On Monday, September 25, 2023 at 9:26:21 AM UTC-6, erik simpson wrote:[...]
On Sunday, September 24, 2023 at 8:12:23 AM UTC-7, Sight Reader wrote:
On Friday, September 22, 2023 at 6:43:12 PM UTC-7, Peter Nyikos wrote:
I've long been familiar with some strange critters of the Triassic, but I was
really amazed at the variety that was displayed for us by Gary Meany, in Quora, of all places:
https://www.quora.com/What-is-the-most-interesting-period-in-the-ancient-history-of-Earth-Is-it-the-Triassic-the-Jurassic-the-Cambrian-the-Devonian-or-other/answer/Gary-Meaney
extinction event in Earth’s history.He starts out:
"It’s like choosing a favourite child, honestly, but I think I’ll go with the Triassic for today. This period started about 251 million years ago, immediately preceded by the infamous End-Permian Extinction - the most devastating
species. What this means is that, entering the Triassic, evolution practically had a clean slate to experiment with.""The cause of this mass extinction, also known as the Great Dying, is debated, but we do know it was immensely lethal. It’s thought that nearly 60% of all biological families were wiped out, including 70% of the world’s land vertebrate
Then the fun begins: one unusual animal after another, each one with a well-executed color picture.
What little I know I got from the Sues/Fraser book “Triassic Life on Land”. At maybe 20 years old, it’s already aging rapidly thanks to today’s ridiculous pace of discoveries.
The Paleocene resembles the Triassic with respect to the appearance of weird beasts that don't last
long in the evolutionary sense. For that matter, the same can be said for any rapid expansion into
new or recently vacated ecospace. The first arrivals in new territory got out of the blocks fast, but
may not be particularly well-adapted to conditions.
Certainly a lot of these guys fall under the “fast-but-inefficient” category;
however, we also have that end-Triassic extinction that may have wiped out a lotta guys that were doing perfectly well.
From what I recall, our Triassic information is so sparse that it would be hard to tell exactly how long some of these weird experiments persisted.
This is a reply to a post by Sight Reader on the thread, ""Fabulous Triassic Menagerie".
<big snip for focus>
Certainly a lot of these guys fall under the “fast-but-inefficient” category;Would you like to give us some examples that you found particularly striking, and why?
For that matter, the same can be said for any rapid expansion into new or recently vacated ecospace. The first
arrivals in new territory got out of the blocks fast, but may not be particularly well-adapted to conditions.
It would be very interesting to know when and why such big clades went extinct.
We could try chasing down all the critters in these clades for some clue as to whether any
were still hanging on at or near the end of the Triassic. But if that fails, the problem could
be the fault of what you wrote next:
From what I recall, our Triassic information is so sparse that it would be hard to tell exactly how long some of these weird experiments persisted.
There is at least one example of mega-evolution where the extinctions were due
to competition between two huge clades: Pterosauria and Avialae. At the beginning
of the Cretaceous, there were many kinds of small pterosaurs. Near the end, at the Upper Maaristrichtian, there was only one pterosaur whose wingspread was less than 2 meters, while ALL known birds were 2 meters or less, and there
were *many* genera of pterosaurs at 4 or (many!) more meters.
On Thursday, September 28, 2023 at 11:52:15 AM UTC-6, Peter Nyikos wrote:certainly seemed to jump all over the early Triassic when little else appeared to be left in the swamp. As the Triassic wore on, though, it seems as if various archosaurs - most notably phytosaurs - pushed them off the dominant role and started
This is a reply to a post by Sight Reader on the thread, ""Fabulous Triassic Menagerie".
<big snip for focus>To be clear, the comment I made about “fast but inefficient” was in support of the following remark by Mr. Simpson:
Certainly a lot of these guys fall under the “fast-but-inefficient” category;Would you like to give us some examples that you found particularly striking, and why?
For that matter, the same can be said for any rapid expansion into new or recently vacated ecospace. The firstTo me, a possible example of what Mr. Simpson was referring to would be the attempt by temnospondyls to secure the “top swamp predator spot” during the Triassic. I don’t know how important temnospondyls were back in the Permian, but they
arrivals in new territory got out of the blocks fast, but may not be particularly well-adapted to conditions.
Does this mean I am claiming that I know “for a fact” that archosaurs came in and competed for the exact same niche that temnospondyls had, that archosaurs and their hard eggs were provably “more efficient” than the amphibians, and thatarchosaurs were the direct cause for their decline? Of course not: its hard enough to figure out how anyone’s niche actually interacted with others, never mind determining the real reasons why any particular clade may have declined.
The same could be said for Lystrosaurus, those squat dicynodonts who “ruled the earth” (or at least the dry parts of it) for a few million years while everyone else was wiped out. Starting from complete dominance, we then see dicynodonts dwindle toincreasingly smaller and more specialized roles; however, as with temnospondyls, it’s hard to establish the exact details of “who”, “why”, or “how”.
enigmatic as - say - the “aphanosaurs”, it becomes really hard to tell if they were one of these outcompeted “fast and inefficient” guys like Mr. Simpson proposed or if they were a transitional phase of something that shows up later in a moreIt would be very interesting to know when and why such big clades went extinct.
We could try chasing down all the critters in these clades for some clue as to whether any
were still hanging on at or near the end of the Triassic. But if that fails, the problem could
be the fault of what you wrote next:
Well, in addition to the difficulties mentioned above in nailing down the true causes of decline, I find that there’s another problem with the Triassic in that it has a confounding number of transitional species. When they give us something asFrom what I recall, our Triassic information is so sparse that it would be hard to tell exactly how long some of these weird experiments persisted.
tug-of-war starting from back in the Triassic, where one could only seem to rise to dominance at the direct expense of the other. I think there’s only one rhynchocephalian left off of New Zealand somewhere.There is at least one example of mega-evolution where the extinctions were due
to competition between two huge clades: Pterosauria and Avialae. At the beginning
of the Cretaceous, there were many kinds of small pterosaurs. Near the end,
at the Upper Maaristrichtian, there was only one pterosaur whose wingspread
was less than 2 meters, while ALL known birds were 2 meters or less, and there
were *many* genera of pterosaurs at 4 or (many!) more meters.
