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VikasRao's avatar

Draconology: The Ornithodraconia


I had a ton of fun making these, and I think my burnout's gone too. About halfway through the process my computer's OS decided to die without warning, and while I managed to get it back up and running, ALL of my files were gone, and because I had neglected to back everything up, I had to start from scratch 😬

Oh well, c'est la vie!




The Ornithodraconia are the other order of the Draconia, distant relatives of the true dragons (Eudraconia) that are variously referred to as beaked dragons or bird dragons. The clades that fall under this grouping aren’t particularly closely related to each other, and have differing morphologies, leading many to often refer to each clade with a distinct common name.

These dragons possess a number of anatomical similarities to their Eudraconian cousins, such as forelimbs modified into wings, hollow bones, well-developed senses and an unusually high degree of intelligence for a reptile, which reaffirms their phylogenetic affinities, but there are many notable differences. In the wings of true dragons, digit III is the longest, forming the leading edge while digits IV & V are much shorter. In Ornithodraconians though, digit IV is the longest, while digit III is shorter and thicker, thus giving them a more rounded wing shape. Their wings are also more flexible than those of true dragons, which allows them to be folded more tightly and thus makes walking and running easier. While many true dragons can run just as fast, few can match the agility and grace of Ornithodraconians on the ground.

The bones of Ornithodraconians are highly pneumaticised with internal bony struts forming a honey-combed structure similar to those of birds and pterosaurs, unlike the cavity filled bones of the true dragons. And while both have fused wrist bones, those of the Ornithodraconians are much longer, giving their limbs distinctly ungulate-like proportions. They also have much shorter tails in general and less upright bodies.

Ornithodraconians also have unmodified, fur/down-like coelofibers which adds to their bird-like visage, but most notably, the osteoderms on their heads are fused to the skull and covered in a keratinous sheath, giving them a distinctive beak, which while at first glance may appear bird-like, is anatomically closer to a turtle’s beak, and 2 of the 4 extant clades have even lost their teeth. Another notable trait is that unlike the true dragons, Ornithodraconians have lost their ability to breathe fire.

The split between the Ornithodraconia and the Eudraconia occurred in the Middle Jurassic, around 175-170 mya, and both clades went on very separate evolutionary journeys. None of the 36 surviving Ornithodraconian species possess the ability to breathe fire, a trait which arose in the common ancestor of dragons and drakes. It is unclear as to why they would lose such a seemingly valuable trait, but considering that fire breathing among the Pyrosaurians (dragons & drakes) likely arose as the simple means of distraction seen in some drakes today rather than the devastatingly offensive weapon that the true dragons have modified it into, it’s likely that the Ornithodraconians lost it early on in their evolution as it proved bioenergetically expensive to maintain. Indeed, many Ornithodraconians have lower metabolic rates than true dragons of similar size (though they are all still endotherms). Furthermore, the earliest known ancestor of modern Ornithodraconians appears to have been semi-aquatic, which may have given it even more incentive to ditch its fire-breathing ability altogether, as it would be rendered completely useless underwater.


The Ornithodraconia today are represented by 36 species in 4 families that are grouped into 2 superfamilies, the Ornithodraconoidea and Pegasosauroidea. Among other things, the former have lost their teeth, while the latter have retained them.


The Ornithodraconoidea includes 2 extant families, the Ornithodraconidae and Gryphonidae, and at least 2 extinct ones. These dragons bear a strong resemblance to birds even though they're very distantly related, having last shared a common ancestor over 300 mya. This superficial resemblance is mainly due to 2 characteristics: thick, downy integument (coelofibers) and pointed, and sometimes curved, beaks. Apart from these however, they have little else in common, and their overall anatomy is similar to that of the true dragons (Eudraconia), but with short tails and elongated wrists.

Most species are omnivores or carnivores, and no herbivorous species are known. The Ornithodraconoidea are an ancient clade, one that first appeared in the mid Cretaceous, and underwent a burst of adaptive radiation shortly after the K-Pg extinction, evolving into a number of diverse forms adapted to exploit a variety of niches that were left vacant following the extinction of the non-avian dinosaurs and pterosaurs. Some became generalist foragers, some specialised to a particular food source, while others became top predators. Following the rise of the true dragons (Eudraconia) and advanced mammalian predators however, the diversity of Ornithodraconoids decreased considerably, and as birds began to take over some of the more specialised niches, these dragons were relegated to mesopredatory roles through most of their range.


