellum falls within one of
> > > > > >>> the lineages leading to one of the six clades that possess complex multicellularity today: animals, plants, florideophyte algae,
> > > > > >>> brown algae, ascomycete fungi, and basidiomycete fungi."
> > > > > >>>
> > > > > >>> The words "of eukaryotes" should have been inserted after "six clades".
> > > > > >> "complex" would seem to rule out any of the various multicellular
> > > > > >> prokaryotes.
> > > > > >>> They do try to rule out prokaryotes with:
> > > > > >>>
> > > > > >>> "... these cells probably lacked rigid cell walls. This eliminates both cyanobacteria and the eukaryotic chlorophyte algae as likely homologs, because multicellular form in these taxa is strongly influenced by their
> > > > > >>> possession of rigid cell walls."
> > > > > >>>
> > > > > >>> This reliance on a single feature of *extant* cyanobacteria (some of which do have two very distinct kinds of cells)
> > > > > >>> is a weakness which calls for independent corroboration, provided by more characteristically
> > > > > >>> eukaryotic features.
> > > > > >
> > > > > > My first response to this post ended with my answer to the following question:
> > > > > >
> > > > > >> How big are these cells?
> > > > > >
> > > > > > I looked up a cyanobacterium with two very different kinds of cells, one with which I have an intimate acquaintance: *Anabaena*.
> > > > > > Its cells are just about the same size as the ones of *Bicellum* *brasieri.* So the following was a false lead:
> > > > > >
> > > > > >> That could be a good clue. Of course one might
> > > > > >> postulate giant cyanobacteria, I suppose.
> > > > > >
> > > > > >
> > > > > > We are in full agreement about the following:
> > > > > >
> > > > > >> Of course what they would need
> > > > > >> would be some character or other unique to animals. Perhaps something
> > > > > >> molecular, if they can find any traces. Or it would be nice to find
> > > > > >> collar cells or something similar.
> > > > > >
> > > > > > No such luck as collar cells with these organisms . Haven't you looked at the paper yet?
> > > > > > You did not answer this question in your reply to my first reply.
> > > > You seem uninterested in this whole discovery, John. This is the second time you've failed
> > > > to answer this simple question.
> > > >
> > > > <snip for focus>
> > > > > >>> The cyanobacteria of today may only represent the hardiest kinds that survived this ordeal by ice.
> > > > > >
> > > > > >> Still, cells similar to the cyanobacteria of today are the only ones we
> > > > > >> have fossil evidence of before or after the Cryogenian.
> > > > > >
> > > > > > Can you give me a good source for them, apart from the ones (if any) found in stromatolites?
> > > >
> > > > > Those are the ones.
> > > > Do you know of any articles or books that go into the exterior covering? Do we have any evidence that they
> > > > were made of peptidoglycan, as is the case with modern cyanobacteria?

> > > Here's the most recent comprehensive review of Cyanobacteria fossils:
> > >
> > > https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub
> > Cyanobacteria evolution: Insight from the fossil record
> > Catherine F.Demoulin, Yannick J.Lara, Luc Cornet, CamilleFrançois, DenisBaurain, AnnickWilmotte, Emmanuelle J.Javaux,
> > Free Radical Biology and Medicine Volume 140, 20 August 2019, Pages 206-223
> >
> > Thank you very much, Erik. It does look like a very valuable resource on the subject.
> > > Chemical remains are important information, but peptidoglycan (mentioned in the review) isn't discussed as
> > > present in the fossils (no surprise there).
> > >
> > > I haven't read all of it yet, but I intend to. Considerable info is new to me.
> > For me too. A quick skim fails to provide answers to the two questions that interest me most at the present time:
> > (1) are cyanobacteria fossils from a billion or more years ago exclusively from stromatolites and
> > (2) are they all thick-walled?
> >
> >
> > I'll be looking at it off and on for about a week before posting on it. Mostly off: for the better part
> > of this past academic year, my family has had to ration their time with me due to the tremendous burden
> > of online teaching -- almost three times as time-consuming as in-person teaching. I've decided to give
> > them some real quality and quantity time, so I'm going on a posting break until next Tuesday.
> >
> > Meanwhile, here's something y'all might think about: how rare is it to have fossils of any organisms which,
> > like *Bicellum* *brasieri,* are from a billion or more years ago and are NOT from stromatolites?
> >
> >

> I believe most of the cyanobacterial fossils are derived from stromatolites, but some are found in other
> "microbially induced sedimentary structures (MISS)".
>
> Unsheathed cyanobacteria are known in the fossil record, but the majority of fossils are thick-walled, probably
> due to tophonomy favoring the thick-walled specimens.

There is also what might be called "identification bias": there are lots of different microorganisms in
stromatolites, but the article you showed us judges whether a microorganism is a cyanobacterium
based on its resemblance to extant cyanobacteria.

https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub

Its criteria are sufficiently stringent so that "only three taxa are unambiguously identified as cyanobacteria." [p. 209] Earlier on that page we see:

"In this section, we discuss a selection of (1) unambiguous cyanobacteria microfossils for which morphological features and habitats coincide strikingly with modern lineages, (2) probable and possible cyanobacteria microfossils that share morphological similarities both with a taxon belonging to the cyanobacterial phylum and with other lineages belonging to another phylum or domain of life. The limited number of preservable characters, along with their taphonomic alteration, and possible morphological convergence, limits the interpretation of the fossil record."