Well, my knowledge is not as encyclopedic as yours, but the battle you relate reminds me of the epic battle between rhynchocephalians and today’s lizards. Those two clades seem to consist of guys that seemingly look and act alike and had an endless
It bears reiterating, though - I find it very dangerous to assume any of the wacky and weird animals running around towards the end of the Triassic (drepanosaurs, aetosaurs and the like) disappeared because they were in the “fast and inefficient”category when there’s a mass extinction looming. For all we know, such weirdos may have been on the verge of explosive dominance had not the wrath of the T-Jr extinction swept them from the stage.
On Thursday, September 28, 2023 at 11:52:15 AM UTC-6, Peter Nyikos wrote:certainly seemed to jump all over the early Triassic when little else appeared to be left in the swamp. As the Triassic wore on, though, it seems as if various archosaurs - most notably phytosaurs - pushed them off the dominant role and started
This is a reply to a post by Sight Reader on the thread, ""Fabulous Triassic Menagerie".
<big snip for focus>
Certainly a lot of these guys fall under the “fast-but-inefficient” category;
Would you like to give us some examples that you found particularly striking, and why?
To be clear, the comment I made about “fast but inefficient” was in support of the following remark by Mr. Simpson:
For that matter, the same can be said for any rapid expansion into new or recently vacated ecospace. The first
arrivals in new territory got out of the blocks fast, but may not be particularly well-adapted to conditions.
To me, a possible example of what Mr. Simpson was referring to would be the attempt by temnospondyls to secure the “top swamp predator spot” during the Triassic. I don’t know how important temnospondyls were back in the Permian, but they
Does this mean I am claiming that I know “for a fact” that archosaurs came in and competed for the exact same niche that temnospondyls had, that archosaurs and their hard eggs were provably “more efficient” than the amphibians, and thatarchosaurs were the direct cause for their decline? Of course not: its hard enough to figure out how anyone’s niche actually interacted with others, never mind determining the real reasons why any particular clade may have declined.
The same could be said for Lystrosaurus, those squat dicynodonts who “ruled the earth” (or at least the dry parts of it) for a few million years while everyone else was wiped out. Starting from complete dominance, we then see dicynodonts dwindle toincreasingly smaller and more specialized roles; however, as with temnospondyls, it’s hard to establish the exact details of “who”, “why”, or “how”.
enigmatic as - say - the “aphanosaurs”, it becomes really hard to tell if they were one of these outcompeted “fast and inefficient” guys like Mr. Simpson proposed or if they were a transitional phase of something that shows up later in a moreIt would be very interesting to know when and why such big clades went extinct.
We could try chasing down all the critters in these clades for some clue as to whether any
were still hanging on at or near the end of the Triassic. But if that fails, the problem could
be the fault of what you wrote next:
From what I recall, our Triassic information is so sparse that it would be hard to tell exactly how long some of these weird experiments persisted.
Well, in addition to the difficulties mentioned above in nailing down the true causes of decline, I find that there’s another problem with the Triassic in that it has a confounding number of transitional species. When they give us something as
There is at least one example of mega-evolution where the extinctions were due
to competition between two huge clades: Pterosauria and Avialae. At the beginning
of the Cretaceous, there were many kinds of small pterosaurs. Near the end,
at the Upper Maaristrichtian, there was only one pterosaur whose wingspread
was less than 2 meters, while ALL known birds were 2 meters or less, and there
were *many* genera of pterosaurs at 4 or (many!) more meters.
Well, my knowledge is not as encyclopedic as yours, but the battle you relate reminds me of the epic battle between rhynchocephalians and today’s lizards. Those two clades seem to consist of guys that seemingly look and act alike and had an endlesstug-of-war starting from back in the Triassic, where one could only seem to rise to dominance at the direct expense of the other. I think there’s only one rhynchocephalian left off of New Zealand somewhere.
It bears reiterating, though - I find it very dangerous to assume any of the wacky and weird animals running around towards the end of the Triassic (drepanosaurs, aetosaurs and the like) disappeared because they were in the “fast and inefficient”category when there’s a mass extinction looming. For all we know, such weirdos may have been on the verge of explosive dominance had not the wrath of the T-Jr extinction swept them from the stage.
Some of the giant Triassic temnospondyls have been described as "toilet seats with teeth", a very scary idea. Actually,
they probably occupied a niche since filled by alligators and crocodiles, but these came much later. They actually lasted
into the early Cretaceous, so they weren't really bad adapted for the job. But for the end-Triassic extinction, a fair number
of the early Triassic beasts may have stayed in the race. Dinosaurs didn't really "take over" until the Juirassic.
Some of the giant Triassic temnospondyls have been described as "toilet seats with teeth", a very scary idea.
Actually,
they probably occupied a niche since filled by alligators and crocodiles, but these came much later.
They actually lasted
into the early Cretaceous, so they weren't really bad adapted for the job.
But for the end-Triassic extinction, a fair number
of the early Triassic beasts may have stayed in the race. Dinosaurs didn't really "take over" until the Juirassic.
BTW, you could drop the "Mr. Simpson" address. I haven't been called that since grad school except by insurance agents
and the like. It's actually Dr. Simpson, but that's even worse. "Erik" is fine. I've been called that all my life.
On Friday, September 29, 2023 at 11:39:24 AM UTC-4, erik simpson wrote:
Some of the giant Triassic temnospondyls have been described as "toilet seats with teeth", a very scary idea.That's because they were incredibly flattened, like Gerrothorax in the Quora article I linked in the OP.
Otherwise, they were most like angler fish, which have even more formidable looking teeth.
Actually,IIRC the heyday of the temnospondyls was the Carboniferous. In the Permian, they were
they probably occupied a niche since filled by alligators and crocodiles, but these came much later.
already under attack by synapsids; Dimetrodon was one top predator, barring the bigger ones
from much of the dry land.
They actually lastedThey were, however, a rather specialized lot. Modern day amphibians are generally
into the early Cretaceous, so they weren't really bad adapted for the job.
believed to be descended from them, but there are other opinions held by many
paleontologists, including the one that frogs descended from temnospondyls, while salamanders and caecilians were lepospondyls.
