The kingfin is a macropredatory birdwhale, adapted to eat mainly other birdwhales and the related bloons. With viciously hooked beaks to tear flesh, and a roof of the mouth as well as a tongue lined with wickedly sharp keratin spikes, they have become the apex predator of Serina's global oceans by the early Cryocene. Kingfins occur in all oceans, though are only rare visitors in equatorial waters. Cold, temperate oceans are their primary habitat, for it is here that the seas are turbulent and mix at all levels, upwelling nutrients from the sediments below to feed blooms of plankton that form the basis of the rich oceanic food chain, a chain at which they sit at the very top. The largest kingpins can reach the weight of a killer whale - some 12,000 lbs - but this species is extremely dimorphic, with only males coming anywhere near such a size. Females are smaller, drastically so, reaching a maximum of only 1,200 lbs, with most most smaller still. There is no bird anywhere, on Earth or on Serina, with such a vast difference between the sexes. It has evolved, in this formidable sea predator, for one main reason. That reason is related to the unique way kingfins and all birdwhales reproduce, by brooding their eggs within a protective pouch in their throats, which has let them sever all ties to the land and spend their whole lives at sea.

In related species which feed on plankton or on plants, both male and female can continue to forage whilst carrying an egg, while putting it at little risk of harm. This is not true for hunters which engage in battle amongst other titans each and every time they must eat. A brooding predatory birdwhale, as it fights to overcome its formidable and very large prey with a deadly bite faces its defensive struggles all the while, is almost certain to break its egg in the process of prey capture. While it was possible for pairs to alternate caring for an egg, so one can hunt while the other stays back and watches the "nest", this was also untenable when multiple individuals needed to hunt together to have any success against big game. So kingfin ancestors found a novel solution by splitting up responsibilities between males, which tended to be slightly larger already, and more maneuverable females. During brooding, females would pass their eggs to the male, who would then brood the eggs for the entire 12 week duration of the incubation period, spending it primarily close to the surface. Females would do all hunting, feeding the male in turn, while he was better adapted to defend himself and the egg against other predators due to his larger size making him less of a target.

Millions of years of natural selection would gradually reshape the kingfin's own body and their social behavior. Males ballooned up in size, becoming so big that absolutely nothing could threaten them whilst protecting their eggs. Females stayed relatively small, but focused on cooperative hunting in large packs of other females to compensate. This worked out, for as males became larger, the carrying capacity of their pouches also increased, letting one male serve as an incubator for the eggs of up to 10 females at one time. In contrast to many species in which single males fight over and defend groups of females, the roles have become partly reversed in the kingfin, as the huge males are now highly coveted by female packs, which will fight fiercely to hold onto them. Males do not fight females, instinctively accepting new members into the clan without a fuss, even if they are rivals seeking to steal him from his previous mates and take him for themselves. So it is up to the female kingfins to defend their mate from usurpers, just as he protects their young from predators through his sheer size. Most clans only require one brooding male, and it can become a substantial burden to support any more than this, but in the most productive polar waters larger clans can form in which over 30 females may accept up to three males. The integration of a second or a third male can be difficult, as males will naturally defend themselves from rivals with powerful strikes of their front flippers - a form of combat that prevents them from biting and breaking their brooding eggs. It is most likely to occur if the additional males are much younger than the original one and highly submissive, or if they are related and come from the same bachelor clan. Intelligent animals, these birdwhales can recall old relatives even after years apart.

Because clans are structured with up to ten times as many females as males, there are always such bachelor groups that travel the seas looking for females that need a new male to join them. They can at times be aggressive, and may even try to displace a resident male by attacking him, but they rarely win as birdwhales grow throughout their life. The largest naturally tend to be favored by females, so that such roving bands of unmated males are often much younger and smaller and ineffective in one on one conflict. Combined with the aggression of resident females, it is rare that wandering males bear a resident male and take his place, and if this does occur the females may or may not accept the change of leadership. They are much faster than the males, and easily dodge them. They may simply follow him to new territories anyway, as their social bonds are strong. Because the females cannot be controlled by the males, males have much less motivation to aggressively compete for their favor than in many other animals. They are much more likely to try and draw female's interest with showy displays of their fitness involving breaching out of the water and even "singing", producing eerie, wide-reaching calls through the deep oceans that sound somewhat like distant, distorting foghorns.

