Paleognathae

Ratites and Tinamous

The 46 Orders

Paleognathae

Galloanserae

Columbimorphae

Otidimorphae

Strisores

Opisthocomiformes

Gruiformes

Mirandornithes

Ardeae

Charadriiformes

Telluraves

Afroaves

Australaves

The TiF Checklist

The checklist can be viewed in two ways. You can either view the annotated checklist on these web pages or download a list. The downloadable lists are Excel csv files that can be imported into spreadsheets such as Excel, or easily manipulated by programs such as perl. Four lists are available in csv format. The ABA list includes only ABA recognized species, but in TiF order, with TiF families. The South American list uses TiF species rather than SACC species.

Further, Stephen Nawrocki has provided an excel version of the worldlist, version 2.79.

You can view an annotated version by clicking on the list of bird orders on the right, or by going to the family index, or by clicking on the family names in the various tree view pages. In the annotated list, recently extinct species and species whose taxonomic placement is particularly uncertain are color-coded. In some cases, superfamilies, subfamilies, tribes, and other groups have been added to help show how the birds are related.

The 46 Orders

The TiF checklist currently groups the birds in 46 Orders and 252 families. Both a order-level and family-level trees are now availalbe in pdf format. Due to its length, the family tree is split into 5 parts.

Click for order-level tree Click for family-level tree
46 Orders 252 Families

The 46 orders of the TiF list include a few more orders than most other lists. However, I wanted to make sure that each of the orders was monophyletic, meaning that they include all descendants of a common ancestor. I did not have confidence that a shorter list would do. As it currently stands, I am highly confident that each order is monophyletic.

Supra-ordinal Groups

I am also highly confident in 12 supraordinal groups (including 4 subgroups) that are supported by Jarvis et al. (2014), Prum et al. (2015), and Suh (2016). Except for Otidimorphae, Eurypygimorphae, and Ardeae, these are also supported by Hackett et al. (2008). Figure 1 in Suh (2016) gives more detail on support for these groups. Not all of the papers include all 46 TiF orders. They are listed below, along with 3 orders that do not belong to any of the groups.

PALEOGNATHAE

STRUTHIONIFORMES
RHEIFORMES
CASUARIIFORMES
APTERYGIFORMES
TINAMIFORMES

GALLOANSERAE

ANSERIFORMES
GALLIFORMES

COLUMBIMORPHAE

MESITORNITHIFORMES
PTEROCLIFORMES
COLUMBIFORMES

OTIDIMORPHAE

MUSOPHAGIFORMES
OTIDIFORMES
CUCULIFORMES

STRISORES

CAPRIMULGIFORMES
STEATORNITHIFORMES
NYCTIBIIFORMES
PODARGIFORMES
APODIFORMES

MIRANDORNITHES

PHOENICOPTERIFORMES
PODICIPEDIFORMES

ARDEAE

EURYPYGIMORPHAE

EURYPYGIFORMES
PHAETHONTIFORMES

AEQUORNITHES

GAVIIFORMES
SPHENISCIFORMES
PROCELLARIIFORMES
CICONIIFORMES
SULIFORMES
PLATALEIFORMES
PELECANIFORMES
ARDEIFORMES

TELLURAVES

AFROAVES

COLIIFORMES
CATHARTIFORMES
ACCIPITRIFORMES
STRIGIFORMES
LEPTOSOMIFORMES
TROGONIFORMES
BUCEROTIFORMES
CORACIIFORMES
PICIFORMES

AUSTRALAVES

CARIAMIFORMES
FALCONIFORMES
PSITTACIFORMES
PASSERIFORMES

Independent Orders

OPISTHOCOMIFORMES
GRUIFORMES
CHARADRIIFORMES

Higher Phylogeny

The basic problem of higher phylogeny has now been reduced to the appropriate placement of the 8 high order groups and 3 independent orders.

The division into Paleognathae and Neognathe (all other living birds) was first proposed by Pycraft (1900). Sibley, Ahlquist, and Monroe (1988) suggested that the Galloanserae and Paleognathae were basal lineages among the living birds (Neornithes) and united them as Eoaves, with all other birds grouped as Neoaves. Sibley and Ahlquist (1990) recognized that the Paleognathae and Galloanserae were separate branches, and restricted Eoaves to be identical to Paleognathae. Since then, the evidence in favor of this arrangement has only grown stronger. I use Paleognathae and Neognathae as in Pycraft (1900), and Neoaves as in Sibley, Ahlquist, and Monroe (1988). The Galloanserae are included in Neognathae, but excluded from Neoaves.

This leaves us with 6 major supra-ordinal groups and 3 independent orders to classify. Here, we run into a big problem. Jarvis et al. (2014), Prum et al. (2015), and Suh et al. (2015) have given somewhat inconsistent results concerning how these 9 groups relate. Indeed, we have been seeing such inconsistencies for some time. Thus both Brown et al. (2008) and Morgan-Richards et al. (2008) informed us that the Metaves hypothesis was incorrect. However, their own preferred topologies would likely have been rejected by each other's data, and have since fared no better than Metaves.

The Polytomy: The Hoatzin Problem on Steroids

Suh (2016) has argued that these inconsistencies stem from a hard polytomy at the base of Neoaves involving all 9 groups, a polytomy that cannot be satisfactorily resolved with current data and methods of analysis.