On Tuesday, June 8, 2021 at 8:00:29 AM UTC-7, nyik...@gmail.com wrote:
> On Wednesday, June 2, 2021 at 7:13:58 PM UTC-4, erik simpson wrote:
> > On Wednesday, June 2, 2021 at 3:01:16 PM UTC-7, Peter Nyikos wrote:
> > > On Tuesday, June 1, 2021 at 8:04:07 PM UTC-4, erik simpson wrote:
> > > > On Tuesday, June 1, 2021 at 3:52:28 PM UTC-7, nyik...@gmail.com wrote:
> > > > > On Tuesday, June 1, 2021 at 2:02:59 PM UTC-4, John Harshman wrote:
> > > > > > On 6/1/21 10:12 AM, Peter Nyikos wrote:
> > > > > > > On Saturday, May 29, 2021 at 9:16:28 AM UTC-4, John Harshman wrote:
> > > > > > >> On 5/28/21 7:07 PM, Peter Nyikos wrote:
> > > > > > >>> Over in talk.origins, there was a brief discussion of some fascinating fossils of first rate importance. Except for stromatolites, they are one of only a handful of fossil organisms from a gigayear or more ago.. Named *Bicellum* *brasieri,* it possesses two distinct cell types, and AFAIK this sets it apart from all fossil species from more than 600 million years ago.
> > > > > > >>>
> > > > > > >>> It was described scientifically here:
> > > > > > >>>
> > > > > > >>> "A possible billion-year-old holozoan with differentiated multicellularity,"
> > > > > > >>> by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
> > > > > > >>> Martin Saunders, Charles H. Wellman,
> > > > > > >>> Current Biology 31, 1--8 June 21, 2021
> > > > > > >>>
> > > > > > >>> https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3
> > > > > > >>>
> > > > > > >>> The article is free access. It includes many detailed photographs of a high magnification.
> > > > > > >>>
> > > > > > >>> The title is guardedly optimistic about it being an animal. It does try to narrow it down somewhat:
> > > > > > >>>
> > > > > > >>> "It seems reasonable to assume that Bicellum falls within one of
> > > > > > >>> the lineages leading to one of the six clades that possess complex multicellularity today: animals, plants, florideophyte algae,
> > > > > > >>> brown algae, ascomycete fungi, and basidiomycete fungi."
> > > > > > >>>
> > > > > > >>> The words "of eukaryotes" should have been inserted after "six clades".
> > > > > > >> "complex" would seem to rule out any of the various multicellular
> > > > > > >> prokaryotes.
> > > > > > >>> They do try to rule out prokaryotes with:
> > > > > > >>>
> > > > > > >>> "... these cells probably lacked rigid cell walls. This eliminates both cyanobacteria and the eukaryotic chlorophyte algae as likely homologs, because multicellular form in these taxa is strongly influenced by their
> > > > > > >>> possession of rigid cell walls."
> > > > > > >>>
> > > > > > >>> This reliance on a single feature of *extant* cyanobacteria (some of which do have two very distinct kinds of cells)
> > > > > > >>> is a weakness which calls for independent corroboration, provided by more characteristically
> > > > > > >>> eukaryotic features.
> > > > > > >
> > > > > > > My first response to this post ended with my answer to the following question:
> > > > > > >
> > > > > > >> How big are these cells?
> > > > > > >
> > > > > > > I looked up a cyanobacterium with two very different kinds of cells, one with which I have an intimate acquaintance: *Anabaena*.
> > > > > > > Its cells are just about the same size as the ones of *Bicellum* *brasieri.* So the following was a false lead:
> > > > > > >
> > > > > > >> That could be a good clue. Of course one might
> > > > > > >> postulate giant cyanobacteria, I suppose.
> > > > > > >
> > > > > > >
> > > > > > > We are in full agreement about the following:
> > > > > > >
> > > > > > >> Of course what they would need
> > > > > > >> would be some character or other unique to animals. Perhaps something
> > > > > > >> molecular, if they can find any traces. Or it would be nice to find
> > > > > > >> collar cells or something similar.
> > > > > > >
> > > > > > > No such luck as collar cells with these organisms . Haven't you looked at the paper yet?
> > > > > > > You did not answer this question in your reply to my first reply.
> > > > > You seem uninterested in this whole discovery, John. This is the second time you've failed
> > > > > to answer this simple question.
> > > > >
> > > > > <snip for focus>
> > > > > > >>> The cyanobacteria of today may only represent the hardiest kinds that survived this ordeal by ice.
> > > > > > >
> > > > > > >> Still, cells similar to the cyanobacteria of today are the only ones we
> > > > > > >> have fossil evidence of before or after the Cryogenian.
> > > > > > >
> > > > > > > Can you give me a good source for them, apart from the ones (if any) found in stromatolites?
> > > > >
> > > > > > Those are the ones.
> > > > > Do you know of any articles or books that go into the exterior covering? Do we have any evidence that they
> > > > > were made of peptidoglycan, as is the case with modern cyanobacteria?
> > > > Here's the most recent comprehensive review of Cyanobacteria fossils:
> > > >
> > > > https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub
> > > Cyanobacteria evolution: Insight from the fossil record
> > > Catherine F.Demoulin, Yannick J.Lara, Luc Cornet, CamilleFrançois, DenisBaurain, AnnickWilmotte, Emmanuelle J.Javaux,
> > > Free Radical Biology and Medicine Volume 140, 20 August 2019, Pages 206-223
> > >
> > > Thank you very much, Erik. It does look like a very valuable resource on the subject.
> > > > Chemical remains are important information, but peptidoglycan (mentioned in the review) isn't discussed as
> > > > present in the fossils (no surprise there).
> > > >
> > > > I haven't read all of it yet, but I intend to. Considerable info is new to me.
> > > For me too. A quick skim fails to provide answers to the two questions that interest me most at the present time:
> > > (1) are cyanobacteria fossils from a billion or more years ago exclusively from stromatolites and
> > > (2) are they all thick-walled?
> > >
> > >
> > > I'll be looking at it off and on for about a week before posting on it. Mostly off: for the better part
> > > of this past academic year, my family has had to ration their time with me due to the tremendous burden
> > > of online teaching -- almost three times as time-consuming as in-person teaching. I've decided to give
> > > them some real quality and quantity time, so I'm going on a posting break until next Tuesday.
> > >
> > > Meanwhile, here's something y'all might think about: how rare is it to have fossils of any organisms which,
> > > like *Bicellum* *brasieri,* are from a billion or more years ago and are NOT from stromatolites?
> > >
> > >
> > I believe most of the cyanobacterial fossils are derived from stromatolites, but some are found in other
> > "microbially induced sedimentary structures (MISS)".
> >
> > Unsheathed cyanobacteria are known in the fossil record, but the majority of fossils are thick-walled, probably
> > due to tophonomy favoring the thick-walled specimens.
> There is also what might be called "identification bias": there are lots of different microorganisms in
> stromatolites, but the article you showed us judges whether a microorganism is a cyanobacterium
> based on its resemblance to extant cyanobacteria.
>
> https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub
>
> Its criteria are sufficiently stringent so that "only three taxa are unambiguously identified as cyanobacteria." [p. 209] Earlier on that page we see:
>
> "In this section, we discuss a selection of (1) unambiguous cyanobacteria microfossils for which morphological features and habitats coincide strikingly with modern lineages, (2) probable and possible cyanobacteria microfossils that share morphological similarities both with a taxon belonging to the cyanobacterial phylum and with other lineages belonging to another phylum or domain of life. The limited number of preservable characters, along with their taphonomic alteration, and possible morphological convergence, limits the interpretation of the fossil record."
>
> Criteria like these can also be responsible for putting the "first known cyanobacterium" a billion or
> more years later than the first photosynthetic autotroph on a direct line to the "first known." This
> autotroph might well qualify as a "cyanobacterium" if we knew it as intimately as we know extant ones.
>
> There is plenty of evidence, in the form of stromatolites and banded iron formations, of the action of
> photosynthetic autotrophs, going to maybe as billion years before the Great Oxidation Event (GOE).
> This article places the beginning of the GOE at 2.4 Ga, which itself is half a billion years before
> the "unambiguous" 1.9 Ga. for "the first known..."
>
> The 2.4 Ga dating seems to be "settled science":
>
> https://en.wikipedia.org/wiki/Great_Oxidation_Event
> Peter Nyikos
> Professor, Dept. of Mathematics -- standard disclaimer--
> U. of South Carolina at Columbia
> http://people.math.sc.edu/nyikos