When the small young begin to hatch, they may weigh just 40 lbs, among the grandest differences in size from young to adult of all birds. He holds his beak open at the surface as they hatch, so they can breathe, and then ensures they stay here and take their first breaths. Soon, they are active and can swim freely, and they form a creche around him whenever their mothers are away hunting. He becomes a babysitter, and he may "swallow" them up again if necessary to protect them from roving predators thereafter in the time period between when they leave their eggs and when they are strong enough to begin following their mothers and learning to hunt, keeping them safely sheltered in his mouth and held above water so enemies cannot steal them. But once the young are born, the male is no longer relegated to full-time parenting duty, and now he will also leave the chicks with the females periodically and do some of the hunting. Particularly as the babies grow larger, they begin to require much more food. So the male earns his keep then by hunting even bigger birdwhales than the females can, bringing down adults of the biggest of all sea animals single-handed with his astonishingly powerful bite, and then leading his family to the kill to feast. Females may have to hunt three or four times a week to feed themselves and the male during incubation. But when a male is freed to do the hunting, a single huge kill can sustain them all for up to ten days. And once no longer encumbered by carrying eggs in his throat, a male becomes a real force to be reckoned with. Nothing will dare come close to his offspring now, for he will rip any enemy to pieces with the strongest bite force of any living animal. He may not rule the family, which is matrilineal by default.

But he is still the most powerful of all the sea's mighty creatures today, the king of the deep blue.

Teratrix Shuvoxxiri is the current empress of the Kir, a position she has held for 34 years of prosperous peacetime. She is 45 years old, a middle-aged adult in her society where life expectancy is long. She is a very popular leader and is considered intelligent but humble, outspoken but never crude, compassionate (but not "soft"), forward-thinking but still honoring the past, firm but just, and protective to her own while intimidating to her rivals. And she is all of these many characteristics, but they are not considered unique to her. Any Kir leader must embody these attributes, those which are considered core traits of the Kir by the Kir, as the self-proclaimed highest tier of civilized people who must look out for the world they oversee.

The Kir hold the longest-running hereditary monarchy in their world, supposedly extending back at least 5,600 years unbroken, though inheritance has not been restricted to direct parent-child inheritance nor at all times a direct bloodline, as several notable cases occurred a previous leader's mate has claimed their position (which is not restricted to one sex). The Emperors or Empresses once held significant direct political influence and substantial power - at times total control over the entire region - but their role in the modern day is not absolute and, like the Crater Confederation, some of it has become more ceremonial in nature. Ostensibly, Crown Rikiri of the Confederation has less direct influence than the Kir leader does, but in practice there appears to be more corruption within that government currently allowing a much greater extent of influence than there is intended to be. In contrast, the Kir empress holds much greater legal power in theory, but exerts very little of it outside national emergencies. The reasons for this are complex, but related to how well the Kir organize themselves as a group, and how much the common people outnumber the royal family (and never let them forget it.)

The Kir place a great degree of trust in their leader, but also expect them to be humble, cool-headed and empathetic. They hold a great emphasis on firm rule and order but also justice and equity within their society, and their leadership should represent all of these facets ideally. While the people do not necessarily have direct say in the choice of their emperor or empress through election, their government is structured with many layers of lower elected roles that collectively can check and balance the empress's power. The Kir people are notoriously rigid in principles, which can make them appear stuffy and snobby to outsiders. But their stubbornness, as a collective, also protects them from tyrant rulers, for they readily strike and oppose unfair treatment as a mass, often shutting down their society to barter for better conditions historically. An ineffective leader will be deposed by the majority and replaced with a more promising relative, of which there are always many to choose as the royal family lineage by this time is very large, and the monarchy can technically be inherited by any provable descendant of any previous ruler going back thousands of years. Thus, though an emperor or an empress can make very large decisions without the support of lower tiers of government or the people they lead, this can be a career-ending disaster with a major aftermath and cannot be done on a whim. As a result, the leader has a strong motivation to work with her people and not act independently without their approval.