But for the end-Triassic extinction, a fair number
of the early Triassic beasts may have stayed in the race. Dinosaurs didn't really "take over" until the Juirassic.
BTW, you could drop the "Mr. Simpson" address. I haven't been called that since grad school except by insurance agentsYou reminded me of an incident in soc.history.medieval ca. 1998, where some newcomer complained
and the like. It's actually Dr. Simpson, but that's even worse. "Erik" is fine. I've been called that all my life.
about people being disrespectful by not calling me Dr. Nyikos or Prof. Nyikos. One of the more
hostile women there said that I'm lucky if I'm called "Mr. Nyikos."
In reply, I paraphrased a beer commercial that had been popular two and a half decades earlier:
"You can call me `Pete,' you can call me `Peter', you can call me `Nyikos'; but you *doesn't* hafta call me `Mr. Nyikos'."
The bad grammar is from the commercial, which featured a yokel talking that way
about a brand of beer whose name ended with "Natural Light". The message was that
"Natural" was quite adequate for identification.
Peter Nyikos
Professor, Dept. of Mathematics
Univ. of South Carolina -- standard disclaimer-- http://people.math.sc.edu/nyikos
On Thursday, September 28, 2023 at 11:52:15 AM UTC-6, Peter Nyikos wrote:certainly seemed to jump all over the early Triassic when little else appeared to be left in the swamp.
This is a reply to a post by Sight Reader on the thread, ""Fabulous Triassic Menagerie".
<big snip for focus>
Certainly a lot of these guys fall under the “fast-but-inefficient” category;
Would you like to give us some examples that you found particularly striking, and why?
To be clear, the comment I made about “fast but inefficient” was in support of the following remark by Mr. Simpson:
For that matter, the same can be said for any rapid expansion into new or recently vacated ecospace. The first
arrivals in new territory got out of the blocks fast, but may not be particularly well-adapted to conditions.
To me, a possible example of what Mr. Simpson was referring to would be the attempt by temnospondyls to secure the “top swamp predator spot” during the Triassic. I don’t know how important temnospondyls were back in the Permian, but they
As the Triassic wore on, though, it seems as if various archosaurs - most notably phytosaurs - pushed them off the dominant role and started diminishing them, after which they were dealt a crippling blow by the T-Jr extinction.
Does this mean I am claiming that I know “for a fact” that archosaurs came in and competed for the exact same niche that temnospondyls had, that archosaurs and their hard eggs were provably “more efficient” than the amphibians, and thatarchosaurs were the direct cause for their decline? Of course not: its hard enough to figure out how anyone’s niche actually interacted with others, never mind determining the real reasons why any particular clade may have declined.
The same could be said for Lystrosaurus, those squat dicynodonts who “ruled the earth” (or at least the dry parts of it) for a few million years while everyone else was wiped out. Starting from complete dominance, we then see dicynodonts dwindle toincreasingly smaller and more specialized roles; however, as with temnospondyls, it’s hard to establish the exact details of “who”, “why”, or “how”.
enigmatic as - say - the “aphanosaurs”, it becomes really hard to tell if they were one of these outcompeted “fast and inefficient” guys like Mr. Simpson proposed or if they were a transitional phase of something that shows up later in a moreIt would be very interesting to know when and why such big clades went extinct.
We could try chasing down all the critters in these clades for some clue as to whether any
were still hanging on at or near the end of the Triassic. But if that fails, the problem could
be the fault of what you wrote next:
From what I recall, our Triassic information is so sparse that it would be hard to tell exactly how long some of these weird experiments persisted.
Well, in addition to the difficulties mentioned above in nailing down the true causes of decline, I find that there’s another problem with the Triassic in that it has a confounding number of transitional species. When they give us something as
Really hard to say much about such clades when the entire world has produced only a few fragments of them.
tug-of-war starting from back in the Triassic, where one could only seem to rise to dominance at the direct expense of the other.There is at least one example of mega-evolution where the extinctions were due
to competition between two huge clades: Pterosauria and Avialae. At the beginning
of the Cretaceous, there were many kinds of small pterosaurs. Near the end,
at the Upper Maaristrichtian, there was only one pterosaur whose wingspread
was less than 2 meters, while ALL known birds were 2 meters or less, and there
were *many* genera of pterosaurs at 4 or (many!) more meters.
Well, my knowledge is not as encyclopedic as yours, but the battle you relate reminds me of the epic battle between rhynchocephalians and today’s lizards. Those two clades seem to consist of guys that seemingly look and act alike and had an endless
What else was in the swamp before? There were a lot of lepospondyls, and I'll have to
review things later this week to see how they fared in the Triassic, or the Permian for that matter.
As for the Permian and Triassic amniotes, I didn't think of them as swamp critters.
Do you have any indication that the Permian ones played a big swamp role?
Their ancestors appeared well back in the Carboniferous, and I'll have to check
on them too this weekend.
As the Triassic wore on, though, it seems as if various archosaurs - most notably phytosaurs - pushed them off the dominant role and started diminishing them, after which they were dealt a crippling blow by the T-Jr extinction.Don't forget about the synapsids. There were some carnivorous ones all through
the Permian and the Triassic. The Triassic was dominated by the carnivorous therocephalians and the cynodonts, among whom the iconic *Cynognathus* was
a predator. The cynodonts also included *Thrinaxodon*, a genus used as the moniker
of a former sci.bio.paleontology regular, who almost destroyed s.b.p. by spam
before reinventing herself as Oxyaena, after having cleaned up that part of her act.
The synapsids were decimated by the end of Triassic extinction,
but were doing rather well before that:
This looks very promising, but it will take me quite a while to get really well-informed about this. My first impression is that lizards really
started to take off in the Cretaceous, followed by a big explosion after the K-P extinction.
But the Triassic and the Jurassic might have seen some real competition.
On Tuesday, October 3, 2023 at 12:18:04 PM UTC-7, Peter Nyikos wrote:
On Friday, September 29, 2023 at 11:39:24 AM UTC-4, erik simpson wrote:
Some of the giant Triassic temnospondyls have been described as "toilet seats with teeth", a very scary idea.That's because they were incredibly flattened, like Gerrothorax in the Quora article I linked in the OP.
