03-11-2020, 08:38 PM
Survival in the IDU
Our world’s different pattern of continents presumably indicates a different history of ‘plate tectonic’ events going back a long way, quite possibly even back past the beginning of the Cambrian Period. This being the case, our world’s history of ‘mass extinction’ events could plausibly have been different as well, even if external factors such as the ones that might help to start Ice Ages — or major meteoric impacts — were the same here as in RL.
I am not going to suggest that all of our world’s ‘mass extinctions’ were less severe than those of RL Earth, nor to deny that ecosystems here might then also have had to cope with one or two additional such events which RL ecosystems did not. Nevertheless, it seems reasonable to me to presume that these differences also led to some differences in the compositions of the post-extinction ecosystems… although some of those differences would probably later have been evened-out by some extinct groups being replaced — and possibly some surviving groups being out-competed, as well — by members of groups that had survived in one or more RL-like Earths and “leaked” across to here. (I had already mentioned that idea elsewhere in this sub-forum, in the specific context of the mass-extinction at the end of the Mesozoic Era and the subsequent developments of — especially — our Mammal and Bird faunas…).
Unless any of you insist on changing this, I think that our modern-day Trilobites would belong to two or three separate Orders, one or two of which had also existed in RL but one of which would be endemic.
The Proetida were the last order of Trilobites to appear on RL Earth, and were also the order to which the last surviving Trilobites on RL Earth belonged. They seem to have lasted that long because they had become adapted to deeper waters, where there was less competition: As some other groups of animals that followed such a pattern have survived on RL Earth until today, even though all of their close relatives living in shallower water have long been extinct, it doesn’t stretch probability too far to suggest that these could also have done so. Thus, this order would contain our deep-sea species.
The Lichida were among the orders that became extinct during the latter half of the Devonian period on RL Earth. Their members were characteristically spiny, which is why they’re distinct enough from all the others for me to consider them worth using. I don’t yet have any particular theory about how & why they would have survived here when so many others do not, so would suggest that if we do use them then it as the stock for an area isolated from the world’s “main” Trilobite populations — perhaps the coastal waters of Libertas Omnium Maximus, as that nation was among those voting for the presence of trilobites “in the shallows” but the only other nations near there who voted at all were against that possibility — with their origin a mystery (and possibly due, although nobody IC would know this, to [fairly recent?] interdimensional “leakage” from a version of Earth that is still in its Ordovician or Devonian period?)
The Neotrilobita — unless I find a better name for them — would then be our endemic order, containing primarily species resident in the shallower waters around [some of the] shores of the Olympic Ocean. As my ideas about the region’s geological history involve that ocean only having formed as a former super-continent (including all four of our present main land-mases) broke up from the mid-Mesozoic onwards, my suggestion for their evolution & survival is that their ancestors had actually managed to spread — unlike any Trilobites known of so far on RL Earth — successfully through the brackish water of estuaries into the fresh waters further inland: This let them survive the sea-level changes of the later Devonian and even the end-Permian mass extinction. During the Mesozoic they then expanded back downstream into the shallow seas (or, at least, salty “lakes”) that existed at times in various places “within” the super-continent, and thence into the Olympic Ocean as that opened up as well. Any last freshwater Trilobites that managed to survive until the end of the Mesozoic were probably wiped out in the ‘K-Pg Event’ (i.e. “Death of the Dinosaurs”), although some limited re-colonisation of that environment might have taken place more recently. I will presume that they and Crustaceans such as those that fill [probably similar] ecological roles today on RL Earth are ecologically balanced enough against each other for both groups to exist here, although in some cases conditions in certain areas may favour one or the other.
Arcadia Dazeber voted in favour of trilobites in shallow waters, but Legionas to their north voted against us having any surviving Trilobites at all: If those views are matched by their decisions now about having Trilobites in their own nations’ coastal waters, and if no linking populations around the southern end of that continent are approved by players there, then possibly the ancestors of Arcadia Dazeber’s stocks “returned to the sea” locally in the late Mesozoic, separately from those that populated the Olympic Ocean, and have been unable to spread further because (? reason still to be determined…).
The basic ecological role filled by these coastal species would be as scavengers & sometimes predators, although the latter would be probably limited to smaller and relatively slow-moving (or even sessile) prey, without heavy armour of its own, as is also the case for many types of Crab or Lobster, but I have some ideas about various more-specialised lifestyles & forms that would also be possible.
Bearing in mind the “origin story” that I now suggest for our main group of Trilobites, and having done some more research into the RL ones, I am dropping my suggestion that some species might — like the Horseshoe Crabs — crawl ashore to lay their eggs in beach sands. However, if we do go with my suggestion of a ‘freshwater’ stage in the evolution of the endemic order Neotrilobita, there might be species whose adults normally live in brackish estuaries or swamps but migrate upriver to reproduce and whose young spend some time developing in freshwater before moving back downstream…
Our world’s different pattern of continents presumably indicates a different history of ‘plate tectonic’ events going back a long way, quite possibly even back past the beginning of the Cambrian Period. This being the case, our world’s history of ‘mass extinction’ events could plausibly have been different as well, even if external factors such as the ones that might help to start Ice Ages — or major meteoric impacts — were the same here as in RL.
