Powered flight is a very ambitious capability for any animal clade to evolve towards. In order to fly, an animal not only has to be aerodynamic and capable of catching the wind, but also has to fight against the forces of gravity in order to stay aloft as long and efficiently as possible. Despite this, powered flight has evolved independently at least four times on Earth, so it seems like flight is almost a guarantee if the conditions are correct. With roughly 99% of Earth's gravity and an atmosphere of nearly identical density and composition, Athyrmagaia has also managed to develop its own menagerie of independently evolved flight-capable animals.
A very notable clade of volant creatures are the Pachyalatans ("thick fliers"), a class of flight-capable, warm-blooded Heteropods that are found on all parts of the planet. The Pachyalatans are the planet's closest analogues to birds, and have evolved to occupy a similar range of ecological niches in a world that is otherwise dominated by Athyrmatherians. They even resemble their Earthen counterparts in many ways, making them very far removed from the marine radially symmetrical lineage their earliest pisciphysan ancestors evolved from. Like all Heteropods, they possess four lungs, four vertebral columns, and an inverted upper jaw that opens upward, with the nostrils located on the sides of an immobile lower jaw and a specialized pair of front nostrils called a nasorium at the chin. Additionally, both male and female Pachyalatans possess a "genital tail", a specialized secondary tail used for reproduction as either a penis or an ovipositor. Their bodies are covered in fur and feather-like integumentary structures called pectinofibers, which are used for thermoregulation as well as aerodynamics. Their jaws, while inverted, are often beaked with an outer sheathe made of keratin. Their wings are composed of membranes of muscular, reinforced skin, which are supported by a thick, bony wingtip of heavily fused digits (hence the clade's systematic name). When on the ground, they walk quadrupedally by bearing their weight on their splayed-out hind limbs and the thumbs of their wings. For efficient and maintained flight, their four lungs contain unique channels and pockets that allow for a unidirectional air flow while breathing. Unlike either pterosaurs or birds, however, their bones are relatively dense and lack hollow spaces, which limits their maximum size and flight altitude. Despite this, their additional body weight does prove to be beneficial in flight, using inertia to make sharp turns and quick aerial maneuvers.
The Pachyalatans have enjoyed a quite lengthy and prosperous existence, having first evolved roughly 315 MYA back when megafaunal Heteropods still dominated Borea and Comedia. Even after the Borea-Comedian mass extinction 230 MYA, the Pachyalatans have managed to reclaim their former niches, though it is uncertain if the modern Borea-Comedian Pachyalatan clade is descended from extinction event survivors or colonists from Austrus. Though they continue to be quite prevalent in the Borea-Comedian skies, they, like their terrestrial Saurophysan cousins, are facing a degree of competition from Athyrmatherian copycats. About 70 MYA, the Polypterans, a class of flight capable Euathyrmatherians, had entered the evolutionary scene, and at some point in more recent prehistory they managed to outcompete the Pachyalatans in the "bird of prey" niche thanks to their lighter bone structures allowing for larger body sizes. Considering the extremely malleable nature of the Athyrmatherian anatomy, it's entirely possible that one day these creatures may eventually replace the Pachyalatans as the dominant aerial fauna. For the time being however, the Polypterans have been unable to expand beyond the niches of aerial hypercarnivores, so the Pachyalatans have managed to endure the trials of natural selection. A very good sample of the diversity of Pachyalatans can be glimpsed in the grasslands and steppes of Borea, the largest continent on the planet.
Yellow-chested seeder (Passermimus crocogastrus) - The yellow-chested seeder is a small, roughly pigeon-sized diurnal Passermimid ("passerine mimic"). Passermimids belong to a larger order of Pachyalatans called the Passercnemiformes ("passerine legs"), which are the planet's rough equivalent to perching birds. Named after the bold, yellow coloration of its chest, neck and abdomen, the yellow-chested seeder almost resembles a songbird when in flight, but once it lands on the ground it exhibits a quadrupedal, bat-like gait. The way it "perches" on branches is oddly bat-like as well, as it hangs upside-down with its reversed hind feet. Though it belongs to a clade of mostly tree-dwelling fliers, the yellow-chested seeder has adapted to its vast, open grassland environment by becoming a generalist ground forager, its diet being comprised largely of the dropped seeds of star grasses as well as small ground invertebrates such as Stegospondyls.
The yellow-chested seeder is represented by three genetically isolated regional subspecies. The eastern yellow-chested seeder lives in the steppes of Borea's far east, which intersect both the eastern and western hemispheres of Athyrmagaia. The two other subspecies, the greater and lesser yellow-chested seeders, lives in the two larger steppes at Borea's west, the fomer having a larger yellow chest marking than the latter.