The Ornithodraconidae are the most speciose clade of the Ornithodraconia as a whole, with 14 known species in 2 subfamilies. The species in this clade are often called cockatrices, due to their elaborate crests & wattles and overall reptilian morphology. Although they’ve lost teeth over the course of their evolution, many species, particularly the omnivorous ones, have keratinous serrations and ridges in their jaws that aid them in processing food. Most cockatrices are quite small, and while some can grow as large as cassowaries, this is quite modest by dragon standards. They differ from their gryphonid cousins in having slender, straight beaks and ornate structures in the form of crests, wattles and are oftentimes quite brightly coloured. While no Ornithodraconians can breathe fire, many cockatrices appear to have retained some vestiges of their ancestral ability. When threatened, they can spit out a mist of fatty acids (mostly acetone) along with certain other organic compounds as well as partially-digested food at their attackers.

The Common cockatrice (Ornithodraco ornatus) is the best known and most widespread member of this clade, being distributed through Western Asia, North Africa and Southern Europe. With a 3m wingspan, it is similar in size to a large eagle or vulture, but weighs much less at 4-5 kg. Highly opportunistic foragers, common cockatrices will feed on just about anything, from invertebrates to small vertebrates and occasionally even plant matter, as well as carrion. Their heads are covered in a loose skin, which covers most of their beak as well except the very tip. This species specialises in feeding on burrowing prey; using its long, flexible neck & curved beak tip to pry small prey from their burrows. A uniquely serrated and ridged tongue also allows them to feed on snails by holding the shell in their jaws and tease out the soft body of the mollusc with their tongue.

Common cockatrices mate for life, and generally live in pairs. The myth of cockatrices hatching from a chicken egg that was incubated by a toad may stem from the fact that these reptiles actually lay their eggs in burrows dug out by certain species of burrowing toads and lizards. They do not harm the burrowers in these cases, and the burrowers themselves benefit from the additional protection they receive from the cockatrice. Although normally very skittish, cockatrices defending their eggs have been known to take on even the most formidable of predators, from big cats to other dragons. Their spitting attack is known to be especially harsh and irritating, and this species has a particular penchant for aiming at an aggressor’s eyes. Despite this, they often end up as prey for the aforementioned predators, as well as eagles and large constrictor snakes.


The members of the Gryphonidae are often referred to as gryphons or griffins. Their general morphology is very similar to that of the Ornithodraconidae, but differ in enough aspects that it’s rare to confuse the 2. Gryphons have much larger beaks, and a keratinous sheath that covers much of their rostrum, and, in most species, a strongly hooked beak tip that gives them a distinctive, raptor-like head. This hooked tip is actually a keratin-covered premaxillary tooth. While all known dragon species do possess a premaxillary tooth/egg tooth as embryos and hatchlings, these are lost fairly quickly, but in gryphons, this trait is retained well into adulthood and modified to serve as a weapon. None of the 11 known gryphon species possess teeth or ridges like their Ornithodraconid cousins, but their hooked beaks have more than made up for this. Barring 2 omnivorous species, all other gryphons are obligate carnivores, feeding on just about everything from fish to carrion to medium & large game. These are medium-sized dragons, with the smallest being about the size of a large eagle to the largest rivalling some true dragons, although none are as large as the largest true dragons. The terms gryphon and hippogryph are often used when describing the larger species, but these terms hold little taxonomic weight, and the term gryphon generally refers to species that spend more time hunting from the air while hippogryph generally refers to species that spend more time hunting on the ground. All gryphons are quite agile on the ground, as with most Ornithodraconians, and some are even arboreal.

