Hey guys, my readings about the end-Permian extinction have sparked some questions about it.

The book I read postulates that a massive meteor strike in the Panthalassic might have led to “antipodal” shockwave disruption of the Siberian crust opposite the strike, much as Deccan volcanism has been blamed on shockwaves from the antipodal Chicxulub strike. The reason no crater has been found would then attributed to the fact that the Panthalassic location where the putative strike would have occurred has since been completely replaced by new sea floor, with Hawaiian volcanism possibly being the last surviving evidence of the strike location.

Tangential to that theory, I find myself wondering the following:

(1) If the crust under the Panthalassic has indeed been completely replaced since then, how do we know that the Panthalassic ocean really had no landmasses? In other words, what evidence do we have for Pangea being the only continent at the time?

There’s also the interesting fact that the ubiquitous Lystrosaurus is everywhere in Early Triassic Gondwana (South Africa, South America, etc) but lacking in Early Triassic Laurasia (Russia, China) where we only find swamp-dwelling temnospondyls.

(2) Is it possible that proximity to active (and presumably dangerous) Siberian Traps made life prohibitively difficult in (nearby?) Russia and China unless you could take shelter in a swamp?

Finally, I’m curious that we are unable to find how marine reptiles like ichthyosaurs and plesiosaurs evolved: they seem to simply appear - rather well-formed - sometime in the Triassic. The book I read postulated that the Early Triassic seas may have been continuously disrupted by heat from the Siberian Traps. Are the gaps in our Triassic marine records so vast and frequent that we’re likely to have completely missed the transition of these marine reptiles - or might another explanation be needed? My question is as follows:

(3) Is it possible that marine reptiles evolved in a body of water isolated (and thus sheltered) from the larger oceans then spread relatively suddenly across the world once rising sea levels reconnected that body of water to improving oceanic conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…

Thanks for your ideas!

On Saturday, March 11, 2023 at 3:03:43 PM UTC-8, Sight Reader wrote:
> Hey guys, my readings about the end-Permian extinction have sparked some questions about it.
>
> The book I read postulates that a massive meteor strike in the Panthalassic might have led to “antipodal” shockwave disruption of the Siberian crust opposite the strike, much as Deccan volcanism has been blamed on shockwaves from the antipodal Chicxulub strike. The reason no crater has been found would then attributed to the fact that the Panthalassic location where the putative strike would have occurred has since been completely replaced by new sea floor, with Hawaiian volcanism possibly being the last surviving evidence of the strike location.
>
> Tangential to that theory, I find myself wondering the following:
>
> (1) If the crust under the Panthalassic has indeed been completely replaced since then, how do we know that the Panthalassic ocean really had no landmasses? In other words, what evidence do we have for Pangea being the only continent at the time?
>
> There’s also the interesting fact that the ubiquitous Lystrosaurus is everywhere in Early Triassic Gondwana (South Africa, South America, etc) but lacking in Early Triassic Laurasia (Russia, China) where we only find swamp-dwelling temnospondyls.
>
> (2) Is it possible that proximity to active (and presumably dangerous) Siberian Traps made life prohibitively difficult in (nearby?) Russia and China unless you could take shelter in a swamp?
>
> Finally, I’m curious that we are unable to find how marine reptiles like ichthyosaurs and plesiosaurs evolved: they seem to simply appear - rather well-formed - sometime in the Triassic. The book I read postulated that the Early Triassic seas may have been continuously disrupted by heat from the Siberian Traps. Are the gaps in our Triassic marine records so vast and frequent that we’re likely to have completely missed the transition of these marine reptiles - or might another explanation be needed? My question is as follows:
>
> (3) Is it possible that marine reptiles evolved in a body of water isolated (and thus sheltered) from the larger oceans then spread relatively suddenly across the world once rising sea levels reconnected that body of water to improving oceanic conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…
>
> Thanks for your ideas!

If I may ask,what book is that? The Wiki entry for the Permian-Triassic extinction is
quite informative, and discusses various impact suggestions (hard to call them"theories").
The principle objection that impresses me is that there is no need to postulate such an event.
The Siberian traps, and other large volcanic events need no such trigger. No extraterrestial minerals
layers (see Iridium) have been found. Some impact events of appropriate age have been detected, but
they seem much too small to account for much.

Ocean crust is recycled, continental masses aren't. There were undoubtably islands or island chains
at the time that were not part of Pangea, but no evidence for continent-sized islands. Different fauna
and flora is not unexpected. Pangea had large interior deserts and quite possibly extreme monsoonal
weather that would have prevented large migrations from homogenizing the whole continent. See
https://en.wikipedia.org/wiki/Pangean_megamonsoon

The problem of sudden appearance of taxa in the fossil record is common, and has many potential
aspects. The Triassic was a dynamic period of rapid developemental radiation into a depauperate
ecosystem, and was capped with its own mass extinction, the Triassic-Jurassic event. It also has a
good Wiki entry. Taphonomy also has a capricious effect on the fossil record. For lots of potential
reasons, some things fossilize well at certain times and conditions, and don't under diffferent
circumstances.

