The New Plains

285 million years post-establishment, southern serinarcta has begun to dry up, and sogland has given way to a new habitat, savannah woodland. The evolution of the animals themselves - especially gantuans such as the soggobbler, which in turn evolved into the cygnosaurs - are responsible. These giant animals now influence the whole ecology of this region. Thorngrazers are destructive to the landscape, and their constant rooting of vegetation and wallowing in mud opens it up for erosion and the formation of pools of standing water that can expand over time into vast wetlands, but with gantuans actively displacing thorngrazers and keeping them from spending all of their time in one place, the land is now being dug up less, and the habitat type is shifting as a result. Soglands wildlife that evolved to navigate through swamps and marshes may now find the land drier and easier to traverse.  

Tribbymaras were one of the first animals to really take advantage of the change. These midsized, long-legged grazers evolved from the larger, semi-aquatic tribbybara around 5 million years ago, as the wetlands receded. Without such an abundance of water, these animals needed to find new ways to escape their enemies without a pond always being a hop, skip, or jump away. They have since become thinner, lighter, and faster, with smaller, more digitigrade feet and enlarged nails that provide additional traction in a smaller area to maximize the length of their stride. Their color has changed too, from a muddy brown that matched silty water to a speckled light green, the color of the grass. Their raised eyes, though previously used to help them see while hiding in water, have not been lost: the plains are now densely overgrown with tall grasses that thrive in the damp soil with reduced grazing pressure, and this provides more cover for stalking predators. With its eyes so high and its face growing more elongated, tribbymaras can feed while keeping their sights higher on the horizon to spot danger as it might approach in the grass. Its long snout has narrowed, too, in an example of convergent evolution to some of the thorngrazers they share these plains with - in both cases, it goes along with a more selective feeding method where choice bits of vegetation are plucked from among the taller and coarser grasses, rather than the wholesale grazing of their ancestor groups with wider jaws. For the tribbymara, a diet of silica-rich land plants is harder on the teeth than their earlier diets, and their beak-like teeth are now thicker and grow faster to compensate for this increased wear. 

Tribbymaras have developed more complex social interactions to facilitate survival with less opportunity to hide from predators. Their ears are larger and more mobile - they no longer dive underwater, and so an earlier selective pressure for their reduction in size has been replaced by an opposing need for excellent hearing as well as gestural communication. Without hands, and lacking crests or horns, the ears of the tribbymara are left as its own structure able to be used to "talk" visually to one another, and a system of signals has developed that help animals to convey information to one another within large social groups. The inner surfaces of their ears are brightly colored in orange and can be swung in a wide degree of motion, the positions conveying not only mood but motivation and social rank, as well as signalling danger. Visual signals sent across through ear movements are combined with vocalizations to warn of threats and direct the herd how to respond to them; sentries - wiser, mature individuals with the most life experience - are employed to guard the group as they feed, which will trade positions every hour or so throughout the day. Tribbymaras live in cohesive herds in which individuals come to know one another well, only occasionally dispersing as juveniles to new groups, and this lets them all learn to work together as a cooperative unit with great ability and to work together with much better coordination that any thorngrazer. For example, childcare in the tribbymara is a community effort; pups are born in litters averaging six and do not attach strongly to their mothers, for all of the litters of every female are grouped together into creches almost immediately for protection, and so come to view all adults in the group generally as their parents. As tribbymara pups are born with a full set of teeth, they do not need any feeding by their mother as in thorngrazers, and so they need only to be supervised by the adults and protected from predation, which the adults accomplish by keeping them in the center of the group. This alone deters small predators which are left unable to single out a single pup. And if threatened by a larger foe, the young - which are strongly banded in brown and yellow patterns that break up their shape - instinctively crouch down and vanish in the tall grass while the adults run, scattering widely and making it impossible for hunters to focus upon and pursue more than one or two. This way, when the herd reassembled when the danger has passed, most of the adults will have survived and will resume care of all of the young that are rounded up and brought back into the fold; the death of any single female does not reduce the chance of survival in her young as a result of this group mentality.

