10 Million Years Post-Establishment

Without many predators, animals of all sorts have grown enormous in Serina's warm shallow seas 10 million years hence, as 6 foot long giant livebearer fishes descended from the platy and swordtail graze on meadows of marine algae alongside man-sized sea slugs, colorful giant crayfish, and one of Serina's early predator fishes - a barricuda-like ambush-hunting swordtail that lurks beneath floating algae.

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The world is now stable yet in ever-changing flux, as the Hypostecenic era, the era of new beginnings, draws to a close. In millennia to come, the tropical planet - for the most part quite equally warm and mild throughout the era - will begin to cool, entering into a new and more temperate climactic condition brought about by the simultaneous separation of Anciska and Striata through tectonic forces, opening up a wide expanse of water and altering global currents, and the formation of a stark, tall mountain ridge as Striata continues to collide southwards with Wahlteria, closing in an inland sea and dramatically altering weather patterns. Within only a few million years more, the ribbon-shaped arching 'super-continent' of Cirrus will become two independent landmasses stretched broadly parallel north to south, separated by a growing expanse of sea, not to collide again for over one hundred million years.

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Ten million years PE has brought great changes to the world of Serina as for perhaps the first time, life has evolved to fill the once-vacuum of the moon's young ecosystem with a thriving, stable, and diverse, if still relatively conservative, array of lifeforms growing increasingly distinct from their earthly counterparts with each generation. The seas now experience fewer die-offs, as a number of small but very numerous organisms - among them crustaceans, copepods, and even fishes - finally adapt to colonize deeper and deeper depths to make use of an accumulating and untouched food source in the form of marine snow - organic surface debris carried from teeming sunlit waters into the darkness below, which without anything to consume it, can sometimes be found built up into layers several meters thick on the deepest sea floors. Moving vertically through these waters from seabed to surface, they now pull with them water molecules, unsettling stagnant waters and kick-starting the actions of the currents and circulation necessary to move nutrients and oxygen through the seas to support a stable ecosystem.

With carbon, in the form of decomposed nutrients, which for the past millions of years has settled out of reach at the bottoms of the worlds seas now returning to the surface, healthy plant growth flourishes in the sunlit waters, starving off more opportunistic but harmful bacterial and fungal outbreaks that now struggle to explode into their prior numbers as the sea around them grows stronger and more established. Marine fishes and invertebrates experience their greatest booms yet in diversity as the seas of the world of birds begin to clear. Shallow, sunlit regions support unfathomably large fields of kelp and macroscopic algae, which without competition spread across calm seabeds as densely as grass upon the shore. Oceanic regions support enormous tracts of sargassum and similar untethered foliage that forms dense green mats across the surface, forming free-floating reefs tens of miles wide in places and home to infinite sorts of small creatures - shrimps, fishes, snails, and bivalves, the latter hitching a ride on mobile floating forests to filter the seas in style, no longer tied down to a single rocky spot like their ancestors. Though there are no sea cows or turtles to browse them, they support literal herds of hundreds of millions of herbivores nonetheless - toothed-carps, some of which grow as long as a small car - and descendants of the little red and yellow platyfishes once kept so often as aquarium pets - shoal along the sand, mowing down great tracts of greenery with vacuum-like down-turned mouths alongside shoals of enormous sea slugs heavier than a man - the largest gastropods ever to evolve.

Along coastal regions the land begins to grow out further to sea as sediment begins to build up amongst the roots and shoots of sea-side bamboos, already spread across the globe through all but the most inhospitable terrestrial habitats, following the example of the mangrove and beginning to test their legs at sea as they've begun to develop more and more advanced methods of removing salt from their tissues in order to take first claim on one of the last biomes they've yet to gain total domination of. They take with them their armies of insects - leafcutter ants, following an initial and significant decline at the hands of newly-evolving predators, begin now to recover their diversity following the new tendencies of some species to chew out their nests directly within the naturally hollow shoots of their host plants, making themselves much less available to predation whilst simultaneously avoiding many of the troubles of hitchhikers and unwanted nest parasites in the forms of countless other insects which are more than happy to exploit the ants' efforts as their colonies, with still little to stop them, grow to hundreds if not thousands of times the size of what nature probably intended on Earth. On the ground many birds have already specialized as myrmecophages, consuming great quantities of ants as they forage, but few have yet adapted that are able to reach the insects within the hard shells of bamboo stalks, with one notable exception; one group of small and brilliantly colorful insect-eating birds, still rather generalistic and clearly finch-like, begins to adopt the use of sharp stems stuck through the insects' small entrance holes to fish out the plump larvae and circumvent this new defense. Originating in the south of Anciska, the Toolfinches, their successful abilities becoming genetically inherited, begin to spread across the supercontinent, exploiting all manner of new niches as they go along.