Otherwise, they were most like angler fish, which have even more formidable looking teeth.
Actually,IIRC the heyday of the temnospondyls was the Carboniferous. In the Permian, they were
they probably occupied a niche since filled by alligators and crocodiles, but these came much later.
already under attack by synapsids; Dimetrodon was one top predator, barring the bigger ones
from much of the dry land.
They actually lasted
into the early Cretaceous, so they weren't really bad adapted for the job.
They were, however, a rather specialized lot. Modern day amphibians are generally
believed to be descended from them, but there are other opinions held by many
paleontologists, including the one that frogs descended from temnospondyls,
while salamanders and caecilians were lepospondyls.
But for the end-Triassic extinction, a fair number
of the early Triassic beasts may have stayed in the race. Dinosaurs didn't really "take over" until the Juirassic.
You probably meant that crown amphibians are descended from lepospondyls.
Paleontological consensus
is that temnospondyls are stem lissamphibians. https://en.wikipedia.org/wiki/Temnospondyli
As usual, my various commitments [many having to do with a test I gave one class and another
that I'll give on Monday] have left me with very little time for posting this week.
This is the only s.b.p. post I can do before going on my usual weekend posting break.
On Tuesday, October 3, 2023 at 7:06:12 PM UTC-4, erik simpson wrote:
On Tuesday, October 3, 2023 at 12:18:04 PM UTC-7, Peter Nyikos wrote:
On Friday, September 29, 2023 at 11:39:24 AM UTC-4, erik simpson wrote:
This was a mild senior moment. The OP where I linked that Quora article was in the other recentSome of the giant Triassic temnospondyls have been described as "toilet seats with teeth", a very scary idea.That's because they were incredibly flattened, like Gerrothorax in the Quora article I linked in the OP.
thread, "Fabulous Triassic Menagerie." Here is a link to the article itself:
https://www.quora.com/What-is-the-most-interesting-period-in-the-ancient-history-of-Earth-Is-it-the-Triassic-the-Jurassic-the-Cambrian-the-Devonian-or-other/answer/Gary-Meaney
Otherwise, they were most like angler fish, which have even more formidable looking teeth.
Actually,IIRC the heyday of the temnospondyls was the Carboniferous. In the Permian, they were
they probably occupied a niche since filled by alligators and crocodiles, but these came much later.
already under attack by synapsids; Dimetrodon was one top predator, barring the bigger ones
from much of the dry land.
They actually lasted
into the early Cretaceous, so they weren't really bad adapted for the job.
By "them" I meant some temnospondyls, but not the ones that survived into the Jurassic.They were, however, a rather specialized lot. Modern day amphibians are generally
believed to be descended from them, but there are other opinions held by many
paleontologists, including the one that frogs descended from temnospondyls,
while salamanders and caecilians were lepospondyls.
<snip to get to your latest words>But for the end-Triassic extinction, a fair number
of the early Triassic beasts may have stayed in the race. Dinosaurs didn't really "take over" until the Juirassic.
You probably meant that crown amphibians are descended from lepospondyls.No, I was just grabbing a few hypotheses that I have encountered over the years.
The actual phylogeny of early amphibians is a god-awful mess of competing hypotheses.
The "split ancestry" of lissamphibians (crown group amphibians) that I mentioned above
is the one endorsed by Romer, Colbert, and even Carroll (1988).
Paleontological consensusDid you not see the second cladogram on that webpage, which makes them out to be descended
is that temnospondyls are stem lissamphibians. https://en.wikipedia.org/wiki/Temnospondyli
from lepospondyls? That's exactly what you thought I meant to say (see above) --
but then, why did you make this last comment?
Peter NyikosThe second cladogram shows Lissamphibians and Temnospodyls (both within lepospondyla) are sister groups,
Professor, Dept. of Mathematics -- standard disclaimer--
University of South Carolina
https://people.math.sc.edu/nyikos
On Friday, October 6, 2023 at 6:02:08 PM UTC-7, Peter Nyikos wrote:
As usual, my various commitments [many having to do with a test I gave one class and another
that I'll give on Monday] have left me with very little time for posting this week.
This is the only s.b.p. post I can do before going on my usual weekend posting break.
On Tuesday, October 3, 2023 at 7:06:12 PM UTC-4, erik simpson wrote:
On Tuesday, October 3, 2023 at 12:18:04 PM UTC-7, Peter Nyikos wrote:
On Friday, September 29, 2023 at 11:39:24 AM UTC-4, erik simpson wrote:
This was a mild senior moment. The OP where I linked that Quora article was in the other recentSome of the giant Triassic temnospondyls have been described as "toilet seats with teeth", a very scary idea.That's because they were incredibly flattened, like Gerrothorax in the Quora article I linked in the OP.
thread, "Fabulous Triassic Menagerie." Here is a link to the article itself:
https://www.quora.com/What-is-the-most-interesting-period-in-the-ancient-history-of-Earth-Is-it-the-Triassic-the-Jurassic-the-Cambrian-the-Devonian-or-other/answer/Gary-Meaney
Otherwise, they were most like angler fish, which have even more formidable looking teeth.
Actually,IIRC the heyday of the temnospondyls was the Carboniferous. In the Permian, they were
they probably occupied a niche since filled by alligators and crocodiles, but these came much later.
already under attack by synapsids; Dimetrodon was one top predator, barring the bigger ones
from much of the dry land.
They actually lasted
into the early Cretaceous, so they weren't really bad adapted for the job.
By "them" I meant some temnospondyls, but not the ones that survived into the Jurassic.They were, however, a rather specialized lot. Modern day amphibians are generally
believed to be descended from them, but there are other opinions held by many
paleontologists, including the one that frogs descended from temnospondyls,
while salamanders and caecilians were lepospondyls.
<snip to get to your latest words>But for the end-Triassic extinction, a fair number
of the early Triassic beasts may have stayed in the race. Dinosaurs didn't really "take over" until the Juirassic.
You probably meant that crown amphibians are descended from lepospondyls.No, I was just grabbing a few hypotheses that I have encountered over the years.
The actual phylogeny of early amphibians is a god-awful mess of competing hypotheses.
