Things should be made as simple as possible, but not any simpler.- Albert Einstein
In our own timeline, there are clear differences between birds and everything else. Birds have feathers, toothless beaks, short tails, and so on… just like mammals have fur and produce milk. In Spec, however, the matter is somewhat more complex.
Is a bureaucratbird a bird? Some would say yes, as bureaucrats have wing feathers and use them to fly. But, if the newest genetic data hasn't fooled us, bureaucrat-birds are more closely related to draks than to ducks. So if a bureaucrat-bird is a bird, a hundrak must be a bird as well; either both or neither. If a hundrak can be a gigantic secondarily flightless bird -after all, deinonychosaurs have a distant flying ancestry- then one must remember that it is likely that hogbirds and even arctotitans had flying ancestors, too.
If, on the other hand, lumping tiny tangerines with enormous therizinosaurs seems too ridiculous, then perhaps one could suggest that only those dinosaurs with unambiguous wings, means, with reduced 3rd fingers be called birds? But then our definition excludes bunglebirds, which look far more birdlike than draks? The problem refuses to clarify.
While our Home Earth has only unambiguous neornithian birds, Spec possesses semi-birds and perhaps-birds with long and short tails, with and without beaks, with and without teeth, with fully free fingers and with fingers that fully integrated in the wing, and almost all imaginable combinations thereof. Some, like the massive therizinosaurs and vicious deinonychosaurs, are obviously far from the birds of our backyards. But even among Spec's more familiar-looking birds (those with short tails and beaks and no teeth and no free fingers), few are as familiar as they seem.
THERIZINOSAURIA (Yandos, lammoxes, arctotitans, and hornclaws)
Bipedal, heavily plumaged herbivores
OVIRAPTOROSAURIA (Vulgures, gollums, hogbirds, nostriches, and seedcrackers)
A few relics of a strange clade
The pathetic remnants of a once worldwide group
DEINONYCHOSAURIA (Mattiraptors, hesperonychids, draks, ninjas, and arbros)
Bipedal predators with hyperextendable inner toes
RAHONAVIDAE (Bureaucratbirds and stefs)
Just as weird now as they were then
XENORNITHES (Bunglebirds and carpos)
Good climbers and strange fliers
In our home timeline, of all dinosaurs only a few species of Neornithes (see below) survived the end of the Cretaceous. Those few species all seem to have lived in Antarctica or perhaps its surroundings (South America, Madagascar-India, Australia, and New Zealand). Therefore it is no wonder that Home Earth's birds are all so similar. Our birds are the descendants of a mere handful of species to survive the end-Cretaceous apocalypse.
In Spec, where the Earth ticked through the Cretaceous-Paleogene boundary with only the mildest of hiccups, most of the old bird groups still exist. Most notable among these are the Enantiornithes, which have enjoyed a global distribution more or less since the age of their oldest fossil representative, some 135 million years ago. These "opposite-birds", so called for some "upside down" skeletal features, make up most of Spec's landbird diversity, with a few water-loving forms thrown in.
The normal dinosaur condition is to grow slowly if one's adult size is small. A little hona chick will therefore grow much more slowly than the progeny of a massive Arctotitan, so the young of both species will reach adult size at approximately the same time. The birds of our Home Earth are not normal in this respect, as they grow very quickly, but opposite-birds follow the older, dinosaurian pattern. It is not uncommon for opposite birds to reach adulthood only after several years. In addition, almost all enantiornith species are precocial, meaning they can fly and leave the nest just a few days after hatching. At first glance this is a serious drawback against the much faster breeding "true" birds, these traits have allowed opposite-birds to evolve some features that more familiar avians could never afford. Most conspicuous among those is the poison of the tweety-birds and the false panha. Less spectacularly, larger opposite birds go through several different ecological niches through their life cycle, which allows population densities which higher than any in our world, but comes at the price of considerably lower species diversity.
AVISAURIDAE (Avisaurs and scowls)
Toothed birds of prey
Diving freshwater birds
ALLOSPIZIFORMES (Otherworld finches, cityfinches, parrothawks and otherworld parrots)
Small seed-eaters, for the most part
Spec's poisonous answer to songbirds
PSEUDORAPTORIDAE (False panha)
A strange and poisonous creature
EUORNITHES (Seaguins, ducks, etc.)
The "True" birds. Unlike Enantiornithes, Euornithes has been very successful in producing a diversity of waterfowl. However, numerous landbirds are "true", too.
ALLOCOLUMBIFORMES (Otherworld pigeons and sandgrouse)
Fast-flying fruit- and seed-eaters
HESPERORNITHES (Hespero-cormorants, sea parrots and seaguins)
Toothed, mostly flightless seabirds
ICHTHYORNITHIDAE (Baygulls, toothauks, surfbirds, and harpies)
Toothed birds of air and sea
NEORNITHES (Ducks, penguins, gobblers, etc.)
Mostly familiar birds
- Daniel Bensen and David Marjanovic
,=Oviraptorosauria ,=| | `=Therizinosauria | |=Troodontidae | |=Alvarezsauridae
| ,=Deinonychosauria | ,=??| | | | ,=â€ Archaeopteryx | | `=??| | | `=Rahonavidae | | `=Eumaniraptora=| ,=â€ Confuciusornis ,=Avisauridae | ,=| ,=| | | `=Xenornithes ,=| `=â€ Enantiornis walkeri | | | | | | ,=??| `=â€ Sinornis santensis `=Pygostylia=| | | | ,=Enantiornithes=| `=Enantibaptidae | | | | | | ,=Allospiziformes | | `=| `=Ornithothoraces=| | ,=Twitiaviformes | `=??| | `=Pseudoraptoridae | | ,=Allocolumbiformes `=Euornithes=| | ,=Hesperornithes `=| | ,=Ichthyornithidae `=| `=Neornithes