Trilobites were evidently well-distributed globally before they developed calcified exoskeletons,
which made them much more easily preserved as fossils. Nobody has definitivly identified the "soft" trilobites,
although there are some suggested possibilities. Check out https://www.trilobites.info/ for a readable
discussion of Trilobites, accessible to non-specialists.

I haven't included lots of references for these assertions, but they are legion. GIYF.

On Saturday, March 11, 2023 at 5:40:47 PM UTC-7, erik simpson wrote:
> On Saturday, March 11, 2023 at 3:03:43 PM UTC-8, Sight Reader wrote:
> > Hey guys, my readings about the end-Permian extinction have sparked some questions about it.
> >
> > The book I read postulates that a massive meteor strike in the Panthalassic might have led to “antipodal” shockwave disruption of the Siberian crust opposite the strike, much as Deccan volcanism has been blamed on shockwaves from the antipodal Chicxulub strike. The reason no crater has been found would then attributed to the fact that the Panthalassic location where the putative strike would have occurred has since been completely replaced by new sea floor, with Hawaiian volcanism possibly being the last surviving evidence of the strike location.
> >
> > Tangential to that theory, I find myself wondering the following:
> >
> > (1) If the crust under the Panthalassic has indeed been completely replaced since then, how do we know that the Panthalassic ocean really had no landmasses? In other words, what evidence do we have for Pangea being the only continent at the time?
> >
> > There’s also the interesting fact that the ubiquitous Lystrosaurus is everywhere in Early Triassic Gondwana (South Africa, South America, etc) but lacking in Early Triassic Laurasia (Russia, China) where we only find swamp-dwelling temnospondyls.
> >
> > (2) Is it possible that proximity to active (and presumably dangerous) Siberian Traps made life prohibitively difficult in (nearby?) Russia and China unless you could take shelter in a swamp?
> >
> > Finally, I’m curious that we are unable to find how marine reptiles like ichthyosaurs and plesiosaurs evolved: they seem to simply appear - rather well-formed - sometime in the Triassic. The book I read postulated that the Early Triassic seas may have been continuously disrupted by heat from the Siberian Traps. Are the gaps in our Triassic marine records so vast and frequent that we’re likely to have completely missed the transition of these marine reptiles - or might another explanation be needed? My question is as follows:
> >
> > (3) Is it possible that marine reptiles evolved in a body of water isolated (and thus sheltered) from the larger oceans then spread relatively suddenly across the world once rising sea levels reconnected that body of water to improving oceanic conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…
> >
> > Thanks for your ideas!
> If I may ask,what book is that? The Wiki entry for the Permian-Triassic extinction is
> quite informative, and discusses various impact suggestions (hard to call them"theories").
> The principle objection that impresses me is that there is no need to postulate such an event.
> The Siberian traps, and other large volcanic events need no such trigger. No extraterrestial minerals
> layers (see Iridium) have been found. Some impact events of appropriate age have been detected, but
> they seem much too small to account for much.
>
> Ocean crust is recycled, continental masses aren't. There were undoubtably islands or island chains
> at the time that were not part of Pangea, but no evidence for continent-sized islands. Different fauna
> and flora is not unexpected. Pangea had large interior deserts and quite possibly extreme monsoonal
> weather that would have prevented large migrations from homogenizing the whole continent. See
> https://en.wikipedia.org/wiki/Pangean_megamonsoon
>
> The problem of sudden appearance of taxa in the fossil record is common, and has many potential
> aspects. The Triassic was a dynamic period of rapid developemental radiation into a depauperate
> ecosystem, and was capped with its own mass extinction, the Triassic-Jurassic event. It also has a
> good Wiki entry. Taphonomy also has a capricious effect on the fossil record. For lots of potential
> reasons, some things fossilize well at certain times and conditions, and don't under diffferent
> circumstances.
>
> Trilobites were evidently well-distributed globally before they developed calcified exoskeletons,
> which made them much more easily preserved as fossils. Nobody has definitivly identified the "soft" trilobites,
> although there are some suggested possibilities. Check out https://www.trilobites.info/ for a readable
> discussion of Trilobites, accessible to non-specialists.
>
> I haven't included lots of references for these assertions, but they are legion. GIYF.

It was a cute little book called, “The Triassic Period: The History and Legacy of the Geologic Era that Witnessed the Rise of the Dinosaurs”. Very compact little thing but very hard to tell who the author was (“Charles River Editors”). Dunno how reliable it is; the author seemed like he knew he was talking about but was trying to dumb things down for kids, got frustrated with it, and possibly gave up on the whole thing and left them in the lurch… I dunno.

