Molecular clock analyses definitely suggest that Bryozoa (AKA, the ectoprocts) should have been around during early Cambrian Explosion
times, though direct fossil evidence had long-constrained their first geologic occurrence to the early Ordovician, with a hotly debated,
putative bryozoa example reported from the late Cambrian.
A paper just published online, and now available for pdf download (as of October 27, 2021), describes what the authors call a potential
stem-group bryozoan, preserved as secondarily mineralized--phosphatized--specimens from Cambrian Stages 4 and 3,
Australia (Wirrealpa Limestone) and South China (Dengying Formation), respectively. They call it Protomelission gatehousei, whose original unmineralized body plan shares traits with several Bryozoa classes, including the soft-bodied Gymnolaemata (Ctenostomata).
By the way, the oldest bryozoans I've personally collected derives from
the lower Middle Ordovician Antelope Valley Limestone, Great Beatty Mudmound, western Nevada. See a photograph of them over at http://inyo.coffeecup.com/site/beatty/beatty15.html ,
Download the entire paper over at https://www.nature.com/articles/s41586-021-04033-w .
The abstract:
Bryozoans (also known as ectoprocts or moss animals) are aquatic,
dominantly sessile, filter-feeding lophophorates that construct an
organic or calcareous modular colonial (clonal) exoskeleton1–3. The presence of six major orders of bryozoans with\advanced polymorphisms in lower Ordovician rocks strongly suggests a Cambrian origin for the
largest and most diverse lophophorate phylum2,4–8. However, a lack of convincing bryozoan fossils from the Cambrian period has hampered
resolution of the true origins and character assembly of the earliest members of the group. Here we interpret the millimetric, erect,
bilaminate, secondarily phosphatized fossil Protomelission gatehousei9
from the early Cambrian of Australia and South China as a potential stem-group bryozoan. The monomorphic zooid capsules, modular
construction, organic composition and simple linear budding growth
geometry represent a mixture of organic Gymnolaemata and biomineralized Stenolaemata character traits, with phylogenetic analyses identifying P. gatehousei as a stem-group bryozoan. This aligns the origin of phylum Bryozoa with all other skeletonized phyla in Cambrian Age 3, pushing
back its first occurrence by approximately 35 million years. It also reconciles the fossil record with molecular clock estimations of an
early Cambrian origination and subsequent Ordovician radiation of
Bryozoa following the acquisition of a carbonate skeleton.
Molecular clock analyses definitely suggest that Bryozoa (AKA, the ectoprocts) should have been around during early Cambrian Explosion
times, though direct fossil evidence had long-constrained their first geologic occurrence to the early Ordovician, with a hotly debated,
putative bryozoa example reported from the late Cambrian.
A paper just published online, and now available for pdf download (as of October 27, 2021), describes what the authors call a potential
stem-group bryozoan, preserved as secondarily mineralized--phosphatized--specimens from Cambrian Stages 4 and 3,
Australia (Wirrealpa Limestone) and South China (Dengying Formation), respectively. They call it Protomelission gatehousei, whose original unmineralized body plan shares traits with several Bryozoa classes,
including the soft-bodied Gymnolaemata (Ctenostomata).
By the way, the oldest bryozoans I've personally collected derives from
the lower Middle Ordovician Antelope Valley Limestone, Great Beatty
Mudmound, western Nevada. See a photograph of them over at http://inyo.coffeecup.com/site/beatty/beatty15.html ,
Download the entire paper over at https://www.nature.com/articles/s41586-021-04033-w .
The abstract:
Bryozoans (also known as ectoprocts or moss animals) are aquatic,
dominantly sessile, filter-feeding lophophorates that construct an
organic or calcareous modular colonial (clonal) exoskeleton1–3. The presence of six major orders of bryozoans with\advanced polymorphisms in lower Ordovician rocks strongly suggests a Cambrian origin for the
largest and most diverse lophophorate phylum2,4–8. However, a lack of convincing bryozoan fossils from the Cambrian period has hampered
resolution of the true origins and character assembly of the earliest
members of the group. Here we interpret the millimetric, erect,
bilaminate, secondarily phosphatized fossil Protomelission gatehousei9
from the early Cambrian of Australia and South China as a potential stem-group bryozoan. The monomorphic zooid capsules, modular
construction, organic composition and simple linear budding growth
geometry represent a mixture of organic Gymnolaemata and biomineralized Stenolaemata character traits, with phylogenetic analyses identifying P. gatehousei as a stem-group bryozoan. This aligns the origin of phylum
Bryozoa with all other skeletonized phyla in Cambrian Age 3, pushing
back its first occurrence by approximately 35 million years. It also reconciles the fossil record with molecular clock estimations of an
early Cambrian origination and subsequent Ordovician radiation of
Bryozoa following the acquisition of a carbonate skeleton.
On Wednesday, October 27, 2021 at 5:43:37 PM UTC-7, Inyo wrote:
Molecular clock analyses definitely suggest that Bryozoa (AKA, the
ectoprocts) should have been around during early Cambrian Explosion
times, though direct fossil evidence had long-constrained their first
geologic occurrence to the early Ordovician, with a hotly debated,
putative bryozoa example reported from the late Cambrian.
A paper just published online, and now available for pdf download (as of
October 27, 2021), describes what the authors call a potential
stem-group bryozoan, preserved as secondarily
mineralized--phosphatized--specimens from Cambrian Stages 4 and 3,
Australia (Wirrealpa Limestone) and South China (Dengying Formation),
respectively. They call it Protomelission gatehousei, whose original
unmineralized body plan shares traits with several Bryozoa classes,
including the soft-bodied Gymnolaemata (Ctenostomata).
By the way, the oldest bryozoans I've personally collected derives from
the lower Middle Ordovician Antelope Valley Limestone, Great Beatty
Mudmound, western Nevada. See a photograph of them over at
http://inyo.coffeecup.com/site/beatty/beatty15.html ,
Download the entire paper over at
https://www.nature.com/articles/s41586-021-04033-w .
