Mouth of the Matplains

Formerly known as the Founding Plains, the Matplains are Apterra's oldest complex ecosystem. This location, on the northern side of Abeli, is where the "big seven" macroscopic land organisms were first introduced to the planet. Most of the earliest-branching clades within those lineages got their start here in the Dawn and Early Muricene, but the landscape has changed a lot since those days. Since the end of the Ice Age, the plains have found themselves partially inundated by rising sea levels. In fact, about 60% of the matplains is technically below sea level at high tide, although the water does not make it very far inland due to the structure of the local ecosystem. Across much of the matplains, there is no clear division between an upper layer of vascular plants, an underlying matkelp structure of immense proportions, and the inorganic soil and bedrock below. 

On the inland side of the plains, where the land gradually slopes upward towards the mid-Abelian foothills, matkelp is unable to grow, as it requires an underlying source of saltwater to survive. Another hundred kilometers coastward, a thin layer of Continental Matkelp (Megaplanalgarum continentalis) begins to grow, supported by seawater that slowly leaches through the loose, sandy substrate beneath. Though Apterra's great tides have no visible effect here, they are responsible for pushing water from the sea many kilometers through the ground. Nearer to the sea, a layer of water begins to form beneath the algae, which rises and sinks with the tide, causing the overlying landscape to inflate and deflate like a balloon. Within sight of the Medithalassic, these cavities become roaring subsurface channels where tides flow like whitewater, sometimes tearing apart the three-meter-thick mats above. In the heart of the matplains is a brackish inlet that flows both ways as far as 350 kilometers inland, powered entirely by tidal flow. True rivers do not exist on the matplains, as rainwater simply seeps into the porous algal structure. Phytotelmata are thus the only source of standing freshwater across the region.

Luckily, thousands of species of plants grow atop the matkelp, including some that use their stored water as a reward for pollinators. The Provider Pitcher (Carnivorodendron aquifer) is a species of small pitcher-palm that now only employs carnivorous tendencies at one stage of its reproductive cycle. After flowering, it needs a lot of protein to pack its seeds full of nutrients for its offspring, so it releases a pheromone that induces its symbiotes to go looking for prey. But before it can get to that point, it needs to get its florets pollinated in the first place. Unlike most woodlouse-grasses, pitcher-palms cannot self-pollinate. This was not an issue in their ancestral home in the forests of Ailuropia, which supported the trees in densities of over 2 per hectare. On the matplains, there may not be another tree for a kilometer or more, much too far for the wind to carry the heavy pollen grains of the provider pitcher. Instead, it bears flowers in the center of leaf whorls. Each has eight leaves in total - the first four are normal-looking and provide most of the tree's photosynthesis, while the other four are fused along their margins to form a spherical shell around the central inflorescence. The ends of the blades are unfused and can move independently; they form a funnel-shaped entrance that can open or close as needed. When it rains, these vessels turn upward, each gathering half a liter of water. The thin stems droop to the ground, allowing animals of all sizes to take a drink. The florets release their pollen into the chamber, and a few grains are inevitably deposited on the face of any creature that visits. They can then enter the shell of another Carnivorodendron, which  switches into its predatory phase. Mature provider pitchers, up to four meters tall, can have dozens of branches, with just a handful collecting prey at any given time.

There is not much diversity of animals over a few dozen kilograms on the matplains, as the ground is never fully solid. However, many have evolved to spread their weight across the algae, preventing them from sinking into the sludge. Latifimbriine pillbirds, descendants of the mudtrotter and periscope bird, have lobed toes, and some have been able to reach megafaunal sizes without trouble. Hooved Muridiungulates cannot grow large here, but their role is filled by a new species of giant soft-toed Abelithere. Boxerbirds, the only quadrupedal birds, sometimes outweigh their solid-ground conspecifics by a factor of two. The top predator is a population of packslash carnivorns, which are a species of social predators with cognitive abilities not yet seen on Apterra. These belong to the same gracile morph as those that live on the snapscrub, but the two groups have been reproductively isolated for a few hundred thousand years now. Matplains packslashes have evolved wider padded feet, and they have a different social structure than others of their species. With eyes nearly two meters off the ground, these hunters keep track of all the life of the plains, and through these eyes we will see their ecosystem in better focus.

