The fish pictured above would’ve lived between 0 and 40 million years P.I. (Post Introduction) and would largely not have coexisted with each other.
1. One of the earliest representatives of the clasper-finned coelacanths formally known as the Baculopterichthyes. These fish have adapted their pelvic fins to function similar to gonopodia or claspers in more derived forms. While the Baculopterichthyes today are among the most successful and diverse of all living fish, they had very humble beginnings and did not get a place in the spotlight until after the greatest massextinction Eryobis has ever seen. The species here would’ve lived in shallow coastal seas somewhere between 3 and 7 million years P.I. being among the very first to sexually select for larger fins that would later be used as intromittent organs.
2. While the land was still barren and devoid of large animals in the early ages of Eryobis, the waters just bordering the land were full of life. Rivers and lakes were very diverse ecosystems and pioneers in adapting to higher radiation levels that were present there. Clouds of Rhodophytic algae and Florideophycean forest stained the shallow waters red. Just as many river inhabitants on Earth are coloured green to blend in with vegetation, so are many creatures that live in Eryobis’ rivers coloured red. In these early crimson rivers, arose some of the most fearsome predators to ever swim. The Smaugpikes were a long-lived group of specialised carnivores that made freshwater systems unsafe between 6 and 84 million years P.I. until they were replaced by a new kind of river monster. They were all red on coloration, often with stripes and spots to help camouflage themselves. They swallowed their prey whole and if that wasn’t possible, they tore their prey to shreds with their double rows of backwards pointing teeth.
3. Another kind of fluvial predators that lived in the early ages was a group known as the Caesodonts. These vaguely shark-like coelacanths lived in murky waters near the bottom where they hunted for crustaceans and benthic fish. They used their exceptional rostral organs to detect electric fields and were this way able to hunt very well in the dark.
4. The Lagotoichthyiforms were not the only coelacanths to inhabit the early reefs. Another group of small fish also started to inhabit the reefs shortly after the anoxic event of 25 million years P.I.. These were herbivores that fed on sea weeds growing between the coral. With their many shovel shaped teeth, the Ptyariodonts made short work of cutting plants and with multiple chambered stomach and long guts, they were able to digest most of the plant matter they ate.
5. A very successful group, the Eelacanths (debut in part 1) spread far and wide after leaving the deep waters they originated from. Coastal zones were a very popular habitat for Eelacanths and they were met with unrivalled success in those shallow waters. Most were migratory, but some made it their permanent home. And strangely, so did Gulper-Eelacanths, a family of normally deep water inhabiting fish that evolved huge mouth to swallow prey with. As they adapted to swallower waters, their bodies became shorter, stockier and more muscular, capable of very powerful bursts of speed to overwhelm their prey. The species depicted above is about to swallow a primitive tadporpion, though the crustacean might be a bit too prickly to handle for the Gulper’s throat.
6. First arising in 21 million years P.I., they began giving the previous top predators, the Coelosphyraenids, some competition until the anoxic event of 25 million years P.I. completely wiped the Coelosphyraenids out. With the former apex predators gone, some surviving big-finned coelacanth quickly rose to the top. These were the Teratobatoids. With somewhat laterally compressed bodies, but with huge flat pectoral fins, they didn’t quite resemble anything on Earth, the closest similarity being to ratfishes. Teratobatoids lived a long time and during their time, they filled mostly what we would consider to be “shark-niches”. Being not the fastest of fish, their domain was mostly restricted to continental waters, as they were unable to compete in the open ocean. Here they reigned for a long time until their eventual displacement as top predators by a new kind of fin-swimming predator.
7. Thunniform bodies are nothing new, as they are the most advantageously shaped bodies for traversing open water. On Eryobis, the Thunnitricids were the first to reach such body shapes. Already being well represented before and really dominating after the anoxic event, they swam the world’s oceans from 18 to 85 million years P.I. when a global warming event got the best of them. These fast swimming predators could reach up to 50 km/h and were the very first animals on Eryobis to evolve partial endothermy.
8. Of the species depicted above, this one is actually the closest to the Flattacanths. It came from an early offshoot of the branch that would lead to Brachysomatids (part 1&2). But instead of living in shallow water reefs, the ancestors of this fish dove down into the deep. Here they became mesopelagic superpredators. Fast paced fish with a wide gape and sharp teeth, few things could escape it once locked as a target. They were the Seiomourids, a family of large carnivores that hunted just above the twilight zone for anything foolish enough to come close, but they had a particular taste for lanternfish-like holosteans and schooling crustaceans. Being adapted to lower oxygen levels, they managed to survive the anoxic event of 25 million years P.I. and went on to thrive long after. Among their ranks, many independently went even deeper into the abyss, causing the strange phenomenon deep sea Seiomourids existing all over the world and yet being unrelated to each other.
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