The abstract:
Bryozoans (also known as ectoprocts or moss animals) are aquatic,
dominantly sessile, filter-feeding lophophorates that construct an
organic or calcareous modular colonial (clonal) exoskeleton1–3. The
presence of six major orders of bryozoans with\advanced polymorphisms in
lower Ordovician rocks strongly suggests a Cambrian origin for the
largest and most diverse lophophorate phylum2,4–8. However, a lack of
convincing bryozoan fossils from the Cambrian period has hampered
resolution of the true origins and character assembly of the earliest
members of the group. Here we interpret the millimetric, erect,
bilaminate, secondarily phosphatized fossil Protomelission gatehousei9
from the early Cambrian of Australia and South China as a potential
stem-group bryozoan. The monomorphic zooid capsules, modular
construction, organic composition and simple linear budding growth
geometry represent a mixture of organic Gymnolaemata and biomineralized
Stenolaemata character traits, with phylogenetic analyses identifying P.
gatehousei as a stem-group bryozoan. This aligns the origin of phylum
Bryozoa with all other skeletonized phyla in Cambrian Age 3, pushing
back its first occurrence by approximately 35 million years. It also
reconciles the fossil record with molecular clock estimations of an
early Cambrian origination and subsequent Ordovician radiation of
Bryozoa following the acquisition of a carbonate skeleton.
My first reaction is "how could I have missed this?", then I saw Oct. 27 2021! >Interesting find, confirming the molecular clock (and abundant and diverse Ordovician
forms) that the LCA must have been at least as far back as the early Cambrian. Good
catch!
On Wed, 27 Oct 2021 21:11:55 -0700 (PDT), erik simpson <eastside.erik@gmail.com> wrote:
On Wednesday, October 27, 2021 at 5:43:37 PM UTC-7, Inyo wrote:
Molecular clock analyses definitely suggest that Bryozoa (AKA, the
ectoprocts) should have been around during early Cambrian Explosion
times, though direct fossil evidence had long-constrained their first
geologic occurrence to the early Ordovician, with a hotly debated,
putative bryozoa example reported from the late Cambrian.
A paper just published online, and now available for pdf download (as of >>> October 27, 2021), describes what the authors call a potential
stem-group bryozoan, preserved as secondarily
mineralized--phosphatized--specimens from Cambrian Stages 4 and 3,
Australia (Wirrealpa Limestone) and South China (Dengying Formation),
respectively. They call it Protomelission gatehousei, whose original
unmineralized body plan shares traits with several Bryozoa classes,
including the soft-bodied Gymnolaemata (Ctenostomata).
By the way, the oldest bryozoans I've personally collected derives from
the lower Middle Ordovician Antelope Valley Limestone, Great Beatty
Mudmound, western Nevada. See a photograph of them over at
http://inyo.coffeecup.com/site/beatty/beatty15.html ,
Download the entire paper over at
https://www.nature.com/articles/s41586-021-04033-w .
The abstract:
Bryozoans (also known as ectoprocts or moss animals) are aquatic,
dominantly sessile, filter-feeding lophophorates that construct an
organic or calcareous modular colonial (clonal) exoskeleton1–3. The
presence of six major orders of bryozoans with\advanced polymorphisms in >>> lower Ordovician rocks strongly suggests a Cambrian origin for the
largest and most diverse lophophorate phylum2,4–8. However, a lack of
convincing bryozoan fossils from the Cambrian period has hampered
resolution of the true origins and character assembly of the earliest
members of the group. Here we interpret the millimetric, erect,
bilaminate, secondarily phosphatized fossil Protomelission gatehousei9
from the early Cambrian of Australia and South China as a potential
stem-group bryozoan. The monomorphic zooid capsules, modular
construction, organic composition and simple linear budding growth
geometry represent a mixture of organic Gymnolaemata and biomineralized
Stenolaemata character traits, with phylogenetic analyses identifying P. >>> gatehousei as a stem-group bryozoan. This aligns the origin of phylum
Bryozoa with all other skeletonized phyla in Cambrian Age 3, pushing
back its first occurrence by approximately 35 million years. It also
reconciles the fossil record with molecular clock estimations of an
early Cambrian origination and subsequent Ordovician radiation of
Bryozoa following the acquisition of a carbonate skeleton.
My first reaction is "how could I have missed this?", then I saw Oct. 27 2021!
Interesting find, confirming the molecular clock (and abundant and diverse Ordovician
forms) that the LCA must have been at least as far back as the early Cambrian. Good
catch!
Both the article, and what the article discusses are indeed
interesting finds. The discovery of a fossil bed that pushes the
origin of a phylum back over halfway across the Cambrian, is a
remarkable event indeed.
To refresh my understanding of Bryozoa, I looked up the Wikipedia
article. It mentions that it's unclear whether bryozoans should be considered protostomes or deuterostomes. Dare I ask, could this
discovery settle that question? And if so, would that have any impact
on the overall understanding of the evolution of life on Earth?
On Wed, 27 Oct 2021 21:11:55 -0700 (PDT), erik simpson
<eastsi...@gmail.com> wrote:
On Wednesday, October 27, 2021 at 5:43:37 PM UTC-7, Inyo wrote:
Molecular clock analyses definitely suggest that Bryozoa (AKA, the
ectoprocts) should have been around during early Cambrian Explosion
times, though direct fossil evidence had long-constrained their first
geologic occurrence to the early Ordovician, with a hotly debated,
putative bryozoa example reported from the late Cambrian.
A paper just published online, and now available for pdf download (as of >> October 27, 2021), describes what the authors call a potential
stem-group bryozoan, preserved as secondarily
mineralized--phosphatized--specimens from Cambrian Stages 4 and 3,
Australia (Wirrealpa Limestone) and South China (Dengying Formation),
respectively. They call it Protomelission gatehousei, whose original
unmineralized body plan shares traits with several Bryozoa classes,
including the soft-bodied Gymnolaemata (Ctenostomata).
By the way, the oldest bryozoans I've personally collected derives from >> the lower Middle Ordovician Antelope Valley Limestone, Great Beatty
Mudmound, western Nevada. See a photograph of them over at
http://inyo.coffeecup.com/site/beatty/beatty15.html ,
Download the entire paper over at
https://www.nature.com/articles/s41586-021-04033-w .