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Cygnosaurs affect the cementree forests too, by making it much harder for them to disperse, for all but the oldest and largest of the spires can be toppled and destroyed by their feeding. This has led to them becoming more isolated and separated, increasing more in height than width, by adding more material on top of themselves and forming a sort of reef-like colony above the reach of browsers. The longer distances between such forest stands required some animals that lived there to brave the ground and make the dangerous trek over land to reach new homes more often. For some skuossums, this ultimately has led them to abandon life in the spire forests all together. 

The skungaru genus are the descendants of scaly-tailed skuossums, which have evolved longer hind legs to facilitate quick bounding movement from one tree in the spire forest to the next, and gradually adapted to live most, then all of the time on the ground. They are medium-sized animals about the size of a beagle, weighing about 23 lbs and reaching up to six feet in length, much of this a long, highly flexible tail which the skungaru uses to balance itself as it leaps as far as 20 feet in a single bound. They are mostly featherless, their skin covered in small scales, which keeps them cool in the heat. Sparse plumage is still present on the back, where it absorbs secretions from the skin which are then used to mark rocks and trees with a rubbing motion; other skungaroos can tell whether a female is receptive to breed from the scent of these marks, as well as determine the size of a male (with bigger ones being preferred) depending on how high he can mark up a tree. A thick tail tuft is also present, which is used to swat flies that settle on the animal's body. To better jump quickly and reduce the time the foot is on the ground, the hind toes are reduced in size, with the central one largest and bearing most of the weight and the outer one small; the inner toe is now a blade-like claw which is used to kick out defensively.  

These animals are loosely social omnivores which mostly pick up seeds, greens, and insects from the grasslands in their blunt beaks, though they can catch and kill small vertebrate prey such as molodonts with a strike of their formidable claw. They move in small, changing groups over the plains, reaching top speeds of 45 miles per hour to escape predators, though they are still capable of climbing trees if necessary with small but sharp-clawed hands; the arms are now much weaker than the hind legs, so that climbing is mostly accomplished with the latter as well as the muscular tail, with sharp forward-facing scutes on its underside, which are used to prevent back-sliding. The skungaru's unique tail is both strong and extremely mobile; it can be used as a third leg, letting the animal raise up to kick enemies with both hind legs, and it can also be curled all the way around to swat bugs on its face. At high speed, it becomes a rudder, letting the skungaru change course on a dime and outmaneuver avian and tribbethere predators.

Females give birth to only two offspring at a time, well-developed but especially large at birth, about 7 pounds each, in thickets of spire forests, and then abandon them. The chicks live in groups of similarly-aged peers and are more avid climbers than the adults and run up the towers to flee their many predators, becoming more inclined to run on the plains after the first few months, when they begin to reach their top speeds and become less vulnerable.

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The need to run fast on the drier landscape has affected all sorts of animals. Thorngrazers, once all burly, slow-moving brutes that survived through their ferocity and durability, have largely been transformed now by the pressures of their new cygnosaur-dominated world. Many are now gracile, fast-running animals with bodyplans that more resemble the circuagodonts of the Mid-Ultimocene than any thorngrazers before them - and new predators have evolved to chase down these quicker and more nimble prey, too. For this is the battle that never ends. The fight for survival, to eat and to avoid being eaten, is just one of the countless life or death endurance competitions organisms go through each and every day. The stakes? For one, a day's meal. For the other? Everything 

A heelhound, a descendant of the springheel, speeds along the plain on its two long legs with an energy-efficient leaping locomotion, touching both feet to the ground at once and pushing off again, storing the energy of each bound in huge, stretchy tendons to make its movement fluid and easy, even over long distances. Just ahead, its target bolts at full gallop, racing for its life. A male fanfaloot, one of the most extravagant crested thorngrazers and a distant descendant of the rumbling helmethead, it is a species of loopalope; thorngrazers with remarkably shaped, curving horns form circles and may even loop together, evolved for visual display on top of their loud song-like vocalizations. The fanfaloot is faster for a short distance than its enemy, but it has less endurance. The hunter does not seem to tire, and the gap is closing fast. The thorngrazer begins to zigzag and leap as the predator closes in, seeking to outmaneuver it, to stay out of reach. 

