In a world were neornithes dominate over the terrestrial/semi-aquatic avian niches, it is surprising how an externally similar group of birds managed to carve an ecological space for themselves. Yet, while Gondwanaviformes resemble fowl, they are as different from them as a flying humbug is from an afrohea - these are opposite birds, Enantiornithes.
Gondwanaviformes seem to be closely related to the Late Cretaceous Enantiornis, a big enantiornithe from Argentina. This pretty much reflects the gondwannan ancestry of this clade: the earliest recognisable fossils of a member of this clade are known from the earlimost Paleocene of Patagonia, and for the best part of the Eocene most fossils occur in South America and Africa. However, while perhaps conservative in terms of external appearence, they changed a lot in dietary habits, which in turn led to interesting internal adaptations.
Gondwanaviformes are herbivorous. Therefore, like the aoteroan megaducks and HE's hoatzins, they evolved proportionally huge guts, which make their body more round in shape. The feet are (as usual among birds) anisodactyl, with the first toe opposing the other three to provide a strong grip used by these animals when climbing.
Like all ornithothoraces, their third digit is small and "glued" to the second, and all species have large wing claws on both the thumb and the second digit, used for climbing. Like the probably closely related twitiaviformes, Gondwanaviformes are poisonous; chicks produce a noxious skin irritant, while the adults of some species deliver lethal, pain delivering ichor. While tweety poison glands are simply modified preening glands, Gondwanaviformes also have poison glands in the hands, usually next to the claws.
Currently the number of gondwanaviformes species is uncertain. At least 17 known species are recognised, and the number might increase in the near future.
The HE birds that pseudophasianids resemble most are hoatzins: like them, they are tree dwelling birds that feed on leaves, specialising in the rarely contested niche of the arboreal browser. But unlike hoatzins, they enjoy a much wider distribuition: there are species spread across the tropics, from the mangroves of the Caribbean to the cloud forests of Papua New Guinea. The secret behind their success probably lies in the enantiornithe life cycle – like most opposite-birds, the chicks of the skitkins and ballbirds are highly precocial, and as such they are totally independent as soon as they hatch from their eggs. In fact, much like HE’s own megapodes, as well as several other Spec birds, some can even fly in the same day as they are born. Adults are fairly weak flyers, sometimes even outrightly flightless, but the chicks, while not very agile in the air, are quite resistent, and can in fact fly for hours, spreading the natural ranges of these birds well into the oceanic islands of the three major oceans.
Known as ballbirds, these pseudophasianids are mostly known from the Americas, and seemingly diverged from other gondwanavids quite early in the Cenozoic. Of all pseudophasianids, they are the ones that most live up to the hoatzin comparision, being mostly riverine forest dwellers. Four species so far have been recognised.
Magestic Ballbird (Pseudophasianus opisthocomus)
Spec’s answer to HE’s hoatzin, this ballbird’s range extends across the amazonian wet forests, from inland swamps to coastoal mangroves. Externally it strongly resembles its HE analogue, except the generic opposite-bird differences like the lack of tail feathers. In the mating season males produce a loud KALINKWA!!! call across the forest, across day and night. Disharmonic events are usually avoided, but if inevitable fights are quite impressive, frequently resulting in the death of a weaker combatant. Females, slightly smaller than males, and less “regal”, without the eye patches and with dark body plumage, are responsible for the incubation of the eggs, usually on a broad nest platform. Chicks leave after a few days, feeding first on insects, before switching to a fully herbivorous diet in the span of an year.
Jack-Sparrow (Pseudophasianus maiaparasitica)
A smaller cousin to the Magestic Ballbird, the Jack-Sparrow is blessed with darker feathers, and red naked patches of skin in the throat and around the eyes, like a bizarro guan. It inhabits the Caribbean, and its range extends from the Bahamas to Yucatan and Trinidad, with small populations occuring in Florida, its favoured habitats being mangrove forests, being among the few animals to specialise in the salty leaves of these trees, having developed quite large salt glands to cope with this. It’s mostly noted as a nest parasite, usually targetting waterfowl nests, such as those belonging to screamers. It’s eggs specicially resemble those of their victims, white with occasional patterns. However, few waterfowl seem to mind the presence of Jack-Sparrow eggs, as the chicks leave imediately after birth.
