5 Million Years Post-Establishment

Land

The brief age of insect dominion begins to wane as a growing diversity of birds begin to displace them.

Five million years after the first canary birds were freed upon a world of endless grassland and meadow, the world of Serina has already undergone several major transformations. It did not take long for the prairie grasses that initially covered the world to be pushed back by their distant relatives, the hard-wooded bamboo, as they rapidly spread and shaded the land of a world which offered them no competition. Among the fastest growing of all plants, they spread and filled in a world otherwise without trees at a phenomenal rate, by now growing in dense and often mono-cropped thickets from pole to pole wherever sufficient soil moisture allows, leaving expansive grasslands only where precipitation is too minimal for the growth of bamboo woodland. The domain of the leaf-cutter ant, innumerable billions of these insects still scurry in hordes throughout the forest, gathering leaves and shoots at a rate only surpassed by the incredible growth of the grass they feed on, with shoots rising from expansive rhizomes at up to four feet per day. Underground, colonies of the insects now extend for hundreds of miles in all directions under the ground. Super-colonies have begun to form, combining their efforts to produce the largest single colonies of any insect ever documented with likely populations reaching into the trillions, each and every one of which is a member of a single cohesive colony providing food for a series of underground fungus gardens that might extend 100 feet bellow ground. Without moles or rodents, subterranean habitats are home instead to gigantic earthworms, crickets, and millipedes, while an ecosystem still deficient in large predators experiences nutrient turnover instead through the actions of billions of burying beetles, which following the extinction of the empire ant are provided with an infinite and mostly untapped food source in the form of deceased birds, resulting now in their own population boom. By working to turn all carcasses they discover under the soil, they not only provide food for their own young but keep the surface environment clean and free of disease while also returning needed nutrients to the soil, where they will feed countless insects and micro-organisms before one day being returned to the plants themselves.

A world so far dominated by insects is slowly being taken over again by the vertebrates, as the birds - equally freed from empire ant predations - begin to diversify at their fastest rate yet. The age of the leaf-cutter ant is far from over, but the insects are no longer the sole rulers of their niche now as various forms, not only of birds but also of other invertebrates, begin to compete with, prey upon, or otherwise exploit the leaf-cutters. Five million years PE, herbivorous canaries, which feed predominately on leafy plant matter in favor of seeds or insect food, are well represented. Several unique forms have simultaneously lost power of flight, or at least reduced it, and begun to develop an increasingly large, powerful bill to tear coarse foliage and a large gut to digest and make use of it. For another brief time, the world is largely free of predators, and flocks of increasingly squat, poor-flying and flightless birds are free to spread out far and wide. From plump, dove-like ancestors two million years ago have already emerged forms as large as chickens, turkeys, even geese, an exponential increase in size allowed by a total lack of predatory selection or competition for resources. The wings and often even legs of these birds have rarely grown in tandem with their immense bodies, and they are slow, awkward animals, nesting on the ground and out in the open and having few if any defenses - they still needn't worry about predators. Faced with this first major wave of avian diversity, the leaf-cutter ant empire begins to wane in both northern and southern temperate belts as the ants are slowly squeezed back to their ancestral tropical climes, unable to compete during cold winters with growing hordes of plant-eating birds that can remain active throughout the year, and ravaged during their seasonal hibernation by equally large flocks of increasingly specialized insectivores.

Five million years has been sufficient time for several independent lineages of ancestral seed-eaters to take almost completely to a diet of insects and arthropods, and quickly converge upon the warblers, the thrushes, and the wrens of their ancestral world. Among the most derived of such forms are the poor-flying Sprinter Serins, which are now among the most common of all the ground-feeding birds. With long, probing bills and lengthy, sturdy legs, some of these vaguely plover-like passerines have already largely given up flight - one of the first carnivorous lines to do so - and taken to a terrestrial habit, some dashing through the undergrowth of the bamboo forests and others scurrying through sandy savannahs and between sparse prairie grasses, with a few forms, such as the red-sided pond-diver, even beginning to feed from the water in riverine environments. All are in search of the insects and other invertebrates they now feed almost exclusively upon, but the diver may already include fishes in its catholic diet. With others favoring ants, others slugs, and others still crickets or beetles, this earliest wave of ground-predators shows great potential for long-term survival as still infinite food supplies fuel an incredible rate of evolution, as a world unnaturally barren continues to fill in its own gaps.

Carnivory is also beginning in the skies as the ancestral egg-eater canaries have given rise to increasingly bold and opportunistic forms, the Shriekers. Relatively large birds, these boisterous and social species have taken their egg-eating tendencies well past hatching and have become particularly suited to the killing and eating of nestlings, fledgelings, and even weak adult birds with their increasingly sharp, sometimes hooked beaks. The jays of the canary world, though they remain highly generalistic - indeed still consuming a fare amount of green food, seeds, and insects - they are already beginning to show increasing adaptations of both form and habit to a predatory ideal. Forest birds can no longer leave their nests unattended without worry as the shriekers, having been watching from a distance, may now descend immediately to savage their young, one member of a mated pair distracting the mother hen and the other going in to slaughter the chicks.