On Saturday, March 11, 2023 at 5:06:00 PM UTC-8, Sight Reader wrote:
> On Saturday, March 11, 2023 at 5:40:47 PM UTC-7, erik simpson wrote:
> > On Saturday, March 11, 2023 at 3:03:43 PM UTC-8, Sight Reader wrote:
> > > Hey guys, my readings about the end-Permian extinction have sparked some questions about it.
> > >
> > > The book I read postulates that a massive meteor strike in the Panthalassic might have led to “antipodal” shockwave disruption of the Siberian crust opposite the strike, much as Deccan volcanism has been blamed on shockwaves from the antipodal Chicxulub strike. The reason no crater has been found would then attributed to the fact that the Panthalassic location where the putative strike would have occurred has since been completely replaced by new sea floor, with Hawaiian volcanism possibly being the last surviving evidence of the strike location.
> > >
> > > Tangential to that theory, I find myself wondering the following:
> > >
> > > (1) If the crust under the Panthalassic has indeed been completely replaced since then, how do we know that the Panthalassic ocean really had no landmasses? In other words, what evidence do we have for Pangea being the only continent at the time?
> > >
> > > There’s also the interesting fact that the ubiquitous Lystrosaurus is everywhere in Early Triassic Gondwana (South Africa, South America, etc) but lacking in Early Triassic Laurasia (Russia, China) where we only find swamp-dwelling temnospondyls.
> > >
> > > (2) Is it possible that proximity to active (and presumably dangerous) Siberian Traps made life prohibitively difficult in (nearby?) Russia and China unless you could take shelter in a swamp?
> > >
> > > Finally, I’m curious that we are unable to find how marine reptiles like ichthyosaurs and plesiosaurs evolved: they seem to simply appear - rather well-formed - sometime in the Triassic. The book I read postulated that the Early Triassic seas may have been continuously disrupted by heat from the Siberian Traps. Are the gaps in our Triassic marine records so vast and frequent that we’re likely to have completely missed the transition of these marine reptiles - or might another explanation be needed? My question is as follows:
> > >
> > > (3) Is it possible that marine reptiles evolved in a body of water isolated (and thus sheltered) from the larger oceans then spread relatively suddenly across the world once rising sea levels reconnected that body of water to improving oceanic conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…
> > >
> > > Thanks for your ideas!
> > If I may ask,what book is that? The Wiki entry for the Permian-Triassic extinction is
> > quite informative, and discusses various impact suggestions (hard to call them"theories").
> > The principle objection that impresses me is that there is no need to postulate such an event.
> > The Siberian traps, and other large volcanic events need no such trigger. No extraterrestial minerals
> > layers (see Iridium) have been found. Some impact events of appropriate age have been detected, but
> > they seem much too small to account for much.
> >
> > Ocean crust is recycled, continental masses aren't. There were undoubtably islands or island chains
> > at the time that were not part of Pangea, but no evidence for continent-sized islands. Different fauna
> > and flora is not unexpected. Pangea had large interior deserts and quite possibly extreme monsoonal
> > weather that would have prevented large migrations from homogenizing the whole continent. See
> > https://en.wikipedia.org/wiki/Pangean_megamonsoon
> >
> > The problem of sudden appearance of taxa in the fossil record is common, and has many potential
> > aspects. The Triassic was a dynamic period of rapid developemental radiation into a depauperate
> > ecosystem, and was capped with its own mass extinction, the Triassic-Jurassic event. It also has a
> > good Wiki entry. Taphonomy also has a capricious effect on the fossil record. For lots of potential
> > reasons, some things fossilize well at certain times and conditions, and don't under diffferent
> > circumstances.
> >
> > Trilobites were evidently well-distributed globally before they developed calcified exoskeletons,
> > which made them much more easily preserved as fossils. Nobody has definitivly identified the "soft" trilobites,
> > although there are some suggested possibilities. Check out https://www.trilobites.info/ for a readable
> > discussion of Trilobites, accessible to non-specialists.
> >
> > I haven't included lots of references for these assertions, but they are legion. GIYF.
> It was a cute little book called, “The Triassic Period: The History and Legacy of the Geologic Era that Witnessed the Rise of the Dinosaurs”. Very compact little thing but very hard to tell who the author was (“Charles River Editors”). Dunno how reliable it is; the author seemed like he knew he was talking about but was trying to dumb things down for kids, got frustrated with it, and possibly gave up on the whole thing and left them in the lurch… I dunno.

I'll recommend two books by Stephen Brusatte:
The Rise and Fall of the Dinosaurs
The Rise and Reign of the Mammals

Brusatte is a currently active paleontologist who has specialized in both of these areas
of study. They are quite readable by a lay audience, and he has a very "friendly" style, quite
up-to-date. A good story teller.

A good read on triolobites is by Richard Fortey: Eyewitness to Evolution
Another fine readable book by one of the foremost paleontogist trilobite specialists