On Tuesday, June 8, 2021 at 8:30:08 AM UTC-7, erik simpson wrote:
> On Tuesday, June 8, 2021 at 8:00:29 AM UTC-7, nyik...@gmail.com wrote:
> > On Wednesday, June 2, 2021 at 7:13:58 PM UTC-4, erik simpson wrote:
> > > On Wednesday, June 2, 2021 at 3:01:16 PM UTC-7, Peter Nyikos wrote:
> > > > On Tuesday, June 1, 2021 at 8:04:07 PM UTC-4, erik simpson wrote:
> > > > > On Tuesday, June 1, 2021 at 3:52:28 PM UTC-7, nyik...@gmail.com wrote:
> > > > > > On Tuesday, June 1, 2021 at 2:02:59 PM UTC-4, John Harshman wrote:
> > > > > > > On 6/1/21 10:12 AM, Peter Nyikos wrote:
> > > > > > > > On Saturday, May 29, 2021 at 9:16:28 AM UTC-4, John Harshman wrote:
> > > > > > > >> On 5/28/21 7:07 PM, Peter Nyikos wrote:
> > > > > > > >>> Over in talk.origins, there was a brief discussion of some fascinating fossils of first rate importance. Except for stromatolites, they are one of only a handful of fossil organisms from a gigayear or more ago. Named *Bicellum* *brasieri,* it possesses two distinct cell types, and AFAIK this sets it apart from all fossil species from more than 600 million years ago.
> > > > > > > >>>
> > > > > > > >>> It was described scientifically here:
> > > > > > > >>>
> > > > > > > >>> "A possible billion-year-old holozoan with differentiated multicellularity,"
> > > > > > > >>> by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
> > > > > > > >>> Martin Saunders, Charles H. Wellman,
> > > > > > > >>> Current Biology 31, 1--8 June 21, 2021
> > > > > > > >>>
> > > > > > > >>> https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3
> > > > > > > >>>
> > > > > > > >>> The article is free access. It includes many detailed photographs of a high magnification.
> > > > > > > >>>
> > > > > > > >>> The title is guardedly optimistic about it being an animal. It does try to narrow it down somewhat:
> > > > > > > >>>
> > > > > > > >>> "It seems reasonable to assume that Bicellum falls within one of
> > > > > > > >>> the lineages leading to one of the six clades that possess complex multicellularity today: animals, plants, florideophyte algae,
> > > > > > > >>> brown algae, ascomycete fungi, and basidiomycete fungi."
> > > > > > > >>>
> > > > > > > >>> The words "of eukaryotes" should have been inserted after "six clades".
> > > > > > > >> "complex" would seem to rule out any of the various multicellular
> > > > > > > >> prokaryotes.
> > > > > > > >>> They do try to rule out prokaryotes with:
> > > > > > > >>>
> > > > > > > >>> "... these cells probably lacked rigid cell walls. This eliminates both cyanobacteria and the eukaryotic chlorophyte algae as likely homologs, because multicellular form in these taxa is strongly influenced by their
> > > > > > > >>> possession of rigid cell walls."
> > > > > > > >>>
> > > > > > > >>> This reliance on a single feature of *extant* cyanobacteria (some of which do have two very distinct kinds of cells)
> > > > > > > >>> is a weakness which calls for independent corroboration, provided by more characteristically
> > > > > > > >>> eukaryotic features.
> > > > > > > >
> > > > > > > > My first response to this post ended with my answer to the following question:
> > > > > > > >
> > > > > > > >> How big are these cells?
> > > > > > > >
> > > > > > > > I looked up a cyanobacterium with two very different kinds of cells, one with which I have an intimate acquaintance: *Anabaena*.
> > > > > > > > Its cells are just about the same size as the ones of *Bicellum* *brasieri.* So the following was a false lead:
> > > > > > > >
> > > > > > > >> That could be a good clue. Of course one might
> > > > > > > >> postulate giant cyanobacteria, I suppose.
> > > > > > > >
> > > > > > > >
> > > > > > > > We are in full agreement about the following:
> > > > > > > >
> > > > > > > >> Of course what they would need
> > > > > > > >> would be some character or other unique to animals. Perhaps something
> > > > > > > >> molecular, if they can find any traces. Or it would be nice to find
> > > > > > > >> collar cells or something similar.
> > > > > > > >
> > > > > > > > No such luck as collar cells with these organisms . Haven't you looked at the paper yet?
> > > > > > > > You did not answer this question in your reply to my first reply.
> > > > > > You seem uninterested in this whole discovery, John. This is the second time you've failed
> > > > > > to answer this simple question.
> > > > > >
> > > > > > <snip for focus>
> > > > > > > >>> The cyanobacteria of today may only represent the hardiest kinds that survived this ordeal by ice.
> > > > > > > >
> > > > > > > >> Still, cells similar to the cyanobacteria of today are the only ones we
> > > > > > > >> have fossil evidence of before or after the Cryogenian.
> > > > > > > >
> > > > > > > > Can you give me a good source for them, apart from the ones (if any) found in stromatolites?
> > > > > >
> > > > > > > Those are the ones.
> > > > > > Do you know of any articles or books that go into the exterior covering? Do we have any evidence that they
> > > > > > were made of peptidoglycan, as is the case with modern cyanobacteria?
> > > > > Here's the most recent comprehensive review of Cyanobacteria fossils:
> > > > >
> > > > > https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub
> > > > Cyanobacteria evolution: Insight from the fossil record
> > > > Catherine F.Demoulin, Yannick J.Lara, Luc Cornet, CamilleFrançois, DenisBaurain, AnnickWilmotte, Emmanuelle J.Javaux,
> > > > Free Radical Biology and Medicine Volume 140, 20 August 2019, Pages 206-223
> > > >
> > > > Thank you very much, Erik. It does look like a very valuable resource on the subject.
> > > > > Chemical remains are important information, but peptidoglycan (mentioned in the review) isn't discussed as
> > > > > present in the fossils (no surprise there).
> > > > >
> > > > > I haven't read all of it yet, but I intend to. Considerable info is new to me.
> > > > For me too. A quick skim fails to provide answers to the two questions that interest me most at the present time:
> > > > (1) are cyanobacteria fossils from a billion or more years ago exclusively from stromatolites and
> > > > (2) are they all thick-walled?
> > > >
> > > >
> > > > I'll be looking at it off and on for about a week before posting on it. Mostly off: for the better part
> > > > of this past academic year, my family has had to ration their time with me due to the tremendous burden
> > > > of online teaching -- almost three times as time-consuming as in-person teaching. I've decided to give
> > > > them some real quality and quantity time, so I'm going on a posting break until next Tuesday.
> > > >
> > > > Meanwhile, here's something y'all might think about: how rare is it to have fossils of any organisms which,
> > > > like *Bicellum* *brasieri,* are from a billion or more years ago and are NOT from stromatolites?
> > > >
> > > >
> > > I believe most of the cyanobacterial fossils are derived from stromatolites, but some are found in other
> > > "microbially induced sedimentary structures (MISS)".
> > >
> > > Unsheathed cyanobacteria are known in the fossil record, but the majority of fossils are thick-walled, probably
> > > due to tophonomy favoring the thick-walled specimens.
> > There is also what might be called "identification bias": there are lots of different microorganisms in
> > stromatolites, but the article you showed us judges whether a microorganism is a cyanobacterium
> > based on its resemblance to extant cyanobacteria.
> >
> > https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub
> >
> > Its criteria are sufficiently stringent so that "only three taxa are unambiguously identified as cyanobacteria." [p. 209] Earlier on that page we see:
> >
> > "In this section, we discuss a selection of (1) unambiguous cyanobacteria microfossils for which morphological features and habitats coincide strikingly with modern lineages, (2) probable and possible cyanobacteria microfossils that share morphological similarities both with a taxon belonging to the cyanobacterial phylum and with other lineages belonging to another phylum or domain of life. The limited number of preservable characters, along with their taphonomic alteration, and possible morphological convergence, limits the interpretation of the fossil record."
> >
> > Criteria like these can also be responsible for putting the "first known cyanobacterium" a billion or
> > more years later than the first photosynthetic autotroph on a direct line to the "first known." This
> > autotroph might well qualify as a "cyanobacterium" if we knew it as intimately as we know extant ones.
> >
> > There is plenty of evidence, in the form of stromatolites and banded iron formations, of the action of
> > photosynthetic autotrophs, going to maybe as billion years before the Great Oxidation Event (GOE).
> > This article places the beginning of the GOE at 2.4 Ga, which itself is half a billion years before
> > the "unambiguous" 1.9 Ga. for "the first known..."
> >
> > The 2.4 Ga dating seems to be "settled science":
> >
> > https://en.wikipedia.org/wiki/Great_Oxidation_Event
> > Peter Nyikos
> > Professor, Dept. of Mathematics -- standard disclaimer--
> > U. of South Carolina at Columbia
> > http://people.math.sc.edu/nyikos
> There are stromatolites ~3.5 Gy old, but the micro-organisms that made them (assuming they aren't abiotic)
> are hard to identify. Most stromatolites don't contain identifiable bacteria, and there's no reason to
> believe modern examples contain the same micro-ecologies as the fossils. Unambiguity is probably
> inevitable dealing with baterial remains as old as 1 Gy, even if chemical signatures can be found. This
> summer I'm taking a trip to Wyoming to look at 2 Gy stromatolites near Medicine Bow moutain. They're in
> conjuction/contact with microbial mat fossils, but identification of specific organisms hasn't been made, that
> I'm aware of.

