The devastating mass extinction known as the World Scarring happened around 121 million Eryobian years ago, marking the end of the Bobossic period and subsequently the Prosarmozoic.
Palaeontologists knew for a while that a there had been a massive die off among virtually all organisms at the end of the Kikilian age of the Bobossic period, but weren’t really sure what caused it. The Kikilian-Thyellian boundary is clearly defined as a jet black layer in the rock, but surprisingly there is no iridium to be found here. This ruled out an asteroid impact, but it contains mostly the burned plant material and very little volcanic ash in most places, which means it couldn’t possibly have been formed by volcanic activity. Yet, the layer seems appears in rock formations all over the world and even some marine deposits feature what seems like a burn layer. There is no gradual evolution in deposits from the Kikilian to the Thyellian and animals and plants alike appear to have died rather sudden, which means that whatever caused the extinction happened very quickly. But if asteroid and volcanoes can be ruled out, what could have caused this massive die off?
Scientists started looking for clues and began hypothesising about what might have happened. Some thought it was a big solar storm, others assumed it was a nearby supernova or gamma ray burst. Some thought it was a global fire caused by sudden release of methane in the ground and others thought that a nearby moon came too close to Eryobis and caused tidal forces to burn the surface of the world. There was even a theory that a technologically advanced species caused global warming and climate change as we did back on Earth and perhaps they nuked their world to near extinction. Unfortunately, all of these theories would have left clearer traces if they did in fact happen than what we can actually find.
Then a new theory arose. First thought of by a geologist who was digging in Lotharca and discovered a layer of obsidian that seemed to have been formed at a temperature comparable to the surface of a star and quickly cooled as if exposed to the cold vacuum of space. Curiously, this layer can be found nearly all over Lotharca and even seems to be visible in parts of Rubiëra and appears to line up almost exactly with the Kikilian-Thyellian boundary, be that it seems it cut into Bobossic deposits while Thyellian deposits lie neatly on top. So it appeared that we finally discovered a geological anomaly that correlates with the Kikilian-Thyellian mass extinction, but it only complicated the matter. There is no natural phenomenon that could have literally melted the crust these continents and then let them cool quick enough for this large an amount of glass to form. Besides, there’s no impact sites on that seem to date the same age… or is there?
Turns out there’s a huge nearly straight canyon that runs through the middle of Lotharca. It’s so large in fact that it can clearly seen from space and is one of the most defining features of Eryobis. It appears like a scar on the world and is not surprisingly called the World Scar. Due to its size and shape, we assumed it was the result of tectonic forces ripping the plates in Lotharca apart. A recent scanning of the surface of the world however revealed that Lotharca is pretty much a single solid plate there are no boundaries even near the World Scar. This had led to the formulation of a theory that is equally outlandish as it is horrifying: the Kikilian-Thyellian extinction event was caused by an alien weapon.
While to many it sounded absolutely ridiculous at first, quick came the realisation that this very world we stand on was created by extraterrestrial beings with powers beyond our comprehension. It also wouldn’t be the first time we have encountered the effects of alien technology. On several of our colonised worlds we found traces of ancient civilisations and then ofcourse there’s the screaming case of the alien mega station that has led humanity to many of its current advancements, though its existence has been forgotten by most.
Then came the question: why? Why was an ancient super weapon fired against Eryobis? The answer that most seem to agree on, is that it wasn’t. Instead, they propose the projectile was once shot in an ancient battle fought by forgotten civilisations in an unknown part of the galaxy. The projectile could have travelled countless years through the emptiness of space before it eventually came to Eryobis by accident. The formation of the World Scar suggests the projectile merely scraped the surface of the world, but still managed to cause a mass extinction that is only rivalled by the Permian-Triassic extinction of Earth in severity, except far more sudden. The amount of energy this projectile must have carried is most likely incomprehensible to us humans. While we ourselves do not possess such weaponry, the projectile that caused the World Scarring would have been fired out of a “planet killer”, a weapon with enough power to vaporise the crusts of planets or outright destroy them.
We can see this in the soil turned glass found all over Lotharca and parts of Rubiëra. The projectile sliced through the atmosphere and likely formed a huge hole over the impact that exposed the molten surface to the coldness of space for just a moment. The impact vaporised the entire top 200-500 meters of water in a 500 kilometer radius and might have even set the atmosphere itself ablaze, sending a burning shockwave around the globe that would have consumed all organic matter in an apocalyptic inferno. Nearly all life on the surface of Eryobis seems to have been killed off almost instantly.
Yet, evidently, some survived. Flora might have survived in the form of heat resistant spores and seeds that had already settled in the ground on the opposite side of the globe compared to where the impact happened.
The animals on land seem to offer a clue as to why they even survived in the first place. While we have very little remains of the actual creatures that made it through the apocalypse, their descendants that took over after the dust had settled often show adaptations for digging. Moreover, fossils from the latest Kikilian indicate that the World Scarring happened during northern hemisphere winter and impacted the Lotharca which at the time was closer to the South Pole than it is now. This means that most of the surviving terrestrial animals were likely either fossorial or hibernating near the North Pole, thus escaping the blazing shockwave and not being affected by the extreme heat as much as the rest of Eryobis was.