While largely solitary, the yellow-chested seeder mates for life in monogamous pairs, and have strong parental instincts. It is also migratory, traveling to the dry shrublands of southern Comedia during the winter seasons. It breeds during mid spring, and females lay a total of four to five eggs. Like a majority of Passermimids, it prefers to nest above ground in the branches of tree-like Olekirkophytes, and its young, which are initially blind and naked, grow to maturity at a fast rate. As adolescents, they typically learn how to fly by the time summer ends.
Rainbow wangrouse (Galliphallus chromacalvus) - The rainbow wangrouse is a large, diurnal Phalliphasianid ("penis pheasant"), a family of medium to large-sized Pachyalatans that occupy a game fowl-like niche in the western steppes. The Phalliphasianids are representative of a much more basal group of modern Borea-Comedian Pachyalatans, and are presumed to be the closest living relatives of the prehistoric Pachyalatans that outlived the Borea-Comedia Mass Extinction Event. Though it is still capable of flight, the rainbow wangrouse is primarily a ground-dwelling creature that both forages and nests on solid ground. As a direct result of a more terrestrial existence, it is also a comparatively poor flier, and usually only flies in short, low-altitude bursts in order to evade predators. Most Phalliphasianids tend to be omnivores that feed on a combination of fruit, small herpetofauna and invertebrates. In the absence of fruit bearing plants in its native range, however, the rainbow wangrouse has become a generalist mesocarnivore, with its preferred prey being cold-blooded herpetofauna such as small Saurophysans and ophidimorph Tagmatasaurians. If available, it will also feed on fresh carrion. It is especially well-adapted for feeding on ophidimorphs, as they have evolved a high tolerance to their stinging, electrically charged bites. Bodies of water are relatively sparse in its range, so it gains a large bulk of its hydration from the food it eats.
The rainbow wangrouse is a very sexually dimorphic animal, and males are significantly larger and more colorful than females. Aside from his bald, brightly colored face with garish wattles and combs, the most distinctive feature of the male rainbow wangrouse is his hypertrophied genital tail, which is tipped with a brightly colored, star-shaped fringe of retractable hydrostatic soft tissue that enlarges when pumped full of blood. Male wangrouses are typically solitary and highly territorial creatures, but during the breeding season of early spring, they will gather in large groups called leks to attract mates, displaying to females by wobbling their facial growths and waving their engorged genital fringes. Males with the largest and most colorful wattles and genital fringes are favored most by females, as the brighter and larger display features are apparently indicative of a healthier and more worthy mate. Unlike the yellow-chested seeder, the rainbow wangrouse does not mate for life, and males prefer to mate with as many females as possible rather than invest in a lifelong commitment to a single mate. Despite this, female rainbow wangrouses are dedicated and loving parents, and though their offspring are born with fully developed eyes and learn to walk within mere minutes, the mother diligently protects and raises her young until they are ready to live entirely on their own.
With underdeveloped flight capabilities limiting their ability to travel, rainbow wangrouses do not fly south during the winter. To make things more difficult, the herpetofauna that the wangrouse preys on sleep off the winter by going into torpor underground, which means it is unable to hunt as soon as the cold sets in. To survive the winter, the rainbow wangrouse experiences a radical shift in diet, preying on endothermic Monotherians that remain active even during the midst of the cold season. It even has a winter season coat, which is greyer in color, and its skin changes from brightly colored hues to a purplish black, with the wattles receding in size. Their genital tail, which is prone to frostbite, is held flush against the chest and abdomen, kept warm by the animal's own body heat.
Oxfeeding skeet (Culicirhynchus orlok) - The oxfeeding skeet is a small, nocturnal Proboscirhynid ("proboscis nose") that lives in the western Borean steppes. It is a member of a superfamily of Passercnemiformes that are highly specialized for a diet comprised of liquids. Proboscirhynids have evolved to feed by using a modified nasorium as a proboscis, to the point that it has basically become a secondarily evolved mouth that has entirely replaced the function of the true mouth. As a result of this, their actual mouths are almost entirely vestigial save for a small claw-like upper jaw, leaving the nasorium as the sole inlet for the buccal cavity. They retain both of their tongues, which are elongated and capable of darting in and out of the nasorium. Most Proboscirhynids are nectarivores or frugivores that live in forests and jungles, drinking nectar or injecting digestive enzymes into fruit to drink the liquid soup. Others, however, are predators, using their proboscis to skewer prey and inject them with a corrosive venom.