On Saturday, March 11, 2023 at 5:40:47 PM UTC-7, erik simpson wrote:
> On Saturday, March 11, 2023 at 3:03:43 PM UTC-8, Sight Reader wrote:
> > Hey guys, my readings about the end-Permian extinction have sparked some questions about it.
> >
> > The book I read postulates that a massive meteor strike in the Panthalassic might have led to “antipodal” shockwave disruption of the Siberian crust opposite the strike, much as Deccan volcanism has been blamed on shockwaves from the antipodal Chicxulub strike. The reason no crater has been found would then attributed to the fact that the Panthalassic location where the putative strike would have occurred has since been completely replaced by new sea floor, with Hawaiian volcanism possibly being the last surviving evidence of the strike location.
> >
> > Tangential to that theory, I find myself wondering the following:
> >
> > (1) If the crust under the Panthalassic has indeed been completely replaced since then, how do we know that the Panthalassic ocean really had no landmasses? In other words, what evidence do we have for Pangea being the only continent at the time?
> >
> > There’s also the interesting fact that the ubiquitous Lystrosaurus is everywhere in Early Triassic Gondwana (South Africa, South America, etc) but lacking in Early Triassic Laurasia (Russia, China) where we only find swamp-dwelling temnospondyls.
> >
> > (2) Is it possible that proximity to active (and presumably dangerous) Siberian Traps made life prohibitively difficult in (nearby?) Russia and China unless you could take shelter in a swamp?
> >
> > Finally, I’m curious that we are unable to find how marine reptiles like ichthyosaurs and plesiosaurs evolved: they seem to simply appear - rather well-formed - sometime in the Triassic. The book I read postulated that the Early Triassic seas may have been continuously disrupted by heat from the Siberian Traps. Are the gaps in our Triassic marine records so vast and frequent that we’re likely to have completely missed the transition of these marine reptiles - or might another explanation be needed? My question is as follows:
> >
> > (3) Is it possible that marine reptiles evolved in a body of water isolated (and thus sheltered) from the larger oceans then spread relatively suddenly across the world once rising sea levels reconnected that body of water to improving oceanic conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…
> >
> > Thanks for your ideas!
> If I may ask,what book is that? The Wiki entry for the Permian-Triassic extinction is
> quite informative, and discusses various impact suggestions (hard to call them"theories").
> The principle objection that impresses me is that there is no need to postulate such an event.
> The Siberian traps, and other large volcanic events need no such trigger. No extraterrestial minerals
> layers (see Iridium) have been found. Some impact events of appropriate age have been detected, but
> they seem much too small to account for much.
>
> Ocean crust is recycled, continental masses aren't. There were undoubtably islands or island chains
> at the time that were not part of Pangea, but no evidence for continent-sized islands. Different fauna
> and flora is not unexpected. Pangea had large interior deserts and quite possibly extreme monsoonal
> weather that would have prevented large migrations from homogenizing the whole continent. See
> https://en.wikipedia.org/wiki/Pangean_megamonsoon
>
> The problem of sudden appearance of taxa in the fossil record is common, and has many potential
> aspects. The Triassic was a dynamic period of rapid developemental radiation into a depauperate
> ecosystem, and was capped with its own mass extinction, the Triassic-Jurassic event. It also has a
> good Wiki entry. Taphonomy also has a capricious effect on the fossil record. For lots of potential
> reasons, some things fossilize well at certain times and conditions, and don't under diffferent
> circumstances.
>
> Trilobites were evidently well-distributed globally before they developed calcified exoskeletons,
> which made them much more easily preserved as fossils. Nobody has definitivly identified the "soft" trilobites,
> although there are some suggested possibilities. Check out https://www.trilobites.info/ for a readable
> discussion of Trilobites, accessible to non-specialists.
>
> I haven't included lots of references for these assertions, but they are legion. GIYF.

Yes, I’ve read the Rise and Fall of Dinosaurs, but not that of mammals.

One more question: is it possible that the lack of non-swamp creatures in the earliest Triassic (Induan?) of the Urals and China - at least compared to Gondwana - was due to their proximity to the Siberian Traps or might that difference purely have been a matter of latitude? After all, it seems like some of the same temnospondyls are both in the north and south, but not the dicynodonts, cynodonts, or very many of the other guys living outside the swamp…