A hunting party rests in the shade of an old provider, gathering their energy to drag their kill the rest of the way back to the nest. Some kind of large seabird washed inland by a storm surge, none of the three carnivorns know exactly what they've caught, but a few bites from its blubbery flank have convinced them it's worthwhile to bring home. The largest stands first; she knows she is running the risk of losing social status if she takes too long to return. Her higher-ranking sister is currently watching over her chicks, but her patience has been running thin recently. The huntress wasn't supposed to rear a clutch at all this year, but she incubated them in secret outside the protection of the pack. Her parents, leaders of the pack, permitted the chicks to live, but her sister's young have gotten a lot of preferential treatment since they hatched a week ago. 

At three months old, the huntress's clutch have are more food-demanding than any other stage; they are in the middle of a massive growth spurt, taking up much of the pack's resources. Thus, this individual, who would normally spend most of her time at home with her offspring, has no choice but to hunt until she makes up for the ravenous youngsters. In just a few more weeks, they'll be able to join her when she goes out, and the pack's hostility will quickly wane.

The other two members of the hunt are young males, just beginning to grow display feathers around their eyes and the backs of their heads. Their main task at this life stage is to hone a particular hunting style, something to make themselves stand out from the others. Neither is happy today; though their bellies are full, they've missed an opportunity to develop their skills. With the dispersal season in full swing, they are eager to get in on the action. Only one in ten males breed in their first year, and these two intend to be part of this exclusive fraction.

The sister emerges from a den sculpted out of algae and debris. A nest that dipped far belowground would quickly become waterlogged, so the pack has constructed theirs above the surface level. It contains half a dozen "rooms", each the size of a small pickup truckbed. During plentiful years, it can host five clutches of as many chicks, but this year there are only two new families. The sister squawks gently towards the dark space behind her, and the chicks emerge - her own five, and the huntress's two. The larger juveniles rush out but are prevented from eating, as is their mother, by the sister and her mate. The pair, along with the matriarch and patriarch, always get first pick of whatever the hunting party brings back. Mid-ranking females like the huntress are typically next in line, but she has been demoted to the bottom of the pack - beneath even the unrelated males - because of her transgression. By the time she and her two young get a chance to eat, it's too late. She must go out hunting again if she wants the nestlings to eat today.

The wiry-feathered chicks eye their downy young cousins with something akin to jealousy, but they keep quiet as night grows closer. The faint green-brown glow of sunlight diffusing through the algae fades slowly until nothing can be seen. Their mother has been out for some hours now, following only a brief reunion that brought no relief from their hunger. The faint squelching and clicking sounds of small creatures beneath the muck proves too tantalizing for one of the two  - smaller than its sibling, the keen-eared packslash sinks first a single claw, then its whole left foot into the floor of its home. It pulls out a hard-shelled hissing thing that immediately riles up the hatchlings, but it ignores them; it has not yet learned the pecking order, and it isn't about to allow some chicks a tenth its size to steal its catch.

It will never see one again, but it has just caught a type of shrimpbug mosquito called a Giant Plowfly (Forticulicaris continentalis), which feeds on large roots between 30-100 centimeters beneath the matkelp. It has a shovel-like cover on its face to push material out of the way, and the bird is about to find out just how strong its cutting jaws are. As it holds the insect in front of its face, failing to make out any detail, it feels a bite beneath its chin, cutting a short but deep gash into the fleshy wattle. This isn't enough to dissuade the hungry slashstepper, who quickly crushes its prey with its lower beak against the roof of its mouth. 

Its larger sibling, stronger and possessing longer hand claws, wakes from deep sleep, and at the same time the huntress's sister arrives to investigate. She won't be able to see the den and figure out what just happened until morning, but she takes the opportunity to preemptively punish the two; each gets a sharp peck in the side. In response, the smaller one instinctively regurgitates its meal, which is quickly torn away by the now wide-awake hatchlings. 

The chase is on. A Long-Beaked Apteroo (Macropodornis syndigitus) has strayed too far from its herd, and it now flees for its life from the mother packslash. With webbed toes and a light build, this is the largest of the matplains' pouchwings. This one weighs about twenty-five kilos, plenty for the huntress and her young. In the moonlight, the pale skin of the apteroo's pygostyle shines just bright enough for the huntress to follow it. Though she closed a lot of distance in her initial charge, her pouched relative is gaining speed with every hop, storing more energy than she can from one stride to the next. It will be out of sight soon if she doesn't do something.