On Tuesday, June 1, 2021 at 8:12:43 AM UTC-4, John Harshman wrote:
> On 5/31/21 3:15 PM, Peter Nyikos wrote:
> > On Saturday, May 29, 2021 at 9:16:28 AM UTC-4, John Harshman wrote:
> >> On 5/28/21 7:07 PM, Peter Nyikos wrote:
> >>> Over in talk.origins, there was a brief discussion of some fascinating fossils of first rate importance. Except for stromatolites, they are one of only a handful of fossil organisms from a gigayear or more ago. Named *Bicellum* *brasieri,* it possesses two distinct cell types, and AFAIK this sets it apart from all fossil species from more than 600 million years ago.
> >>>
> >>> It was described scientifically here:
> >>>
> >>> "A possible billion-year-old holozoan with differentiated multicellularity,"
> >>> by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
> >>> Martin Saunders, Charles H. Wellman,
> >>> Current Biology 31, 1--8 June 21, 2021
> >>>
> >>> https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3
> >>>
> >>> The article is free access. It includes many detailed photographs of a high magnification.
> >>>
> >>> The title is guardedly optimistic about it being an animal. It does try to narrow it down somewhat:
> >>>
> >>> "It seems reasonable to assume that Bicellum falls within one of the lineages leading
> >>> to one of the six clades that possess complex multicellularity today: animals, plants, florideophyte algae,
> >>> brown algae, ascomycete fungi, and basidiomycete fungi."
> >>>
> >>> The words "of eukaryotes" should have been inserted after "six clades".
> >
> >> "complex" would seem to rule out any of the various multicellular
> >> prokaryotes.
> >
> > It also rules out these cells. The quoted "complex multicellularity" is pure gravy.

> If that's pure gravy, how much more gravious would addding "eukaryote" be?

It would have made the focus sharper on what they were talking about, as well as
helping to understand how "complex multicellularity" is defined by the authors.

Their definition is demanding enough to exclude a seventh and eighth clade of eukaryotes: the plasmodial slime molds
and the cellular slime molds. One plasmodial slime mold produces 8 different kinds of reproductive cells:

When *Physarum* *polycephalum* is ready to make its reproductive cells, it grows a bulbous extension of its body to contain them.[15] Each cell is created with a random combination of the genes that the slime mold contains within its genome. Therefore, it can create cells with up to eight different gene types. Once these cells are released, they are independent and tasked with finding another cell it is able to fuse with.

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

Then this webpage talks about a cellular slime mold that produces eleven different gene types.

Before we get further, it may

> > By the way, I saw no argument in the paper that they ought to be on the stem of one of the six clades; why not
> > a clade that includes two or three of them, eh?

> Because multicellularity arose independently within each of those six
> clades and can't parsimoniously be attributed to the common ancestor of
> any two of them.

As you know, characters can frequently be lost, and multicellularity strikes me as being one of them,
as long as some cell is capable of reproducing on its own. Some slime molds may be like that.
> > Remember all the different ways of rooting the tree Eukaria, that could not be ruled out? We took a
> > good long look at them on the talk.origins thread where the mysteries of meiosis were the topic.

