List of fossil bird genera

Birds evolved from certain feathered theropod dinosaurs, and there is no real dividing line between birds and non-avian dinosaurs except that some of the former survived the Cretaceous–Paleogene extinction event while the latter did not. For the purposes of this article, a 'bird' is considered to be any member of the clade Aves in the broadest sense. Some dinosaur groups which may or may not be true birds are listed below under Proto-birds.
This page contains a listing of prehistoric bird taxa only known from completely fossilized specimens. These extinctions took place before the Late Quaternary and thus took place in the absence of significant human interference. While the earliest hominids had been eating birds and especially their eggs, human population and technology was simply insufficient to seriously affect healthy bird populations until the Upper Paleolithic Revolution. Rather, reasons for the extinctions listed here are stochastic abiotic events such as bolide impacts, climate changes due to orbital shifts, mass volcanic eruptions etc. Alternatively, species may have gone extinct due to evolutionary displacement by successor or competitor taxa – it is notable that an extremely large number of seabirds have gone extinct during the mid-Tertiary; this seems at least partly due to competition by the contemporary radiation of marine mammals.
The relationships of these taxa are often hard to determine, as many are known only from very fragmentary remains and due to the complete fossilization precluding analysis of information from DNA, RNA or protein sequencing. The taxa listed in this article should be classified with the "Fossil".
Before the late 19th century, when minerals were still considered one of the kingdoms of binomial nomenclature, fossils were often treated according to a parallel taxonomy. Rather than assigning them to animal or plant genera, they were treated as mineral genera and given binomial names typically using Osteornis ("bone-bird") or Ornitholithus ("bird fossil") as "genus". The latter name, however, is still in use for an oogenus of fossil bird eggs. Also, other animals (in particular pterosaurs) were placed in these "genera". In sources pre-dating the Linnean system, the above terms are also seen in the more extensive descriptions used to name taxa back then.
Taxonomic list of fossil prehistoric birds.
Higher-level taxa are presented in likely or suspected phylogenetic order. Genus-level taxa and lower are sorted chronologically, in ascending order (i.e., older taxa first).
The higher-level groups of non-Neornithes are arranged based on the phylogeny proposed by Luis Chiappe, updated and expanded to incorporate recent research. The categories are inclusive in ascending order.
"Taxonomic assignments, especially in the pygostylian to early neornithine genera, are still very provisional and subject to quite frequent change."
Basal Avialae (extinct).
The most primitive "birds", usually still possessing a long bony tail with generally unfused vertebrae. Not all of these may be on the line of bird ancestors; whether they are not closer to other theropods groups than to the Avialae remains to be thoroughly tested (see "Xiaotingia").
Basal Pygostylia (extinct).
The earliest birds with a modern pygostyle: a reduction and fusion of the tail vertebrae; possibly a paraphyletic group. Two types of pygostyle are known, a rod-shaped one found in Confuciusornithidae, Enantiornithes and some non-avian theropods such as "Nomingia", and a plowshare-shaped one, only known in the lineage leading to modern birds. It is not certain that the pygostyles found in birds are indeed synapomorphies.
Enantiornithes (extinct).
The taxonomic list of enantiornithine groups presented here follows a summary published by Thomas R. Holz, Jr. in 2011.
†Enantiornithes
Note that Holtz (2011) also included "Zhyraornis" in his classification of euenantiornithines, though this genus is more often classified as an ornithuran. Holtz also placed "Liaoningornis" as an ornithuromorph, though more recent studies have placed it as a close relative of "Eoalulavis".
Basal Euornithes (extinct).
Also called "basal Ornithuromorpha". Essentially modern birds, except many still possess a few primitive features such as teeth or wing claws. These have the plowshare-shaped pygostyle and proper tail fan as seen in most living birds. The taxonomy of this group is confusing; the name "Ornithurae" was first proposed by Ernst Haeckel in 1866 and has been revised in meaning several times since.
The following is a list of primitive euornithian genera and those that cannot be confidently referred to any subgroups, following Holtz (2011).
Note that Holtz also included the genera "Eurolimnornis", "Holbotia", "Palaeocursornis" and "Piksi" as euornitheans, though they have since been re-identified as pterosaurs.
Neornithes.
The subclass that contains all modern birds.
Unresolved and basal forms
These modern birds are known from remains that cannot be placed in relation to any one modern group and are neither autapomorphic enough to assign them to own orders. Especially the Late Cretaceous/early Paleogene taxa are probably basal to several modern orders, while later Paleogene taxa often represent extinct lineages outside the modern families.
Struthioniformes.
Ostrich and related ratites.
Casuariiformes.
Cassowaries, emus and related ratites.
Rheiformes.
Rheas and related ratites.
†Dinornithiformes.
Moas.
Two unnamed Saint Bathans Fauna species.
Anseriformes.
The group that includes modern ducks and geese.
Galliformes.
The group that includes domestic chickens and their relatives.
Charadriiformes.
Gulls, auks, shorebirds
†Gastornithiformes (extinct).
The diatrymas, a group of huge flightless Paleogene birds of unclear affinities. Traditionally placed within the Gruiformes, they are usually considered a distinct order nowadays and appear closer to the Anseriformes.
Gruiformes.
The group that includes modern rails and cranes. Probably paraphyletic.
Ciconiiformes.
The diverse group that includes storks, herons and New World vultures. Paraphyletic as listed here.
Pelecaniformes.
The group that includes modern pelicans and cormorants. As presented here paraphyletic; the tropicbird lineage is not part of this group and relationships with Procellariiformes and Sphenisciformes require more research. Also, as the pelicans are at least as close to the Ciconiiformes as to cormorants, the latter group is being recognized as Phalacrocoraciiformes by some recent authors and the core Pelecaniformes are occasionally merged into the Ciconiiformes.
Procellariiformes.
The group that includes modern albatrosses, petrels and storm-petrels.
Psittaciformes.
Unresolved and basal fossil parrots:
Opisthocomiformes.
Hoatzins
Cuculiformes.
Cuckoos, turacos and allies.
Aegotheliformes.
Owlet-nightjars
Apodiformes.
Swifts and hummingbirds.
Coliiformes.
Mousebirds and relatives
Strigiformes.
Owls and barn owls
Coraciiformes.
Rollers and allies. Probably paraphyletic.
Avialans "incertae sedis".
These fossil taxa cannot be assigned to any major group with reasonable certainty. The "proto-birds" above are of some indeterminate basal position in the entire avialan (and paravian) radiation, but known from such diagnostic material that their relationships at the family level are known. In contrast, the taxa here have a hypodigm that is usually just sufficient for giving them a valid scientific name, but not for phylogenetic purposes beyond classing them as pygostylians or more modern birds. Some, however, are known from such fragmentary remains that the possibility that they are non-avian "reptiles" such as dinosaurs cannot be ruled out at present.