A hill looms ahead and to the left of the huntress and her quarry. But there are no hills on the matplains, and she knows it. The tide is rolling in. The apteroo doesn't seem to notice as, with each increasingly powerful leap, it sinks a little further into the algae before launching upward and forward again. The packslash veers right, and her prey responds as she hopes: it darts towards the higher ground, planting its feet one last time on the tangle of roots, leaf litter, and gooey matkelp. As it lands, a series of popping noises rings out in a fraction of a second. This is the sound of roots snapping as water bursts forth from the ground, carrying the apteroo off its feet. It is lifted into the air and touches down some five meters away, while the packslash circles around to deliver a killing bite to its neck. 

She isn't safe here. The seawater will continue pouring out for several hours, and the surrounding area will be swamped until the tide recedes. Then, anything caught in the water will be sucked underneath the matkelp. This will continue for several days or weeks until the roots of large plants restore the structural integrity of the raft. Right now, the huntress begins her return trip, satisfied that she and her offspring will have full bellies at last.

Like many mornings in early spring, this one has brought a new male to try its luck in joining the pack. Those that don't find a mate in their first year are usually thrown out of their natal pack, and bachelor packs of up to twenty individuals are not unheard of, but this one is by itself. Yesterday's two young hunters are no competition for him, as they would never dream of mating with one of the females in their own group - most of them are related, after all. The four already-mated males pay him no mind either. Even the females without partners seem only mildly interested, as if waiting for something else to happen before they make their assessments. In coastal packslash society, it is the parents who must be impressed if a bachelor is to find a mate. 

The matriarch and her mate emerge from the rearmost room of the den. Though the new male is tall and has an attractively red wattle, they pay no attention to these display features; useful for securing a mate, these traits aren't what the parents care about. They stand to either side of the newcomer and lead him out onto the plains. They move landward, the opposite direction from where their rebellious daughter went the night before. As the ground becomes just a tiny degree more solid, low-growing grasses get thicker. Small basket-grasses, sodstalks, and forb-like sweetstalks such as Kelpflame (Ratiscintilla, of the meadowflame group) and Heartbundles (Cardinarium, a sweetheart bush with a compressed stem) are the most common, though occasionally a small salt-tolerant tree will crop up as well. 

The old couple stop at a seemingly random point. They selected it years ago as the proving ground for all their daughters' suitors. By bringing them all to the same place, they are able to make direct comparisons when multiple males are in competition, but today they've returned to this location simply as a matter of habit. The young male keeps walking obliviously for a couple paces, then turns around, momentarily unsure of himself. He sees the parents standing still, shoulder to shoulder, and he understands that the test has now begun.

He tilts his body into a nearly vertical position, see-sawing at the hip to raise his head higher above the plains. He sees movement all around, but he has learned not to read too much into every swaying stalk of grass or ripple in the matkelp. His head swivels slowly until it stops on what appears to be the shadow of a provider pitcher-palm. Lingering a moment, he can't help but notice that the "shadow" seems bigger than the tree itself. This is out of place so late in the morning, and he holds his gaze beneath the tree for over a minute, waiting for something to reveal itself. Unsatisfied and unable to get a good look, he starts the three-kilometer trek to investigate further. The pack leaders follow at a slower pace, affording him the stealth of a solitary approach. 

He stops moving a few hundred meters from the tree, crouching in the half-meter-high grass. In a move that puzzles his onlookers, he begins splaying his legs across the ground and appears to fall asleep. His breaths become slow and regular, and he shuts his eyes. He is not looking or listening for his prey anymore, but rather feeling vibrations in the substrate beneath him. This far inland during a tidal ebb, the free water layer is only a few tens of centimeters thick, barely enough for him to sense anything. A large fish leaves a sharp wake behind it as it swims a handful of meters to the newcomer's right. The ruling duo pace confusedly several hundred meters behind him. Finally, a dull crack rings out. This sound comes from the vessel of a provider bursting, which sometimes happens when large, boisterous animals cause too much disturbance around the tree. The leaves, sensing danger, seal tightly, and when something bumps into them, they come apart at the seams, splashing water on the intruder. 