The heelhound, though, has a secret weapon. At the last moment, when it is just a few feet behind the tiring quarry, it swings its body to the side and sends its long tail out ahead of it. A hooked claw at the end catches the hind leg of the fanfaloot and trips it, sending it tumbling hard to the ground. Instantly the sawjaw is atop its victim, restraining it with its sickle claws and cutting its throat with its teeth. The fallen thorngrazer kicks for less than a minute in its grip before its life forces dwindle away, and the hunter begins to feed. 

Heelhounds are gracile and light, not able to wrestle down the robust thorngrazers their ancestors did or to tackle the huge gantuans that larger contemporary species hunt. They don't need to, for they have become specialized predators of loopalopes, able to chase their equally delicate prey for long distances at speeds of up to 45 miles per hour. Loopalopes have few defenses except their agility, having traded heavy tusks and armor for speed. Some species weigh as little as 20 pounds and few over 200, a modest size spectrum that is largely all within the range that the greyhound-sized heelhound can bring down. Females are solitary and favor smaller prey under 100 lbs, but males hunt in small packs and can hunt even the largest loopalopes. The primary method used to catch food is always to snag its single back leg and exploit the weaknesses of its tripedal prey to trip them, then to overpower it before it can right itself, and its own tail is extremely long and well suited to swing around for this role. Like a shepherd's hook it catches its hapless victim's mid-stride, extending its reach significantly beyond either its jaws or its legs while not requiring it to stop running. 

The fanfaloot lost this race, but overall its species belongs to one of the most successful of all the thorngrazer lineages. With elaborate crests and complex songs, male loopalopes all woo potential mates in huge herds across the savannahs. Fanfaloots specifically belong to a group which have evolved fleshy extensions to the tops of their bony crests, making the top of their display mobile. Evolved from the lip-like muscles that could seal the nostril openings to keep out rain or debris, in these animals has become an extensive hollow tube with a degree of muscle attachment allowing the tips of the horns to fold up and fan out. These sheaths have evolved additional nasal openings to give the fanfaloots a total of six nostrils, each with a sphincter that can open or close it at will to produce an even greater variety of calls like a flute as it is played by a human hand. Two hollow membranes of skin between the horns, separated by a central point at the top of the bone structure where they fuse, function as inflatable air sacs that expand when the fanfaloot sings to increase the length of its calls and produce an impressive, balloon-like visual display. The song of the male is one of the most complex of all the thorngrazers, and includes deep booming elements produced in these air sacs and melodic high-pitched warbles as it quickly closes different valves to adjust its tone. Not only a vocalist, the fanfaloot has evolved a visual spectacle too - a symbiotic bacteria colonizes the warm, humid interior of its sinuses, harmlessly feeding on its mucous, and so helping to keep the interior of the crest free of congestion and debris by loosening accumulations of dried material through digestive action. This bacteria also benefits the thorngrazer by preventing colonization of pathogens both bacterial and vital over surfaces it has colonized. But its most spectacular function is that it is bioluminescent; the male fanfaloot calls by night, and green-blue light shines through areas of the crest where the bony structure has small slits over which only thin, translucent skin is present. It uses this light the same way other thorngrazers use colorful crests by day, to stand out to a mate. But like many elaborate courtship displays, this is a handicap to the male outside mating, as it also makes it more visible to predators. 

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Though deer-like runners such as the fanfaloot are now the most common thorngrazers, they are not the only ones. A few still persist which have not gone down this road. They might recall an age, tens of millions of years ago now, in which their ancestors ruled the land. When Serinarcta thawed, they inherited the world. They were hostile, violent, well-defended against all comers, could eat anything in their wake, and covered the ground in herds of billions. Then the gantuans evolved. Four legs beat three, and they grew, and grew, and grew until they reached sizes physically impossible for thorngrazers, and amassed their own numbers. A huge grazer that physically vacated them from their own habitat through violent conflict, and occasionally even eats them, the thorngrazers could only survive by changing their very nature.  They might feed more efficiently, but this was only a real advantage in the arid ice age world. In a wet, green hothouse one, the gantuans don't need to do better to be competitive if the supply of greenery never dwindles. So many thorngrazers had to become faster, smaller animals and effectively let the newcomers take over their former roles in the environment, as they become something new.