Cloud Ballbird (Pseudophasianus katharmos)
Endemic to the south american Atlantic Forest, this ballbird has a mostly silvery plumage, and bright blue eye patches. It ranges across the forest ecosystems of its range, favouring specifically montane temperate forests, where their main competitors, the treeguanas and the pseudosauropods, are least common. Like it’s relatives, it too is a specialised browser, though it has an unique prefference for granivory. It’s favoured morsels are the seeds of the local auracaurias, ripping the cones open with their more hooked beaks. In return, some of the conifers have developed thornier cones, to little avail from the persistent birds. All ballbirds have potent poison resistance, born of an unique set of bacteria flora that specifically decomposes most plant toxins. In most species, it is passed through faeces ingestion, though Cloud Ballbirds directly feed their young for a week or so after birth, regurgitating in their mouths. Their chicks begin full blown herbivory earlier than other ballbirds, first focusing in granivory and flower consumption before moving on to leaves.
Giant Ballbird (Pseudophasianus atlantotitan)
From the forests of Ascension hails perhaps the most unique of the ballbirds. Having diverged from their closest relatives in the early Pleistocene, the ancestors of these birds found an island devoid of both predators and large herbivorous competitors. As such, evolution took it’s course, and now 1.9 m tall flightless birds roam the island, taking the place of it’s largest native browser. With shaggy brown feathers and simple yellow eye pacthes, the Giant Ballbird has little vibrancy compared to it’s smaller cousins, and it also lost the useful poison glands, now of little utility in an island with few predators. With longer legs and neck, it is an indiscriminate feeder, eating pretty much any native plant it can grab, though it is for the most part a frugivore, dispersing the seeds of the many native plants. Females, which are larger than males, gather a small harem, individual males mating with her across the year, producing a one-egg clutch, incubated by one of the males. The resulting chick is as always supreprecocial, having a longer, slender snout, almost similar to that of the long gone longiperygids, used to probe for invertebrates in the undergrowth. It’s transition to herbivory only takes place two years latter, living it’s early life as a competitor to the local flightless railtites.
Having diverged from their ballbird relatives back in the Oligocene, skitkins have diversified in the Old World, the absence of competing arboreal browsers in the tropical and subtropical canopies allowing these birds to go wild. The bulk of gondwanaviforme diversity is composed of skitkins, 11 species being known, nearly all of them quite diverse in terms of overall range. The birds known as skitkins are distinct from their ballbird cousins for their visage, compensating their lack of colourful naked skin patches for more genuinely vibrant feathers. Most importantly, they are heavier, to the point of flightlessness in the adults of some species, and they are more specialised in mastication like HE cuckoos, their beaks having unique grove-like edges to prevent the bolus from sliding off. Like all Gondwanaviformes, skitkins are poisonous, and in fact they have specialised further: skitkins have sharp spurs on their wings, to which the venom glands are attached, serving to deliver the most potent toxins among all dinosaurs.
Skitkins are recognised mostly in the genus Bovornis, though considering the diverse adaptative radiations across the Cenozoic it is perhaps more accurate to branch them further off.
West African Skitkin (Bovornis senegalensis)
The archetypical skitkin, this bird occurs in the lowlaying rainforests of the Congo. Growing to be as big as an HE Anser goose, the West African Skitin is nowhere as great a flyer, the adults being at most capable of frantic wing strokes occasionally acompanying fairly elegant and long glides, though young birds can fly for miles uninterrupted. All but waddling while moving in the canopy, assisted by their hook-like wing claws, this corpolent bird has a bright yellow head, dark brown body plumage, black feet and beak and orange wing feathers, which acquire bright green and blue eyespots in the males during the breeding season. Such a vibrant creature would likely be the target of many predators, but few creatures dare attack an adult, healthy skitkin, lest they die from a venom dosage capable of bringing down a gihugrongo. Like in most skitkins, these birds are polygamous, the male breeding with several females during the monsoons. Competitions are generally peaceful, males simply exhibiting their wing feathers, often within the company of other males. After mating, the females gather in large flocks, and bury their eggs in an apropriate location, like a large clearing, staying nearby to discourage opportunists from stealing the eggs. After several months, the young emerge, and lead an insectivorous life for several months, before gradually shifting to herbivory.
