On Saturday, March 11, 2023 at 3:03:43 PM UTC-8, Sight Reader wrote: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
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
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 beTangential 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
conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…(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
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.
Hey guys, my readings about the end-Permian extinction have sparked some questions about it.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
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
Tangential to that theory, I find myself wondering the following: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
(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
(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 oceanicconditions? 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 5:40:47 PM UTC-7, erik simpson wrote: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
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
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 beTangential 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
conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…(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
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.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
On Saturday, March 11, 2023 at 3:03:43 PM UTC-8, Sight Reader wrote: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
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
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 beTangential 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
conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…(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
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: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
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
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 beTangential 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
conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…(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
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…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
On Saturday, March 11, 2023 at 9:00:14 PM UTC-8, Sight Reader wrote: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
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
temnospondyls.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
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(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
conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…(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
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…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
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: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
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
time?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
temnospondyls.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
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(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
conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…(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
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…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
Off the top of my head, I don't know. There may (probably is) something in Brusatte's mammal book.Oh no! Are you part of all that flooding in California? Hang in there… and tell us if you see any temnospondyls!
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 10:51:27 AM UTC-7, Sight Reader wrote: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
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
time?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
temnospondyls.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
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(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
oceanic conditions? I’ve heard similar such explanations for the relatively sudden appearance of fully-formed trilobites…(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
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…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
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…I live in the high desert ~6100 ft, but yes we have current flooding. The flooded road turned out to beOff the top of my head, I don't know. There may (probably is) something in Brusatte's mammal book.Oh no! Are you part of all that flooding in California? Hang in there… and tell us if you see any temnospondyls!
I may look later today, but right now I have to deal with flooded roads blocking me in my neighborhood.
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.
right now I have to deal with flooded roads blocking me in my neighborhood.
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:Beware of San Andrean Flood Basalts and tell any Lystrosaurs you see that they may want to wait this one out…
On 3/12/23 12:26, erik simpson wrote:Thanks, but just washed out roads. Boats not needed. Today even presented a usable
right now I have to deal with flooded roads blocking me in my neighborhood.should I send a boat?
detour.
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