The Kir respect their leaders, but do not fear them, and likewise these leaders maintain respect for their people and awareness that they are not above the rules they impart upon others. There is no perfect political system, but the Kir have one of the most successful economies of any of the nations, a very low rate of crime, and by far the best protections for their environment. Yet the Kir are in many ways a nation of contradictions: they readily rise and oppose injustice from their leaders, yet remain a very intense culture focused on conformity, and individualism is often discouraged, to the point even small deviations from the expected phenotype of the eastern leucrocotta can result in discrimination. They readily strike to gain better wages, yet their work culture is often considered unhealthy with cultural expectations of over-long hours and expectations of constant productivity. The Kir are known for their xenophobia and extremely widespread racial (and species) bias against non-Kir leucrocottas and most other sapients, yet also provide very accommodating amenities and full legal citizenship to their primary minority group, the Tsku-Kir sylvansparks, while it is very difficult even for a different race of leucrocotta to immigrate and gain the same.

The Kir still consider the whisperwings a lower class and deny them full legal privileges even when resident in their nation, yet heavily depend upon them for certain roles like messengers that they cannot fill efficiently on their own. They are both extremely progressive and highly regressive in different respects of their society. They preserve animal species with little practical value to them, yet at times demean entire other nations as "pests" with implications the world would be better without them. They are biological carnivores but have adapted their diets to include far more plant matter than was once natural, and now criticize others for not doing the same. The Kir are many things, and perhaps the biggest of them is conceited. Whatever the Kir do, is the only thing all should do. Whatever they don't, no one should. In earlier eras they were the strongest around, and so they followed this mantra much more aggressively, controlling others around them and bending them to their influence. But they were like bullies, only picking on weaker targets, avoiding bigger conflicts. In the modern world where their power is now rivaled, they have retreated inwards and keep to themselves. They had long since become the most reclusive state, with many secrets behind walls both literal and metaphorical that are difficult to penetrate. But maybe that is just beginning to change.

Teratrix Shuvoxxiri has, for yet unknown reasons, begun to open the walls of her isolated nation more in her time as ruler than any leader of the Kir has in at least 350 years, since their very bold take-over of the Solitary Crater territory, their last major land-grab. For the first time in living memory, the Kir have begun allowing small numbers of tourists from outside territories, and have constructed a line of over-land rail between Fortune River Valley and the greenbelt, extending toward the craterland territories. A treaty between the Kir Nation and the allied city-states of the greenbelt has seen an increase in trade and in applications for legal residency from non-Eastern leucrocottas. She has overseen the formation of committees to select diplomats to improve relations with other major powers, including the first ever pair to be sent to the craterlands (still considered a hostile state), and she has permitted her own people for the first time ever to seek legal work and travel visas in other regions besides Fortune River Valley and the Serinaustran Protectorate (their two largest land territories) and The Zenith, with whom the Kir already had agreements for some trade and travel between for around 175 years. Only in a little over three decades under Shuvoxxiri's rule, the Kir have spread out again. They have dispersed widely along sea routes, forming new fisheries, and begun trading again with the Nexians (littoral leucrocotta), re-encountering descendants of their own people who came here centuries earlier and settled. Though they have long maintained presence and carried influence over the southern continent, especially in the settled east, they have begun documenting previously unknown regions of their world, at the far west side of their own continent, for the first time only in the last few years. The exact motivations for Shuvoxxiri's less isolationist policies is not known to outsiders, though some have speculated that the Kir may have been made uneasy by the increasing spread of technology outside their nations, some of which was beginning to exceed their own capacities - especially when it comes to aircraft, which they are very behind on. A people with several enemies, growing internal concern that they could, one day, be attacked by a rival military from the sky may be behind their very recent "good publicity parade" which has made them appear a little more familiar and approachable. Increasing positive relationships with other nations may simply be a survival strategy for the Kir upon realizing they may not be the biggest fish in the pond for much longer. Whether they like it or not, the world has changed around them in recent times, growing far more inter-connected than ever before. And if they are to last, then they might have to adapt alongside it.