> Yes, and none of those ways changes the number of independent origins of
> multicellularity.

That may come down to how you define "multicellularity." Cellular slime molds are unicellular
for most of their life cycles. As for plasmodial slime molds, they could either be regarded in
the main part of their life cycles as one giant cell with innumerable nuclei, or a whole lot of
cells that do not have partitions between the individual cells.

> >>> They do try to rule out prokaryotes with:
> >>>
> >>> "... these cells probably lacked rigid cell walls. This eliminates both cyanobacteria and the eukaryotic chlorophyte algae as likely homologs, because multicellular form in these taxa is strongly influenced by their
> >>> possession of rigid cell walls."
> >>>
> >>> This reliance on a single feature of *extant* cyanobacteria (some of which do have two very distinct kinds of cells)
> >>> is a weakness which calls for independent corroboration, provided by more characteristically
> >>> eukaryotic features.
> >
> >
> >> How big are these cells?
> >
> > Haven't you looked at the paper yet? They are quite small: the whole organism is less than 50 microns in diameter,
> > and the individual cells less than 5 microns.

> That seems quite small for a eukaryotic cell, doesn't it? It's large for
> a prokaryote, but not unreasonably large. The average size is 2.5
> microns.

That's true of the ones in the inner cell masses of *Bicellum* *brasieri* Of the external cells, they say the following:

"The elongate cells that form the peripheral layer are around 1.5 to 2 [microns] in diameter and generally about 3 to 4 times that in length, although, in some cases, they can be much longer (e.g., Figure 2K). The average width-to-length ratio for a set of 6 specimens was 0.28 (Table S1)."

My earlier "less than 5 microns" was due my relying on the photographs which showed the elongate cells
in cross section.

> There are eukaryotes with cells less than 1 micron in diameter.
> Still, if we consider size alone these are more within the prokaryote
> than the eukaryote size distribution.

> >> That could be a good clue.
> >
> > Size is not a useful character at these scales. At one extreme is a giant spherical bacterium that gets to over 500 microns,
> > and thus visible to the naked eye:
> >
> > https://en.wikipedia.org/wiki/Thiomargarita_namibiensis
> >
> > Another of the same order of magnitude typically has an internal cell mass consisting of offspring
> > at some point in its life cycle:
> >
> > https://en.wikipedia.org/wiki/Epulopiscium
> >
> > It's doubtful, though, that the internal cells of *Bicellum* *brasieri* serve the same function; even
> > if they do, this is almost surely due to evolutionary convergence (homoplasy).
> >
> >
> > To be continued, hopefully today; if not, certainly tomorrow.
> >
> >
> > Peter Nyikos
> > Professor, Dept. of Mathematics . . -- standard disclaimer--
> > Univ. of South Carolina
> > http://people.math.sc.edu/nyikos
> >

Sometimes I will start a sentence, then get distracted by something further along.
The following is an amusing example:

On Tuesday, June 8, 2021 at 12:45:19 PM UTC-4, nyik...@gmail.com wrote:

> Before we get further, it may

[intended continuation:]
be good to ask whether this paper gives the first example of unambigously multicellular fossils, or at
least of the ones with more than one cell type. Even the latter would make this article a big game-changer.

A more modest claim would be that this is the earliest known example of an organism which cannot
be ruled out to be a metazoan.

Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
U. of South Carolina in Columbia
http://people.math.sc.edu/nyikos

On Tuesday, June 8, 2021 at 11:30:08 AM UTC-4, erik simpson wrote:
> On Tuesday, June 8, 2021 at 8:00:29 AM UTC-7, nyik...@gmail.com wrote:
> > On Wednesday, June 2, 2021 at 7:13:58 PM UTC-4, erik simpson wrote:
> > > On Wednesday, June 2, 2021 at 3:01:16 PM UTC-7, Peter Nyikos wrote:
> > > > On Tuesday, June 1, 2021 at 8:04:07 PM UTC-4, erik simpson wrote:

> > > > > Here's the most recent comprehensive review of Cyanobacteria fossils:
> > > > >
> > > > > https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub
> > > > Cyanobacteria evolution: Insight from the fossil record
> > > > Catherine F.Demoulin, Yannick J.Lara, Luc Cornet, CamilleFrançois, DenisBaurain, AnnickWilmotte, Emmanuelle J.Javaux,
> > > > Free Radical Biology and Medicine Volume 140, 20 August 2019, Pages 206-223
> > > >
> > > > Thank you very much, Erik. It does look like a very valuable resource on the subject.

> > > > > Chemical remains are important information, but peptidoglycan (mentioned in the review) isn't discussed as
> > > > > present in the fossils (no surprise there).
> > > > >
> > > > > I haven't read all of it yet, but I intend to. Considerable info is new to me.

> > > > For me too. A quick skim fails to provide answers to the two questions that interest me most at the present time:
> > > > (1) are cyanobacteria fossils from a billion or more years ago exclusively from stromatolites and
> > > > (2) are they all thick-walled?
> > > >
> > > >
> > > > I'll be looking at it off and on for about a week before posting on it. Mostly off: for the better part
> > > > of this past academic year, my family has had to ration their time with me due to the tremendous burden
> > > > of online teaching -- almost three times as time-consuming as in-person teaching. I've decided to give
> > > > them some real quality and quantity time, so I'm going on a posting break until next Tuesday.
> > > >
> > > > Meanwhile, here's something y'all might think about: how rare is it to have fossils of any organisms which,
> > > > like *Bicellum* *brasieri,* are from a billion or more years ago and are NOT from stromatolites?
> > > >
> > > >
> > > I believe most of the cyanobacterial fossils are derived from stromatolites, but some are found in other
> > > "microbially induced sedimentary structures (MISS)".
> > >
> > > Unsheathed cyanobacteria are known in the fossil record, but the majority of fossils are thick-walled, probably
> > > due to tophonomy favoring the thick-walled specimens.