The "split ancestry" of lissamphibians (crown group amphibians) that I mentioned above
is the one endorsed by Romer, Colbert, and even Carroll (1988).
Paleontological consensusDid you not see the second cladogram on that webpage, which makes them out to be descended
is that temnospondyls are stem lissamphibians. https://en.wikipedia.org/wiki/Temnospondyli
from lepospondyls? That's exactly what you thought I meant to say (see above) --
but then, why did you make this last comment?
Peter NyikosThe second cladogram shows Lissamphibians and Temnospodyls (both within lepospondyla) are sister groups,
Professor, Dept. of Mathematics -- standard disclaimer--
University of South Carolina
https://people.math.sc.edu/nyikos
of which temnospondyls are extinct.
Frogs are not descended from temnospondyls, although some in the past postulated that they may be.
Pre-1990 phylogenies are no longer "consensus phyulogeny".
On Friday, October 6, 2023 at 11:08:17 PM UTC-4, erik simpson wrote:
On Friday, October 6, 2023 at 6:02:08 PM UTC-7, Peter Nyikos wrote:
As usual, my various commitments [many having to do with a test I gave one class and another
that I'll give on Monday] have left me with very little time for posting this week.
This is the only s.b.p. post I can do before going on my usual weekend posting break.
On Tuesday, October 3, 2023 at 7:06:12 PM UTC-4, erik simpson wrote:
On Tuesday, October 3, 2023 at 12:18:04 PM UTC-7, Peter Nyikos wrote:
On Friday, September 29, 2023 at 11:39:24 AM UTC-4, erik simpson wrote:
This was a mild senior moment. The OP where I linked that Quora article was in the other recentSome of the giant Triassic temnospondyls have been described as "toilet seats with teeth", a very scary idea.That's because they were incredibly flattened, like Gerrothorax in the Quora article I linked in the OP.
thread, "Fabulous Triassic Menagerie." Here is a link to the article itself:
https://www.quora.com/What-is-the-most-interesting-period-in-the-ancient-history-of-Earth-Is-it-the-Triassic-the-Jurassic-the-Cambrian-the-Devonian-or-other/answer/Gary-Meaney
Otherwise, they were most like angler fish, which have even more formidable looking teeth.
Actually,IIRC the heyday of the temnospondyls was the Carboniferous. In the Permian, they were
they probably occupied a niche since filled by alligators and crocodiles, but these came much later.
already under attack by synapsids; Dimetrodon was one top predator, barring the bigger ones
from much of the dry land.
They actually lasted
into the early Cretaceous, so they weren't really bad adapted for the job.
By "them" I meant some temnospondyls, but not the ones that survived into the Jurassic.They were, however, a rather specialized lot. Modern day amphibians are generally
believed to be descended from them, but there are other opinions held by many
paleontologists, including the one that frogs descended from temnospondyls,
while salamanders and caecilians were lepospondyls.
<snip to get to your latest words>But for the end-Triassic extinction, a fair number
of the early Triassic beasts may have stayed in the race. Dinosaurs didn't really "take over" until the Juirassic.
You probably meant that crown amphibians are descended from lepospondyls.No, I was just grabbing a few hypotheses that I have encountered over the years.
The actual phylogeny of early amphibians is a god-awful mess of competing hypotheses.
The "split ancestry" of lissamphibians (crown group amphibians) that I mentioned above
is the one endorsed by Romer, Colbert, and even Carroll (1988).
Paleontological consensusDid you not see the second cladogram on that webpage, which makes them out to be descended
is that temnospondyls are stem lissamphibians. https://en.wikipedia.org/wiki/Temnospondyli
from lepospondyls? That's exactly what you thought I meant to say (see above) --
but then, why did you make this last comment?
Neither of the two cladograms with pictures put temnospondyls anywhere near lepospondyls.Peter NyikosThe second cladogram shows Lissamphibians and Temnospodyls (both within lepospondyla) are sister groups,
Professor, Dept. of Mathematics -- standard disclaimer--
University of South Carolina
https://people.math.sc.edu/nyikos
of which temnospondyls are extinct.
.
You seem to be outdoing me in senior moments on this thread. :-\
Frogs are not descended from temnospondyls, although some in the past postulated that they may be.I was using a little common sense: given their evolutionary history,
the LCA of lissamphibians and temnospondyls must have been much
more like a temnospondyl than a lissamphibian.
A few years ago, we had a similar divergence of opinion about
Ctenophora, and then John even agreed that the LCA of sponges
and ctenophores probably resembled a sponge.
Pre-1990 phylogenies are no longer "consensus phyulogeny".Because they (including Carroll, 1988) did not rely exclusively on cladistic analyses?
Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
University of So. Carolina at Columbia
http://people.math.sc.edu/nyikos
On Wednesday, October 11, 2023 at 1:58:11 PM UTC-7, Peter Nyikos wrote:
On Friday, October 6, 2023 at 11:08:17 PM UTC-4, erik simpson wrote:
On Friday, October 6, 2023 at 6:02:08 PM UTC-7, Peter Nyikos wrote:Neither of the two cladograms with pictures put temnospondyls anywhere near lepospondyls.
As usual, my various commitments [many having to do with a test I gave one class and anotherThe second cladogram shows Lissamphibians and Temnospodyls (both within lepospondyla) are sister groups,
that I'll give on Monday] have left me with very little time for posting this week.
This is the only s.b.p. post I can do before going on my usual weekend posting break.
On Tuesday, October 3, 2023 at 7:06:12 PM UTC-4, erik simpson wrote: >>>>> On Tuesday, October 3, 2023 at 12:18:04 PM UTC-7, Peter Nyikos wrote: >>>>>> On Friday, September 29, 2023 at 11:39:24 AM UTC-4, erik simpson wrote:
This was a mild senior moment. The OP where I linked that Quora article was in the other recent
Some of the giant Triassic temnospondyls have been described as "toilet seats with teeth", a very scary idea.That's because they were incredibly flattened, like Gerrothorax in the Quora article I linked in the OP.
thread, "Fabulous Triassic Menagerie." Here is a link to the article itself:
https://www.quora.com/What-is-the-most-interesting-period-in-the-ancient-history-of-Earth-Is-it-the-Triassic-the-Jurassic-the-Cambrian-the-Devonian-or-other/answer/Gary-Meaney
By "them" I meant some temnospondyls, but not the ones that survived into the Jurassic.Otherwise, they were most like angler fish, which have even more formidable looking teeth.