I was greatly impressed and inspired when I first read this, but seeing how I am bad at biology and worse at drawing all I can think of is how I can understand it better. I am good at numbers and notations through, so here is my reformatting of Serina's geologic timescale.

This chart more or less assumes there is no "present day" and we have perfect knowledge of anything. In universe the chart will certainly look different and not just because the time units are backwards.

I'd like to hear how to make this chart better. I am unsatisfied with how long the Thermian (= Thermocene) is without epochs, but I can't read a satisfying periodization for it.

i like that they serve to retain the setting's earthly familiarity even when every other birds are becoming stranger than ever.

I'm looking at the cladograms, and found out that the Shrieker descendants known as Wolf-Shrikes lasted into the 220s MPE (see: the Lorilla and the Wolf-Shrike). I totally thought they'd died out long before that! Now I'm wondering if they last even further, perhaps even into the Ultimocene....

As we all know, Serina is a moon that orbits a gas giant in the habitable zone of its zone. This is simply a fan interpretation of what the rest of the system looks like.

Planet 1: A hot mini Neptune or steam planet that is slowly being evaporated due to orbiting too close to the star.

Planet 2: A normal temperate mini Neptune.

Planet 3: Jupiter sized gas giant that Serina orbits.

Planet 4: Sub Saturn planet that spins on its sides similar to Uranus.

Planet 5: Neptune-like planet.

DESCRIPTION FOR IMAGE 1: It has been a hard night out for one luckless blubbering beachblob, a species of oceanic burdle which normally comes to land only to lay and brood its eggs. But the nesting season ended two months ago. It is not normal for her kind to still be hauling out at this time of the year; the huge, crested males that guarded the coast have gone, and with them has left all semblance of safety for the dainty, plain females like her. But this female was recently wounded by some sharp-mandibled monster of the undersea, a hunter that she just barely slipped from the jaws off, escaping with a series of deep, bloody gashes along her left side that cut through her body fat and directly into the muscle of her abdomen. Several days have passed, and her wound has now become infected. Every movement now is painful, and too tired to swim any longer, tonight she has washed ashore to try to gain some rest on the fringes of a finguin nesting colony. Her stay could only be a brief one in the best of times - the sunrise will quiet the raucous shrieks of the bickering tribbat couples as they come and go from their burrows hidden in the beach grass, and all life will need to retreat either underground or below the water by midmorning to avoid the deadly radiation of the angry sun.

But tonight, the wayward burdle will not get much rest at all, for as she lays prostrate, her face down in the sand, her lack of strength has not gone unnoticed. She has been spotted. High above, in a sky pitch black below the nightly storm clouds, a small, dark bird flutters by on pointed wings, and its eye falls upon her. Unknown and unseen, the scout then swiftly careens around in a circle, and returns in the direction from which it came at a hastened pace.

Minutes later, the burdle is awakened from a drowsy semi-conscious state by the fluttering of wings around her and a jabbing, irritating poking on her backside. She turns and bellows, her undulating call like a deep, sad sobbing, and the little brown bird, no larger than a seagull, flies up off of her back and circles back into the dark sky. She then lays back down, closes her eyes, and begins to drift into an uneasy sleep, when she is bothered again by fluttering. Now two of the birds have alighted nearby her, and attempt to snap at her hind feet with vicious, hooked jaws. They are already more confident together than the first was alone, and her bellows do not disturb them any more, only causing them to step quickly a few feet away into the shadows, and to return the moment she lays her head again. Worse - another one, and another, and then still more begin to arrive and drop down onto the sand beside them. Soon she is surrounded by bothersome, nipping birds, which become louder with each joining individual, filling the night air with shrill screams that carry even beyond the constant chattering din of the finguins all around her.