> > There is also what might be called "identification bias": there are lots of different microorganisms in
> > stromatolites, but the article you showed us judges whether a microorganism is a cyanobacterium
> > based on its resemblance to extant cyanobacteria.
> >
> > https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub
> >
> > Its criteria are sufficiently stringent so that "only three taxa are unambiguously identified as cyanobacteria." [p. 209] Earlier on that page we see:
> >
> > "In this section, we discuss a selection of (1) unambiguous cyanobacteria microfossils for which morphological features and habitats coincide strikingly with modern lineages, (2) probable and possible cyanobacteria microfossils that share morphological similarities both with a taxon belonging to the cyanobacterial phylum and with other lineages belonging to another phylum or domain of life. The limited number of preservable characters, along with their taphonomic alteration, and possible morphological convergence, limits the interpretation of the fossil record."
> >
> > Criteria like these can also be responsible for putting the "first known cyanobacterium" a billion or
> > more years later than the first photosynthetic autotroph on a direct line to the "first known." This
> > autotroph might well qualify as a "cyanobacterium" if we knew it as intimately as we know extant ones.
> >
> > There is plenty of evidence, in the form of stromatolites and banded iron formations, of the action of
> > photosynthetic autotrophs, going to maybe as billion years before the Great Oxidation Event (GOE).
> > This article places the beginning of the GOE at 2.4 Ga, which itself is half a billion years before
> > the "unambiguous" 1.9 Ga. for "the first known..."
> >
> > The 2.4 Ga dating seems to be "settled science":
> >
> > https://en.wikipedia.org/wiki/Great_Oxidation_Event

Here's where your new text begins, Erik:

> There are stromatolites ~3.5 Gy old, but the micro-organisms that made them (assuming they aren't abiotic)
> are hard to identify.

Don't forget the independent evidence provided by banded iron formations. More about them below.

> Most stromatolites don't contain identifiable bacteria,

I wrote up there about "identification bias". There is a practical angle to it: one does not get
a paper accepted in prestigious journals by just writing

"______ different kinds of bacterial cells were tallied on fossil Stromatolite n.
Figures A through K show microphotographs of one representative of each kind."

One has to make a case for one or more prokaryotes being closely related to __________
if one wants professionals to perk up.

> and there's no reason to
> believe modern examples contain the same micro-ecologies as the fossils.

What sorts of micro-ecologies do you have in mind? One big difference was the nonexistence of
macro-organisms like *Kimberella* of the Ediacaran period that fed on bacterial mats.
We have plenty of animals today that fill a similar role, hence one only finds stromatolites
under harsh conditions such as the high salinity (and, I've been told, low oxygen) in Shark Bay, Australia.

So, the environment back before 1 Ga was probably much more benign, and so there might
be differences in the micro-ecology, but I have little idea of what they might have been.

> Unambiguity is probably
> inevitable dealing with baterial remains as old as 1 Gy, even if chemical signatures can be found. This
> summer I'm taking a trip to Wyoming to look at 2 Gy stromatolites near Medicine Bow moutain.

Happy fossil hunting! Will you be joining a group?

>They're in conjuction/contact with microbial mat fossils, but identification of specific organisms hasn't been made, that I'm aware of.

I first read about banded iron formations in an article by Isaak Asimov, who was a chemist by profession.
He wrote that the early ocean had an enormous amount of ferrous oxide dissolved in it.
[Unlike ferric oxide, which has one more oxygen atom, the ferrous is appreciably soluble in water.]

As oxygen came to be a waste product of various microorganisms [with cyanobacteria believed to
be the big contributors early on], in the oceans, it would change the ferrous form to the ferric, which
would precipitate out of the water and settle to the bottom, building the next band in the formation.

It wasn't until almost all the ferrous had been converted to ferric that free oxygen had a chance to
build up, first in the water and then in the atmosphere, leading to the GOE. After that, eukaryotes were able to come
out of obscurity by enveloping bacteria that were destined to become mitochondria.

For the sake of completeness, I should add that other things in the environment were attacked
by the oxygen (which, next to fluorine and perhaps chlorine, is the most reactive of the negatively acting elements)
and these, too, retarded the advent of the GOE.

Peter Nyikos
Professor, Department of Mathematics
University of So. Carolina at Columbia
http://people.math.sc.edu/nyikos