But some have persisted in older ways, and come to other solutions to survival among new rivals. Monstrocorns went the opposite way of crested thorngrazers early in the hothouse and doubled-down on being big and well-defended in ways their nimicorn ancestors could only have imagined. Huge horns adorned their massive skulls and serrated osteoderms lined their throats and flanks to defend against the teeth of predators. Yet the early monstrocorns were so safe from contemporary dangers that they became solitary animals - an evolutionary course that would come back to bite them, literally. This had to change again, and quickly, as gantuans such as the draconic cygnosaur arose - bullies that could take full advantage of their size and numbers to knock even the biggest monstrocorns around like playthings if they felt they were intruding in their space. By now, all such lonely thorngrazer giants have died out. Yet some monstrocorns have nevertheless survived in a form changed only a little from ancestral thorngrazers - relative to the antelope-like forms that now prance across the plains, at least. They have become smaller and so more maneuverable, but have developed the most complex armor of any so far - a combination of huge bony spikes, defensive plates, mineralized keratin spines that are half hair and half horn, and thousands of sharp bristle hairs in between that are easily shed and jabbed into the skin of anything that comes too close. They have returned to life in herds, and by combining their defenses, they can now hold their own against their rivals. They are the troxupines. 

An average troxupine, of which several species exist, is about as heavy as a sheep but stands only a little over 2 feet high. It is like a rat in comparison to a gigantic cygnosaur, yet its physical and behavioral defenses are sufficient to leave it almost completely invulnerable to anything, predator or territorial rival, that could threaten it. It is still a true generalist, able to digest all types of organic matter from grass to meat and bone to wood, but feeds mostly on grass on the plains simply because this is the most common thing in its environment to eat, and plants make up 95% of its diet. It moves in herds of 10 or 20 to more than a hundred, which often form a line-like formation as they feed, and in doing so forms a moving wall of spines and spikes that can displace even the largest gantuans that find themselves in their path. An individual troxupine can be killed, though likely not without some sort of injury, but the herd is a force not even cygnosaurs can overcome. Like a spreading carpet of needles and knives, it keeps the cygnosaurs moving without any aggression simply by being an immovable force. Their low height leaves them safe from backwards kicks that can kill other thorngrazers, and any cygnosaurs which turn and attempt to attack the herd with their beaks or by stomping their front legs face severe injury if they try to press weight on or bite the animal anywhere on its body. The troxupine doesn't have to be belligerent or hostile to protect itself - all it needs to do is keep walking, and other animals will get out of the way. They are in fact docile and mild-mannered animals, and will not attack other species; the only meat they consume is carrion or incidental while grazing, such as if they come across a bird's nest and eat it in the same mouthful as a tuft of grass. More fleet-footed creatures can thus walk among them and come right up them without being threatened - troxupines are entirely defense, with no offense. No animal should become too complacent near a herd of troxupines, however - the danger they post is unintentional, but still real. Big aggregations can inadvertently kill small animals like trunkos or crested thorngrazers if they become trapped within the herd while the troxupines are grazing in a loose formation and suddenly close ranks. The other animals can then become caught in between without a gap to escape and get skewered or trampled between them. 