Among the first mutations that developed in the Serinan bird population was an incredible diversity of color, evolved for lack of carnivorous concern, but in recent times rising predator worries means many small birds now exhibit increased selection for camouflage, particularly of hens on the nest. So too reappear formerly relaxed, atrophied instincts of parental care, lost during several eons of safety, in all small bird species, while for the large ground birds size, for now, leaves their otherwise defenseless young unmolested by Serina's first small but specializing predators.

above: a newly-evolved species of open-water poeciliid descended from the swordtail; a fast swimming open water predator, it has already evolved a crescent-shaped tail and highly streamlined, torpedo-like body as adaptation for maximum hydrodynamics. It swims just below the surface, where oxygen levels remain habitable even during the frequent anoxia events of this era, and preys on smaller shoals of fish. Known as the emerald keeltail, this is one of the earliest pelagic predators in Serina oceans to evolve. Its perfectly streamlined body shape has been shaped by evolution to allow very fast movement, and with average size of 25 inches long the keeltail is significantly bigger than its Earth ancestors. However its physiology and internal anatomy is still very much unchanged- the only significant difference between the keeltail and the ancestral swordtail is a much greater concentration of myoglobin inside its muscles. This gives the keeltail greater stamina and enables it to stay in motion throughout its entire life without any rest, which is very important in the open sea where food is sparse. Illustration by Preradkor.Deviantart.com 

Sea

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Though riverine habitats now teem with life, Serina's seas have lagged behind the land in developing ecological stability.

The seas of Serina, from a modest initial stock, quickly became rich with life. Billions of fishes soon flocked and shoaled its waters, as a food chain beginning to form in earnest as increasingly large and specialized hunters, mainly in the form of swordtails, pursued unfathomably immense shoals of smaller pelagic live-bearers, fed by copious planktonic algae and copepods. Forests of kelp and algae colonize all sunny seashores, feeding shoals of beautifully-colored, otherworldly grazers - sea slugs - which may grow as large as dogs - and immense herbivorous sea snails with shells over five feet long (a last remnant of a brief time of mollusc domination long since ended on land), taking the niches of sea cows in early Serina's waters. Of all Serina's earliest freshwater stock - the three live-bearers, the crayfishes, the shrimps, the snails - only the platyfish, a creature which had lead far greater success in the niches of riverine cyprinids, has not successfully infiltrated marine environments by this time, though remnant genes resulting from early swordtail hybridization likely still remain within the sea's new apex predator's genomes.

From the sunlit shoreline environments, the Serinan sea often looks completely pristine, with beautiful fishes, great colorful sea slugs, and large, brightly-colored crabs abounding in clear waters. However, as one moves several hundred miles out to sea, the oceans of 5 million PE have slowly become a slowly-ticking time bomb. Gone is the era of unbridled peace of past millennia. As a result of no significant organisms moving through different levels of water as they do on Earth, distributing nutrients and oxygen, and nearly all life existing within one hundred feet of the surface, Serina's benthic zones have become stagnant and anoxic. Blooms of anaerobic bacteria which, in death, release highly toxic substances into the water now occur regularly, inducing large-scale die offs of marine life, which in turn release enough nutrients to produce even larger red tides - toxic algal blooms - which may be carried via currents for thousands of miles, causing harm to all life they come across. Serina's open oceans are in constant flux and lifeforms struggle to establish themselves as great swaths of waters are periodically cleansed of virtually all advanced life, often becoming breeding grounds for fleeting population explosions of jellyfishes and little else. Though rapidly-breeding and highly adaptable live-bearing fishes, shrimps, and copepods are among the best-suited of creatures to rebound following such a calamity, their very ability of rapid reproduction becomes their downfall. Smaller forms able to survive these periodically difficult conditions, left initially after each die-off without less-hardy predators until these are able to migrate back from unaffected regions, then experience enormous population increases until they use up their food supplies and initiate a new die-off and begin the cycle anew.

Life in Serina's open oceans is therefore a rapid race for all creatures, not only against one another but against time, to breed and spread out before ecological collapse occurs again, hoping some of your descendents manage to have migrated far enough way to avoid it this time. Even in the best of times, most of Serina's oceans are at this time only habitable for the first one hundred feet, with waters any deeper exhibiting a fatal lack of oxygen, and the majority of organisms concentrated within the first twenty to fifty feet of depth at the surface where nutrients are most available. Marine predators have adapted towards a highly migratory habit, moving hundreds of miles per week across entire oceans in order to avoid toxic algal blooms and find widely-spaced pockets of high prey concentration, as an odd disparity widens between predator and prey, with prey becoming smaller, hardier, and better able to survive periods of low oxygen, and predators growing increasingly large and mobile in order to find it when times are good and flee toxic conditions when they are bad.

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Inland, rivers and lakes, largely isolated from marine catastrophe, teem with life and ecological stability far ahead of the open sea. A variety of aquatic grasses, algae, clovers and elodea feed and provide cover for countless forms of small fishes, crustaceans, and gastropods. In absence of competition, the parthenogenic crayfish has re-developed a male gender, and subsequently begun to spread and diversify following an initial period of decline due to the harmful effects of Muller's ratchet. Without competition, the descendants of these small lobsters become the first major herbivores as well as scavengers of lake and river and now reach weights of forty pounds or more and lengths of four feet, some of the largest of all arthropods. They share this niche in many regions with the fifteen-pound Great Blue Lake Snail, one of the heaviest (by body weight) of all gastropods, an enormous trapdoor snail which grazes swaths of freshwater vegetation like a veritable lawnmower. The largest active riverine predators of this era are fishes, but not exclusively swordtails as in the sea. In freshwater, the humble guppy has produced its own unique hunters in the Grupfishes, a diverse and rapidly speciating clade of cichlid-like poecillids notable for large, extendable jaws and a muscular, stocky bodyplan much like that of a bass or grouper. In contrast to the streamlined, fast-swimming predatory swordtails, Grupfishes are usually ambush hunters, lying in wait and lunging at small prey which is inhaled and swallowed whole. Ranging in size from less than two inches to more than fifty, they are already one of Serina's most ecologically diverse clades despite current freshwater restriction.