On Wednesday, June 9, 2021 at 2:22:54 PM UTC-7, Peter Nyikos wrote:
> On Tuesday, June 8, 2021 at 11:30:08 AM UTC-4, erik simpson wrote:
> > On Tuesday, June 8, 2021 at 8:00:29 AM UTC-7, nyik...@gmail.com wrote:
> > > On Wednesday, June 2, 2021 at 7:13:58 PM UTC-4, erik simpson wrote:
> > > > On Wednesday, June 2, 2021 at 3:01:16 PM UTC-7, Peter Nyikos wrote:
> > > > > On Tuesday, June 1, 2021 at 8:04:07 PM UTC-4, erik simpson wrote:
>
> > > > > > Here's the most recent comprehensive review of Cyanobacteria fossils:
> > > > > >
> > > > > > https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub
> > > > > Cyanobacteria evolution: Insight from the fossil record
> > > > > Catherine F.Demoulin, Yannick J.Lara, Luc Cornet, CamilleFrançois, DenisBaurain, AnnickWilmotte, Emmanuelle J.Javaux,
> > > > > Free Radical Biology and Medicine Volume 140, 20 August 2019, Pages 206-223
> > > > >
> > > > > Thank you very much, Erik. It does look like a very valuable resource on the subject.
>
> > > > > > Chemical remains are important information, but peptidoglycan (mentioned in the review) isn't discussed as
> > > > > > present in the fossils (no surprise there).
> > > > > >
> > > > > > I haven't read all of it yet, but I intend to. Considerable info is new to me.
>
> > > > > For me too. A quick skim fails to provide answers to the two questions that interest me most at the present time:
> > > > > (1) are cyanobacteria fossils from a billion or more years ago exclusively from stromatolites and
> > > > > (2) are they all thick-walled?
> > > > >
> > > > >
> > > > > I'll be looking at it off and on for about a week before posting on it. Mostly off: for the better part
> > > > > of this past academic year, my family has had to ration their time with me due to the tremendous burden
> > > > > of online teaching -- almost three times as time-consuming as in-person teaching. I've decided to give
> > > > > them some real quality and quantity time, so I'm going on a posting break until next Tuesday.
> > > > >
> > > > > Meanwhile, here's something y'all might think about: how rare is it to have fossils of any organisms which,
> > > > > like *Bicellum* *brasieri,* are from a billion or more years ago and are NOT from stromatolites?
> > > > >
> > > > >
> > > > I believe most of the cyanobacterial fossils are derived from stromatolites, but some are found in other
> > > > "microbially induced sedimentary structures (MISS)".
> > > >
> > > > Unsheathed cyanobacteria are known in the fossil record, but the majority of fossils are thick-walled, probably
> > > > due to tophonomy favoring the thick-walled specimens.
>
> > > There is also what might be called "identification bias": there are lots of different microorganisms in
> > > stromatolites, but the article you showed us judges whether a microorganism is a cyanobacterium
> > > based on its resemblance to extant cyanobacteria.
> > >
> > > https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub
> > >
> > > Its criteria are sufficiently stringent so that "only three taxa are unambiguously identified as cyanobacteria." [p. 209] Earlier on that page we see:
> > >
> > > "In this section, we discuss a selection of (1) unambiguous cyanobacteria microfossils for which morphological features and habitats coincide strikingly with modern lineages, (2) probable and possible cyanobacteria microfossils that share morphological similarities both with a taxon belonging to the cyanobacterial phylum and with other lineages belonging to another phylum or domain of life. The limited number of preservable characters, along with their taphonomic alteration, and possible morphological convergence, limits the interpretation of the fossil record."
> > >
> > > Criteria like these can also be responsible for putting the "first known cyanobacterium" a billion or
> > > more years later than the first photosynthetic autotroph on a direct line to the "first known." This
> > > autotroph might well qualify as a "cyanobacterium" if we knew it as intimately as we know extant ones.
> > >
> > > There is plenty of evidence, in the form of stromatolites and banded iron formations, of the action of
> > > photosynthetic autotrophs, going to maybe as billion years before the Great Oxidation Event (GOE).
> > > This article places the beginning of the GOE at 2.4 Ga, which itself is half a billion years before
> > > the "unambiguous" 1.9 Ga. for "the first known..."
> > >
> > > The 2.4 Ga dating seems to be "settled science":
> > >
> > > https://en.wikipedia.org/wiki/Great_Oxidation_Event
> Here's where your new text begins, Erik:
> > There are stromatolites ~3.5 Gy old, but the micro-organisms that made them (assuming they aren't abiotic)
> > are hard to identify.
> Don't forget the independent evidence provided by banded iron formations. More about them below.
> > Most stromatolites don't contain identifiable bacteria,
> I wrote up there about "identification bias". There is a practical angle to it: one does not get
> a paper accepted in prestigious journals by just writing
>
> "______ different kinds of bacterial cells were tallied on fossil Stromatolite n.
> Figures A through K show microphotographs of one representative of each kind."
>
> One has to make a case for one or more prokaryotes being closely related to __________
> if one wants professionals to perk up.
> > and there's no reason to
> > believe modern examples contain the same micro-ecologies as the fossils..
> What sorts of micro-ecologies do you have in mind? One big difference was the nonexistence of
> macro-organisms like *Kimberella* of the Ediacaran period that fed on bacterial mats.
> We have plenty of animals today that fill a similar role, hence one only finds stromatolites
> under harsh conditions such as the high salinity (and, I've been told, low oxygen) in Shark Bay, Australia.
>
> So, the environment back before 1 Ga was probably much more benign, and so there might
> be differences in the micro-ecology, but I have little idea of what they might have been.
> > Unambiguity is probably
> > inevitable dealing with baterial remains as old as 1 Gy, even if chemical signatures can be found. This
> > summer I'm taking a trip to Wyoming to look at 2 Gy stromatolites near Medicine Bow moutain.
> Happy fossil hunting! Will you be joining a group?
> >They're in conjuction/contact with microbial mat fossils, but identification of specific organisms hasn't been made, that I'm aware of.
> I first read about banded iron formations in an article by Isaak Asimov, who was a chemist by profession.
> He wrote that the early ocean had an enormous amount of ferrous oxide dissolved in it.
> [Unlike ferric oxide, which has one more oxygen atom, the ferrous is appreciably soluble in water.]
>
> As oxygen came to be a waste product of various microorganisms [with cyanobacteria believed to
> be the big contributors early on], in the oceans, it would change the ferrous form to the ferric, which
> would precipitate out of the water and settle to the bottom, building the next band in the formation.
>
> It wasn't until almost all the ferrous had been converted to ferric that free oxygen had a chance to
> build up, first in the water and then in the atmosphere, leading to the GOE. After that, eukaryotes were able to come
> out of obscurity by enveloping bacteria that were destined to become mitochondria.
>
> For the sake of completeness, I should add that other things in the environment were attacked
> by the oxygen (which, next to fluorine and perhaps chlorine, is the most reactive of the negatively acting elements)
> and these, too, retarded the advent of the GOE.
>
>
> Peter Nyikos
> Professor, Department of Mathematics
> University of So. Carolina at Columbia
> http://people.math.sc.edu/nyikos

No one seriously doubts that phototrophic bacteria existed before 1.8 Gya, but hard identification is problematic. The banded iron
formations attest to their existence, as you say.

Microbial mats and stromatolites now (and almost certainly then) contain multiple organisms, and some sort of cyanobacteria
was probably present in all the biotic examples. The pre-Ediacaran environment lacked macro predators or grazers to best of our
knowledge, but bacteria don't constitute the "peaceable kingdom". The GOE made us possible, but at the time it would have
been a catastrophe far exceeding AGW in its effects.