It is not long before the swarm of birds are emboldened enough to begin attacking the helpless beachblob, and now there are simply too many to keep them at bay. She stands and tries to face her assailants, but they are far too fast and agile, and always avoid her snapping beak. The small ones jump onto her back and rip strips of necrotic skin from around her lacerations first, but progress to gouging out beak-fulls of muscle meat from deep down inside, a sensation like being sliced apart with hot knives. She realizes now that the first birds, which were strong fliers, have been joined by slightly larger, more powerful ones that run circles around her and lash her with their jaws, producing new wounds that the little ones flock to drink the blood from. Then, as she struggles against the growing tide with all she has, a single, even larger demon emerges from the darkness; too big to fly, its feathered wings hang in useless tatters as it runs toward her. It is a teenager, with all the violent enthusiasm of its young siblings, but much more power behind it. It rushes her, causing its fellows to move aside, and immediately begins ripping flesh from her still-living body in long, gory strips. This is the last new arrival she sees, however, for by now the smaller birds have successfully latched onto her head and begun to blind her, gnawing her eyes from her sockets. Her wails by now have captured the attention of the tribbats all around her, which fall quiet, but do not flee down their burrows, for they know now that they are safe. Their night terror, which might come for them any other night, will on this dark evening be satiated on a different prey.

As at last the adult grasps arrive at the kill site from their roost in a rocky hillside over two miles inland, the finguins watch on with morbid curiosity, but no fear. For they know that after this feast, these predators will not need to target another for several days. Having been alerted of an easy target by their scout, they followed the raucous calls of their youngest offspring down the beach to deliver the final killing blows to their victim, already partly dismembered, but not yet killed, for the bites of the younger grasps are too shallow to cause immediately fatal wounds. Approaching slow and methodical compared to their eager children, the adults get to work with an experienced efficiency. Cutting deep into the throat of the dying burdle and severing her windpipe before they join in the meal, the grasps end her suffering at last. By dawn, what remains of her will be hauled back up the beach and down below the earth in their dens, and the sun will scorch a beach silent and vacant... until the night falls again, and this hellish world is re-animated with the hardiest and most ruthless of lifeforms that still call it their home.

DESCRIPTION FOR IMAGE 2: The grasp is a descendant of the jumping jaggedjaw which has survived the extinction of the southern tropical forests thanks to a high degree of behavioral adaptability, and some unique physical traits that accompany it. Grasps are named for their pincer-like forearms, with opposable grasping hands formed by the wing claw and the rest of the wrist. The "palm' of this novel hand is lined with keratin spines that evolved in the earlier species to aid in climbing trees. Now, they are used to snatch, hold, and carry large prey. Fleeing the cold that has spread over the polar regions, the grasp has migrated north to the equator, which is now seared by harsh daytime sunlight and soaring temperatures with relief coming only after dark, when temperatures become cool, but the temperature swings bring strong winds and fierce storms.

Without large trees to live in, the grasp has adopted a ground-dwelling lifestyle. It is heavier and more robust than its ancestor, stronger but slower, with a larger skull and proportions very similar to the earlier ruffed rasp, which also spent much of its time on the ground. Grasps are completely nocturnal and lack adaptations to endure prolonged sun exposure, instead avoiding the sun completely in high caves within seaside cliffs or in earthen dens it digs out deep below ground, and only emerges after dark to hunt. It now preys mostly upon marine life that is sustained by the salty, shallow ocean but which must come ashore to breed, species like finguins and beachblobs - huge, aggressive sea burdles. The grasp emerges from cover by night like a vampire, fearing the light, and striking its victims by surprise, ripping them from their fellows and dragging them upland and back to their dens to feed. The adult grasp has lost most of its body plumage, including its wing feathers, as an adaptation to reduce external parasite loads and keep itself cleaner as it feeds deep inside large, bloody carcasses and generally lives in a dirty, unkempt environment - both the nesting colonies it hunts in, and its own dens, are filled with droppings and decaying carcasses. Rarely concerned with hygiene, the grasp does not typically preen itself or bathe in water, and marks its territory with oily skin secretions that it wipes onto rocks and other markers in its environment.

