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.
Recent studies have shown that the aftermath of World Scarring would have been far more destructive than previously thought. All the water that was vaporised in the impact would have rained down and caused deluges of biblical scale as soon as the atmosphere cooled down again, which further explains why there were so ridiculously few animal species on land that made it through.
And while we previously thought that the oceans had been mostly spared save for the surface waters, new evidence suggests that the extinction would have been just bad, if not even worse in the oceans as it was on land. We knew that all surface waters evaporated instantly when the projectile struck killing of most life in the photic zone and all freshwater organisms, but the aftermath would have been even worse. The removal of the at least the top 100 meters of surface waters around the world would have disrupted and destroyed all major currents. And while the rest of the water would not have been vaporised, it would’ve boiling hot for another 100 or so meters down, killing all that lived there. On top of that, the massive displacement of so much water created a vacuum and pulled waters towards Lotharca from all around the world. Deep sea environments would have been completely destroyed as incredible suction forced pulled them from the depths. Then there were the deluges on land, whose water would was not as salty as the sea but carried massive amounts of debris, further causing turmoil in oceans around the world.
If what our simulations suggest actually happened, it’s a miracle anything survived at all. To test the theory, researchers went out and started comparing the genetic material of fish alive today. What they found was horrific. They discovered that all fish alive on Eryobis today can be traced back to a mere 20-ish ancestors that made it through the World Scarring Event. It’s terrifying to think that out of what must have been over 20.000-30.000 fish species in late Kikilian, only an approximate 20 survived, truly showing how devastating the extinction really was.
With this in mind, archeologists went looking for fish fossils from the early Thyellian and indeed, they found 19 clearly distinct genera that appear after the World Scarring.
1-7. Seven of these survivors were Conodonts. Known mostly from their tooth remains, but they were apparently so abundant in the Thyellian that we have more than a few soft tissue fossils of them. They were all quite small and not much is known about them, all we know is that one of them would give rise to the highly successful “murder-molas” known as Nienktvissen.
8. A small species of Seiomourid coelacanth of the Mawsoniid lineage. Curiously, it appears to belong to the genus Tompouzia, which was already known from Kikilian aged rocks. This makes it so far the only surviving creature with fossil records before AND after the World Scarring. Tompouzia typically measured between 10 and 20 centimetres in length and would’ve fed on crustaceans and molluscs most likely.
9. One single species of flattacanth survived the World Scarring: the Onychepizon micrurus. Its pectoral and pelvic fins were small and sported one large claw-like spike that was likely used to dig and cling onto the seafloor. Its tail was small and narrow and it likely swam with its large dorsal and anal fins. It measured roughly 30 centimetres in length.
10. The only true bunnyfish other than flattacanths to make it through was the Lagoselache durus. A small bunnyfish with a shark-like heterocercal tail that would have most likely fed on small invertebrates. Like all bunnyfish and their flattacanth relatives, they come from the Mawsoniid lineage. It grew between 40 and 50 centimetres in length.
11. There were two types of Baculopterygian coelacanths of the Latimeriid lineage to make it through the World Scarring. The most abundant of these was Truemderia tridorsalis, a small fish that grew to about 16 centimeters long. Like all Baculichthyes, it used its pelvic fins as claspers and intromittent organs.
12. The second Baculopterygian was the far larger Serragingivus primivaeus, a predatory fish that might have been the largest animal to survive the World Scarring. Measuring a whopping 90 centimetres long, it would have been the apex predator of the Thyellian oceans. It had a row of teeth in the middle of its upper jaw that were somewhat reminiscent of Eugeneodonts and like them, it probably would’ve hunted mostly soft bodied animals like Conodonts and small fish.
13. A small (yet unnamed) species of Rokanizid coelacanth of the Latimeriid lineage. It was the only Rokanizid to survive due to its deepwater habitat and durophagous habits, unlike most Rokanizids which were herbivores in shallower waters. It measured between 30 and 40 centimetres long.
14. One of the strangest animals to survive the World Scarring was Xenornithogyrinus mirabilis. This animal could best be described as “a fish, but with extra steps”. This creature was a the larval form of “pectoral-fin-first” Octopodichthyian Volichthyiiformes (flish). The ancestors of X. Mirabilis were flying animals that laid their eggs and lived their early lives in water. This variety however, apparently chose to stay in the water. What’s unclear however, is whether Xenornithogyrinus became neotenic before, or after the World Scarring, as no evidence of similar creatures exists from the Bobossic. It was very small, most measuring under 10 centimetres in length.
15. The only non-Octopodichthyian spiderfish to make it through the extinction was the Tetrapodichthyian spiderfish Ericionaris natans. This spiderfish measured about 5 centimetres long and would have had a similar legspan. From its pectoral fins sprang long tendrils, their function is still unknown.
16. A basal Holostean with uncertain affinities, this small fish would have been a bottom feeder that felt the sediment with its barbels, searching for worms. This fish was called Naglimmia diouros and measured between 10 and 15 centimetres long.
17. Another small basal Holostean fish was Pleurolepion labroides. This fish measured around 10 centimetres long and would have lived near the seafloor, feeding on mollusks,
18. Probably the most abundant fish of the early Thyellian was the Paleoeryoscopelus macrolepidotus. A small and basal Diplorachopteran that is thought to have somewhat resembled lanternfish. The frequency in which their fossils are found suggests they formed great shoals. They measured between 8 and 18 centimetres long.
19. Another kind of Diplorachopteran, but much more advanced. This was Pinnansium dimorphis, a predatory fish that showcased distinct sexual dimorphism. The males had a distinct spine on their first dorsal fin that curved forwards, had a long gonopodium on their anal fin and measured 50 centimetres long on average. The females lacked the spine on the first dorsal fin, had no gonopodium and measured 60 centimetres long on average. The large spine of the males likely served as display organ and may have been used by the females to hold onto during mating. They would have preyed mostly on smaller fish.
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