Fossil evidence suggests that gryphons were the first macropredatory dragons to evolve in the aftermath of the K-Pg extinction. They split off from their Ornithodraconid cousins roughly 60 mya in the Paleocene epoch, and took over the role of apex predators, a niche that had been left vacant since the extinction of the non-avian dinosaurs. They held this position until the end of the Eocene, when they were largely outcompeted by the Eudraconoid dragons, mammalian predators, and the Phorusrhacid terror birds (in South America). Although gryphons have disappeared from the Americas, they continue to survive on the other continents, with one species even having successfully established itself in Antarctica.

One species of gryphon that has not just managed to survive but thrived is the garuda or Asiatic gryphon (Gryphon melanops). With a wingspan of 5.5 – 6m, it isn’t the largest gryphon, but with a range extending from Western Europe through virtually all of Asia, is easily the most widespread. A gracile gryphon, it inhabits open steppe, grasslands and scrub forests, preying upon small game such as rodents, lagomorphs, small primates and young ungulates, as well as scavenging upon carrion. Because of its dietary preference, it is able to coexist with the many species of true dragons that also inhabit the continent, as these generally hunt larger game. in addition to being among the fastest running of all gryphons, garudas are also quite aerobatic fliers, which helps them evade attacks from these dragons. Although generally non-aggressive, they will not retreat easily, only giving way to the very largest or fiercest of beasts. During the breeding season however, males can become especially aggressive and ill-tempered. Garudas don’t mate for life, but like many true dragons form monogamous pairings with females for the duration of the breeding season, and males go from their regular dark brown to a striking maroon and white colouration during this time and engage in spectacular fights. These fights can be quite intense, and combatants may sometimes sustain fatal injuries. Pumped with testosterone, breeding males may even attack large dragons and anything else that may get too close.


The Pegasosauroidea includes 2 extant families, the Pegasosauridae and Pteroceratidae, which are characterised by their blunt premaxillary beaks, in contrast to the long, pointed and hooked beaks of the Ornithodraconoids. The common ancestor of both clades appeared shortly after the K-Pg extinction, and the split between the 2 clades is believed to have occurred in the late Paleocene to early Eocene. The members of the Pegasosauroidea comprise the only herbivorous dragons in the world, with virtually all living species having a number of adaptations suited to an herbivorous lifestyle, such as an especially complex digestive system and have even developed a unique form of foregut fermentation, as well as a form of mastication (chewing) via cranial kinesis. Unlike the Ornithodraconoids and the distantly related true dragons, Pegasosauroids have lost the 1st digit of their hindlimbs, and as such have pentadactyl forelimbs and tridactyl hindlimbs. An excellent fossil record shows that these odd dragons became the dominant herbivores following the K-Pg extinction. Throughout the Paleocene and Eocene, when dense forests covered the planet, these dragons browsed on the lush vegetation, exploiting a niche that few other animals had evolved to occupy. However, as the forests began to retreat and grasslands expanded, the Pegasosauroids faced a dilemma: their digestive tracts were ill-equipped to digest the tough & nutrient-poor grass, but to continue browsing on leaves and trees would've meant having to grow much larger, which would have impeded their ability to fly. Mammalian herbivores by this time had become experts at tackling grass, and as such, many Pegasosauroids became flightless, sacrificing flight for size. Soon after however, many mammals also became large, proficient browsers, and together with the appearance of the Eudraconidae and larger, deadlier mammalian predators ultimately saw the decline of these herbivorous dragons. The last surviving members of this clade are today found only in isolated regions. 

The Pegasosauridae include the largest surviving members of the Ornithodraconia. Their name comes from their resemblance to ungulate mammals, particularly horses, and like them, all 8 known species are herbivorous, although hatchlings can be omnivorous. Known by several names, but mostly referred to as pegasi and kirins, these are generally large dragons, with even the smallest species having wingspans of 6-7 m and standing taller than a human. Their jaws have a battery of small, blunt, peg-like teeth perfectly suited to grinding up tough vegetation, and at least one species is capable of digesting grass, albeit only fresh shoots. Most of these dragons only have a minimal covering of coelofibers as adults, as they live in warm climates and, rather interestingly, produce a large amount of heat through digestion. They're also quite agile on the ground, similar to griffins, and only take to the air when faced with a predator that can outrun them. This may be due to the fact that they're quite clumsy fliers in general, and as such cannot evade aerial predators, and thus are much better off on the ground.