The abstract:
Bryozoans (also known as ectoprocts or moss animals) are aquatic,
dominantly sessile, filter-feeding lophophorates that construct an
organic or calcareous modular colonial (clonal) exoskeleton1–3. The
presence of six major orders of bryozoans with\advanced polymorphisms in >> lower Ordovician rocks strongly suggests a Cambrian origin for the
largest and most diverse lophophorate phylum2,4–8. However, a lack of >> convincing bryozoan fossils from the Cambrian period has hampered
resolution of the true origins and character assembly of the earliest
members of the group. Here we interpret the millimetric, erect,
bilaminate, secondarily phosphatized fossil Protomelission gatehousei9
from the early Cambrian of Australia and South China as a potential
stem-group bryozoan. The monomorphic zooid capsules, modular
construction, organic composition and simple linear budding growth
geometry represent a mixture of organic Gymnolaemata and biomineralized >> Stenolaemata character traits, with phylogenetic analyses identifying P. >> gatehousei as a stem-group bryozoan. This aligns the origin of phylum
Bryozoa with all other skeletonized phyla in Cambrian Age 3, pushing
back its first occurrence by approximately 35 million years. It also
reconciles the fossil record with molecular clock estimations of an
early Cambrian origination and subsequent Ordovician radiation of
Bryozoa following the acquisition of a carbonate skeleton.
My first reaction is "how could I have missed this?", then I saw Oct. 27 2021!Both the article, and what the article discusses are indeed
Interesting find, confirming the molecular clock (and abundant and diverse Ordovician
forms) that the LCA must have been at least as far back as the early Cambrian. Good
catch!
interesting finds. The discovery of a fossil bed that pushes the
origin of a phylum back over halfway across the Cambrian, is a
remarkable event indeed.
To refresh my understanding of Bryozoa, I looked up the Wikipedia
article. It mentions that it's unclear whether bryozoans should be considered protostomes or deuterostomes. Dare I ask, could this
discovery settle that question? And if so, would that have any impact
on the overall understanding of the evolution of life on Earth?
On Thursday, October 28, 2021 at 2:03:35 AM UTC-7, 69jp...@gmail.com wrote:
On Wed, 27 Oct 2021 21:11:55 -0700 (PDT), erik simpson
<eastsi...@gmail.com> wrote:
On Wednesday, October 27, 2021 at 5:43:37 PM UTC-7, Inyo wrote:Both the article, and what the article discusses are indeed
Molecular clock analyses definitely suggest that Bryozoa (AKA, the
ectoprocts) should have been around during early Cambrian Explosion
times, though direct fossil evidence had long-constrained their first
geologic occurrence to the early Ordovician, with a hotly debated,
putative bryozoa example reported from the late Cambrian.
A paper just published online, and now available for pdf download (as of >>>> October 27, 2021), describes what the authors call a potential
stem-group bryozoan, preserved as secondarily
mineralized--phosphatized--specimens from Cambrian Stages 4 and 3,
Australia (Wirrealpa Limestone) and South China (Dengying Formation),
respectively. They call it Protomelission gatehousei, whose original
unmineralized body plan shares traits with several Bryozoa classes,
including the soft-bodied Gymnolaemata (Ctenostomata).
By the way, the oldest bryozoans I've personally collected derives from >>>> the lower Middle Ordovician Antelope Valley Limestone, Great Beatty
Mudmound, western Nevada. See a photograph of them over at
http://inyo.coffeecup.com/site/beatty/beatty15.html ,
Download the entire paper over at
https://www.nature.com/articles/s41586-021-04033-w .
The abstract:
Bryozoans (also known as ectoprocts or moss animals) are aquatic,
dominantly sessile, filter-feeding lophophorates that construct an
organic or calcareous modular colonial (clonal) exoskeleton1–3. The
presence of six major orders of bryozoans with\advanced polymorphisms in >>>> lower Ordovician rocks strongly suggests a Cambrian origin for the
largest and most diverse lophophorate phylum2,4–8. However, a lack of >>>> convincing bryozoan fossils from the Cambrian period has hampered
resolution of the true origins and character assembly of the earliest
members of the group. Here we interpret the millimetric, erect,
bilaminate, secondarily phosphatized fossil Protomelission gatehousei9 >>>> from the early Cambrian of Australia and South China as a potential
stem-group bryozoan. The monomorphic zooid capsules, modular
construction, organic composition and simple linear budding growth
geometry represent a mixture of organic Gymnolaemata and biomineralized >>>> Stenolaemata character traits, with phylogenetic analyses identifying P. >>>> gatehousei as a stem-group bryozoan. This aligns the origin of phylum
Bryozoa with all other skeletonized phyla in Cambrian Age 3, pushing
back its first occurrence by approximately 35 million years. It also
reconciles the fossil record with molecular clock estimations of an
early Cambrian origination and subsequent Ordovician radiation of
Bryozoa following the acquisition of a carbonate skeleton.
My first reaction is "how could I have missed this?", then I saw Oct. 27 2021!
Interesting find, confirming the molecular clock (and abundant and diverse Ordovician
forms) that the LCA must have been at least as far back as the early Cambrian. Good
catch!
interesting finds. The discovery of a fossil bed that pushes the
origin of a phylum back over halfway across the Cambrian, is a
remarkable event indeed.
To refresh my understanding of Bryozoa, I looked up the Wikipedia
article. It mentions that it's unclear whether bryozoans should be
considered protostomes or deuterostomes. Dare I ask, could this
discovery settle that question? And if so, would that have any impact
on the overall understanding of the evolution of life on Earth?
A similar situation of long standing is the "origins" or trilobites. Pre-calcification
identification has been very elusive. Even so, the Ordovician Bryozoans display much
more diversity than the earliest trilobites.
On 10/28/21 2:03 AM, jillery wrote:
On Wed, 27 Oct 2021 21:11:55 -0700 (PDT), erik simpsonI don't think it's unclear at all. Bryozoans are protostomes (in the >phylogenetic sense).