On Saturday, March 11, 2023 at 9:00:14 PM UTC-8, Sight Reader wrote:
> On Saturday, March 11, 2023 at 5:40:47 PM UTC-7, erik simpson wrote:
> > On Saturday, March 11, 2023 at 3:03:43 PM UTC-8, Sight Reader wrote:
> > > Hey guys, my readings about the end-Permian extinction have sparked some questions about it.
> > >
> > > The book I read postulates that a massive meteor strike in the Panthalassic might have led to “antipodal” shockwave disruption of the Siberian crust opposite the strike, much as Deccan volcanism has been blamed on shockwaves from the antipodal Chicxulub strike. The reason no crater has been found would then attributed to the fact that the Panthalassic location where the putative strike would have occurred has since been completely replaced by new sea floor, with Hawaiian volcanism possibly being the last surviving evidence of the strike location.
> > >
> > > Tangential to that theory, I find myself wondering the following:
> > >
> > > (1) If the crust under the Panthalassic has indeed been completely replaced since then, how do we know that the Panthalassic ocean really had no landmasses? In other words, what evidence do we have for Pangea being the only continent at the time?
> > >
> > > There’s also the interesting fact that the ubiquitous Lystrosaurus is everywhere in Early Triassic Gondwana (South Africa, South America, etc) but lacking in Early Triassic Laurasia (Russia, China) where we only find swamp-dwelling temnospondyls.
> > >
> > > (2) Is it possible that proximity to active (and presumably dangerous) Siberian Traps made life prohibitively difficult in (nearby?) Russia and China unless you could take shelter in a swamp?
> > >
> > > Finally, I’m curious that we are unable to find how marine reptiles like ichthyosaurs and plesiosaurs evolved: they seem to simply appear - rather well-formed - sometime in the Triassic. The book I read postulated that the Early Triassic seas may have been continuously disrupted by heat from the Siberian Traps. Are the gaps in our Triassic marine records so vast and frequent that we’re likely to have completely missed the transition of these marine reptiles - or might another explanation be needed? My question is as follows:
> > >
> > > (3) Is it possible that marine reptiles evolved in a body of water isolated (and thus sheltered) from the larger oceans then spread relatively suddenly across the world once rising sea levels reconnected that body of water to improving oceanic conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…
> > >
> > > Thanks for your ideas!
> > If I may ask,what book is that? The Wiki entry for the Permian-Triassic extinction is
> > quite informative, and discusses various impact suggestions (hard to call them"theories").
> > The principle objection that impresses me is that there is no need to postulate such an event.
> > The Siberian traps, and other large volcanic events need no such trigger. No extraterrestial minerals
> > layers (see Iridium) have been found. Some impact events of appropriate age have been detected, but
> > they seem much too small to account for much.
> >
> > Ocean crust is recycled, continental masses aren't. There were undoubtably islands or island chains
> > at the time that were not part of Pangea, but no evidence for continent-sized islands. Different fauna
> > and flora is not unexpected. Pangea had large interior deserts and quite possibly extreme monsoonal
> > weather that would have prevented large migrations from homogenizing the whole continent. See
> > https://en.wikipedia.org/wiki/Pangean_megamonsoon
> >
> > The problem of sudden appearance of taxa in the fossil record is common, and has many potential
> > aspects. The Triassic was a dynamic period of rapid developemental radiation into a depauperate
> > ecosystem, and was capped with its own mass extinction, the Triassic-Jurassic event. It also has a
> > good Wiki entry. Taphonomy also has a capricious effect on the fossil record. For lots of potential
> > reasons, some things fossilize well at certain times and conditions, and don't under diffferent
> > circumstances.
> >
> > Trilobites were evidently well-distributed globally before they developed calcified exoskeletons,
> > which made them much more easily preserved as fossils. Nobody has definitivly identified the "soft" trilobites,
> > although there are some suggested possibilities. Check out https://www.trilobites.info/ for a readable
> > discussion of Trilobites, accessible to non-specialists.
> >
> > I haven't included lots of references for these assertions, but they are legion. GIYF.
> Yes, I’ve read the Rise and Fall of Dinosaurs, but not that of mammals.
>
> One more question: is it possible that the lack of non-swamp creatures in the earliest Triassic (Induan?) of the Urals and China - at least compared to Gondwana - was due to their proximity to the Siberian Traps or might that difference purely have been a matter of latitude? After all, it seems like some of the same temnospondyls are both in the north and south, but not the dicynodonts, cynodonts, or very many of the other guys living outside the swamp…

Off the top of my head, I don't know. There may (probably is) something in Brusatte's mammal book.
I may look later today, but right now I have to deal with flooded roads blocking me in my neighborhood.