Predators however are no problem for the largest of the Pegasosaurids, the giant kirin (Giraffadraco limuriensis). At 4m tall, it's nearly as tall as a giraffe, but weighing just 500 kg, just a quarter of the weight. Nonetheless, this does make it the heaviest dragon, so heavy in fact that it's unable to fly.

Native to Lemuria, these are the last remaining flightless Pegasosaurids, having survived due to their large size (which makes them immune to most predators) and little competition from mammals. They inhabit dry, open habitats and feed on woody shrubs and tree leaves that are too nutrient-poor to sustain similarly sized large mammals. To this end, the giant kirin has a very low metabolic rate for a dragon, and, uniquely among Pegasosauroids, is a hindgut fermenter, similar to elephants, horses and rhinos, which, although less efficient, allows it to process large quantities of low-quality food to obtain the maximum possible amount of nutrients. Juveniles however are omnivorous, supplementing their low-quality diet with invertebrates and small vertebrates as well as fruit, which helps them grow faster. Giant kirins have a very sparse coelofiber coat as adults, likely as an adaptation to the tropical climate of their habitat. Both sexes are brightly coloured, but males have a large, fleshy wattle that are probably used for display. The bright colouration is a warning; while they cannot breathe fire, giant kirins are fiercely protective of their young, and will bite, kick and stomp any animal that they feel might pose a threat. They are sociable animals, they live in small family groups, with a single male and 2-3 females and young.


The Pteroceratidae are very closely related to the Pegasosauridae, and possess many similarities, but one trait in which they differ is their elaborate ornamentation. Pteroceratids are characterised by a pair of pronged, almost antler-like crests. While many dragons (especially true dragons) possess ornate crests and horns, these are similar to rhino horns in that they are formed from compacted keratin with little to no bone underneath. The crests of pteroceratids however are unique in that they have a core of spongy bone that's covered with a thick sheath of hard keratin, making them similar to mammalian horns in this regard. Although once diverse, the pteroceratidae is today survived by just 3 living species.

Of these, the peryton (Pteroceras atlanticus) is the most widespread and common, with a range extending from easternmost North America through Atlantis and much of western and southern Europe. With a 6 m wingspan, it is similar in size to the garuda, but heavier due to its larger digestive system.

In contrast to the pegasi, which are exclusively herbivorous as adults, the peryton is a lifelong omnivore, feeding on soft vegetation as well as hunting small prey and scavenging on carrion. This species shows marked sexual dimorphism: although both sexes possess antler-like crests & prominent facial markings, males have a mane of iridescent coelofibers on their necks, and while many dragons develop bright colours during the breeding season, perytons keep their brightly coloured manes throughout the year. Male Perytons are largely solitary, but females generally travel in small groups of 3-5 along with any young. Their crests make formidable weapons, useful for both defence and, in males, combat. Perytons are known to follow flocks of vultures to a carcass, and with their large size, are often able to dominate smaller scavengers. Similar to the common cockatrice, they can spit a noxious blend of fat/oil, stomach acid and partly digested gut contents as a distraction against predators that cannot be dissuaded by their crests.

The Draconimorpha

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KyuremBlack646's avatar

Quite plausible. I have made my own "plausible" dragons myself.

Descended from noasaurs, these flying dinosaurs are fluffy, have pterosaur-like wings, supported by the 4th digit, which connects to a decent portion to the tail(This structure can be fully folded up, due to special cartilage that partially makes up the tail structure, and increases the surface area for the wing.) and leaves the legs free to do other stuff. They, interestingly, quad-launch in order to use all of their muscular power when flying. They have very large wings compared to their body, with their wingspan being about 4 times their body length. They still have long, muscular tails, but they are used to steer and as aerofoils for their wings. They cannot "breathe" fire, but they do have highly advanced infrared vision(more similar to hyperspectral scanning than other animal's infrared vision) and the ability to change their feathers,skin and scales colour and texture(Their feathers are made of a nano-structured, spongy keratin-based material. They have an amazing amount of control over the size, shape, and amount of the holes in the sponge-like structures, fixing them at very specific sizes, determining the colour that is shown, hence allowing them to change their feathers colour and extract pattern at will). They use the more standard colour change with their scales and skin. They are also bipedal, and have many airsacs in their body(25, to be precise-4 cervical, 1 clavicular, 6 cranial thoracic, 6 abdominal, and 8 caudal, as opposed to bird's 9). Also, quite intelligent, nearly human level, but not quite there. Also, love your wyverns and dragons, like the wyvern wing structure a lot.