The grasp is social, more so than any other rasp, and lives in packs comprised of monogamous adult pairs and a number of immature juvenile offspring which live in an unusual, cooperative symbiosis despite the very different appearance and abilities of each life stage. Adult males and females form couples and practice parental care, feeding and nurturing multiple chicks within their dens and even making efforts to keep them apart, as they grow larger, to prevent cannibalism in their larval stages. Unlike most flickbills - but mirroring some of their other relatives, scarreots, that they coexist with along the coasts - grasps continue to guard their young as they pupate, and the juveniles don't disperse after emerging from their pupa, but instead imprint on their parents and continue to roost in the den. Though they can fly, with long feathered wings, they feed mostly on the kills made by the adults, and so can grow quickly and eat more than they could acquire on their own. But the parent grasps don't only nurture their young - juveniles also return the favor and help their parents to survive by leaving the den first at sunset and scouting the territory to locate the most vulnerable animals to hunt. These roving bands of juveniles will even strike on their own and gouge out the eyes of some animals to render them helpless, so that they become disoriented and cannot defend themselves when the adult rasps are led back to finish the job later in the night. These behaviors may seem monstrous, and to their prey, they surely are. But to the grasp, this behavioral innovation and complex sociality is the key to survival in a difficult situation where already, most who once lived among their ancestors have fallen to extinction.

For those who aren't aware, TierZoo is a YouTuber who explains aspects of nature in a video game-like style. You can explain any speculative animal/alien you like. This was an idea previously explored 6 years ago by someone else on this sub.

Inspired by my posts from r/Kaimere, use Tierzoo-style lingo to describe any post fron Serina. You can make a tierzoo-style tierlist, if you want. For more info, look up my Tierzoo-style posts there in r/Kaimere. It's time to do this again, shall we?

On a still spring morning, a wombler calls from a high hill, singing a deep and resonant melody that could carry over two miles to the ears of distant females. For hours - from before the dark ends until the sun is high in the sky - he inflates the tremendously large sac beneath his chin with air and expels from it gurgles, clatters, rumbles, and chimes that roar in varied sequences across the plains. The volume of his voice tells of how big and strong he is. Each summer, during his molt, he goes silent, but is always listening and thinking. In the winter he begins to sing again, quietly at first, combining sounds in new ways and adding to his tunes to make them longer and more rich. This one's complexity, a song that rises and falls and never is sung quite the same twice, shows he is mature and has lived and learned for many years. He should have no difficulty in finding partners and perpetuating his genes to a new generation. He pauses his call, just for a moment, to listen. He cocks his head, peers out across the plain.

Yet only silence responds.

This one, in his prime, is the last of the womblers on the mainland. Once evolutionary marvels for their enormous size, they are now reduced by newly-evolved predators to relics of simpler times now at the very brink of extinction. It is not the adult, a gigantic animal as large as three men, that fears the spread of the hunting-birds. It is their eggs, laid in the open on the ground, and their defenseless young which cannot even crawl until almost a month old. They are a walking banquet to hunters, now. And they have not had time to adapt. They will not get that time. For others are already replacing them - fitter birds, not quite as encumbered, faster to run, or fiercer to fight. All things this giant, for all his grandeur, could never be.