On Sunday, March 12, 2023 at 10:26:23 AM UTC-6, erik simpson wrote:
> On Saturday, March 11, 2023 at 9:00:14 PM UTC-8, Sight Reader wrote:
> > On Saturday, March 11, 2023 at 5:40:47 PM UTC-7, erik simpson wrote:
> > > On Saturday, March 11, 2023 at 3:03:43 PM UTC-8, Sight Reader wrote:
> > > > Hey guys, my readings about the end-Permian extinction have sparked some questions about it.
> > > >
> > > > The book I read postulates that a massive meteor strike in the Panthalassic might have led to “antipodal” shockwave disruption of the Siberian crust opposite the strike, much as Deccan volcanism has been blamed on shockwaves from the antipodal Chicxulub strike. The reason no crater has been found would then attributed to the fact that the Panthalassic location where the putative strike would have occurred has since been completely replaced by new sea floor, with Hawaiian volcanism possibly being the last surviving evidence of the strike location.
> > > >
> > > > Tangential to that theory, I find myself wondering the following:
> > > >
> > > > (1) If the crust under the Panthalassic has indeed been completely replaced since then, how do we know that the Panthalassic ocean really had no landmasses? In other words, what evidence do we have for Pangea being the only continent at the time?
> > > >
> > > > There’s also the interesting fact that the ubiquitous Lystrosaurus is everywhere in Early Triassic Gondwana (South Africa, South America, etc) but lacking in Early Triassic Laurasia (Russia, China) where we only find swamp-dwelling temnospondyls.
> > > >
> > > > (2) Is it possible that proximity to active (and presumably dangerous) Siberian Traps made life prohibitively difficult in (nearby?) Russia and China unless you could take shelter in a swamp?
> > > >
> > > > Finally, I’m curious that we are unable to find how marine reptiles like ichthyosaurs and plesiosaurs evolved: they seem to simply appear - rather well-formed - sometime in the Triassic. The book I read postulated that the Early Triassic seas may have been continuously disrupted by heat from the Siberian Traps. Are the gaps in our Triassic marine records so vast and frequent that we’re likely to have completely missed the transition of these marine reptiles - or might another explanation be needed? My question is as follows:
> > > >
> > > > (3) Is it possible that marine reptiles evolved in a body of water isolated (and thus sheltered) from the larger oceans then spread relatively suddenly across the world once rising sea levels reconnected that body of water to improving oceanic conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…
> > > >
> > > > Thanks for your ideas!
> > > If I may ask,what book is that? The Wiki entry for the Permian-Triassic extinction is
> > > quite informative, and discusses various impact suggestions (hard to call them"theories").
> > > The principle objection that impresses me is that there is no need to postulate such an event.
> > > The Siberian traps, and other large volcanic events need no such trigger. No extraterrestial minerals
> > > layers (see Iridium) have been found. Some impact events of appropriate age have been detected, but
> > > they seem much too small to account for much.
> > >
> > > Ocean crust is recycled, continental masses aren't. There were undoubtably islands or island chains
> > > at the time that were not part of Pangea, but no evidence for continent-sized islands. Different fauna
> > > and flora is not unexpected. Pangea had large interior deserts and quite possibly extreme monsoonal
> > > weather that would have prevented large migrations from homogenizing the whole continent. See
> > > https://en.wikipedia.org/wiki/Pangean_megamonsoon
> > >
> > > The problem of sudden appearance of taxa in the fossil record is common, and has many potential
> > > aspects. The Triassic was a dynamic period of rapid developemental radiation into a depauperate
> > > ecosystem, and was capped with its own mass extinction, the Triassic-Jurassic event. It also has a
> > > good Wiki entry. Taphonomy also has a capricious effect on the fossil record. For lots of potential
> > > reasons, some things fossilize well at certain times and conditions, and don't under diffferent
> > > circumstances.
> > >
> > > Trilobites were evidently well-distributed globally before they developed calcified exoskeletons,
> > > which made them much more easily preserved as fossils. Nobody has definitivly identified the "soft" trilobites,
> > > although there are some suggested possibilities. Check out https://www.trilobites.info/ for a readable
> > > discussion of Trilobites, accessible to non-specialists.
> > >
> > > I haven't included lots of references for these assertions, but they are legion. GIYF.
> > Yes, I’ve read the Rise and Fall of Dinosaurs, but not that of mammals.
> >
> > One more question: is it possible that the lack of non-swamp creatures in the earliest Triassic (Induan?) of the Urals and China - at least compared to Gondwana - was due to their proximity to the Siberian Traps or might that difference purely have been a matter of latitude? After all, it seems like some of the same temnospondyls are both in the north and south, but not the dicynodonts, cynodonts, or very many of the other guys living outside the swamp…
> Off the top of my head, I don't know. There may (probably is) something in Brusatte's mammal book.
> I may look later today, but right now I have to deal with flooded roads blocking me in my neighborhood.

Oh no! Are you part of all that flooding in California? Hang in there… and tell us if you see any temnospondyls!