VikasRao's avatar

Thank you 😀

That's a cool concept you've got there, and it is quite plausible, but I'm a little on the fence about the feathers themselves changing shape, since that would require a lot of muscular control, and I haven't come across any tetrapod that has muscles inside its integument... But it's your idea, so you're free to go about it as you want 😉

KyuremBlack646's avatar

I was thinking of making it's skin change texture like an octopus, and it's feathers being able to say, resemble moss by using it's preening gland(by the way, it has a preening gland, forgot to mention that) in excess to clump up it's feathers and then use it's spongy keratin based feathers to change colour. For the texture of say, wood,, perhaps it would be less of the feathers changing texture, and more of the skin changing texture and the feathers laying flat against the skin, changing colour to sell the illusion better.

VikasRao's avatar

Ah ok that's a lot more likely, but instead of the feathers changing colour, maybe it's easier if they were just translucent, so when the skin changes colour, the feathers let the colour pass through, with the spongy keratin inside being like fiber-optics to enhance the effect :)

KyuremBlack646's avatar

Yeah, I'll probably use that idea, but I'm probably still going to keep the keratin thing. Thank you!!

KyuremBlack646's avatar

Maybe. I based the spongy keratin thing off of birds(surprisingly). Link:

VikasRao's avatar

This looks interesting!

Yup of course, it's your idea after all 😉

KyuremBlack646's avatar

By the way, do your Ornithodraconians have propatagiums? Apparently, they're used to gain extra lift in certain flying tetrapods..

VikasRao's avatar

Yup, they sure do!

VicP25's avatar

These would probably make ideal species or breeds of dragons for How to Train Your Dragon.

By the way, I have my own made up scientifically accurate dragon-like creature which I simply call the mini-drake as it is small. However, it has a bird-like body, bat-like wings, digitigrade (toe-walking) gait, and a pair of tailfins derived from those of the Night Fury from the above mentioned film series. Unlike 'typical' dragons, the mini-drake does not breathe fire but can shoot a venom like a spitting cobra. This venom can cause the sensation of burning if it hits bare skin, but it can be utterly terrible if those venom jets hit the eyes. It is also covered with a coat of pterosaur-like pelt I call 'dracofibres' and they are reptiles. (:

VikasRao's avatar

That seems like a really nice concept! Especially when considering that the whole myth of a fire-breathing dragon was most likely an ancient European's unfortunate encounter with a spitting cobra.

And thank you, the HTTYD series is actually where I got the idea of dragons being a diverse group rather than a single species 😀

Roojoeus's avatar

Oh my! This is the greatest avian design I've ever seen!

A talent indeed!

VikasRao's avatar

Thanks so much! 😀

TheAquariumSlider's avatar
Do these dragons have an obsession over shiny things like real birds ?
VikasRao's avatar

That's a very cool concept, I'll definitely have to go into more detail. But for now I can imagine most of these would show a good deal of curiosity towards a shiny/glowing object like most birds and some mammals.

TheAquariumSlider's avatar
Are there some very nordic dragons where vikings originally lived their daily lives?Anyway,the cockatrice actually existed in China ,in the form of Yi Qi.So the cockatrice looking one should be better be based and actually related to the actual dinosaur rather than an parareptile.
VikasRao's avatar

There are a few dragon species up north but this is kinda set in an alternate Earth where Homo sapiens never appeared, and the few human species around never formed anything close to a civilisation. As for the cockatrice, I intentionally avoided making it too scansoriopterygid-like and instead went with the original mythical depictions :)

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