I am not going to suggest that all of our world’s ‘mass extinctions’ were less severe than those of RL Earth, nor to deny that ecosystems here might then also have had to cope with one or two additional such events which RL ecosystems did not. Nevertheless, it seems reasonable to me to presume that these differences also led to some differences in the compositions of the post-extinction ecosystems… although some of those differences would probably later have been evened-out by some extinct groups being replaced — and possibly some surviving groups being out-competed, as well — by members of groups that had survived in one or more RL-like Earths and “leaked” across to here. (I had already mentioned that idea elsewhere in this sub-forum, in the specific context of the mass-extinction at the end of the Mesozoic Era and the subsequent developments of — especially — our Mammal and Bird faunas…).
Unless any of you insist on changing this, I think that our modern-day Trilobites would belong to two or three separate Orders, one or two of which had also existed in RL but one of which would be endemic.
The Proetida were the last order of Trilobites to appear on RL Earth, and were also the order to which the last surviving Trilobites on RL Earth belonged. They seem to have lasted that long because they had become adapted to deeper waters, where there was less competition: As some other groups of animals that followed such a pattern have survived on RL Earth until today, even though all of their close relatives living in shallower water have long been extinct, it doesn’t stretch probability too far to suggest that these could also have done so. Thus, this order would contain our deep-sea species.
The Lichida were among the orders that became extinct during the latter half of the Devonian period on RL Earth. Their members were characteristically spiny, which is why they’re distinct enough from all the others for me to consider them worth using. I don’t yet have any particular theory about how & why they would have survived here when so many others do not, so would suggest that if we do use them then it as the stock for an area isolated from the world’s “main” Trilobite populations — perhaps the coastal waters of Libertas Omnium Maximus, as that nation was among those voting for the presence of trilobites “in the shallows” but the only other nations near there who voted at all were against that possibility — with their origin a mystery (and possibly due, although nobody IC would know this, to [fairly recent?] interdimensional “leakage” from a version of Earth that is still in its Ordovician or Devonian period?)
The Neotrilobita — unless I find a better name for them — would then be our endemic order, containing primarily species resident in the shallower waters around [some of the] shores of the Olympic Ocean. As my ideas about the region’s geological history involve that ocean only having formed as a former super-continent (including all four of our present main land-mases) broke up from the mid-Mesozoic onwards, my suggestion for their evolution & survival is that their ancestors had actually managed to spread — unlike any Trilobites known of so far on RL Earth — successfully through the brackish water of estuaries into the fresh waters further inland: This let them survive the sea-level changes of the later Devonian and even the end-Permian mass extinction. During the Mesozoic they then expanded back downstream into the shallow seas (or, at least, salty “lakes”) that existed at times in various places “within” the super-continent, and thence into the Olympic Ocean as that opened up as well. Any last freshwater Trilobites that managed to survive until the end of the Mesozoic were probably wiped out in the ‘K-Pg Event’ (i.e. “Death of the Dinosaurs”), although some limited re-colonisation of that environment might have taken place more recently. I will presume that they and Crustaceans such as those that fill [probably similar] ecological roles today on RL Earth are ecologically balanced enough against each other for both groups to exist here, although in some cases conditions in certain areas may favour one or the other.
Arcadia Dazeber voted in favour of trilobites in shallow waters, but Legionas to their north voted against us having any surviving Trilobites at all: If those views are matched by their decisions now about having Trilobites in their own nations’ coastal waters, and if no linking populations around the southern end of that continent are approved by players there, then possibly the ancestors of Arcadia Dazeber’s stocks “returned to the sea” locally in the late Mesozoic, separately from those that populated the Olympic Ocean, and have been unable to spread further because (? reason still to be determined…).
The basic ecological role filled by these coastal species would be as scavengers & sometimes predators, although the latter would be probably limited to smaller and relatively slow-moving (or even sessile) prey, without heavy armour of its own, as is also the case for many types of Crab or Lobster, but I have some ideas about various more-specialised lifestyles & forms that would also be possible.
Bearing in mind the “origin story” that I now suggest for our main group of Trilobites, and having done some more research into the RL ones, I am dropping my suggestion that some species might — like the Horseshoe Crabs — crawl ashore to lay their eggs in beach sands. However, if we do go with my suggestion of a ‘freshwater’ stage in the evolution of the endemic order Neotrilobita, there might be species whose adults normally live in brackish estuaries or swamps but migrate upriver to reproduce and whose young spend some time developing in freshwater before moving back downstream…