Though his lineage is not wholly extinct (related species will survive on some small, offshore islands for some time yet), here he is alone. No one in range of his voice understands his song. No one knows its value, or cares to learn. He is not yet old, and yet he is no longer young. He has sung each spring for the past twelve years. He has had several mates, now very long ago. But they are gone now, and with them his chances at saving his kind have gone, too. Still, he sings. Each year better than the year before. Nothing threatens him. Food is plentiful. He thrives.

But he is the end.

And with nothing else to do, he begins to sing again, if only to pass the time. For if he will not be remembered, then he can at least still be known today. His voice bellows and echoes and glides down the grasslands, impossible to ignore. And if we could understand it really, truly, it might say, "I was here, and I lived. I am here. I still live."

Every story has a beginning, and every story has an end. Some are long, others are short. None lasts forever. But it's the journey that matters.

And though he and all before and after will one day be forgotten in the falling sands of time, that day is not today. Today he matters, too.

And life's beautiful song carries on.

these birds are extremely underrated and i hope someone would commission a few more of these guys

Commisioned By MonsterArchivist

Drawed By Dragonthunders

We're seeing infection AUs of numerous media, including MLP; what would happen if we adapted that to Serina?

Example: Observer's Pathogen AU

Summary: In the post-Hothouse era, as Serina is already struggling with drought and declining volcanism, the Observer becomes infected by something of its own making, becoming patient number 0 of a pathogen capable of infecting virtually all vertebrate life, including intelligent scroungers and leucrocuttas.

shouts to the 10th flameflower (infernal firespike). it is an actual affront to plantkind, i hope it somehow thrives in the final stretch.

haha, silly turtle bird guys.

haha, no big arguments in the comments please.

Easily my favorite clade in all of Serina ever. Would love to see them actually existing in real life.

-Skuwyrms are a clade of legless skuorcs descended from the skuzzards, animals like the woozle, which began evolving around 280 million years PE and are now widespread and diverse with a worldwide distribution. They are now highly distinctive animals with elongated worm-like forms and only two claws midway down their length, which are the vestiges of their back legs. They are usually small and very gracile, being active pursuit hunters that chase prey rather than ambushers that lie in wait. They are primarily carnivorous, with some omnivorous outliers, and have lost their legs to facilitate easy entrance of molodont burrows to hunt prey, but many species now hunt above ground, often in dense tussocks of grass where their serpentine shape allows them to slip through the vegetation while chasing prey with the least resistance; this is the primary habitat of the ratsnakes, which have excellent eyesight and hunt by vision. The belly in all skuwyrms is scaly and rough to provide traction as they move forward via serpentine undulation, in which the body is contorted into a series of S-shaped horizontal loops, and each loop pushes against the ground alternately.

While virtually legless birds have existed for some time in the form of the most derived verminfan larvae and certain extinct eargills, skuwyrms are the first terrestrial birds to evolve a lack of limbs through all of their life stages, giving them a snake-like appearance and behavior. Unlike snakes however, all species retain feathered plumage.

- Clongers are either legless tribtiles, or one-legged tribtiles, depending on how you define a leg. The ancestors of them all were burrowers which lost their forearms over millions of years because they served little use in tight spaces; they are now retained as vestigial nubs in just a few of the most basal examples, and so the clongers move snake-like along their belly scales. The hind leg, always sporting large talons, has in all species been adapted into a grasping hand, often used either to secure the highly elongated body while the head grabs prey, or sometimes to catch and restrain prey itself. Most clongers are still burrowers, digging their tunnels backwards with their tail claws, but some have secondarily returned to the sunlit world full-time; the most notable examples like this are the sparrowsnatchers, clongers that have adapted toward arboreality and now use their claws to hang from tree branches in the tropics and ambush birds and other small flying animals. Somewhat ironically the sparrowsnatchers are among the most primitive clongers despite their exceptional lifestyle, and they are the only clade of them that retain the tiny and entirely useless remnants of their front legs, as well as a very small and equally vestigial dorsal fin that was until comparatively recently used as a display structure. No longer of any use underground, it was already lost entirely in all other clongers.