Epoch 3
At the beginning of this era, global heating was still in full swing, and was in fact getting hotter. As the Moddier eruptions died away, ash particles cleared from the skies allowing sunshine to strike the surface at full force, but this happened while greenhouse gasses still remained - and even increased, with a blooming of anoxic microbes releasing poisonous gasses from the oceans. A thermal maximum event saw equatorial waters reach well above 40 degrees celsius, and scorching temperatures turned the central deserts of Topica and Nessperia vivid gold and red colours as a result of chemical reactions between rocks and the hot, dry air. Indeed, desert conditions were spreading fast, as parts of the exposed land surface were now simply too hot to allow rain to settle; other areas alternated between flash-flood mudslides and baking dryness, rendering them uninhabitable for almost any complex life.
However, with the return of full sunlight, a few kinds of hardy photosynthetic microbes were able to flourish across the central oceans in massive blooms, turning large arcs of ocean vivid hues of green and purple - and with no animals able to survive these hot anoxic waters, the remains of old blooms gradually sank and accumulated as sediment on the ocean floor. This, together with the increased weathering of the land surface as it was battered by endless extreme weather, provided a sink for carbon dioxide and other greenhouse gasses to be gradually leached from the atmosphere. In took roughly a million years from the height of the extinctions, but the climate cooled back to a warm, but much more habitable state. In another million years, a rebounding of land plants (led by hardy seed-fern species) - on continents newly fertilised by volcanic ash deposits - reversed the decline of oxygen in the atmosphere, while various kinds of algae did the same for the oceans. It took many more millions of years, but diversity of plants and animals was now free to recuperate from the ‘Great Dying’.
In the oceans, the dominance of vertebrates (led by bony fish) had been shaken. Squid-like creatures (in reality, what would be called a new branch of Cephalopods) were able to fill many niches previously held by fish, evolving an array of defensive swarming tactics and dazzling patterns of chromatophores; some species even evolving bio-luminescent patches. Other relatives of these pseudo-squid became large, powerful hunters, specialising in large eyes and electro-receptive cells, and lightning strikes with their tentacles, some even evolved the ability to use electric shocks as they hunted in muddy estuaries.
However, fish were far from finished; many new species of bony fish appeared, especially in the tropical waters and around island chains. Fish also had a head start when it came to repopulating freshwater biomes such as lakes and rivers. A big winner of this era was the coelacanth family, which diversified from mainly deep-water species to large, tough, carnivorous forms hunting closer to the surface. Competition for top ocean predator was fierce, however, as many new species of sharks - survivors of a lineage that had been slowly evolving for many millions of years - now also came to prominence, with predatory senses to match those of the leading Cephalopods, at the expense of the strength and toughness of the giant coelacanths. This evolutionary battle in the oceans looks set to continue for some time.
On land, the continents shifted into very different fates. North Topica, now known as Altica, settled across the northern pole of the planet, gradually accumulating the first substantial glaciers that the planet had seen for a long time. South Topica, now known as the separate continent of Otope, remained in tropical latitudes. As for the ocean ridge that had separated them, a few large islands remained above water, known as the Aielan islands. These three areas now harbour the last survivors of fully land-dwelling tetrapods - lizard-like amniotes from the storm-blasted plains of old North Topica, that were able to spread by a few lucky rafting events before continental drift widened the distance.
In Altica, cold winters forced the amniotes to evolve on similar lines to some of their extinct relatives - digging shared burrows for raising their young, with food stores harvested in the warm months. However, a radical new adaptation was the ability to spend energy to temporarily raise their body temperature - the first example of bring warm-blooded - in order to brood their eggs and young. This branch of advanced amniotes with mammal-like features came to dominate Altica as it became colder and colder. Some of these primitive proto-mammals have now evolved to hunt their own relatives, while others are omnivores, growing ever larger and radiating into new niches. Altica also hosts unique plant life - primitive tuberous plants have evolved to survive being covered in snow, and hardy kinds of evergreen pine trees form most of the forests here.
Despite being connected to Altica in recent geological history, Otope is now vastly different; a hot central desert gives way to dry scrubland in the west and tropical forest in the north and east. Lizard-like amniotes thrive here, remaining cold-blooded, but diversifying into many forms and niches, some already growing to several metres in size and gaining a slightly more upright stature. Others have remained small, but already evolved a primitive gliding ability - using flaps of skin to glide between seed-fern trees. Still others have lost their legs and adopted worm-like bodies. Many kinds of amphibious tetrapods have also re-evolved here, tending to dominate the swamps and rivers, while amphibious Trilobytes are limited to the coasts and tidal estuaries, which are also refuges for several species of giant kelp-like plants; some lagoons are home to bizarre new species which are able to float balloon-like appendages clear above muddy water, sometimes breaking off and venturing with the wind - most often to their doom, but sometimes to another bodies of water they can colonise.