Several populations occur in offshore islands like São Tomé and Príncipe. While some do have some regional variation like decreased toxicity and slightly coluration variation, they seem largely uniform in regards to mainland birds, presumably due to constant interbreeding as juveniles from the mainland frequently end up there.
Seychelles Skitkin (Bovornis lemuriensis)
Occuring in most western Indian Ocean islands, and occasionally in East Africa proper, the Seychelles Skitkin is quite well adapted to its often ephemeral and limited habitat. The adult having a grey body with a beige underside – the distinction quite blurred in several individuals -, with a bright green head with red stripes. More terrestrial than most skitkins, it is all but flightless, with the volant, maroon-coloured juveniles travelling from island to island both frequently and very easily, almost to the point that individual island populations are not very distinct genetically. Adult birds make the most of their insular environment, foraging both on the ground and on the canopy, often storing reserves for the hardships of the dry season. The potency of it’s poison varies within individuals, with birds subjected to more stress having more potent venom, thus resulting in a quite flexible level of toxicity, corresponding to the amount of insular predators.
Humaya (Bovornis hierovolans)
This quite large bird occurs in open scrub and temperate forest environments in western Asia, from the Turkey Peninsula to India. It is a better flyer as an adult than it’s relatives, having larger wings to soar across open fields, a necessity for an arboreal browser in such an environment. With a long, crabing neck, this bird spends most of it’s time feeding, picking even the smallest leaves in the midst of thorny trees like acacias. It is also an important seed disperser in these dry forest flora, eating just about any fruit it comes across. It has a mostly white body with dark wings, younger birds being mostly brown-grey in colour. Both parents incubate the eggs like megapodes, tending to a large pile of leaves until the supreprecocial young leave.
Eupelagornithids seemingly diverged from other avisaurs back in the Cretaceous, their ancestor being a critter like †*Halimornis*. Across the Cenozoic, these birds were quite diverse, ranging from pole to pole and producing both flightless marine forms and giants with wingspans of over 5 meters, but competition with Ichthyornithes, pseudodontorns and tube-nosed birds seem to have beat these birds to about 6 species of tropical and subtropical soarers. Unlike other avisaurs, eupelagornithids have naked faces, allowing their long rostrums to dive in the water with minimal resistance, from the surface or from the air. Their jaws are slender and their teeth are conical, superficially resembling the maws of unenlagiines like †*Buitreraptor*, apt for grasping fish. With webbed and naked feet, most species have developed long, ribbon-like tail feathers, used in social displays as well as steering.
Ascension Jarilo (Kirke falco)
Wrongly named, the Ascension Jarilo occurs over the tropical and subtropical seas of the entirity of the Atlantic Ocean. A bird with a 1.2 meter wingspan, the Ascension Jarilo is distinguishable from it’s close relatives by it’s black wings, the rest of the body plumage being otherwise white. Spending most of it’s life in the open ocean, jarilos are more solitary than other seabirds, rarely forming large feeding groups. They hunt primarily from the surface, using mostly their long jaws to capture prey but occasionally also diving underwater, up to depths of 10 meters. The Ascension Jarilo’s diet is composed mostly of cephalopods and crustaceans, being one of the least piscivorous species in the tropical Atlantic, though it will not refuse fish or even smaller seabirds and pterosaur flaplings if they’re availiable. On rare occasions, they may also steal prey from other seabirds, overwhelming them and pressing the crop with it’s toothed jaws.
Every two years, Ascension Jarilos gather in large flocks around remote islands. Birds of both genders display in their air, their red, ribbon-like tail feathers being especially long, twice the size of their wingspan. After mating, females lay bury their eggs on beach sand, usually on places further from the sea. These eggs are especially large by opposite-bird standards, sometimes up to more than one quarter of the female’s body. They hatch in a span of four months, the chicks running to the sea almost imediately, before they can even fly.
Fustabird (Kirke magnificens)
The largest of the Jarilos is a black coloured bird with a 3 meter wingspan that soars over most of the tropical ocean line of the globe. Fustabirds are almost exclusively aerial hunters, even having redeveloped hindwings, catching most of their prey from the air and even resting while gliding. It is more raptorial than it’s relatives, often eating other jarilos in addition to other oceanic flyers, but most of it’s diet is composed of surface dwelling fish. Hunting from the air requires a lot of agility and stealth, circling the prey and ensuring it is caught with a quick snout-dip, making Fustabirds cunning calculators. Their excelling soaring abilities also ensure they reach feeding events faster than other seabirds, and rare are the schools of fish drawn to the surface by mosarks that don’t have at least one Fustabird taking advantage of the situation long in a matter of minutes.