The oxfeeding skeet is a unique outlier among it's needle-nosed brethren. It possesses the same straw-like proboscis as its cousins, but it is far too large in size for the rather small flowers of the plants that live in its native steppe, and none of them bear edible fruit either. As a result of this apparent scarcity of palatable plant-based food, it has developed a very literal taste for blood. Much like the vampire bats of Latin America, members of the genus Culicirhynchus ("mosquito beak") are ectoparasitic hematophages, and feed exlusively on the blood of large, sleeping endotherms. True to its name, the oxfeeding skeet's preferred source of blood are large-bodies Fauxungulates such as the mock ox. The creature feeds at night while its target is asleep, and using specialized heat receptors at the base of its upper mandible, seeks parts of it's target's body where the blood vessels are closest to the surface such as the zooid connection surfaces. It then uses its blade-like tongues to bore into the soft tissues. Its saliva contains a numbing agent, so as it drinks up its fill of blood, its sleeping prey doesn't even notice. As soon as its done feeding, the skeet rests and allows itself to digest its meal before flying back home. During the day, the oxfeeding skeet nests underground, digging burrows using the thick claws of their hind legs. Like many Passercnemiforms, it is a K-strategist that cares for its eggs and young.
Though the skeet's feedings do not usually have long term adverse effects on their victims, this isn't always the case. When an oxfeeding skeet drinks the blood of large herbivores, it may also contract bloodborne pathogens in the prey animal's blood, which results in the skeet becoming an asymptomatic carrier that unwittingly spreads the disease to its other victims via its saliva. Additionally, at least 10% oxfeeders carry Vermibovis hematolateus ("blood-lurking cow-worm") a genetically chimeric endoparasitic Tumeofauna that has evolved to utilize the oxfeeding skeet as a means of spreading. This vicious parasite targets adult individuals of the mock ox species (of which it shares some of its DNA with), and spends its oocyte stage in the salivary glands of the oxfeeding skeet. When the skeet feeds, the Vermibovis oocyte germinates within the blood stream, and starts to steal mitochondrial DNA from neighboring tissues. By combining its own DNA with that of the host through meiosis, it then starts to self-replicate and spread mitochondrial hybrid offspring, which fuse with the host's tissues in the form of malignant tumors that spread through the blood stream, eventually killing the host by invading vital organs. The parasite remains alive for about 30 hours after the host's death, extending fruiting bodies through the tumors on the outside, and by giving off large amounts of heat with muscular vibrations, it coaxes the oxfeeding skeet to drink the infected blood of its fruiting bodies. If the oocyte manages to survive its journey from the stomach to the salivary glands, the reproductive cycle will continue anew.
Unlike a lot of other northern hemisphere Passercnemiformes, the oxfeeding skeet does not have a set breeding season, mating whenever it is ready to do so and if current circumstances allow. It also does not migrate; to survive winter, it goes into a state of torpor within its burrow, surviving off of fat reserves it has accumulated from its feedings. If a female is pregnant while in torpor, she is able to essentially halt the development of the eggs entirely, with the egg formation process resuming as soon as she wakes up in early spring.
Black wormtweezer (Vermivenator melanopterus) - The black wormtweezer is a crepuscular species of ground-foraging Locustarhynchid ("lobster beak") that is slightly smaller than the yellow-chested seeder. Apparently closely related to Proboscirhynchids, the black wormtweezer is part of a comparatively small family that exhibits a cranial anatomy intermediate between that of standard Passercnemiforms and more derived Proboscirhyncids. It is a proficient ground forager that lives in the northernmost areas of the steppes that border Borea's vast temperate forests, hunting invertebrates that dwell in the moister alluvials of this particular area. Its beak is long, thin and pincer-like, with a reduced yet still fully functional mouth at the very back of its jaws. Its tongues, which are elongated and tipped with dense taste receptors, are housed within the passages of the nasorium rather than the mouth proper. The black wormtweezer hunts its wormlike prey by inserting its beak into the ground, using it to detect vibrations while darting the tips of its muscular tongues in and out of its nasorium to find any edible organisms. As soon as it detects the taste or movement of an edible morsel, it quickly displaces the dirt with it's upper mandible to expose the organisms, quickly downing its food with quick snaps of its jaws. To ensure greater success in finding prey, it is most active during the mornings and afternoons, when the lower amounts of sunlight the moist, vulnerable "worms" to dwell closer to the surface.
The black wormtweezer is mainly a solitary animal, breeding during early spring. Males do not form leks, instead establishing individual courting grounds in which they will encourage a female to approach by emitting a coarse, rasping groan. The male will then try to win the female over with a courtship dance involving wing movements and delicate, metronome-like twitches of his upper mandible. The male is not in any way involved in the rearing of young, and will instead aim to copulate with as many females as he can. The female, however, remains a dedicated parent, and will look after her young until they are fully independant. Unlike many other Passercnemiforms, newborn wormtweezers are born with already opened eyes and a full coat of downy pectinofibers. Being dependant on their mother's however, they will cling onto her back and belly until they are large enough to keep up to pace with their mother on foot. During the winter, the black wormtweezer flies to the tropical rainforests of Borea's deep south, where food is plentiful year-round.
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