10-12-2019, 06:15 PM
Presumption #5: Evolution and Faunal Exchanges
(Part One)
Life may or may not have developed separately in parallel here and on more RL-like Earths to startwith, but species and even entire ecosystems have undoubtedly entered our Reality from one or more RL-like Earths at various times as well which helps to explain the modern similarities. These entries were commonly separated by quite lengthy periods of time during which evolution happened independently here, and new arrivals could not always succeed in displacing the earlier natives that already filled comparable ecological roles, which helps to explain the modern differences. The more moderate nature [on average] of conditions here meant that native species had typically faced less evolutionary pressure than had newly-arrived rivals, which helps to explain the success rates of the latter. Small animals generally have shorter lifespans than do larger animals, meaning that they had more generations in which to evolve to fit local conditions in between new groups’ arrivals, and thus were less likely to lose out to those rivals. There were only a few major “exchanges” during the early epochs of the Cenozoic era (“Age of Mammals”), mostly coinciding with significant geological or climatic changes on one or both of the worlds involved (and thus, in some cases, with the dates assigned by RL scientists for the transitions between Epoch as wells…), but they apparently increased in frequency — although perhaps with fewer species involved on each occasion — during the last two or three million years. The most recent few centuries have even some seen entire ‘nations’ “swapped” into (and out of) this reality, in some cases carrying entire ecosystems with them!
Our two continents’ floras & faunas had already diverged from each other to some extent before the end of the Cretaceous. Malabra (and the then-separate north-eastern tip of the southern continent, close to that land, as well) held modified versions of the southern continent’s ecosystems, while the archipelago off the northern continent’s south-western corner held an even more distinct version of the northern continent’s. Apparently the relatively small land-mass that gave rise to the modern ‘Ayyubid Islands’ had already been separate from the super-continent since some point in the Jurassic period, as its fauna was even less like that in any of those other lands by this stage.
Presumably the Cretaceous fauna of these lands included numerous species of [“non-Avian”] dinosaurs of various kinds, gigantic marine reptiles of various kinds, crocodilians, and probably pterosaurs too, as well as the “early” mammals and birds and other relatively small animals. We can discuss what sorts of dinosaurs & other large reptiles you want to have had present here…
Presumption #6: “The Doom of the Dinosaurs”
There was a ‘mass extinction’ event in the IDU’s world at the end of the Cretaceous period, approximately coincident in time with the one that happened on RL Earth, that killed off the [“non-avian”] dinosaurs & most if not all of the other large reptiles: whether or not Crocodilians survived here (as they did on RL Earth) is a question about which — not having any of my nations in places where their presence today would be likely — I don’t particularly care. (In my earlier thoughts about the region’s ecosystems they did [/i become extinct at that stage, although some species later arrived in the relatively recent wholesale “intrusion” of South American ecosystems — particularly that of the Amazon Rainforest — into parts of Malabra… but that was[/i] before we changed the map’s scale so that it now extends deeply into the Tropics…)
There was a meteorite impact involved in the event here, as has now been shown for RL, but the different pattern of lands & waters obviously means that it can’t have hit in the same place (which somebody else who was looking into this matter for similar reasons says has now been identified as just about the worst place that it could have hit, as far as the dinosaurs [etc.] were concerned…) and had identical patterns of effect. I suggest that the body involved here, which might have been slightly larger than its RL counterpart to start with, broke up into several pieces on its way in and gave this world a set of smaller impacts (leaving smaller, & thus even less identifiable, craters)] — simultaneously enough for their effects to combine — for a comparable total effect overall.
Presumption #7: Evolution and Faunal Exchanges
(Part Two)
All the groups of mammals and birds that survived this event in RL also survived it in the IDU, if they were present here before that anyway which some (due to limited geographical ranges on RL Earth which meant that they’d never been able to reach the IDU…) were not, as did a few more groups of mammals and at least one of birds: There were also some endemic lineages in both of those classes that made it successfully through the catastrophe.
Lineages of mammals and birds that reached the IDU’s northern continent from a more RL-like Earth during the Cenozoicseem normally to have done so from either Europe, Asia north of [approximately] a line running east-west through the Himalayas, or North America: Those that reached the southern continent included some that were probably from the same regions, too, but also quite a few that are more likely to have come from Asia south of that line (although apparently not from the tropical forests of that continent’s south-eastern parts) instead. Malabra received its anomalously South American ecosystems no more than half a million years ago, and some species from [probably] India arrived in that land’s western areas even more recently — although still well before the first arrival here of Humans which itself happened no more than 15’00 years (and maybe no more than 10’000 years, but we can discuss this…) — as did the arrival in the mountains to its north & north-west of some species that seem to have come from a RL-Earth’s the mountainous areas between India & China.