Actually,IIRC the heyday of the temnospondyls was the Carboniferous. In the Permian, they were
they probably occupied a niche since filled by alligators and crocodiles, but these came much later.
already under attack by synapsids; Dimetrodon was one top predator, barring the bigger ones
from much of the dry land.
They actually lasted
into the early Cretaceous, so they weren't really bad adapted for the job.
They were, however, a rather specialized lot. Modern day amphibians are generally
believed to be descended from them, but there are other opinions held by many
paleontologists, including the one that frogs descended from temnospondyls,
while salamanders and caecilians were lepospondyls.
<snip to get to your latest words>But for the end-Triassic extinction, a fair number
of the early Triassic beasts may have stayed in the race. Dinosaurs didn't really "take over" until the Juirassic.
You probably meant that crown amphibians are descended from lepospondyls. >>>> No, I was just grabbing a few hypotheses that I have encountered over the years.The actual phylogeny of early amphibians is a god-awful mess of competing hypotheses.
The "split ancestry" of lissamphibians (crown group amphibians) that I mentioned above
is the one endorsed by Romer, Colbert, and even Carroll (1988).
Paleontological consensusDid you not see the second cladogram on that webpage, which makes them out to be descended
is that temnospondyls are stem lissamphibians. https://en.wikipedia.org/wiki/Temnospondyli
from lepospondyls? That's exactly what you thought I meant to say (see above) --
but then, why did you make this last comment?
Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
University of South Carolina
https://people.math.sc.edu/nyikos
of which temnospondyls are extinct.
.
You seem to be outdoing me in senior moments on this thread. :-\
Frogs are not descended from temnospondyls, although some in the pastI was using a little common sense: given their evolutionary history,
postulated that they may be.
the LCA of lissamphibians and temnospondyls must have been much
more like a temnospondyl than a lissamphibian.
A few years ago, we had a similar divergence of opinion about
Ctenophora, and then John even agreed that the LCA of sponges
and ctenophores probably resembled a sponge.
Pre-1990 phylogenies are no longer "consensus phyulogeny".Because they (including Carroll, 1988) did not rely exclusively on cladistic analyses?
Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
University of So. Carolina at Columbia
http://people.math.sc.edu/nyikos
There are several cladograms; look at the second.
Ctenophores have nothing to do with this. Why you're dredging this up is unclear. Whether or
not something "looked like" is irrelevant to the DNA analysis, which is vwery difficult in this
case.
Cladistic analysis has little to do with it, DNA analysis has everything to do with it. All crown amphibians
are lissamphibians.
On Wednesday, October 11, 2023 at 1:58:11 PM UTC-7, Peter Nyikos wrote:
On Friday, October 6, 2023 at 11:08:17 PM UTC-4, erik simpson wrote:
On Friday, October 6, 2023 at 6:02:08 PM UTC-7, Peter Nyikos wrote:
As usual, my various commitments [many having to do with a test I gave one class and another
that I'll give on Monday] have left me with very little time for posting this week.
This is the only s.b.p. post I can do before going on my usual weekend posting break.
On Tuesday, October 3, 2023 at 7:06:12 PM UTC-4, erik simpson wrote:
On Tuesday, October 3, 2023 at 12:18:04 PM UTC-7, Peter Nyikos wrote:
On Friday, September 29, 2023 at 11:39:24 AM UTC-4, erik simpson wrote:
This was a mild senior moment. The OP where I linked that Quora article was in the other recentSome of the giant Triassic temnospondyls have been described as "toilet seats with teeth", a very scary idea.That's because they were incredibly flattened, like Gerrothorax in the Quora article I linked in the OP.
thread, "Fabulous Triassic Menagerie." Here is a link to the article itself:
https://www.quora.com/What-is-the-most-interesting-period-in-the-ancient-history-of-Earth-Is-it-the-Triassic-the-Jurassic-the-Cambrian-the-Devonian-or-other/answer/Gary-Meaney
Otherwise, they were most like angler fish, which have even more formidable looking teeth.
Actually,IIRC the heyday of the temnospondyls was the Carboniferous. In the Permian, they were
they probably occupied a niche since filled by alligators and crocodiles, but these came much later.
already under attack by synapsids; Dimetrodon was one top predator, barring the bigger ones
from much of the dry land.
They actually lasted
into the early Cretaceous, so they weren't really bad adapted for the job.
They were, however, a rather specialized lot. Modern day amphibians are generally
believed to be descended from them, but there are other opinions held by many
paleontologists, including the one that frogs descended from temnospondyls,
while salamanders and caecilians were lepospondyls.
By "them" I meant some temnospondyls, but not the ones that survived into the Jurassic.
But for the end-Triassic extinction, a fair number
of the early Triassic beasts may have stayed in the race. Dinosaurs didn't really "take over" until the Jurassic.
<snip to get to your latest words>
You probably meant that crown amphibians are descended from lepospondyls.
No, I was just grabbing a few hypotheses that I have encountered over the years.
The actual phylogeny of early amphibians is a god-awful mess of competing hypotheses.
The "split ancestry" of lissamphibians (crown group amphibians) that I mentioned above
is the one endorsed by Romer, Colbert, and even Carroll (1988).
Paleontological consensus
is that temnospondyls are stem lissamphibians. https://en.wikipedia.org/wiki/Temnospondyli
Did you not see the second cladogram on that webpage, which makes them out to be descended
from lepospondyls? That's exactly what you thought I meant to say (see above) --
but then, why did you make this last comment?
The second cladogram shows Lissamphibians and Temnospodyls (both within lepospondyla) are sister groups,
of which temnospondyls are extinct.
Neither of the two cladograms with pictures put temnospondyls anywhere near lepospondyls.
.
You seem to be outdoing me in senior moments on this thread. :-\
Frogs are not descended from temnospondyls, although some in the past postulated that they may be.
