The Early Ultimocene

250 Million Years PE: The Early Ultimocene

above: a climate map of Serina in the early Ultimocene, 250 million years PE.

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The Land

The beginning of the Ultimocene features three major continents divided from the single land mass of the Pangeacene. The northern half of the former super continent comprising the combined remnants of North Anciska, Polar Anciska, and much of Wahlteria has broken away and moved northwest, forming a new large landmass centered on the equator known as Serinarcta. The almost identically sized southern portion which originally consisted of South Anciska, Stevhlandea, and Karii has moved easterly but remained along the south pole, and comes to be known as Serinaustra. A portion of the south has broken away in the west; composed of parts of South Anciska and stevhlandea, it becomes the third, smallest continent known as Ansteva. A deep, cold seaway fills a continental rift that now separates north and southern continents, a division that will remain for tens of millions of years.

The Ultimocene starts off mild. The climate is cooler and much wetter than most of the Pangeacene, and a small ice cap exists at the south pole. The enormous interior desert has disappeared, and now forests, varying from temperate to tropical, have come to cover most of the world. The equator supports enormous, diverse rainforests, while in the south a productive steppe biome has appeared that covers much of Serinaustra, the productivity of which rivals the Serengeti. Volcanism is currently in a lull over the majority of the moon, but a hot spot in the eastern sea has appeared and produced a new series of tropical islands, the Meridians.

The Life

Sunflower myrmecophytes remain the dominant forest community across Serina into the early Ultimocene, and the adaptation of producing fully-formed seedlings which then disperse on the wind instead of seeds is becoming widespread. Ant-symbiotic sunflower trees follow in the footsteps of bamboo yet again and colonize the coasts, forming a new mangrove biome. Nanboo continues to survive worldwide, but only the equatorial jungles on Serinarcta can still support them at their greatest diversity, where they still form large clonal forests. Serinarcta is predominately forested, but Serinaustra is comparably arid, particularly in the south. Though the interior desert has broken up into small scattered fragments, a large expanse of puffgrass steppe now occurs around the south pole that supports huge numbers of grazers. Cactus sunflowers from the interior desert adapt to a wetter climate near the south pole as they have done in the past, by becoming conifer-like trees with cold-resistant scales and needles in place of leaves and forming a ring of dense taiga forest around the steppe. A similar ecosystem has developed in the far north, but from a different plant. Here, tall grass-descended trees have developed sharp lance-like leaves full of bitter resin to keep them from freezing and a columnar growth habit suited to shedding snow, and fill the same niche.

Most animal groups evolved during the Pangeacene will persist through the early Ultimocene. Molodont diversity has never been higher; wheeljaws (circuagodonts) especially have experienced incredible success since their appearance more than 20 million years ago and have become both the most abundant large herbivores and carnivores across Serina. Serezelles fare poorly against circuagodont competitors and are in sharp decline, yet one group, the boomsingers, still experiences success by growing taller and accessing food resources beyond their reach. The circuagodonts' more primitive competitors, the dogbeasts, have experienced a degree of decline, certainly for the same reason, with the exception of their aquatic descendants, mertribs, which have diversified well as a clade and spread across all of Serina's oceans. They are not out, though, with new forms evolving to remain competitive in this rapidly changing world.

Tribbetheres have now largely driven most other bird groups back off the ground and into either the air or the sea, with the exception of the live-bearing bumblets. Basal burrowing species still persist, filling the niches of moles and shrews across Serina and largely succeeding in excluding the more rodent-like molodonts from developing similar small, hypercarnivorous forms. Marine bumblets, meanwhile, have given rise to the largest birds ever to exist in the form of giant filter-feeders, and others which are now the apex predators of the sea.

Waterfowl are still extant, but dwindling in diversity compared to their numbers in the Pangeacene, possibly due to their exposed ground-based nests being highly vulnerable to egg-eating moldoonts. A few softbilled birds, descendants of the glove and the mitten, also survive, though their group is now in decline for the same reason. Though the bludgebird has died out, other mitten descendants have adapted to different environments, particularly the forests which are now so widespread, where they learn to shelter their nests in tree hollows for relative protection. Some descendants of the glove specialize as burrowing ambush predators. Aquatic forms, such as the manatweets, continue to thrive in the shallow vegetated seas, but ancestral semi-aquatic species have been displaced by bumblets.