On Sunday, March 12, 2023 at 10:51:27 AM UTC-7, Sight Reader wrote:
> On Sunday, March 12, 2023 at 10:26:23 AM UTC-6, erik simpson wrote:
> > On Saturday, March 11, 2023 at 9:00:14 PM UTC-8, Sight Reader wrote:
> > > On Saturday, March 11, 2023 at 5:40:47 PM UTC-7, erik simpson wrote:
> > > > On Saturday, March 11, 2023 at 3:03:43 PM UTC-8, Sight Reader wrote:
> > > > > Hey guys, my readings about the end-Permian extinction have sparked some questions about it.
> > > > >
> > > > > The book I read postulates that a massive meteor strike in the Panthalassic might have led to “antipodal” shockwave disruption of the Siberian crust opposite the strike, much as Deccan volcanism has been blamed on shockwaves from the antipodal Chicxulub strike. The reason no crater has been found would then attributed to the fact that the Panthalassic location where the putative strike would have occurred has since been completely replaced by new sea floor, with Hawaiian volcanism possibly being the last surviving evidence of the strike location.
> > > > >
> > > > > Tangential to that theory, I find myself wondering the following:
> > > > >
> > > > > (1) If the crust under the Panthalassic has indeed been completely replaced since then, how do we know that the Panthalassic ocean really had no landmasses? In other words, what evidence do we have for Pangea being the only continent at the time?
> > > > >
> > > > > There’s also the interesting fact that the ubiquitous Lystrosaurus is everywhere in Early Triassic Gondwana (South Africa, South America, etc) but lacking in Early Triassic Laurasia (Russia, China) where we only find swamp-dwelling temnospondyls.
> > > > >
> > > > > (2) Is it possible that proximity to active (and presumably dangerous) Siberian Traps made life prohibitively difficult in (nearby?) Russia and China unless you could take shelter in a swamp?
> > > > >
> > > > > Finally, I’m curious that we are unable to find how marine reptiles like ichthyosaurs and plesiosaurs evolved: they seem to simply appear - rather well-formed - sometime in the Triassic. The book I read postulated that the Early Triassic seas may have been continuously disrupted by heat from the Siberian Traps. Are the gaps in our Triassic marine records so vast and frequent that we’re likely to have completely missed the transition of these marine reptiles - or might another explanation be needed? My question is as follows:
> > > > >
> > > > > (3) Is it possible that marine reptiles evolved in a body of water isolated (and thus sheltered) from the larger oceans then spread relatively suddenly across the world once rising sea levels reconnected that body of water to improving oceanic conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…
> > > > >
> > > > > Thanks for your ideas!
> > > > If I may ask,what book is that? The Wiki entry for the Permian-Triassic extinction is
> > > > quite informative, and discusses various impact suggestions (hard to call them"theories").
> > > > The principle objection that impresses me is that there is no need to postulate such an event.
> > > > The Siberian traps, and other large volcanic events need no such trigger. No extraterrestial minerals
> > > > layers (see Iridium) have been found. Some impact events of appropriate age have been detected, but
> > > > they seem much too small to account for much.
> > > >
> > > > Ocean crust is recycled, continental masses aren't. There were undoubtably islands or island chains
> > > > at the time that were not part of Pangea, but no evidence for continent-sized islands. Different fauna
> > > > and flora is not unexpected. Pangea had large interior deserts and quite possibly extreme monsoonal
> > > > weather that would have prevented large migrations from homogenizing the whole continent. See
> > > > https://en.wikipedia.org/wiki/Pangean_megamonsoon
> > > >
> > > > The problem of sudden appearance of taxa in the fossil record is common, and has many potential
> > > > aspects. The Triassic was a dynamic period of rapid developemental radiation into a depauperate
> > > > ecosystem, and was capped with its own mass extinction, the Triassic-Jurassic event. It also has a
> > > > good Wiki entry. Taphonomy also has a capricious effect on the fossil record. For lots of potential
> > > > reasons, some things fossilize well at certain times and conditions, and don't under diffferent
> > > > circumstances.
> > > >
> > > > Trilobites were evidently well-distributed globally before they developed calcified exoskeletons,
> > > > which made them much more easily preserved as fossils. Nobody has definitivly identified the "soft" trilobites,
> > > > although there are some suggested possibilities. Check out https://www.trilobites.info/ for a readable
> > > > discussion of Trilobites, accessible to non-specialists.
> > > >
> > > > I haven't included lots of references for these assertions, but they are legion. GIYF.
> > > Yes, I’ve read the Rise and Fall of Dinosaurs, but not that of mammals.
> > >
> > > One more question: is it possible that the lack of non-swamp creatures in the earliest Triassic (Induan?) of the Urals and China - at least compared to Gondwana - was due to their proximity to the Siberian Traps or might that difference purely have been a matter of latitude? After all, it seems like some of the same temnospondyls are both in the north and south, but not the dicynodonts, cynodonts, or very many of the other guys living outside the swamp…
> > Off the top of my head, I don't know. There may (probably is) something in Brusatte's mammal book.
> > I may look later today, but right now I have to deal with flooded roads blocking me in my neighborhood.
> Oh no! Are you part of all that flooding in California? Hang in there… and tell us if you see any temnospondyls!

I live in the high desert ~6100 ft, but yes we have current flooding. The flooded road turned out to be
a minor difficulty for 4x4 vehicles. As for Tempospondyls, there are Lissamphibia here (frogs and toads),
but unless Temnospondyls are ancestral, none of them. The most current definition has Temnospondyla
as a sister group to moden amphibians.