<eastside.erik@gmail.com> wrote:
On Wednesday, October 27, 2021 at 5:43:37 PM UTC-7, Inyo wrote:
Molecular clock analyses definitely suggest that Bryozoa (AKA, the
ectoprocts) should have been around during early Cambrian Explosion
times, though direct fossil evidence had long-constrained their first
geologic occurrence to the early Ordovician, with a hotly debated,
putative bryozoa example reported from the late Cambrian.
A paper just published online, and now available for pdf download (as of >>>> October 27, 2021), describes what the authors call a potential
stem-group bryozoan, preserved as secondarily
mineralized--phosphatized--specimens from Cambrian Stages 4 and 3,
Australia (Wirrealpa Limestone) and South China (Dengying Formation),
respectively. They call it Protomelission gatehousei, whose original
unmineralized body plan shares traits with several Bryozoa classes,
including the soft-bodied Gymnolaemata (Ctenostomata).
By the way, the oldest bryozoans I've personally collected derives from >>>> the lower Middle Ordovician Antelope Valley Limestone, Great Beatty
Mudmound, western Nevada. See a photograph of them over at
http://inyo.coffeecup.com/site/beatty/beatty15.html ,
Download the entire paper over at
https://www.nature.com/articles/s41586-021-04033-w .
The abstract:
Bryozoans (also known as ectoprocts or moss animals) are aquatic,
dominantly sessile, filter-feeding lophophorates that construct an
organic or calcareous modular colonial (clonal) exoskeleton1–3. The
presence of six major orders of bryozoans with\advanced polymorphisms in >>>> lower Ordovician rocks strongly suggests a Cambrian origin for the
largest and most diverse lophophorate phylum2,4–8. However, a lack of >>>> convincing bryozoan fossils from the Cambrian period has hampered
resolution of the true origins and character assembly of the earliest
members of the group. Here we interpret the millimetric, erect,
bilaminate, secondarily phosphatized fossil Protomelission gatehousei9 >>>> from the early Cambrian of Australia and South China as a potential
stem-group bryozoan. The monomorphic zooid capsules, modular
construction, organic composition and simple linear budding growth
geometry represent a mixture of organic Gymnolaemata and biomineralized >>>> Stenolaemata character traits, with phylogenetic analyses identifying P. >>>> gatehousei as a stem-group bryozoan. This aligns the origin of phylum
Bryozoa with all other skeletonized phyla in Cambrian Age 3, pushing
back its first occurrence by approximately 35 million years. It also
reconciles the fossil record with molecular clock estimations of an
early Cambrian origination and subsequent Ordovician radiation of
Bryozoa following the acquisition of a carbonate skeleton.
My first reaction is "how could I have missed this?", then I saw Oct. 27 2021!
Interesting find, confirming the molecular clock (and abundant and diverse Ordovician
forms) that the LCA must have been at least as far back as the early Cambrian. Good
catch!
Both the article, and what the article discusses are indeed
interesting finds. The discovery of a fossil bed that pushes the
origin of a phylum back over halfway across the Cambrian, is a
remarkable event indeed.
To refresh my understanding of Bryozoa, I looked up the Wikipedia
article. It mentions that it's unclear whether bryozoans should be
considered protostomes or deuterostomes. Dare I ask, could this
discovery settle that question? And if so, would that have any impact
on the overall understanding of the evolution of life on Earth?
But this discovery has no bearing on the question.
What it clarifies is a taphonomic issue: bryozoans didn't originate in
the Ordovician; that's just when some of them gained mineralized skeletons.
On Thu, 28 Oct 2021 06:09:43 -0700, John Harshman
<jharshman@pacbell.net> wrote:
On 10/28/21 2:03 AM, jillery wrote:
On Wed, 27 Oct 2021 21:11:55 -0700 (PDT), erik simpsonI don't think it's unclear at all. Bryozoans are protostomes (in the
<eastside.erik@gmail.com> wrote:
On Wednesday, October 27, 2021 at 5:43:37 PM UTC-7, Inyo wrote:
Molecular clock analyses definitely suggest that Bryozoa (AKA, the
ectoprocts) should have been around during early Cambrian Explosion
times, though direct fossil evidence had long-constrained their first >>>>> geologic occurrence to the early Ordovician, with a hotly debated,
putative bryozoa example reported from the late Cambrian.
A paper just published online, and now available for pdf download (as of >>>>> October 27, 2021), describes what the authors call a potential
stem-group bryozoan, preserved as secondarily
mineralized--phosphatized--specimens from Cambrian Stages 4 and 3,
Australia (Wirrealpa Limestone) and South China (Dengying Formation), >>>>> respectively. They call it Protomelission gatehousei, whose original >>>>> unmineralized body plan shares traits with several Bryozoa classes,
including the soft-bodied Gymnolaemata (Ctenostomata).
By the way, the oldest bryozoans I've personally collected derives from >>>>> the lower Middle Ordovician Antelope Valley Limestone, Great Beatty
Mudmound, western Nevada. See a photograph of them over at
http://inyo.coffeecup.com/site/beatty/beatty15.html ,
Download the entire paper over at
https://www.nature.com/articles/s41586-021-04033-w .
The abstract:
Bryozoans (also known as ectoprocts or moss animals) are aquatic,
dominantly sessile, filter-feeding lophophorates that construct an
organic or calcareous modular colonial (clonal) exoskeleton1–3. The >>>>> presence of six major orders of bryozoans with\advanced polymorphisms in >>>>> lower Ordovician rocks strongly suggests a Cambrian origin for the
largest and most diverse lophophorate phylum2,4–8. However, a lack of >>>>> convincing bryozoan fossils from the Cambrian period has hampered
resolution of the true origins and character assembly of the earliest >>>>> members of the group. Here we interpret the millimetric, erect,
bilaminate, secondarily phosphatized fossil Protomelission gatehousei9 >>>>> from the early Cambrian of Australia and South China as a potential
stem-group bryozoan. The monomorphic zooid capsules, modular
construction, organic composition and simple linear budding growth
geometry represent a mixture of organic Gymnolaemata and biomineralized >>>>> Stenolaemata character traits, with phylogenetic analyses identifying P. >>>>> gatehousei as a stem-group bryozoan. This aligns the origin of phylum >>>>> Bryozoa with all other skeletonized phyla in Cambrian Age 3, pushing >>>>> back its first occurrence by approximately 35 million years. It also >>>>> reconciles the fossil record with molecular clock estimations of an
early Cambrian origination and subsequent Ordovician radiation of
Bryozoa following the acquisition of a carbonate skeleton.