Sparrowgulls also thrive at the start of the Ultimocene. To protect their eggs from new, pervasive molodont predators, they use their relatively high intelligence and learn to carry their eggs and move their nestlings if they feel their nest is vulnerable, a skill which so far has been uncommon in egg-laying birds; some mitten descendants utilize the same trick. The inability for Serinan waterfowl to do so is presumably a major factor in their relative lack of reproductive success since the diversity boom of molodonts.

Many groups of primitive changelings - metamorph birds - are slowly dying out as sparrowgulls displace them, leaving only the most derived lineages extant. They survive now as highly derived small flyers with aquatic or parasitic larvae, ornimorphs which progress through a number of highly disparate life stages culminating in a fully airborne adult form, as fully neotenic aquatic species, and as live-bearing placental birds which have long since abandoned their larval stages altogether. Flying quadruped birds including archangels are still extant, but as the climate cools the regions in which the largest species can reproduce become more restricted, causing many species to become migratory. The largest archangels now fly south to the cold southern steppe in the summer to graze and fatten upon lush grasses and then return to the equator to lay their eggs, where their young initially mature and feed on a more omnivorous diet in the tropical wetlands. Smaller species develop in response to the changing climate, which can hatch more quickly in the summer in temperate climates. A clade of small archangels become semi-aquatic like geese, ducks, and grebes, where the adults feed in wetlands or near water and in some species only come on land to lay their eggs, which are buried in the river bank and left to mature on their own. When confronted with egg-eating molodonts, this is apparently a more successful strategy than trying to incubate hard-shelled eggs in exposed nests, and in time these waterfowl archangels will fully replace the last of the primitive water birds.

In the sea, Serina's intelligent marine snails, snarks, are thriving at the start of the Ultimocene, and semi-aquatic forms begin now to experiment in life out of water in mangrove forests. Reef-building snails which thrived through the Pangeacene are also still present and successful toward the start of the Ultimocene, but periodic bursts of volcanic activity, which release large amounts of carbon dioxide into the atmosphere, will result in several ocean acidification events that weaken them substantially as the epoch wears on. Sea bamboo fares better, and thrives across all of Serina's shallow seas, including those which would formerly have been too cool, as new kelp-like species adapt to the changing climate and make the most of fertile polar oceans. Chainjellies persist in the tropics, especially in nutrient-poor regions, where they survive through a combination of passive filter-feeding and photosynthesis. Burdles are still successful, and forms that can regulate their body temperatures reappear as the global oceans cool, allowing them to feed toward the fertile polar regions. Other burdles move inland, into freshwater rivers and ponds, and converge upon crocodiles - scaly ambush predators with elongated beaks that prey on fish, water birds, and any unfortunate land animals coming to drink. Other than burdles, the muck lineage is by this time almost completely extinct, except for a single family of very different land animals that include armored insectivores and a single enormous herbivore.

Mudwickets and non-tribbethere tribbets remain successful in primitive forms. Predatory legless tribbets, which move on scaly bellies like snakes, are some of the most widespread, but they have not displaced an older lineage of a similar form, the eelsnakes. Eelsnakes have rarely made the complete leap from an aquatic to a terrestrial existence and most survived through the entire Pangeacene and beyond as semi-aquatic predators which can move over land in wet conditions and often estivate in the mud to survive dry spells, much like lungfish. The largest species hunt like crocodiles and rarely leave the water, and many can transition readily between fresh and salt water. Being cold tolerant, they can survive as far south as the southern steppe, where in the summer they swim inland from the sea through the mouths of rivers to prey on the seasonal influx of grazers.

Handfishes are at their most diverse at the start of the Ultimocene. Gibbets and dropdowns thrive in the tropical forests and begin moving into cooler climates, surviving the winter by hibernating, abilities that will allow them to continue to survive in a changing world. Some tropical handfishes develop skin membranes on their front legs, become parachutists, and even approach powered flight in their pursuit of flying insect prey. Many gibbets reduce their dependence on animal prey and begin to eat mostly fruit and plant matter, evolving into primate-like animals that compete with tribbats. Behavioral adaptations occur between the two groups in response to this competition for resources which causes many frugivorous gibbets to become nocturnal. This not only lets them avoid day-flying frugivore tribbets, but also more dangerous carnivorous species. By the Ultimocene many well-adapted predatory tribbats have evolved, most of which hunt by day.

The world is changing, but life is not out yet as we enter the Ultimocene.