The ecosystems arriving when some entire nations were “swapped in” from elsewhere may have been more diverse in origins than that, and of course this can continue if the nations’ players want it to do so.
The collision of Malabra with the northern continent allowed their floras & faunas to mix, of course.
The land-bridges that sometimes linked our continents allowed a limited amount of expansion by various groups of animals, and to a lesser extent plants, from one continent onto the other. There are also quite a few cases where the continents share groups, or even species, for whose passage no such bridges seem to have existed… but almost all of those taxa are ones that also exist (or existed, anyway) on Earth-RL and so presumably entered the two continents by two separate routes from one or more RL-like Earths instead. Maybe the remaining anomalies spread from one of our continents to the other via another Earth during those interchanges?
In fact, there are even a few groups of animals (e.g. Lagomorphs, Bats) for whom various combinations of earlier fossils and greater diversity suggest that early evolution took place mainly in the IDU with a subsequent spread to those more RL-like Earths that also have them!
The southern continent seems to have received significantly fewer species from RL-like Earths during the last few million years than did the northern continent, so that even its larger mammals are more likely to be from lineages with longer histories of ‘native’ status and there is therefore an even higher proportion of endemic genera or even endemic families in its fauna & flora than for those of the northern continent.
The higher average levels of warmth and moisture don’t just allow temperate forests to be more extensive, they probably allow many plants (especially in between the equatorial rainforests and the polar regions) to grow a bit more vigorously than they would have done in the closest equivalent areas on more RL-like Earths too, thus supporting higher densities of herbivorous and omnivorous animals which in turn support higher concentrations of, carnivores and scavengers (or people, of course) too. Combine this with the fact that the lengthy periods of relatively stable condition would have encouraged a phenomenon called ‘niche partitioning’, in which the members of long-running lineages diverge into sets of differing forms that each specialise in slightly different lifestyles, and I can “reasonably” give areas here greater numbers of animal species than the closest equivalent areas on a more RL-like Earth would possess.
(Part One)
Life may or may not have developed separately in parallel here and on more RL-like Earths to startwith, but species and even entire ecosystems have undoubtedly entered our Reality from one or more RL-like Earths at various times as well which helps to explain the modern similarities. These entries were commonly separated by quite lengthy periods of time during which evolution happened independently here, and new arrivals could not always succeed in displacing the earlier natives that already filled comparable ecological roles, which helps to explain the modern differences. The more moderate nature [on average] of conditions here meant that native species had typically faced less evolutionary pressure than had newly-arrived rivals, which helps to explain the success rates of the latter. Small animals generally have shorter lifespans than do larger animals, meaning that they had more generations in which to evolve to fit local conditions in between new groups’ arrivals, and thus were less likely to lose out to those rivals. There were only a few major “exchanges” during the early epochs of the Cenozoic era (“Age of Mammals”), mostly coinciding with significant geological or climatic changes on one or both of the worlds involved (and thus, in some cases, with the dates assigned by RL scientists for the transitions between Epoch as wells…), but they apparently increased in frequency — although perhaps with fewer species involved on each occasion — during the last two or three million years. The most recent few centuries have even some seen entire ‘nations’ “swapped” into (and out of) this reality, in some cases carrying entire ecosystems with them!
Our two continents’ floras & faunas had already diverged from each other to some extent before the end of the Cretaceous. Malabra (and the then-separate north-eastern tip of the southern continent, close to that land, as well) held modified versions of the southern continent’s ecosystems, while the archipelago off the northern continent’s south-western corner held an even more distinct version of the northern continent’s. Apparently the relatively small land-mass that gave rise to the modern ‘Ayyubid Islands’ had already been separate from the super-continent since some point in the Jurassic period, as its fauna was even less like that in any of those other lands by this stage.