Sawjaws, big or small, also struggle to subdue the troxupine. Low to the ground, it can just lay down and protect its underside with a skirting of outward-projected scutes that run along the perimeter of its body that leaves it all but invulnerable to bigger predators, since they can neither bite it nor flip it over. With its legs closely-spaced, it can also move more quickly than could the earlier, similarly-armored razorback, with less distance to pull its hind leg up to meet the forelegs in each walk cycle, and less sloshing of its gut contents. The ventral surface is flattened, supported by fused tooth plates on its underside, and rather than hanging low under the body the large stomach is now pushed up into the body cavity, closer to the spine, letting the limbs have a wider range of movement below without bumping into the belly. This combination of small changes, combined with its small overall size making it easier to bear the weight of is armor, means that unlike that extinct relative, the troxupine can still run with a bounding gallop when necessary, and can pivot quickly to face danger head-on. The only weak points are its eyes, its groin, and its unarmored legs, none of which is readily accessible when the animals are in a herd in defense formation. But even the biggest, strongest troxupine eventually gets old, or sick, or weak. When it lingers behind the rest, and ends up on its own, its defenses can eventually be infiltrated by packs of cunning small sawjaws, which circle the creature and try to pull its back leg out from under it with their tails each time it jumps forward to defend itself from another in the pack. If it lays down, they try to gouge out its eyes, forcing it to stand and try to defend itself just enough to let them snatch its leg and pull it over. Once they grab it, they try to bite the limb off, subduing the animal through shock via blood loss, and then chewing it off and accessing the rest of the meat by entering through the hole where the leg once was. Likewise the young are born without any defenses at all, and can sometimes be separated from the adults - or even crushed by them - if the herd can be encouraged to run before they have time to gather and stand their ground. A fit adult troxupine may have very few threats, but mortality of outliers younger or older is very high. This means most of the population at any given time is in the same age group, and only a few young survive to adulthood, while any which become even a little older than the average begin to trail behind the herd and get picked off. 

And it is not just sawjaws that the outlying troxupine fears. There is also the red devil, the only animal against which their defenses may not work at all, if the hunter is hungry enough.

The castacrane is a small, terrestrial scrounger that resembles a wading bird and is a member of the only scrounger genus to have colonized Serinarcta's land. It hails from the same common ancestor that gave rise to the squibis and the squelican around 275 million years PE, and forms a third sister lineage to these groups. Though the living species is plains-dweller, firmly land-living, fast-running, and not inclined to swim, it evolved from a wading bird with long legs but also webbed feet, which crossed the seaway between the hemispheres about seven million years ago. Unlike the modern squelican and their relatives, such a bird would not have been strong enough to make this voyage under its own power. But it would have already been able to dive underwater to catch food, and associated with seashore environs, and so would only require a place to rest intermittently while crossing, which was likely provided by a large mass of floating vegetation washed out to sea from the coast by a powerful storm. In this way, its ancestors were semi-rafters; animals that relied on temporary floating islands to cross the ocean, but which were not helpless upon them. They would have been fully able to find food on their own by briefly leaving the raft to hunt - and it would likely have attracted an entourage of small marine life seeking shelter, which would be easy prey to these birds, which would then climb back atop the raft to rest. After several months time, when the raft washed ashore, these castaways would have found themselves in a new habitat, and though some remained coastal others moved further inland, not inhibited by the more advanced aquatic adaptations of the squelicans and still capable of long-distance over land migration.

Castacranes are now the most terrestrial northern scrounger, being completely independent of the ocean and only loosely connected to wet grassland habitats, where they feed on seeds, invertebrates and small animals by probing in the mud and between the bases of grass stalks. They are small, very gregarious birds with strong social bonds. Standing about two feet in height, they live and travel a nomadic existence in large, boisterous flocks and run across the ground, often bursting into a loud cacophony of alarm calls when they come across another animal that could potentially threaten one, but would not mess with a group; the many watchful eyes of a castacrane flock make them good watchdogs, and so other animals may associate with them and take advantage of their wariness and loud alarm calls to spot danger they might otherwise miss. Both sexes of the castacrane have colorful red facial skin, which is typical for monogamous birds in which both sexes help equally in rearing the young. Stable flocks temporarily disband at nesting grounds, the only place where these birds regularly return year after year, and pairs make inconspicuous nests in tall grass to brood two to four eggs. The chicks hatch a month later and can run within a few days of hatching, at which time the flock members begin to rejoin and care for their young collectively in a creche. Chicks are born with striped patterns that break up their outlines and let them hide in the grass; if predators threaten the chicks, they crouch and freeze as the adults feign injury dramatically and lead the hunters away on a wild goose chase until they are safely away from their babies. Then they backtrack and dash away at high speed, and return to lead the chicks to safety, much like the tribbymaras that share their habitat do.