A sudden drop, then a series of sideways ripples in the matkelp signals that a large animal has just stood up and shaken itself off. Two more rise in turn. The newcomer can tell by the rhythm of the footsteps that these are quadripeds, and they are now heading east. He slinks along next to them, keeping too low for either to see the other. By now, the matriarch and patriarch have completely lost sight of him, and they won't wait much longer before assuming he's given up. Every few dozen steps, he lies down again, recalibrating his path to put him next to the largest of the group. He circles in front, waits until he feels footsteps just meters away, and launches himself into the small herd of Megabelitheres (Eumegabelitherium latipes).

The grandfather packslash notices the commotion before his partner does. The newcomer hadn't wandered off after all, and he is now locked in battle with a bull megabelithere some 50% bigger than himself. Though it isn't usually good practice for a predator to attack a large, healthy prey animal in its prime, it makes much more sense in this case; the bull would fight to protect his mates, but not vice versa. Instead, they sit back and watch. They too are making a cold assessment: should the male rat lose the fight, then perhaps he was not the best choice to father their pups anyway. Whether he succeeds or fails, the two females will gain valuable insight into his genetic fitness, helping them ensure the best odds for their offspring.

He fails. 

A long-term mate would be both a blessing and a curse for the huntress. With the newcomer officially joining the pack, she can regain her old rank by partnering up, but he will almost certainly kill her chicks. This early in the year, she would likely be able to lay and rear a second clutch, especially with his help. Given how much energy she's invested in her two fatherless young, plus how close they are to independence, she cannot make such a decision lightly. If she could only stall the newcomer for a few weeks, she could have the best of both worlds. 

Her younger sister, sole survivor of the clutch that hatched the year after the huntress, has other ideas. Ever since the middle sibling went against their parents, the thirdborn has been enjoying the privileges afforded to the second-highest subordinate in the pack. Noticing her sister's hesitancy, she takes the opportunity to endear herself to the newcomer. She tilts her head skyward when he displays for her, signaling that she's interested and may be receptive to mating soon. This spurs the huntress into action; if her sister secures a partner first, she may never rise to her former position again. Still in fear for her clutch, she nonetheless has no choice but to endanger them. But despite her stress and bottom-rung social status, she still has one card up her sleeve. She hasn't yet gotten the chance to employ her specialized hunting technique this year, but it may be her saving grace.

He came here expecting to have to compete with many other males, but this year has brought few from other packs so far. This and the convolutions of intra-pack politics have created a backwards situation where two females are now competing over him instead. The older one played hard to get at first, but now they both fawn over him in equal measure. He shows off his feathers and wattle time and again, and he shares portions of his catch with both of them. Though his species does not build harems, this is an opportunity to pass down his genes to twice as many offspring, and he isn't about to let it slip away from him. He'll have to work twice as hard to support two mates, but his new pack is small - he can tell it was once larger, but now it is below its carrying capacity. This will be a summer of abundant prey, and he feels confident that he can support two new families. 

The females are less so. Though they would typically select a mate based on honest fitness signals like his feathers, wattle, and a complex "dance" of pygostylic waggling, today these are not enough to satisfy them. To make matters worse, their parents have returned from patrolling the border with a rival pack. They will never approve of his ambitions, as they would rather see each of their daughters paired with a single dedicated male. He will have to court the sisters in secret, and the older one seems to know just the place. 

The summer hunting grounds near the open channel won't be fully stocked with prey for another month or two, but neither the newcomer nor the thirdborn knows that. The huntress wouldn't have otherwise come here so soon, but she needs to get the others used to the area as quickly as possible. Sure of foot, she leads them to within a few strides of the water, which is currently sitting at a low slack. The male follows with only a brief hesitation; he can feel the strong and weak spots in the mat more keenly than either of the females. The two are soon marching side by side, while the youngest of the three cautiously hops behind them from root to root, too scared to set foot on bare algae. 