My first reaction is "how could I have missed this?", then I saw Oct. 27 2021!
Interesting find, confirming the molecular clock (and abundant and diverse Ordovician
forms) that the LCA must have been at least as far back as the early Cambrian. Good
catch!
Both the article, and what the article discusses are indeed
interesting finds. The discovery of a fossil bed that pushes the
origin of a phylum back over halfway across the Cambrian, is a
remarkable event indeed.
To refresh my understanding of Bryozoa, I looked up the Wikipedia
article. It mentions that it's unclear whether bryozoans should be
considered protostomes or deuterostomes. Dare I ask, could this
discovery settle that question? And if so, would that have any impact
on the overall understanding of the evolution of life on Earth?
phylogenetic sense).
Your absolute certainty on the point raises the question why anybody
ever thought differently.
But this discovery has no bearing on the question.
What it clarifies is a taphonomic issue: bryozoans didn't originate in
the Ordovician; that's just when some of them gained mineralized skeletons.
I caught that from the cited article.
On 10/28/21 6:10 PM, jillery wrote:first
On Thu, 28 Oct 2021 06:09:43 -0700, John Harshman
<jharshman@pacbell.net> wrote:
On 10/28/21 2:03 AM, jillery wrote:
On Wed, 27 Oct 2021 21:11:55 -0700 (PDT), erik simpson
<eastside.erik@gmail.com> wrote:
On Wednesday, October 27, 2021 at 5:43:37 PM UTC-7, Inyo wrote:
Molecular clock analyses definitely suggest that Bryozoa (AKA, the
ectoprocts) should have been around during early Cambrian Explosion
times, though direct fossil evidence had long-constrained their
Formation),geologic occurrence to the early Ordovician, with a hotly debated,
putative bryozoa example reported from the late Cambrian.
A paper just published online, and now available for pdf download
(as of
October 27, 2021), describes what the authors call a potential
stem-group bryozoan, preserved as secondarily
mineralized--phosphatized--specimens from Cambrian Stages 4 and 3,
Australia (Wirrealpa Limestone) and South China (Dengying
lack ofrespectively. They call it Protomelission gatehousei, whose original
unmineralized body plan shares traits with several Bryozoa classes,
including the soft-bodied Gymnolaemata (Ctenostomata).
By the way, the oldest bryozoans I've personally collected derives
from
the lower Middle Ordovician Antelope Valley Limestone, Great Beatty
Mudmound, western Nevada. See a photograph of them over at
http://inyo.coffeecup.com/site/beatty/beatty15.html ,
Download the entire paper over at
https://www.nature.com/articles/s41586-021-04033-w .
The abstract:
Bryozoans (also known as ectoprocts or moss animals) are aquatic,
dominantly sessile, filter-feeding lophophorates that construct an
organic or calcareous modular colonial (clonal) exoskeleton1–3. The
presence of six major orders of bryozoans with\advanced
polymorphisms in
lower Ordovician rocks strongly suggests a Cambrian origin for the
largest and most diverse lophophorate phylum2,4–8. However, a
earliestconvincing bryozoan fossils from the Cambrian period has hampered
resolution of the true origins and character assembly of the
phylummembers of the group. Here we interpret the millimetric, erect,
bilaminate, secondarily phosphatized fossil Protomelission
gatehousei9
from the early Cambrian of Australia and South China as a potential
stem-group bryozoan. The monomorphic zooid capsules, modular
construction, organic composition and simple linear budding growth
geometry represent a mixture of organic Gymnolaemata and
biomineralized
Stenolaemata character traits, with phylogenetic analyses
identifying P.
gatehousei as a stem-group bryozoan. This aligns the origin of
I don't think it's unclear at all. Bryozoans are protostomes (in theBryozoa with all other skeletonized phyla in Cambrian Age 3, pushing
back its first occurrence by approximately 35 million years. It also
reconciles the fossil record with molecular clock estimations of an
early Cambrian origination and subsequent Ordovician radiation of
Bryozoa following the acquisition of a carbonate skeleton.
My first reaction is "how could I have missed this?", then I saw
Oct. 27 2021!
Interesting find, confirming the molecular clock (and abundant and
diverse Ordovician
forms) that the LCA must have been at least as far back as the
early Cambrian. Good
catch!
Both the article, and what the article discusses are indeed
interesting finds. The discovery of a fossil bed that pushes the
origin of a phylum back over halfway across the Cambrian, is a
remarkable event indeed.
To refresh my understanding of Bryozoa, I looked up the Wikipedia
article. It mentions that it's unclear whether bryozoans should be
considered protostomes or deuterostomes. Dare I ask, could this
discovery settle that question? And if so, would that have any impact
on the overall understanding of the evolution of life on Earth?
phylogenetic sense).
Your absolute certainty on the point raises the question why anybody
ever thought differently.
Simple enough: molecular data have greatly changed what we know and
don't know. Based purely on morphology, bryozoans are hard to figure
out. (So are brachiopods.) But the molecular data are clear.
But this discovery has no bearing on the question.
What it clarifies is a taphonomic issue: bryozoans didn't originate in
the Ordovician; that's just when some of them gained mineralized
skeletons.
I caught that from the cited article.
On 10/28/21 8:14 PM, John Harshman wrote:
On 10/28/21 6:10 PM, jillery wrote:first
On Thu, 28 Oct 2021 06:09:43 -0700, John Harshman
<jharshman@pacbell.net> wrote:
On 10/28/21 2:03 AM, jillery wrote:
On Wed, 27 Oct 2021 21:11:55 -0700 (PDT), erik simpson
<eastside.erik@gmail.com> wrote:
On Wednesday, October 27, 2021 at 5:43:37 PM UTC-7, Inyo wrote:
Molecular clock analyses definitely suggest that Bryozoa (AKA, the
ectoprocts) should have been around during early Cambrian Explosion
times, though direct fossil evidence had long-constrained their
Formation),geologic occurrence to the early Ordovician, with a hotly debated,
putative bryozoa example reported from the late Cambrian.