Like other Jarilos, Fustabirds also select islands to breed on, though they frequently “nest” in less remote locations. During the breeding season, males exhibit a fan of bright tail feathers, still ribbon like but wider than in their relatives. Unlike other jarilos, females lack these tail feathers, and as such the breeding behaviour is lek based. In spite of the aberrant traits of this species, it is nested well within the jarilos, having diverged from them in the mid-Pleistocene, appearently in response to the extinct of the highly similar †Netjerornis.
Ebergs can be found on almost every body of freshwater in Spec that isn’t too small. Even though only some 5 or 6 species of these foot-propelled diving birds exist, most species have very wide distributions, for example two species range all over the Old World, Madagascar and Australia, with one of them extending to Aotearoa as well.
Like snakeneck-birds (and the grebes of HE), ebergs have long toes with lobes that work as a webbing during the backstroke but let water pass through during the recovery stroke. Unlike them, their teeth are restricted to the tip of the jaws; they are very useful for holding slippery fish or tadpoles, piercing crustacean armour or snail shells, or pulling freshwater clams off the mud.
The ancestry of the ebergs is shrouded in mystery. It is obvious that ebergs are opposite-birds like flankers, riffs and scowls, otherworld finches, tweety-birds and the skitkins and ballbirds; their slow growth – the largest species reach maturity at 3 years – suggests the same. Within that large group, however, things become murky. Molecular data suggest, tentatively, that the closest living relatives of the ebergs are Spec’s predatory birds, which would mean that the fossil history of ebergs reaches back into the Early Cretaceous. (Currently the oldest known eberg comes from the Eocene site of Messel.) Consequently, there are reasonably plausible attempts in the literature to tie the ebergs to either †Yungavolucris, a Late Cretaceous foot bone (tarsometatarsus) from Argentina that looks much like that of an eberg, or to †Longirostravis, an Early Cretaceous shorebird from China, which sports teeth only at the tip of its beak like an eberg, or to both. But due to the paucity of known fossils, the low signal/noise ratio of the few molecular data that have been compared so far, and of course the absence of molecular data from fossils like †Yungavolucris and †Longirostravis, most workers prefer to withhold judgement.
Hooded eberg (Enantibaptus cucullatus)
The Hooded Eberg is among the largest (adult length being about half a meter) and most common eberg species, and the most widely distributed one, occurring on all vaguely continental landmasses sans most of North America, Australia and southern Africa. It can easily be recognised by its long, narrow black “beak”, the distinctive feather “hood” of adults, white dots on the back, and an range underside. Males develop weird keratin protusions on the jaws, sometimes only for the mating season, sometimes year-round. Hatching in a drifting nest with 10 or more eggs, the tiny hatchlings jump into the water almost immediately and begin hunting for water insects. As they grow over four years, their diet gradually shifts over crustaceans, small snails and tadpoles to freshwater clams, frogs and fish.
Collared Eberg (Enantibaptus americanus)
A close relative of the Hooded Eberg, this american species is about the same size, but has a very distinct colouration, with a black head and wings and a mostly white torso sans for black dorsal stripes, as well as a black and white “colar” in it’s neck. Collared Ebergs are migratory, breeding as far north as Bear Lake and migrating to warm shorelines in the winter, as far south as Trinidad. A population of these birds also exists on the Azores, frequently supplied by north american birds blown by the Gulf currents into the islands.
Black-Necked Eberg (Podicipoides nigricollis)
Occuring through most of the Old World, Madagascar and Australia, the Black Necked-Eberg is the main member of the genus Podicipoides. It specialised in feeding on clams and freshwater crustaceans, having a shorter, deeper “beak” than other ebergs with teeth distributed along instead of being restricted to the jaw tips. These teeth are broader and shorter, perfectly adapted to smash hard shells. Occuring frequently in the vicinity of other species, adults rarely compete with their relatives, but the young feed on the same prey. To avoid competition, Black-Necked Eberg chicks specialise mostly on aquatic insects and crustaceans: like the adults, their teeth line the whole of the jaw, but they are long and slender, used basically in rudimentary filter feeding.