The huntress doubles back. Like all packslashes, she is a complex social creature with an ability to plan ahead, and her plan will not work if something bad happens to her sister right now. Today, she has only two goals: to present herself as the more competent sister, and to acquaint the newcomer with her hunting style. Her first task completed, she now sets out in search of prey. Many techniques can work in this part of the matplains; some packslashes creep up to the very edge of the water to fish, while others seek to trick they prey into miring itself in the algae. The huntress is a specialized predator of smaller carnivores. Kiweasels are common near the water's edge, feeding mostly on small rodents that eat the seeds of sailtrees and other marginal plants. The mudtrotter tribe, known as Pillplunges (Arthrophilonatatorini), contains several species of small semiaquatic birds that make for easy prey when they rest in the summer sun. These are close relatives of the sometimes giant seabirds descended from the periscope bird, one of which the huntress met for the first time just a few days ago. Three different species of ratweasels can also be found here, and these are what the huntress is looking for today.

The trio creeps towards a particularly dense stand of sailtrees, walking along its thick roots as they get closer to the seaway. The ground sags with each footfall, but all three gather their courage and make their way to the very edge of the thicket. Fruitgrasses grow beneath the chaintrees, and branchblooms flower amongst their foliage. A soft rustle is barely audible over the rippling of waves just two meters away. It's a Diving Ratweasel (Durophagomys marinus), the largest predatory mammal of the matplains. The huntress takes a step back, egging the newcomer on to show off his hunting prowess. Though outside his preferred terrain, he can still get a vague feeling of his target's movements. He swings his head down like a hatchet, slamming into the algal mat where he thinks the ratweasel should be. Somehow, it escapes him, and he recoils empty-beaked and with a face covered in slimy matkelp. 

Day after day, he is unable to catch food at the water's edge. Embarrassed, he returns many times, and with each failure he can tell the sisters are losing interest. What he doesn't know is that he's being set up. The huntress wants him desperate, so she withholds from him the secret to her hunting strategy. She knows the best way to kill a fellow predator is to lay a trap.

The huntress has stalled long enough. Despite the newcomer's humiliation at the open channel, he has proven himself an effective hunter in many other situations, and the thirdborn seems ready to officially settle down with him. Though he may have his hopes set on scoring both of them, the huntress knows her younger sister will never actually put up with this. To share a mate would be to sacrifice some of her own status. With the nestlings almost ready to strike out on their own, it is time for the middle sister to make her move.

The huntress, newcomer, and thirdborn approach the channel. The older sister finds a spot at the water's edge without sailtrees. Here, a thick and hedge-like form of loop-grass creates a barrier between water and "land". The huntress, without alerting her companions, has brought along a piece of bait. A fist-sized hunk of boxerbird meat, taken from her own meager daily rations, rests precariously between her claws, hidden in her chest feathers. She sets it down next to the thicket, stirring confusion in the other two, and lies down in the muck, allowing water to cover nearly her whole body. The others back away, but they won't be willing to give her the benefit of the doubt for long. The male in particular, owing to his low social position, is still hungry, and he will eventually take the opportunity to snap up the apparently unwanted food morsel.

The channelside grass shifts, then parts in two as a different ratweasel emerges, attracted by the scent of food. The Matweasel (Phycomys ratiensis) is a small omnivore, barely a snack for a packslash. The thirdborn and the necomer crouch lower, making themselves inconspicuous as they begin to understand what their packmate is doing. The rat ventures into the open, latching onto the boxerbird meat. The huntress rises from her hiding spot and begins her strike in one movement, aiming about twenty centimeters behind the rat. Its reaction time is impressive, but she has predicted its retreat; instead of the safety of the loop-grass, it finds only the jaws of the larger predator. 

Perhaps if they had greater critical thinking skills, the other two packslashes might begin to question the huntress's motives right about now. Why had she led them on so many useless hunts, refusing to show them this simple trick? But despite their creative hunting strategies and complicated social memories, these animals lack the imagination to predict what's going on in the mind of the huntress. Formulating plans in the medium-term may be possible for packslashes, but thinking critically about the plans of another individual is still beyond them. Oblivious, they remain under the assumption that this is simply a regular hunt. The newcomer eagerly adopts this new tactic, tearing off the matweasel's tail to serve as bait for the next target. 

All three pass the afternoon this way, eating their fill as they go. The huntress leads them gradually to a place she typically avoids. Here, there is no vegetation next to the channel. Instead, the algae slopes down to meet the water, which laps over its edge and extends several meters onto the otherwise flat plain. Taller grasses grow on either side of this little inlet, though the newcomer can't sense anything hiding within. He doesn't know why the group is stopping here, but he won't go against the older female, who he is finally beginning to impress with the very skills she taught him. He backs away a bit, assuming the huntress knows what she's doing. She nudges the thirdborn into a waiting position in the submerged area, and she deposits another piece of bait on the dry ground. 

