Actually scientists are still divided over what caused the MC event and whether the mass extinction was caused by just meteorites or meteorites in conjunction with climate change, volcanic activity and changing continental orientations which posed multiple shocks to the system.

You have made the question a bit easier by not including all the conifers though they aren't flowering plants - these occupy massive stretches of North Eurasia and America and would indeed leave a massive vacancy. But I'm a bit confused, why would an extreme heat-and-drought event wipe out just the named divisions? Indeed, mosses are the oldest land plants and a resistant bunch, ranging from the tropics to polar regions. The humble moss and its spores can survive under all weather conditions and repeat droughts. Moss has even been revived after as long as 1500 years. If really pushed, why wouldn't mosses build upon their drought tolerance capabilities and evolve to survive? A couple of more links: Moss myths, why moss is drought resistant, ancient moss revived and Arid bryophyta. Ferns adapt so well that they have turned a pest in many areas. Again like moss, they grow under a variety of conditions including arid regions. If it's hot enough to kill these, it would be hot enough to kill most else.

Mosses and worts - bryophyta - would be the hardest to replace. Ancient moss is said to have brought on the Ordovician ice age and I'm not sure what would replace this voracious carbon sink. They reduce erosion along streambanks, retain water in tropical forests, form a layer of soil/vegation over polar regions, fix CO₂ and provide nutrition to the animal species around. Some of this niche could be taken over by sedge grasses, lichen and algae.

As to the other species, their passing would not mean much difference. Some of these plants such as cycads are not found in single stands. Though they do have some medicinal and food value (ephedrine, gingko), most are living fossils and curiously resistant and thriving relics of a bygone era. They do not actually occupy large niches that can't be replaced by some other species. The current landscape as it stands in most places would not look very different without these.

Refuge 'islands' such New Zealand, Chile or western NorAm would have the existing competing flowering plants/trees/conifers take over the vacancy. Take New Zealand, for example, home to most of the southern Gondwana paleo-flora. Take out the podocarps but there are still the southern beeches. Australia, the nearest neighbour, once had similar vegetation, which retreated to a few isolated stands in the east and south once the climate got drier and favoured the eucalypt family.

And umm, have you checked Pteridospermophyta? Seed ferns died out mostly by the Cretaceous and are no longer around. And it's Anthocerotophyta, not Anthotocerotophyta.

Actually scientists are still divided over what caused the MC event and whether the mass extinction was caused by just meteorites or meteorites in conjunction with climate change, volcanic activity and changing continental orientations which posed multiple shocks to the system.

You have made the question a bit easier by not including all the conifers though they aren't flowering plants - these occupy massive stretches of North Eurasia and America and would indeed leave a massive vacancy. But I'm a bit confused, why would an extreme heat-and-drought event wipe out just the named divisions/orders/families? Indeed, mosses are the oldest land plants and a resistant bunch, ranging from the tropics to polar regions. The humble moss and its spores can survive under all weather conditions and repeat droughts. Moss has even been revived after as long as 1500 years. If really pushed, why wouldn't mosses build upon their drought tolerance capabilities and evolve to survive? A couple of more links: Moss myths, why moss is drought resistant, ancient moss revived and Arid bryophyta. Ferns adapt so well that they have turned a pest in many areas. Again like moss, they grow under a variety of conditions including arid regions. If it's hot enough to kill these, it would be hot enough to kill most else.

Mosses and worts - bryophyta - would be the hardest to replace. Ancient moss is said to have brought on the Ordovician ice age and I'm not sure what would replace this voracious carbon sink. They reduce erosion along streambanks, retain water in tropical forests, form a layer of soil/vegation over polar regions, fix CO₂ and provide nutrition to the animal species around. Some of this niche could be taken over by sedge grasses, lichen and algae.

As to the other species, their passing would not mean much difference. Some of these plants such as cycads are not found in single stands. Though they do have some medicinal and food value (ephedrine, gingko), most are living fossils and curiously resistant and thriving relics of a bygone era. They do not actually occupy large niches that can't be replaced by some other species. The current landscape as it stands in most places would not look very different without these.

Refuge 'islands' such New Zealand, Chile or western NorAm would have the existing competing flowering plants/trees/conifers take over the vacancy. Take New Zealand, for example, home to most of the southern Gondwana paleo-flora. Take out the podocarps but there are still the southern beeches. Australia, the nearest neighbour, once had similar vegetation, which retreated to a few isolated stands in the east and south once the climate got drier and favoured the eucalypt family.