Presumably the Cretaceous fauna of these lands included numerous species of [“non-Avian”] dinosaurs of various kinds, gigantic marine reptiles of various kinds, crocodilians, and probably pterosaurs too, as well as the “early” mammals and birds and other relatively small animals. We can discuss what sorts of dinosaurs & other large reptiles you want to have had present here…
Presumption #6: “The Doom of the Dinosaurs”
There was a ‘mass extinction’ event in the IDU’s world at the end of the Cretaceous period, approximately coincident in time with the one that happened on RL Earth, that killed off the [“non-avian”] dinosaurs & most if not all of the other large reptiles: whether or not Crocodilians survived here (as they did on RL Earth) is a question about which — not having any of my nations in places where their presence today would be likely — I don’t particularly care. (In my earlier thoughts about the region’s ecosystems they did [/i become extinct at that stage, although some species later arrived in the relatively recent wholesale “intrusion” of South American ecosystems — particularly that of the Amazon Rainforest — into parts of Malabra… but that was[/i] before we changed the map’s scale so that it now extends deeply into the Tropics…)
There was a meteorite impact involved in the event here, as has now been shown for RL, but the different pattern of lands & waters obviously means that it can’t have hit in the same place (which somebody else who was looking into this matter for similar reasons says has now been identified as just about the worst place that it could have hit, as far as the dinosaurs [etc.] were concerned…) and had identical patterns of effect. I suggest that the body involved here, which might have been slightly larger than its RL counterpart to start with, broke up into several pieces on its way in and gave this world a set of smaller impacts (leaving smaller, & thus even less identifiable, craters)] — simultaneously enough for their effects to combine — for a comparable total effect overall.
Presumption #7: Evolution and Faunal Exchanges
(Part Two)
All the groups of mammals and birds that survived this event in RL also survived it in the IDU, if they were present here before that anyway which some (due to limited geographical ranges on RL Earth which meant that they’d never been able to reach the IDU…) were not, as did a few more groups of mammals and at least one of birds: There were also some endemic lineages in both of those classes that made it successfully through the catastrophe.
Lineages of mammals and birds that reached the IDU’s northern continent from a more RL-like Earth during the Cenozoicseem normally to have done so from either Europe, Asia north of [approximately] a line running east-west through the Himalayas, or North America: Those that reached the southern continent included some that were probably from the same regions, too, but also quite a few that are more likely to have come from Asia south of that line (although apparently not from the tropical forests of that continent’s south-eastern parts) instead. Malabra received its anomalously South American ecosystems no more than half a million years ago, and some species from [probably] India arrived in that land’s western areas even more recently — although still well before the first arrival here of Humans which itself happened no more than 15’00 years (and maybe no more than 10’000 years, but we can discuss this…) — as did the arrival in the mountains to its north & north-west of some species that seem to have come from a RL-Earth’s the mountainous areas between India & China.
The ecosystems arriving when some entire nations were “swapped in” from elsewhere may have been more diverse in origins than that, and of course this can continue if the nations’ players want it to do so.
The collision of Malabra with the northern continent allowed their floras & faunas to mix, of course.
The land-bridges that sometimes linked our continents allowed a limited amount of expansion by various groups of animals, and to a lesser extent plants, from one continent onto the other. There are also quite a few cases where the continents share groups, or even species, for whose passage no such bridges seem to have existed… but almost all of those taxa are ones that also exist (or existed, anyway) on Earth-RL and so presumably entered the two continents by two separate routes from one or more RL-like Earths instead. Maybe the remaining anomalies spread from one of our continents to the other via another Earth during those interchanges?
In fact, there are even a few groups of animals (e.g. Lagomorphs, Bats) for whom various combinations of earlier fossils and greater diversity suggest that early evolution took place mainly in the IDU with a subsequent spread to those more RL-like Earths that also have them!
The southern continent seems to have received significantly fewer species from RL-like Earths during the last few million years than did the northern continent, so that even its larger mammals are more likely to be from lineages with longer histories of ‘native’ status and there is therefore an even higher proportion of endemic genera or even endemic families in its fauna & flora than for those of the northern continent.
The higher average levels of warmth and moisture don’t just allow temperate forests to be more extensive, they probably allow many plants (especially in between the equatorial rainforests and the polar regions) to grow a bit more vigorously than they would have done in the closest equivalent areas on more RL-like Earths too, thus supporting higher densities of herbivorous and omnivorous animals which in turn support higher concentrations of, carnivores and scavengers (or people, of course) too. Combine this with the fact that the lengthy periods of relatively stable condition would have encouraged a phenomenon called ‘niche partitioning’, in which the members of long-running lineages diverge into sets of differing forms that each specialise in slightly different lifestyles, and I can “reasonably” give areas here greater numbers of animal species than the closest equivalent areas on a more RL-like Earth would possess.