A paper just published online, and now available for pdf download
(as of
October 27, 2021), describes what the authors call a potential
stem-group bryozoan, preserved as secondarily
mineralized--phosphatized--specimens from Cambrian Stages 4 and 3,
Australia (Wirrealpa Limestone) and South China (Dengying
originalrespectively. They call it Protomelission gatehousei, whose
lack ofunmineralized body plan shares traits with several Bryozoa classes,
including the soft-bodied Gymnolaemata (Ctenostomata).
By the way, the oldest bryozoans I've personally collected derives
from
the lower Middle Ordovician Antelope Valley Limestone, Great Beatty
Mudmound, western Nevada. See a photograph of them over at
http://inyo.coffeecup.com/site/beatty/beatty15.html ,
Download the entire paper over at
https://www.nature.com/articles/s41586-021-04033-w .
The abstract:
Bryozoans (also known as ectoprocts or moss animals) are aquatic,
dominantly sessile, filter-feeding lophophorates that construct an
organic or calcareous modular colonial (clonal) exoskeleton1–3. The
presence of six major orders of bryozoans with\advanced
polymorphisms in
lower Ordovician rocks strongly suggests a Cambrian origin for the
largest and most diverse lophophorate phylum2,4–8. However, a
earliestconvincing bryozoan fossils from the Cambrian period has hampered
resolution of the true origins and character assembly of the
phylummembers of the group. Here we interpret the millimetric, erect,
bilaminate, secondarily phosphatized fossil Protomelission
gatehousei9
from the early Cambrian of Australia and South China as a potential
stem-group bryozoan. The monomorphic zooid capsules, modular
construction, organic composition and simple linear budding growth
geometry represent a mixture of organic Gymnolaemata and
biomineralized
Stenolaemata character traits, with phylogenetic analyses
identifying P.
gatehousei as a stem-group bryozoan. This aligns the origin of
pushingBryozoa with all other skeletonized phyla in Cambrian Age 3,
alsoback its first occurrence by approximately 35 million years. It
I don't think it's unclear at all. Bryozoans are protostomes (in thereconciles the fossil record with molecular clock estimations of an
early Cambrian origination and subsequent Ordovician radiation of
Bryozoa following the acquisition of a carbonate skeleton.
My first reaction is "how could I have missed this?", then I saw
Oct. 27 2021!
Interesting find, confirming the molecular clock (and abundant and
diverse Ordovician
forms) that the LCA must have been at least as far back as the
early Cambrian. Good
catch!
Both the article, and what the article discusses are indeed
interesting finds. The discovery of a fossil bed that pushes the
origin of a phylum back over halfway across the Cambrian, is a
remarkable event indeed.
To refresh my understanding of Bryozoa, I looked up the Wikipedia
article. It mentions that it's unclear whether bryozoans should be
considered protostomes or deuterostomes. Dare I ask, could this
discovery settle that question? And if so, would that have any impact
on the overall understanding of the evolution of life on Earth?
phylogenetic sense).
Your absolute certainty on the point raises the question why anybody
ever thought differently.
Simple enough: molecular data have greatly changed what we know and
don't know. Based purely on morphology, bryozoans are hard to figure
out. (So are brachiopods.) But the molecular data are clear.
So based on the molecular data, is it clear that bilatera is
monophyletic?
Is there anything from it that could suggest that some animals
with taxonomic bilateral symmetry at some stage of their development (including the echinoderms) could have separately arisen as offshoots
of the cnidarians in more than one branch?
Does the molecular evidence tend to indicate that animalia itself is polyphyletic? In other words sponges, cnidarians, ctenophores, and bilaterans all arose from eukaryotes separately and the nervous systems
of three of the four are the result of convergent evolution?
Is the least common ancestor of what is now called animalia not even multicellular, and it is not just sponges that are that way? Thus
perhaps the only thing they have in common is cholesterol to make cell membranes tough but flexible, and no cell walls?
You know, with every possibe branch, there is the possibility of
different interpretations.
What is the orthodox view on the formation of nervous systems?
Did they arise only once in the animal kingdom or did they
arise separately, once among the Cnidarians and a second
time among the Ctenophorans, with both of then having
similarities due to the functional nature of what nervous
systems do?
But this discovery has no bearing on the question.
What it clarifies is a taphonomic issue: bryozoans didn't originate in
the Ordovician; that's just when some of them gained mineralized
skeletons.
I caught that from the cited article.
Molecular clock analyses definitely suggest that Bryozoa (AKA, the ectoprocts) should have been around during early Cambrian Explosion
times, though direct fossil evidence had long-constrained their first geologic occurrence to the early Ordovician, with a hotly debated,
putative bryozoa example reported from the late Cambrian.
A paper just published online, and now available for pdf download (as of October 27, 2021), describes what the authors call a potential
stem-group bryozoan, preserved as secondarily mineralized--phosphatized--specimens from Cambrian Stages 4 and 3,
Australia (Wirrealpa Limestone) and South China (Dengying Formation), respectively. They call it Protomelission gatehousei, whose original unmineralized body plan shares traits with several Bryozoa classes,
including the soft-bodied Gymnolaemata (Ctenostomata).
By the way, the oldest bryozoans I've personally collected derives from
the lower Middle Ordovician Antelope Valley Limestone, Great Beatty
Mudmound, western Nevada. See a photograph of them over at http://inyo.coffeecup.com/site/beatty/beatty15.html ,
Download the entire paper over at https://www.nature.com/articles/s41586-021-04033-w .