Avian diversity elsewhere has also sky-rocketed within the last five million years as truly distinguishable new families appear, with carnivores, insectivores, ground predators, and all variety of herbivores in addition to ancestral seed-eaters popping up from initially modest stocks, spreading across the world from pole-to-pole and following the spread of the forests to the edge of the sea and beyond as multiple groups, both plant- and meat-eating, expand their views for the first significant time to the sea as a source of sustenance and shelter. Canaries run about the ground like game-fowl, they flit through the trees and glean insects with long pointed bills - some even wade in rivers, nibbling at water plants or snapping at the bounty of piscine, insect and invertebrate life that flourish within them - some birds - such as the ancestors of the pond-divers, even submerge and swim for their supper, grabbing insects from the riverbed several meters below the surface. True predators diversify from the Shrieker line as well as several terrestrial sorts, as the former, with increasingly hooked bills and strong talons, become increasingly specialized as airborne hunters of other birds while the latter in cursorial predators - if for now only of bugs. Throughout inland habitats many species, provided limitless food, begin to break the megafaunal size barrier in the evolutionary arms-race to out-size their predators - a race that can only go so far. Some plant-eating birds are now approaching for the first time sizes of hundreds of pounds or even more. These first megafauna are lethargic, slow-breeding, and short-legged animals, having evolved no need for speed or defense. Being so large, they find little concern in the predations of small ground-hunters and so have had no need to evolve the long-legs and endurance of most earthly ground birds. Far larger than any airborne predators, they have had no need to evolve any defensive behaviors or counters beyond bigness. Swollen, placid, and quite honestly over-grown, the reign of this second diversity of non-flying birds¹ - though not the earliest forms, still an early, rapidly-scrawled draft unlikely to make it into the final production - is, with no particular evolutionary innovations beyond vacuum-induced gigantism, clearly not one intended to last in a rapidly changing world, but is a plan that, for now, still works.

While bamboo in its various forms has come to fill the ecological niches of broad-leafed trees on Earth, flowering plants are beginning to catch up. Clovers grow to the size of small trees in wet tropical forests while dry plains insufficient in precipitation to permit the growth of fleshier plants are dominated by patchy scrub-woodlands of strange trunked flowers; hardy dandelions begin to grow considerably taller than their ancestral populations in response to a lack of competition, with woody rhizomes once confined to spreading below the soil now occurring above the ground, sometimes carrying their terminal tuft of greens and blossoms five feet above the soil or more, escaping the hungers of most smaller animals whilst simultaneously rising above the prairie grasses that provide their main competition at the time. A world without conifers also leaves giant perennial sunflowers with blossoms three feet in diameter the base of the forest ecosystem in temperate regions too dry for bamboo forest but wetter than scrubland, annual forests that die to the soil with each winter but rise with the warmth of spring to heights of fifteen meters to bloom and set seed, an enormous bounty exploited by immense flocks of migratory finches several billions in number which travel continents north to south, timing their travels to coincide with the setting of seed of different species and in different climate zones. These sunflower woodlands are particularly prone to wildfire as they dry up and brown in the late summer, but are ideally adapted to survive this, with deeply insulated root systems below the soil and the ability to re-grow to their entire height in a single season, leaving them much more stable than conifer woodlands but also even less diverse - very little survives in them throughout the year, with most species able to survive here only seasonally and leaving for better territory during the winter when their food and shelter runs out.

Scuttling beneath the soil, earthworms, crickets, and of course ants still find little competition for fossorial niches, with some being free to grow to relatively enormous sizes - earthworms thirty feet long are not uncommon deep in the subsoils of the north, and your average burrowing cricket of maybe four inches long is now considered quite a small-fry compared to the largest living forms, the rabbit-sized, root-eating behemoths that come out to graze by night in the southern prairies of Wahlteria, where to supplement their diets they may even overpower and consume birds as large as themselves as they sleep on their roosts at night. By the time chordates get around to adopting to the same niches, many will find that there's not very much room, as for once in their lives, the invertebrates find themselves with an upper hand to the vertebrates - a songbird is simply not meant to burrow and will require much modification before it can ever truly compete; the most the canaries do at this time is perhaps nest in small soil depressions scratched out with the talons, and the largest specialized insect hunter is still scarcely larger than a gull, leaving the insects very much dominant in at least one biome for perhaps many more millennia.

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^1. Remember the first was quickly selected against during Serina's early, violent but short-lived age of ants.