The young female is excited to finally get her turn to catch something. Emulating her sister, she holds completely still, only allowing her head to peek above the water. The newcomer lies down not far away, curious to find out what sort of prey item she'll catch. At last, he feels a light rumbling beneath the surface, similar to a burrowing creature emerging from the algae. It moves in a way he doesn't understand, seemingly out beyond the extent of the algae itself. In one final calm moment, he feels nothing, as the unknown object is apparently in open water, beyond the reach of his senses. The next second, he has no need to feel for vibrations in the muck, for his eyes tell him everything he needs to know.

The Mouth of the Matplains (Forticaudosaurus vadosiensis) is a giant Euthalassaur native to the Medithalassic coasts of Abeli and Aglirium, with occasional vagrants as far east as Abelox. Its genus, which contains over a dozen species, is descended from the shortfin spearflipper. Compared to other large thalassaurs, Forticaudosaurus have conspicuously little sexual dimorphism, as they've solved the issue of females having to haul out on land to lay eggs. This genus is now ovoviviparous; up to thirty offspring at a time can develop and hatch internally before escaping through their mother's cloaca. The pups are born precocial and require no dedicated care, but they may stay with their mother (or a larger social group in some species of livebearing thalassaurs) for several months for protection. 

Forticaudosaurus species are universally large-game-specialists, with most hunting other thalassaurs, marine birds, and giant fishes on the open ocean. Only the mouth of the matplains goes for land-based prey, though around 50% of its diet still comes from the shallow waters of the open channel and other tidal estuaries. At five meters long, it isn't the biggest member of its genus, but its moderate size gives it an advantage in this habitat; it can rest semi-submerged at the edge of the algae, basking to regain body heat at a rate impossible for its larger cousins, which remain relegated to the water. Adult mouths of the matplains usually have one or a few preferred basking spots, which regularly become the source of territorial disputes. In these prized locations, a thalassaur can haul most of its mass above the waterline while still being supported by a soft, bouyant raft below. This prevents the lizard from being crushed under its own body weight, and it serves as a safe refuge for mother lizards to leave their young when it's time for a hunting trip.

Today's hunt was another failure - the fourth in a row for this gravid female. She has never been the best at catching aquatic prey, for her eyes are more sensitive to color than to light and dark, rendering her ineffective beneath the algae. It's a tradeoff that different members of her species fall on different sides of; those with better underwater vision are similarly impaired when ambushing terrestrial prey. The two budding ecotypes are not yet reproductively isolated, especially in an environment like the matplains, where there is little barrier between land and water.

The lizard's jaws clamp down as she reaches the apex of her leap. Her neck bends back as her prey absorbs the momentum of her head, but the bulk of her body keeps sailing forward. Her barrel chest crashes into her sculpted algal ramp, which buckles and splits open under the force of her fall. Roots snap and recoil, and one whips across the ground in the direction of the huntress, leaving a thin gash around her ankle. Now only the mouth of the matplains' tail is sticking out above the surface, and she frees herself by wriggling left and right once. There are many kleptoparasites beneath the algae, and she'd usually drag her prey onto the ramp to eat in peace, but now she no longer has that option. Instead, she brings the body of the thirdborn out to open water, where she will have an easier time noticing and fighting off competitors. 

This mother has no knowledge of the intricate life of her prey, and she may never interact with its species again. Her long-term impact on the pack's leadership is of no meaning to her. The same goes for the many other species they share a habitat with - none know or care that they are in the presence of Apterra's most socially complex organism yet to evolve. As the Arthrocene draws to a close, their cultural practices, more so than physical differences between ecotypes, will be the factor that drives populations into permanent reproductive isolation. Once these distinctions become set in stone by increasing genetic distance, only then will the daughter species begin to experiment with novel body plans to reduce competition. It's safe to predict the terrestrial ecosystems of Apterra's next epoch will be a landscape of cooperative predators and an intensifying predator-prey arms race, though it's unlikely that any of these future hunters will be quite as generalized or adaptable as their present form.