And umm, have you checked Pteridospermophyta? Seed ferns died out mostly by the Cretaceous and are no longer around. And it's Anthocerotophyta, not Anthotocerotophyta.

Actually scientists are still divided over what caused the MC event and whether the mass extinction was caused by just meteorites or meteorites in conjunction with climate change, volcanic activity and changing continental orientations which posed multiple shocks to the system.

You have made the question a bit easier by not including all the conifers though they aren't flowering plants - these occupy massive stretches of North Eurasia and America and would indeed leave a massive vacancy. But I'm a bit confused, why would an extreme heat-and-drought event wipe out just the named species? Indeed, mosses are the oldest land plants and a resistant species, ranging from the tropics to polar regions. Ferns adapt so well that they have turned a pest in many areas. If it's hot enough to kill these, it would be hot enough to kill most else.

Mosses and worts - bryophyta - would be the hardest to replace. Ancient moss is said to have brought on the Ordovician ice age and I'm not sure what would replace this voracious carbon sink. They reduce erosion along streambanks, retain water in tropical forests, form a layer of soil/vegation over polar regions, fix CO₂ and provide nutrition to the animal species around. Some of this niche could be taken over by sedge grasses, clubmosses (lycopods aren't on the list above), lichen and algae.

As to the other species, their passing would not mean much difference. Some of these plants such as cycads are not found in single stands. Though they do have some medicinal and food value (ephedrine, gingko), most are living fossils and curiously resistant and thriving relics of a bygone era. They do not actually occupy large niches that can't be replaced by some other species. The current landscape as it stands in most places would not look very different without these.

Refuge 'islands' such New Zealand, Chile or western NorAm would have the existing competing flowering plants/trees/conifers take over the vacancy. Take New Zealand, for example, home to most of the southern Gondwana paleo-flora. Take out the podocarps but there are still the southern beeches. Australia, the nearest neighbour, once had similar vegetation, which retreated to a few isolated stands in the east and south once the climate got drier and favoured the eucalypt family.

And umm, have you checked Pteridospermophyta? Seed ferns died out mostly by the Cretaceous and are no longer around. And it's Anthocerotophyta, not Anthotocerotophyta.

Actually scientists are still divided over what caused the MC event and whether the mass extinction was caused by just meteorites or meteorites in conjunction with climate change, volcanic activity and changing continental orientations which posed multiple shocks to the system.

You have made the question a bit easier by not including all the conifers though they aren't flowering plants - these occupy massive stretches of North Eurasia and America and would indeed leave a massive vacancy. But I'm a bit confused, why would an extreme heat-and-drought event wipe out just the named divisions? Indeed, mosses are the oldest land plants and a resistant bunch, ranging from the tropics to polar regions. The humble moss and its spores can survive under all weather conditions and repeat droughts. Moss has even been revived after as long as 1500 years. If really pushed, why wouldn't mosses build upon their drought tolerance capabilities and evolve to survive? A couple of more links: Moss myths, why moss is drought resistant, ancient moss revived and Arid bryophyta. Ferns adapt so well that they have turned a pest in many areas. Again like moss, they grow under a variety of conditions including arid regions. If it's hot enough to kill these, it would be hot enough to kill most else.

Mosses and worts - bryophyta - would be the hardest to replace. Ancient moss is said to have brought on the Ordovician ice age and I'm not sure what would replace this voracious carbon sink. They reduce erosion along streambanks, retain water in tropical forests, form a layer of soil/vegation over polar regions, fix CO₂ and provide nutrition to the animal species around. Some of this niche could be taken over by sedge grasses, lichen and algae.

As to the other species, their passing would not mean much difference. Some of these plants such as cycads are not found in single stands. Though they do have some medicinal and food value (ephedrine, gingko), most are living fossils and curiously resistant and thriving relics of a bygone era. They do not actually occupy large niches that can't be replaced by some other species. The current landscape as it stands in most places would not look very different without these.

Refuge 'islands' such New Zealand, Chile or western NorAm would have the existing competing flowering plants/trees/conifers take over the vacancy. Take New Zealand, for example, home to most of the southern Gondwana paleo-flora. Take out the podocarps but there are still the southern beeches. Australia, the nearest neighbour, once had similar vegetation, which retreated to a few isolated stands in the east and south once the climate got drier and favoured the eucalypt family.

And umm, have you checked Pteridospermophyta? Seed ferns died out mostly by the Cretaceous and are no longer around. And it's Anthocerotophyta, not Anthotocerotophyta.