The cladogram at left is reasonably accurate, though not quite technically precise. The reason for this, is that a detailed representation would be too complex, even if one is to isolate the evolution of aves alone, as I've tried to do here.
I wanted to keep this as simple as possible to illustrate the relationship of ancient aves to their closest saurian kin, limiting it only to those taxa that are immediately relevant to the origins of birds.
An example cladogram in detail is the one for ratites that included the link that brings you here. And that illustration would neatly fit at the top of this tree. But even that one falls short because seperate species within the cassowaries, ostriches, moas, and especially tinamou were not represented. So one can easily imagine how greatly reduced this one at left is. Dinosauria alone consists of literally hundreds of indevidual species within the ceratopsians, sauropods, ankylosaurs, stegosaurs, etc. And of course, each of these groups contain sub-groups. There are at least four distinct families within Sauropoda alone.
I think critics of evolution must be so strictly out of ignorance of the staggering number of finds unearthed so far! Were I to do this tree in detail, it would take up more megs than I have available to me to be sure!
There are many other feathered dinosaurs, primitive aves, and giant flightless "terror birds", which could not be included here. And many of the ones that are should be in a seperate clade, an offshoot of the stem in the picture. But as I said, I was going for simplicity here.
If you want to see a more detailed cladogram of avian specific relationships,
and trace your roots from Eukaryotes through primates to homo sapiens.
Were I to show every example known from the fossil record, there would be an immediately evident fluidity between the phytosaurs through postasuchus to coelophysis and on to eoraptor, velociraptor, rahona ostromi, etc. This same fluidity of gradual steps is evident in every clade. There are clear transitionals between stegosaurs and ankylosaurs, numerous transitional ceratopsians and carnosaurs, and literally dozens of dozens more dinosaurs, scores of birds, and myriads more mammals and reptiles and other things than creationists were ever aware of. Education is the key to understanding. Not indoctrination. And the total combined wealth of human understanding is to be found in millions of books. There is no sense reading one book millions of times, especially when that one book is demonstrably wrong about so many things.
Pterosaurs aren't related to birds
or even dinosaurs, except for common ancestry with another high-energy warm-blooded reptile, such as no longer exists today. But that animal likely spawned the hair-like downy insulation of pterosaurs and the plumage of the dinosaurs who eventually followed.