On Sunday, March 12, 2023 at 4:19:53 PM UTC-6, erik simpson wrote:
> On Sunday, March 12, 2023 at 10:51:27 AM UTC-7, Sight Reader wrote:
> > On Sunday, March 12, 2023 at 10:26:23 AM UTC-6, erik simpson wrote:
> > > On Saturday, March 11, 2023 at 9:00:14 PM UTC-8, Sight Reader wrote:
> > > > On Saturday, March 11, 2023 at 5:40:47 PM UTC-7, erik simpson wrote:
> > > > > On Saturday, March 11, 2023 at 3:03:43 PM UTC-8, Sight Reader wrote:
> > > > > > Hey guys, my readings about the end-Permian extinction have sparked some questions about it.
> > > > > >
> > > > > > The book I read postulates that a massive meteor strike in the Panthalassic might have led to “antipodal” shockwave disruption of the Siberian crust opposite the strike, much as Deccan volcanism has been blamed on shockwaves from the antipodal Chicxulub strike. The reason no crater has been found would then attributed to the fact that the Panthalassic location where the putative strike would have occurred has since been completely replaced by new sea floor, with Hawaiian volcanism possibly being the last surviving evidence of the strike location.
> > > > > >
> > > > > > Tangential to that theory, I find myself wondering the following:
> > > > > >
> > > > > > (1) If the crust under the Panthalassic has indeed been completely replaced since then, how do we know that the Panthalassic ocean really had no landmasses? In other words, what evidence do we have for Pangea being the only continent at the time?
> > > > > >
> > > > > > There’s also the interesting fact that the ubiquitous Lystrosaurus is everywhere in Early Triassic Gondwana (South Africa, South America, etc) but lacking in Early Triassic Laurasia (Russia, China) where we only find swamp-dwelling temnospondyls.
> > > > > >
> > > > > > (2) Is it possible that proximity to active (and presumably dangerous) Siberian Traps made life prohibitively difficult in (nearby?) Russia and China unless you could take shelter in a swamp?
> > > > > >
> > > > > > Finally, I’m curious that we are unable to find how marine reptiles like ichthyosaurs and plesiosaurs evolved: they seem to simply appear - rather well-formed - sometime in the Triassic. The book I read postulated that the Early Triassic seas may have been continuously disrupted by heat from the Siberian Traps. Are the gaps in our Triassic marine records so vast and frequent that we’re likely to have completely missed the transition of these marine reptiles - or might another explanation be needed? My question is as follows:
> > > > > >
> > > > > > (3) Is it possible that marine reptiles evolved in a body of water isolated (and thus sheltered) from the larger oceans then spread relatively suddenly across the world once rising sea levels reconnected that body of water to improving oceanic conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…
> > > > > >
> > > > > > Thanks for your ideas!
> > > > > If I may ask,what book is that? The Wiki entry for the Permian-Triassic extinction is
> > > > > quite informative, and discusses various impact suggestions (hard to call them"theories").
> > > > > The principle objection that impresses me is that there is no need to postulate such an event.
> > > > > The Siberian traps, and other large volcanic events need no such trigger. No extraterrestial minerals
> > > > > layers (see Iridium) have been found. Some impact events of appropriate age have been detected, but
> > > > > they seem much too small to account for much.
> > > > >
> > > > > Ocean crust is recycled, continental masses aren't. There were undoubtably islands or island chains
> > > > > at the time that were not part of Pangea, but no evidence for continent-sized islands. Different fauna
> > > > > and flora is not unexpected. Pangea had large interior deserts and quite possibly extreme monsoonal
> > > > > weather that would have prevented large migrations from homogenizing the whole continent. See
> > > > > https://en.wikipedia.org/wiki/Pangean_megamonsoon
> > > > >
> > > > > The problem of sudden appearance of taxa in the fossil record is common, and has many potential
> > > > > aspects. The Triassic was a dynamic period of rapid developemental radiation into a depauperate
> > > > > ecosystem, and was capped with its own mass extinction, the Triassic-Jurassic event. It also has a
> > > > > good Wiki entry. Taphonomy also has a capricious effect on the fossil record. For lots of potential
> > > > > reasons, some things fossilize well at certain times and conditions, and don't under diffferent
> > > > > circumstances.
> > > > >
> > > > > Trilobites were evidently well-distributed globally before they developed calcified exoskeletons,
> > > > > which made them much more easily preserved as fossils. Nobody has definitivly identified the "soft" trilobites,
> > > > > although there are some suggested possibilities. Check out https://www.trilobites.info/ for a readable
> > > > > discussion of Trilobites, accessible to non-specialists.
> > > > >
> > > > > I haven't included lots of references for these assertions, but they are legion. GIYF.
> > > > Yes, I’ve read the Rise and Fall of Dinosaurs, but not that of mammals.
> > > >
> > > > One more question: is it possible that the lack of non-swamp creatures in the earliest Triassic (Induan?) of the Urals and China - at least compared to Gondwana - was due to their proximity to the Siberian Traps or might that difference purely have been a matter of latitude? After all, it seems like some of the same temnospondyls are both in the north and south, but not the dicynodonts, cynodonts, or very many of the other guys living outside the swamp…
> > > Off the top of my head, I don't know. There may (probably is) something in Brusatte's mammal book.
> > > I may look later today, but right now I have to deal with flooded roads blocking me in my neighborhood.
> > Oh no! Are you part of all that flooding in California? Hang in there… and tell us if you see any temnospondyls!
> I live in the high desert ~6100 ft, but yes we have current flooding. The flooded road turned out to be
> a minor difficulty for 4x4 vehicles. As for Tempospondyls, there are Lissamphibia here (frogs and toads),
> but unless Temnospondyls are ancestral, none of them. The most current definition has Temnospondyla
> as a sister group to moden amphibians.
Be careful! Oh, and I was kidding about the temnospondyls, lol… I don’t think any of them made it past the Jurassic, although I’m not sure…

On 3/12/23 12:26, erik simpson wrote:
> right now I have to deal with flooded roads blocking me in my neighborhood.

should I send a boat?

On Monday, March 13, 2023 at 1:52:36 PM UTC-7, Popping Mad wrote:
> On 3/12/23 12:26, erik simpson wrote:
> > right now I have to deal with flooded roads blocking me in my neighborhood.
> should I send a boat?

Thanks, but just washed out roads. Boats not needed. Today even presented a usable
detour.

On Monday, March 13, 2023 at 7:12:26 PM UTC-4, erik simpson wrote:
> On Monday, March 13, 2023 at 1:52:36 PM UTC-7, Popping Mad wrote:
> > On 3/12/23 12:26, erik simpson wrote:
> > > right now I have to deal with flooded roads blocking me in my neighborhood.
> > should I send a boat?
> Thanks, but just washed out roads. Boats not needed. Today even presented a usable
> detour.
Beware of San Andrean Flood Basalts and tell any Lystrosaurs you see that they may want to wait this one out…