As was previously stated, we actually have very few remains of the actual survivors, but we have been able to mostly deduct what they likely looked like based on their descendants after the World Scarring and relatives from the Kikilian.
1. A single kind of Dextrotselan Anisospondyl appears to have survived the apocalypse, but it did not much resemble its more famous Dextrotselan cousins like the Aurispinids. Instead was a serpentine creature that likely lived somewhat like a caecilian. (Has no living descendants)……
2. Three lineages of Brachiostomatan Anisospondyls managed to make it through the World Scarring. A fraction of their previous diversity, but it was this diversity that allowed them to survive in the first place. The first of these three was a Folicervauridian, a kind of Brachiostome that has a single ear located on the visendal side right behind the head. We know the surviving member also had such an ear because it was already present in its relatives in the Kikilian. (Has a handful of living descendants)……
3. The second of the three was also the only ear-sail-backed animal to make it through the apocalypse. While sails were a somewhat common sighting in the Prosarmozoic, the Akinitotosaurs are the only Anisospondyls with sails in the Afthonozoic. Apparently the last of many groups of Anisospondyls to evolve a sail-for-an-ear, they are also the last ones to survive. (Has a handful of living descendants)……
4. The third Brachiostome lineage to survive was also the shortest lived. While the other two lineages have member surviving into the present, the Jerounopetonids did not make it beyond the early Farathenian. While Brachiostomes were never able to reclaim the dominance and diversity they had during the Bobossic, the Jerounopetonids did honour their ancestry by becoming some of the largest animals to have ever walked upon Eryobis, with some fossils suggesting a shoulder height of over 5 meters and a weight of up to 30 tons. (Has no living descents)……
5. A Mesotolophid, a kind of Kleisopneumoid Anisospondyl with a row of filaments on the lateral line to aid in detecting sound. (Has no living descendants)……
6. A Kinetognath, a kind of Pleurotaridan Anisospondyl quite closely related to the Cryptognaths. However instead of a second set of jaws, Kinetognaths had jaws that moved like a ball joint to aid in holding and chewing food. (Has no living descendants)……
7. A basal Trapezostomatan Anisospondyl. This lineage is especially obscure because the earliest evidence of their survival only appears over 12 million years after the World Scarring, so the appearance of the survivor remains somewhat unclear. (Has some living descendants)……
8. A Liomedactylomorph Trapezostome. The ancestor of all Liomedactyls that we can see today, the animal that survived the apocalypse was probably already mesothermic and had some form of filament covering. (Has many living descendants)……
9. A basal Cryptognath Pleurotaridan. While the exact reasons are unknown, it’s apparent that Cryptognaths were the winners of the apocalypse, surviving with 4 different lineages of which even the most basal lineage still remains today. Cryptognaths are best known for their second set of jaws composed of the tongue and freed palate. (Has a handful of living descendants)……
10. One of the most important groups of animals today appears to had already evolved before the World Scarring: the Eusymmetrodactyl Cryptognaths. Already being fully homeothermic back then, the Eusymmetrodactyls of today show a staggering diversity and are the most specious clade of Anisospondyls ever. (Has many living descendants)……
11. While likely not a true Parasymmetrodactyl Cryptognath, the animal that survived the apocalypse must have been a close relative as the Parasymmetrodactyls evolved within 10 million years after the dust settled. (Has many living descendants)……
12. The last lineage of Cryptognaths to survive was the ancestor of the Effingodactyls, one of the most diverse clades of Anisospondyls ever, surpassed only by the Eusymmetrodactyls. (Has many living descendants)……
13. Ancestor of the Dactylouran Arachnopods, it’s a bit unclear how a largely arboreal animal managed to survive the inferno, but perhaps they hibernated underground. (Has some living descents)……
14. The ancestor of the Euarachnopods that dominate over all other Arachnopods today. It was probably a lizard like animal that digged for food and safety. (Has many living descendants)……
15. An obscure kind of non-Euarachnopod that also appears to have survived the World Scarring, they appear rather sudden and disappear from the fossil record soon after. (Has no living descendants)……
16. A kind of very basal serpentine Arachnopod, a distant relative of creatures like Maxillolonchodonts, they only lived for a short time before going extinct all together. (Has no living descendants)……
17. Two types of Pulvinopods survived the World Scarring, which is rather miraculous given their semi aquatic lifestyles. They might have survived by being buried in the mud in riverbeds, but that remains speculation. One of the these survivors was the ancestor of today’s Polytryposternids, a group which was quite diverse early in the Afthonozoic but gradually declined due to competition from other groups of animals. (Has a handful of living descendants)……
18. The other surviving Pulvinopod was the ancestor of the Neopulvinopods that occupy most niches we’d associate with Lepospondyl amphibians on Earth. (Has many living descendants)……
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