I was using a little common sense: given their evolutionary history,
the LCA of lissamphibians and temnospondyls must have been much
more like a temnospondyl than a lissamphibian.
A few years ago, we had a similar divergence of opinion about
Ctenophora, and then John even agreed that the LCA of sponges
and ctenophores probably resembled a sponge.
Pre-1990 phylogenies are no longer "consensus [phylogeny]".
Because they (including Carroll, 1988) did not rely exclusively on cladistic analyses?
There are several cladograms; look at the second.
Ctenophores have nothing to do with this. Why you're dredging this up is unclear.
Whether or
not something "looked like" is irrelevant to the DNA analysis,
which is vwery difficult in this
case.
Cladistic analysis has little to do with it, DNA analysis has everything to do with it. All crown amphibians
are lissamphibians.
On Wednesday, October 11, 2023 at 5:22:26 PM UTC-4, erik simpson wrote:My mistake. I should have said the first cladogram. The relationship of Temnospondlys and LIssamphibia
On Wednesday, October 11, 2023 at 1:58:11 PM UTC-7, Peter Nyikos wrote:
On Friday, October 6, 2023 at 11:08:17 PM UTC-4, erik simpson wrote:
On Friday, October 6, 2023 at 6:02:08 PM UTC-7, Peter Nyikos wrote:
As usual, my various commitments [many having to do with a test I gave one class and another
that I'll give on Monday] have left me with very little time for posting this week.
This is the only s.b.p. post I can do before going on my usual weekend posting break.
On Tuesday, October 3, 2023 at 7:06:12 PM UTC-4, erik simpson wrote:
On Tuesday, October 3, 2023 at 12:18:04 PM UTC-7, Peter Nyikos wrote:
On Friday, September 29, 2023 at 11:39:24 AM UTC-4, erik simpson wrote:
This was a mild senior moment. The OP where I linked that Quora article was in the other recentSome of the giant Triassic temnospondyls have been described as "toilet seats with teeth", a very scary idea.That's because they were incredibly flattened, like Gerrothorax in the Quora article I linked in the OP.
thread, "Fabulous Triassic Menagerie." Here is a link to the article itself:
https://www.quora.com/What-is-the-most-interesting-period-in-the-ancient-history-of-Earth-Is-it-the-Triassic-the-Jurassic-the-Cambrian-the-Devonian-or-other/answer/Gary-Meaney
Otherwise, they were most like angler fish, which have even more formidable looking teeth.
Actually,IIRC the heyday of the temnospondyls was the Carboniferous. In the Permian, they were
they probably occupied a niche since filled by alligators and crocodiles, but these came much later.
already under attack by synapsids; Dimetrodon was one top predator, barring the bigger ones
from much of the dry land.
They actually lasted
into the early Cretaceous, so they weren't really bad adapted for the job.
They were, however, a rather specialized lot. Modern day amphibians are generally
believed to be descended from them, but there are other opinions held by many
paleontologists, including the one that frogs descended from temnospondyls,
while salamanders and caecilians were lepospondyls.
By "them" I meant some temnospondyls, but not the ones that survived into the Jurassic.
<snip to get to your latest words>But for the end-Triassic extinction, a fair number
of the early Triassic beasts may have stayed in the race. Dinosaurs didn't really "take over" until the Jurassic.
You probably meant that crown amphibians are descended from lepospondyls.
No, I was just grabbing a few hypotheses that I have encountered over the years.
The actual phylogeny of early amphibians is a god-awful mess of competing hypotheses.
The "split ancestry" of lissamphibians (crown group amphibians) that I mentioned above
is the one endorsed by Romer, Colbert, and even Carroll (1988).
Paleontological consensus
is that temnospondyls are stem lissamphibians. https://en.wikipedia.org/wiki/Temnospondyli
<crickets>Did you not see the second cladogram on that webpage, which makes them out to be descended
from lepospondyls? That's exactly what you thought I meant to say (see above) --
but then, why did you make this last comment?
The second cladogram shows Lissamphibians and Temnospodyls (both within lepospondyla) are sister groups,
of which temnospondyls are extinct.
Either that, or you are trolling by making one "mistake" after another.Neither of the two cladograms with pictures put temnospondyls anywhere near lepospondyls.
.
You seem to be outdoing me in senior moments on this thread. :-\
Frogs are not descended from temnospondyls, although some in the past postulated that they may be.
I was using a little common sense: given their evolutionary history,
the LCA of lissamphibians and temnospondyls must have been much
more like a temnospondyl than a lissamphibian.
I did, but you either did not, or you have been trolling these last two roundsA few years ago, we had a similar divergence of opinion about Ctenophora, and then John even agreed that the LCA of spongesThere are several cladograms; look at the second.
and ctenophores probably resembled a sponge.
Pre-1990 phylogenies are no longer "consensus [phylogeny]".Because they (including Carroll, 1988) did not rely exclusively on cladistic analyses?
by deliberately posting false information to get my dander up.
And at this point you may be thinking, "Ha-Ha! Made you look!"
Ctenophores have nothing to do with this. Why you're dredging this up is unclear.It should be clear to anyone with a serious interest in scientific research. Competent researchers are on the lookout for general phenomena that
tie together specific observations which have a lot in common.
It is in the realm of polemic (specifically, secondary school debating conventions)
that it is a criticism that one is straying from the topic. This is a science "newsgroup,"
and it isn't supposed to be as saturated with polemic as talk.origins.
And your past behavior shows that your heart is in the atmosphere of talk.origins
whenever you deal with me. It's been that way since mid-2017, when Richard Norman
stopped posting to both groups.
Whether orI was using the sophisticated version of "looked like," which takes into account internal anatomy as well as external appearances.
not something "looked like" is irrelevant to the DNA analysis,
With extinct animals, we need to focus on the former, although
really competent reproductions do give some clue to internal anatomy.
which is vwery difficult in this
case.
Cladistic analysis has little to do with it, DNA analysis has everything to do with it. All crown amphibiansBY DEFINITION!! How typical of you to obscure that fact.
are lissamphibians.
What other DNA analyses do evolutionary biologists use, besides those following cladistic methods like MP, ML, and NJ? Molecular clocks are generally considered to be a poor substitute.
Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
University of So. Carolina in Columbia
http://people.math.sc.edu/nyikos
On Friday, October 20, 2023 at 3:05:13 PM UTC-7, Peter Nyikos wrote:
On Wednesday, October 11, 2023 at 5:22:26 PM UTC-4, erik simpson wrote:
On Wednesday, October 11, 2023 at 1:58:11 PM UTC-7, Peter Nyikos wrote:
On Friday, October 6, 2023 at 11:08:17 PM UTC-4, erik simpson wrote:
On Friday, October 6, 2023 at 6:02:08 PM UTC-7, Peter Nyikos wrote:
As usual, my various commitments [many having to do with a test I gave one class and another
that I'll give on Monday] have left me with very little time for posting this week.
This is the only s.b.p. post I can do before going on my usual weekend posting break.
On Tuesday, October 3, 2023 at 7:06:12 PM UTC-4, erik simpson wrote:
On Tuesday, October 3, 2023 at 12:18:04 PM UTC-7, Peter Nyikos wrote:
On Friday, September 29, 2023 at 11:39:24 AM UTC-4, erik simpson wrote:
This was a mild senior moment. The OP where I linked that Quora article was in the other recentSome of the giant Triassic temnospondyls have been described as "toilet seats with teeth", a very scary idea.That's because they were incredibly flattened, like Gerrothorax in the Quora article I linked in the OP.
thread, "Fabulous Triassic Menagerie." Here is a link to the article itself:
https://www.quora.com/What-is-the-most-interesting-period-in-the-ancient-history-of-Earth-Is-it-the-Triassic-the-Jurassic-the-Cambrian-the-Devonian-or-other/answer/Gary-Meaney
Otherwise, they were most like angler fish, which have even more formidable looking teeth.
Actually,IIRC the heyday of the temnospondyls was the Carboniferous. In the Permian, they were
they probably occupied a niche since filled by alligators and crocodiles, but these came much later.
already under attack by synapsids; Dimetrodon was one top predator, barring the bigger ones
from much of the dry land.
They actually lasted
into the early Cretaceous, so they weren't really bad adapted for the job.
They were, however, a rather specialized lot. Modern day amphibians are generally
believed to be descended from them, but there are other opinions held by many
paleontologists, including the one that frogs descended from temnospondyls,
while salamanders and caecilians were lepospondyls.
By "them" I meant some temnospondyls, but not the ones that survived into the Jurassic.
<snip to get to your latest words>But for the end-Triassic extinction, a fair number
of the early Triassic beasts may have stayed in the race. Dinosaurs didn't really "take over" until the Jurassic.
You probably meant that crown amphibians are descended from lepospondyls.
No, I was just grabbing a few hypotheses that I have encountered over the years.
The actual phylogeny of early amphibians is a god-awful mess of competing hypotheses.
The "split ancestry" of lissamphibians (crown group amphibians) that I mentioned above
is the one endorsed by Romer, Colbert, and even Carroll (1988).
Paleontological consensus
is that temnospondyls are stem lissamphibians. https://en.wikipedia.org/wiki/Temnospondyli
<crickets>Did you not see the second cladogram on that webpage, which makes them out to be descended
from lepospondyls? That's exactly what you thought I meant to say (see above) --
but then, why did you make this last comment?
The second cladogram shows Lissamphibians and Temnospodyls (both within lepospondyla) are sister groups,
of which temnospondyls are extinct.
Either that, or you are trolling by making one "mistake" after another.Neither of the two cladograms with pictures put temnospondyls anywhere near lepospondyls.
.
You seem to be outdoing me in senior moments on this thread. :-\
Frogs are not descended from temnospondyls, although some in the past
postulated that they may be.
I was using a little common sense: given their evolutionary history, the LCA of lissamphibians and temnospondyls must have been much
more like a temnospondyl than a lissamphibian.
A few years ago, we had a similar divergence of opinion about Ctenophora, and then John even agreed that the LCA of spongesThere are several cladograms; look at the second.
and ctenophores probably resembled a sponge.
Pre-1990 phylogenies are no longer "consensus [phylogeny]".Because they (including Carroll, 1988) did not rely exclusively on cladistic analyses?
I did, but you either did not, or you have been trolling these last two rounds
by deliberately posting false information to get my dander up.
And at this point you may be thinking, "Ha-Ha! Made you look!"
Ctenophores have nothing to do with this. Why you're dredging this up is unclear.It should be clear to anyone with a serious interest in scientific research.
Competent researchers are on the lookout for general phenomena that
tie together specific observations which have a lot in common.
It is in the realm of polemic (specifically, secondary school debating conventions)
that it is a criticism that one is straying from the topic. This is a science "newsgroup,"
and it isn't supposed to be as saturated with polemic as talk.origins.
And your past behavior shows that your heart is in the atmosphere of talk.origins
whenever you deal with me. It's been that way since mid-2017, when Richard Norman
stopped posting to both groups.
Whether orI was using the sophisticated version of "looked like," which takes into account internal anatomy as well as external appearances.
not something "looked like" is irrelevant to the DNA analysis,
With extinct animals, we need to focus on the former, although
really competent reproductions do give some clue to internal anatomy.
which is vwery difficult in this
case.
Cladistic analysis has little to do with it, DNA analysis has everything to do with it. All crown amphibians
are lissamphibians.
BY DEFINITION!! How typical of you to obscure that fact.
What other DNA analyses do evolutionary biologists use, besides those following cladistic methods like MP, ML, and NJ? Molecular clocks are generally considered to be a poor substitute.
My mistake. I should have said the first cladogram.
[end of quote]The second cladogram shows Lissamphibians and Temnospodyls (both within lepospondyla) are sister groups,
of which temnospondyls are extinct.
Neither of the two cladograms with pictures put temnospondyls anywhere near lepospondyls.
.
You seem to be outdoing me in senior moments on this thread. :-\
The relationship of Temnospondlys and LIssamphibia
is clear.
You're letting past problems inflame you.
I'm through with this thread.
<clip for focus>
Neither Temnospodyls nor Lissamphibians are Lepospondyls.
If you want further elucidations, talk to the hand.
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