On 6/9/21 3:04 PM, erik simpson wrote:
> On Wednesday, June 9, 2021 at 2:22:54 PM UTC-7, Peter Nyikos wrote:
>> On Tuesday, June 8, 2021 at 11:30:08 AM UTC-4, erik simpson wrote:
>>> On Tuesday, June 8, 2021 at 8:00:29 AM UTC-7, nyik...@gmail.com wrote:
>>>> On Wednesday, June 2, 2021 at 7:13:58 PM UTC-4, erik simpson wrote:
>>>>> On Wednesday, June 2, 2021 at 3:01:16 PM UTC-7, Peter Nyikos wrote:
>>>>>> On Tuesday, June 1, 2021 at 8:04:07 PM UTC-4, erik simpson wrote:
>>
>>>>>>> Here's the most recent comprehensive review of Cyanobacteria
fossils:
>>>>>>>
>>>>>>>
https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub
>>>>>> Cyanobacteria evolution: Insight from the fossil record
>>>>>> Catherine F.Demoulin, Yannick J.Lara, Luc Cornet,
CamilleFrançois, DenisBaurain, AnnickWilmotte, Emmanuelle J.Javaux,
>>>>>> Free Radical Biology and Medicine Volume 140, 20 August 2019,
Pages 206-223
>>>>>>
>>>>>> Thank you very much, Erik. It does look like a very valuable
resource on the subject.
>>
>>>>>>> Chemical remains are important information, but peptidoglycan
(mentioned in the review) isn't discussed as
>>>>>>> present in the fossils (no surprise there).
>>>>>>>
>>>>>>> I haven't read all of it yet, but I intend to. Considerable
info is new to me.
>>
>>>>>> For me too. A quick skim fails to provide answers to the two
questions that interest me most at the present time:
>>>>>> (1) are cyanobacteria fossils from a billion or more years ago
exclusively from stromatolites and
>>>>>> (2) are they all thick-walled?
>>>>>>
>>>>>>
>>>>>> I'll be looking at it off and on for about a week before posting
on it. Mostly off: for the better part
>>>>>> of this past academic year, my family has had to ration their
time with me due to the tremendous burden
>>>>>> of online teaching -- almost three times as time-consuming as
in-person teaching. I've decided to give
>>>>>> them some real quality and quantity time, so I'm going on a
posting break until next Tuesday.
>>>>>>
>>>>>> Meanwhile, here's something y'all might think about: how rare is
it to have fossils of any organisms which,
>>>>>> like *Bicellum* *brasieri,* are from a billion or more years ago
and are NOT from stromatolites?
>>>>>>
>>>>>>
>>>>> I believe most of the cyanobacterial fossils are derived from
stromatolites, but some are found in other
>>>>> "microbially induced sedimentary structures (MISS)".
>>>>>
>>>>> Unsheathed cyanobacteria are known in the fossil record, but the
majority of fossils are thick-walled, probably
>>>>> due to tophonomy favoring the thick-walled specimens.
>>
>>>> There is also what might be called "identification bias": there
are lots of different microorganisms in
>>>> stromatolites, but the article you showed us judges whether a
microorganism is a cyanobacterium
>>>> based on its resemblance to extant cyanobacteria.
>>>>
>>>>
https://www.sciencedirect.com/science/article/pii/S0891584918324845?via%3Dihub
>>>>
>>>> Its criteria are sufficiently stringent so that "only three taxa
are unambiguously identified as cyanobacteria." [p. 209] Earlier on that
page we see:
>>>>
>>>> "In this section, we discuss a selection of (1) unambiguous
cyanobacteria microfossils for which morphological features and habitats
coincide strikingly with modern lineages, (2) probable and possible
cyanobacteria microfossils that share morphological similarities both
with a taxon belonging to the cyanobacterial phylum and with other
lineages belonging to another phylum or domain of life. The limited
number of preservable characters, along with their taphonomic
alteration, and possible morphological convergence, limits the
interpretation of the fossil record."
>>>>
>>>> Criteria like these can also be responsible for putting the "first
known cyanobacterium" a billion or
>>>> more years later than the first photosynthetic autotroph on a
direct line to the "first known." This
>>>> autotroph might well qualify as a "cyanobacterium" if we knew it
as intimately as we know extant ones.
>>>>
>>>> There is plenty of evidence, in the form of stromatolites and
banded iron formations, of the action of
>>>> photosynthetic autotrophs, going to maybe as billion years before
the Great Oxidation Event (GOE).
>>>> This article places the beginning of the GOE at 2.4 Ga, which
itself is half a billion years before
>>>> the "unambiguous" 1.9 Ga. for "the first known..."
>>>>
>>>> The 2.4 Ga dating seems to be "settled science":
>>>>
>>>> https://en.wikipedia.org/wiki/Great_Oxidation_Event
>> Here's where your new text begins, Erik:
>>> There are stromatolites ~3.5 Gy old, but the micro-organisms that
made them (assuming they aren't abiotic)
>>> are hard to identify.
>> Don't forget the independent evidence provided by banded iron
formations. More about them below.
>>> Most stromatolites don't contain identifiable bacteria,
>> I wrote up there about "identification bias". There is a practical
angle to it: one does not get
>> a paper accepted in prestigious journals by just writing
>>
>> "______ different kinds of bacterial cells were tallied on fossil
Stromatolite n.
>> Figures A through K show microphotographs of one representative of
each kind."
>>
>> One has to make a case for one or more prokaryotes being closely
related to __________
>> if one wants professionals to perk up.
>>> and there's no reason to
>>> believe modern examples contain the same micro-ecologies as the
fossils.
>> What sorts of micro-ecologies do you have in mind? One big
difference was the nonexistence of
>> macro-organisms like *Kimberella* of the Ediacaran period that fed
on bacterial mats.
>> We have plenty of animals today that fill a similar role, hence one
only finds stromatolites
>> under harsh conditions such as the high salinity (and, I've been
told, low oxygen) in Shark Bay, Australia.
>>
>> So, the environment back before 1 Ga was probably much more benign,
and so there might
>> be differences in the micro-ecology, but I have little idea of what
they might have been.
>>> Unambiguity is probably
>>> inevitable dealing with baterial remains as old as 1 Gy, even if
chemical signatures can be found. This
>>> summer I'm taking a trip to Wyoming to look at 2 Gy stromatolites
near Medicine Bow moutain.
>> Happy fossil hunting! Will you be joining a group?
>>> They're in conjuction/contact with microbial mat fossils, but
identification of specific organisms hasn't been made, that I'm aware of.
>> I first read about banded iron formations in an article by Isaak
Asimov, who was a chemist by profession.
>> He wrote that the early ocean had an enormous amount of ferrous
oxide dissolved in it.
>> [Unlike ferric oxide, which has one more oxygen atom, the ferrous is
appreciably soluble in water.]
>>
>> As oxygen came to be a waste product of various microorganisms [with
cyanobacteria believed to
>> be the big contributors early on], in the oceans, it would change
the ferrous form to the ferric, which
>> would precipitate out of the water and settle to the bottom,
building the next band in the formation.
>>
>> It wasn't until almost all the ferrous had been converted to ferric
that free oxygen had a chance to
>> build up, first in the water and then in the atmosphere, leading to
the GOE. After that, eukaryotes were able to come
>> out of obscurity by enveloping bacteria that were destined to become
mitochondria.
>>
>> For the sake of completeness, I should add that other things in the
environment were attacked
>> by the oxygen (which, next to fluorine and perhaps chlorine, is the
most reactive of the negatively acting elements)
>> and these, too, retarded the advent of the GOE.
>>
>>
>> Peter Nyikos
>> Professor, Department of Mathematics
>> University of So. Carolina at Columbia
>> http://people.math.sc.edu/nyikos
>
> No one seriously doubts that phototrophic bacteria existed before 1.8
Gya, but hard identification is problematic. The banded iron
> formations attest to their existence, as you say.
>
> Microbial mats and stromatolites now (and almost certainly then)
contain multiple organisms, and some sort of cyanobacteria
> was probably present in all the biotic examples. The pre-Ediacaran
environment lacked macro predators or grazers to best of our
> knowledge, but bacteria don't constitute the "peaceable kingdom".
The GOE made us possible, but at the time it would have
> been a catastrophe far exceeding AGW in its effects.
>
> My planned trip to Wyoming isn't with any group other than possibly a
few of my outback friends. The hunting will be very easy,
> as I have GPS coordinate points to many of the fossils of interest.
They're also very macroscopic, some measuring many
> meters in diameter.