The continents of Nessperia and Panzerna, meanwhile, have yet to be reached by the amniotes, and here evolution has taken a different turn...
In the archipelago of Panzerna (the remnants that have not fused to Nessperia), the old dynasty of terrestrial Trilobite species still dominate, though these are now radically different to their ancient ancestors in appearance. In the mountainous terrain, some have evolved into long-legged, rock-climbing species, while others have grown rather large - up to several metres long - with special respiration sacs made from modified legs that they have evolved to survive the ages of low oxygen in the atmosphere. These giants reside in caves for shelter, venturing out to gorge on local plant life when the weather is clear, with large rasping mouthparts acting somewhat like a tree shredder. No large predators exist; tetrapods in Panzerna remain limited to some rather primitive amphibian species. Quiet, cool coastal forests thrive in sheltered bays and fjords, harbouring many survivors of more primitive plant species from previous eras.
In Nessperia, meanwhile, in diverse terrain that stretches from hot desert, to dry plains, to snow-capped mountains, to thriving swampy rainforest - it seems that evolution has run riot. Here, terrestrial trilobites - spreading from the part of Panzerna that fused with the larger continent - now compete with oversized beetle-like insects, giant land snails and slugs, and a revival of large arachnoid predators. The dry plains and deserts of the interior are also home to bizarre cactus-like plants, evolved from fern-like ancestors. But the big winners here are descendents of velvet worms, having evolved their own kind of primitive internal lungs during the oxygen crisis, enabling them to grow substantially larger in size. Though their internal biology and nervous systems are rather basic, some have evolved very specialised modes of attack - such a poisoned-tipped, pneumatically-launched harpoon that can be used to attack prey. Other members of this family are peaceful herbivores, which have evolved detachable tail segments which they use to distract and escape from predators. A variety of these super-velvet worms now dominate the forested, western half of Nessperia.
Indeed the long eastern coast of Nessperia is now home to the densest rainforest that the planet has ever seen up to this point, and this alone is responsible for drawing a large chunk of greenhouse gas from the atmosphere. In many areas the forest is occasionally flooded by rivers, or is home to large lakes, forming ideal habitat for all kinds of amphibious species - descendants of the old amphibious tetrapods have thrived here, evolving into recognizably frog-like forms, as well as bizarre hammerhead varieties, and some enormous amphibian predators. However, the most remarkable are Cephalopd invaders, relatives of the new squid-like species thriving in the oceans, which have evolved the ability to breath air to a limited extent, and are able to haul out of water to climb trees - either for laying eggs out of reach of aquatic predators, or for a vantage point from which to snatch small prey with their tentacles. The habitat is also home to many unique species of fungii, a leftover of the era when giant fungus was one of the dominant life forms on the continent.
To the north, the microcontinent of Moddier - once the site of active supervolcanoes that devasated the planet - is now a quiet place of dramatic, stepped volcanic landscapes frozen in time. Former volcanoes have already begun eroding into granite monoliths. Only plants and insects have colonised the land here - indeed, coastal plains have formed from eroded rocks and are fertile ground for many species of plants and trees. Amphibious Coelacanth descendents are sometimes to be seen here, hauling onto land in search of a meal. The offshore waters, however, are home to a spectacle - where underwater volcanic vents still occur in relatively shallow, fertile waters, communities of chemotroph ‘reefs’ have emerged, some of sessile species using bioluminescence to lure tiny marine creatures as a compliment to their diet.
Finally, to return to the tropical Ailean Islands, in the geographic centre of all this strange new world, evolution is experimenting yet further. Here, amniotes have colonised forest-covered islands rich in insects. Some of the lizard-like forms have evolved to return to the waters, becoming adept swimmers, and competing as predators for small fish and cephalopds; though these swimming lizards have yet to establish any colonies beyond the islands. The amphibious trilobites of these islands have richly coloured, metallic-looking exoskeletons. The waters just offshore are unique in being home to the first true coral reefs to re-evolve following the mass extinction; the old volcanic islands are slowly sinking, but this forms ideal habitat for the reefs. Relatives of the Moddier chemotrophs are also found here, adding a sparkle of bioluminescence to the reefs.
Globally, the climate continues to cool as this era draws to a close - more and more carbon dioxide is being absorbed by plants and locked away in sediment. The tropical regions remain very warm, and the south pole remains free of ice, but glaciers are spreading along the old mountains of Nessperia and Panzerna.
As the continents drift, Nessperia and Moddier are on a gradual collision course. Otope is heading east at a relatively fast pace. Panzerna is moving slightly south, while Altica seems settled for now at the north pole.