The abstract:
Bryozoans (also known as ectoprocts or moss animals) are aquatic,
dominantly sessile, filter-feeding lophophorates that construct an
organic or calcareous modular colonial (clonal) exoskeleton1–3. The presence of six major orders of bryozoans with\advanced polymorphisms in lower Ordovician rocks strongly suggests a Cambrian origin for the
largest and most diverse lophophorate phylum2,4–8. However, a lack of convincing bryozoan fossils from the Cambrian period has hampered
resolution of the true origins and character assembly of the earliest
members of the group. Here we interpret the millimetric, erect,
bilaminate, secondarily phosphatized fossil Protomelission gatehousei9
from the early Cambrian of Australia and South China as a potential stem-group bryozoan. The monomorphic zooid capsules, modular
construction, organic composition and simple linear budding growth
geometry represent a mixture of organic Gymnolaemata and biomineralized Stenolaemata character traits, with phylogenetic analyses identifying P. gatehousei as a stem-group bryozoan. This aligns the origin of phylum
Bryozoa with all other skeletonized phyla in Cambrian Age 3, pushing
back its first occurrence by approximately 35 million years. It also reconciles the fossil record with molecular clock estimations of an
early Cambrian origination and subsequent Ordovician radiation of
Bryozoa following the acquisition of a carbonate skeleton.
On 10/27/2021 5:43 PM, Inyo wrote:
Molecular clock analyses definitely suggest that Bryozoa (AKA, the
ectoprocts) should have been around during early Cambrian Explosion
times, though direct fossil evidence had long-constrained their first
geologic occurrence to the early Ordovician, with a hotly debated,
putative bryozoa example reported from the late Cambrian.
A paper just published online, and now available for pdf download (as of
October 27, 2021), describes what the authors call a potential
stem-group bryozoan, preserved as secondarily
mineralized--phosphatized--specimens from Cambrian Stages 4 and 3,
Australia (Wirrealpa Limestone) and South China (Dengying Formation),
respectively. They call it Protomelission gatehousei, whose original
unmineralized body plan shares traits with several Bryozoa classes,
including the soft-bodied Gymnolaemata (Ctenostomata).
By the way, the oldest bryozoans I've personally collected derives from
the lower Middle Ordovician Antelope Valley Limestone, Great Beatty
Mudmound, western Nevada. See a photograph of them over at
http://inyo.coffeecup.com/site/beatty/beatty15.html ,
Download the entire paper over at
https://www.nature.com/articles/s41586-021-04033-w .
The abstract:
Bryozoans (also known as ectoprocts or moss animals) are aquatic,
dominantly sessile, filter-feeding lophophorates that construct an
organic or calcareous modular colonial (clonal) exoskeleton1–3. The
presence of six major orders of bryozoans with\advanced polymorphisms in
lower Ordovician rocks strongly suggests a Cambrian origin for the
largest and most diverse lophophorate phylum2,4–8. However, a lack of
convincing bryozoan fossils from the Cambrian period has hampered
resolution of the true origins and character assembly of the earliest
members of the group. Here we interpret the millimetric, erect,
bilaminate, secondarily phosphatized fossil Protomelission gatehousei9
from the early Cambrian of Australia and South China as a potential
stem-group bryozoan. The monomorphic zooid capsules, modular
construction, organic composition and simple linear budding growth
geometry represent a mixture of organic Gymnolaemata and biomineralized
Stenolaemata character traits, with phylogenetic analyses identifying P.
gatehousei as a stem-group bryozoan. This aligns the origin of phylum
Bryozoa with all other skeletonized phyla in Cambrian Age 3, pushing
back its first occurrence by approximately 35 million years. It also
reconciles the fossil record with molecular clock estimations of an
early Cambrian origination and subsequent Ordovician radiation of
Bryozoa following the acquisition of a carbonate skeleton.
On the paleontological heels of discovering the earliest
non-mineralized, soft-bodied byrozoan in Earth history (described in the
link provided, above) we now have a published report of possibly the
oldest mineralized bryozoan colony yet recovered from the fossil
record--it's from the lower Cambrian (Stage 4) Harkless Formation of Esmeralda County, Nevada, north of Death Valley National Park.
One caveat is that the investigators allow that confirmation of a "palaeostomate bryozoan affinity," would certainly involve finding an
early growth stage, bearing the ancestrula with an associated
protoecium. Nevertheless, the morphologic and taphonomic evidence
already scrutinized does indeed point to fully mineralized bryozoans
already well established in early Cambrian Explosion times, pushing back their first known mineralized occurrence in the geologic record by some
30 million years.
The abstract, from the full paper published online over at https://www.science.org/doi/10.1126/sciadv.abm8465 :
"All skeletal marine invertebrate phyla appeared during the Cambrian explosion, except for Bryozoa with mineralized skeletons, which first
appear in the Early Ordovician. However, the skeletal diversity of Early Ordovician bryozoans suggests a preceding interval of diversification.
We report a possible earliest occurrence of palaeostomate bryozoans in limestones of the Cambrian Age 4 Harkless Formation, western United
States. Following recent interpretations of the early Cambrian
Protomelission as a soft-bodied bryozoan, our findings add to the
evidence of early Cambrian roots for the Bryozoa. The Harkless fossils resemble some esthonioporate and cystoporate bryozoans, showing a
radiating pattern of densely packed tubes of the same diameter and cross-sectional shape. Further, they show partitioning of new
individuals from parent tubes through the formation of a separate wall,
a characteristic of interzooecial budding in bryozoans. If confirmed as bryozoans, these fossils would push back the appearance of mineralized skeletons in this phylum by ~30 million years and impact interpretations
of their evolution."
On 10/27/2021 5:43 PM, Inyo wrote:
Molecular clock analyses definitely suggest that Bryozoa (AKA, the ectoprocts) should have been around during early Cambrian Explosion
times, though direct fossil evidence had long-constrained their first geologic occurrence to the early Ordovician, with a hotly debated, putative bryozoa example reported from the late Cambrian.
A paper just published online, and now available for pdf download (as of October 27, 2021), describes what the authors call a potential
stem-group bryozoan, preserved as secondarily mineralized--phosphatized--specimens from Cambrian Stages 4 and 3, Australia (Wirrealpa Limestone) and South China (Dengying Formation), respectively. They call it Protomelission gatehousei, whose original unmineralized body plan shares traits with several Bryozoa classes, including the soft-bodied Gymnolaemata (Ctenostomata).
By the way, the oldest bryozoans I've personally collected derives from the lower Middle Ordovician Antelope Valley Limestone, Great Beatty Mudmound, western Nevada. See a photograph of them over at http://inyo.coffeecup.com/site/beatty/beatty15.html ,
Download the entire paper over at https://www.nature.com/articles/s41586-021-04033-w .
The abstract:
Bryozoans (also known as ectoprocts or moss animals) are aquatic, dominantly sessile, filter-feeding lophophorates that construct anOn the paleontological heels of discovering the earliest
organic or calcareous modular colonial (clonal) exoskeleton1–3. The presence of six major orders of bryozoans with\advanced polymorphisms in lower Ordovician rocks strongly suggests a Cambrian origin for the
largest and most diverse lophophorate phylum2,4–8. However, a lack of convincing bryozoan fossils from the Cambrian period has hampered resolution of the true origins and character assembly of the earliest members of the group. Here we interpret the millimetric, erect, bilaminate, secondarily phosphatized fossil Protomelission gatehousei9 from the early Cambrian of Australia and South China as a potential stem-group bryozoan. The monomorphic zooid capsules, modular
construction, organic composition and simple linear budding growth geometry represent a mixture of organic Gymnolaemata and biomineralized Stenolaemata character traits, with phylogenetic analyses identifying P. gatehousei as a stem-group bryozoan. This aligns the origin of phylum Bryozoa with all other skeletonized phyla in Cambrian Age 3, pushing
back its first occurrence by approximately 35 million years. It also reconciles the fossil record with molecular clock estimations of an
early Cambrian origination and subsequent Ordovician radiation of
Bryozoa following the acquisition of a carbonate skeleton.
non-mineralized, soft-bodied byrozoan in Earth history (described in the link provided, above) we now have a published report of possibly the
oldest mineralized bryozoan colony yet recovered from the fossil record--it's from the lower Cambrian (Stage 4) Harkless Formation of Esmeralda County, Nevada, north of Death Valley National Park.
One caveat is that the investigators allow that confirmation of a "palaeostomate bryozoan affinity," would certainly involve finding an
early growth stage, bearing the ancestrula with an associated
protoecium. Nevertheless, the morphologic and taphonomic evidence
already scrutinized does indeed point to fully mineralized bryozoans
already well established in early Cambrian Explosion times, pushing back their first known mineralized occurrence in the geologic record by some
30 million years.
The abstract, from the full paper published online over at https://www.science.org/doi/10.1126/sciadv.abm8465 :
"All skeletal marine invertebrate phyla appeared during the Cambrian explosion, except for Bryozoa with mineralized skeletons, which first
appear in the Early Ordovician. However, the skeletal diversity of Early Ordovician bryozoans suggests a preceding interval of diversification.
We report a possible earliest occurrence of palaeostomate bryozoans in limestones of the Cambrian Age 4 Harkless Formation, western United
States. Following recent interpretations of the early Cambrian Protomelission as a soft-bodied bryozoan, our findings add to the
evidence of early Cambrian roots for the Bryozoa. The Harkless fossils resemble some esthonioporate and cystoporate bryozoans, showing a
radiating pattern of densely packed tubes of the same diameter and cross-sectional shape. Further, they show partitioning of new
individuals from parent tubes through the formation of a separate wall,
a characteristic of interzooecial budding in bryozoans. If confirmed as bryozoans, these fossils would push back the appearance of mineralized skeletons in this phylum by ~30 million years and impact interpretations
of their evolution."
On 10/27/2021 5:43 PM, Inyo wrote:
Molecular clock analyses definitely suggest that Bryozoa (AKA, the ectoprocts) should have been around during early Cambrian Explosion
times, though direct fossil evidence had long-constrained their first geologic occurrence to the early Ordovician, with a hotly debated, putative bryozoa example reported from the late Cambrian.
A paper just published online, and now available for pdf download (as of October 27, 2021), describes what the authors call a potential
stem-group bryozoan, preserved as secondarily mineralized--phosphatized--specimens from Cambrian Stages 4 and 3, Australia (Wirrealpa Limestone) and South China (Dengying Formation), respectively. They call it Protomelission gatehousei, whose original unmineralized body plan shares traits with several Bryozoa classes, including the soft-bodied Gymnolaemata (Ctenostomata).
By the way, the oldest bryozoans I've personally collected derives from the lower Middle Ordovician Antelope Valley Limestone, Great Beatty Mudmound, western Nevada. See a photograph of them over at http://inyo.coffeecup.com/site/beatty/beatty15.html ,
Download the entire paper over at https://www.nature.com/articles/s41586-021-04033-w .
On the paleontological heels of discovering the earliest
non-mineralized, soft-bodied byrozoan in Earth history (described in the link provided, above) we now have a published report of possibly the
oldest mineralized bryozoan colony yet recovered from the fossil record--it's from the lower Cambrian (Stage 4) Harkless Formation of Esmeralda County, Nevada, north of Death Valley National Park.
One caveat is that the investigators allow that confirmation of a "palaeostomate bryozoan affinity," would certainly involve finding an
early growth stage, bearing the ancestrula with an associated
protoecium. Nevertheless, the morphologic and taphonomic evidence
already scrutinized does indeed point to fully mineralized bryozoans
already well established in early Cambrian Explosion times, pushing back their first known mineralized occurrence in the geologic record by some
30 million years.
The abstract, from the full paper published online over at https://www.science.org/doi/10.1126/sciadv.abm8465 :
"All skeletal marine invertebrate phyla appeared during the Cambrian explosion, except for Bryozoa with mineralized skeletons, which first
appear in the Early Ordovician. However, the skeletal diversity of Early Ordovician bryozoans suggests a preceding interval of diversification.
We report a possible earliest occurrence of palaeostomate bryozoans in limestones of the Cambrian Age 4 Harkless Formation, western United
States. Following recent interpretations of the early Cambrian Protomelission as a soft-bodied bryozoan, our findings add to the
evidence of early Cambrian roots for the Bryozoa. The Harkless fossils resemble some esthonioporate and cystoporate bryozoans, showing a
radiating pattern of densely packed tubes of the same diameter and cross-sectional shape. Further, they show partitioning of new
individuals from parent tubes through the formation of a separate wall,
a characteristic of interzooecial budding in bryozoans. If confirmed as bryozoans, these fossils would push back the appearance of mineralized skeletons in this phylum by ~30 million years and impact interpretations
of their evolution."
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