In alphabetical order, the nine troublesome taxa are: Ardeae, Charadriiformes, Columbimorphae, Gruiformes, Mirandornithes, Opisthocomiformes, Otidimorphae, Strisores, and Telluraves.

So how should we arrange this hard polytomy? If Suh (2016) is correct, any arrangement will be pretty arbitrary. That's what a hard polytomy means. One way to handle it is to order them from least diverse to most diverse. On the TiF list, this means ordering them by species diversity rather than by diversity of the next lower major group. The reason for this is that the groups between the group we are ordering and species are quite arbitrary. They mean different things in terms of time depth and genetic distance depending on where you are in the tree. Biological species have a greater tie to biological reality than do these other groups, even though that tie is still fairly loose. So I count species in each group at a given level to order them.

If I ordered them by species diversity, the order would be Opisthocomiformes, Mirandornithes, Gruiformes, Otidimorphae, Columbimorphae, Ardeae, Charadriiformes, Strisores, Telluraves.

However, I think we can do a little better. I don't think there's zero information about the polytomy. Indeed, looking at Figure 2 of Suh (2016), it appears that the Columbimorphae (which are probably, but not certainly monophyletic) are closest to the root and the Otidimorphae are probably next. The Strisores may come next. After that, things are murkier. Indeed, these groups often show up near the root of Neoaves in other analyses.

That reduces the problem to 6 taxa: Opisthocomiformes, Mirandornithes, Gruiformes, Ardeae, Charadriiformes, and Telluraves. How should we then order these? I've played around with different arrangements, trying to group waterbirds and landbirds separately, or with other intuititive groupings. In the end, I decided it was better to acknowledge our lack of knowledge.

I've ordered the remaining six taxa by size. In the TiF list, size means number of species. We could use the number of orders, or families, or genera, but I like to use number of species. The reason for this is simple. The number of species is less arbitrary—we have a biological criterion for species status. The other concepts are more arbitrary, and too often reflect the preferences of a particular ornithologist or committee.

What Caused the Polytomy?

The likely cause of the hard polytomy lies with the end-Cretaceous extinction. The scenario is that a single neoavian lineage survived (as did at least one lineage each of Galloanseres and Paleognathae). The single lineage soon evolved into many lineages to cope with the new, post-apocalyptic ecology. The ancestors of the 9 groups diversified too quickly for it to be reflected in the genes (incomplete lineage sorting) and may have also have continued to hybridize. This makes the genetics of the splits difficult or even impossible to sort out. It is certainly beyond what we can do in 2016.

When thinking about the polytomy, you should keep in mind that the ancestors of the nine groups would have orginally been subspecies, fully capable of interbreeding. Eventually they attained full species status, and over time became the orders we know now. There were probably other lineages that didn't survive to the present.

At present we don't know what these ancestral species were like, but they may have been sort of shorebirdy, as in Feduccia's (1999) “transitional shorebirds” hypothesis. Near relatives to all modern birds include taxa such as Ichthyornis and Iaceornis (see, e.g., Longrich et al., 2011). Interestingly, Longrich et al. found fossils of one such relative, which they designate “Ornithurine C”, on both sides of the K/Pg boundary (K/T boundary). Since no representatives of Neoaves were included in the analysis, we cannot say if this taxon was closer to Neoaves than to Galloanserae and Paleognathae.

Further Thoughts on the Polytomy

We now see why the relationships within Neoaves have been so problematic. The Vegavis fossil (Clarke et al., 2005) tells us that the Paleognathae and Galloanserae lineages date separated from the other birds in the Cretaceous. Neoaves seems to owe its orgina to the consequences of the bolide that crashed into Chicxulub at the end of the Cretaceous (66.04 million years ago, see Renne et al., 2013).

The resulting environmental devastation wiped out many species, genera, families, and even orders of living organisms. Even some of those that survived proved unable to thrive in the new world of the Paleogene.

The surviving birds rapidly diversified following the impact, creating problems such as incomplete lineage sorting at supra-ordinal levels within Neoaves. Untangling this has been a protracted process. It is now twenty-five years after Sibley and Ahlquist, and the problem has still not been completely solved. Jarvis et al. (2014) threw a huge amount of data at the problem, three orders of magnitude more depth than Hackett et al. (2008). In spite of all this, Suh (2016) informs us that we are still left with an intractable polytomy in Neoves.

Perhaps new methods and still more data will lead to resolution of the problem, but we shouldn't count on it.

PALEOGNATHAE Pycraft, 1900

Paleognathae tree

The first major division among the living birds is between the Paleognathae and Neognathae, as recognized by Pycraft (1900). The taxonomy of the Paleognathae continues to be controversial. Traditionally, they have been divided into the flightless ratites and the volant tinamous. Some of the earlier generic evidence seemed to support this (e.g., Haddrath and Baker, 2001).

However, the recent studies of Chojnowski et al. (2008), Hackett et al. (2008), Harshman et al. (2008), and Phillips et al. (2009), Faircloth et al. (2012), Haddrath and Baker (2012), and J.V. Smith et al. (2013) have come to a very different conclusion. The ratites are not monophyletic. Some of the them are more closely related to the volant tinamous than to other ratites. In particular, the ostriches are no more closely related to the other ratites than to the tinamous, and the other ratites share a more recent common ancestor with the tinamous than with the ostriches.

Once we get beyond the ostriches, things are not so clear-cut. There are three major groups: (1) rheas, (2) tinamous (and the recently extinct moas), and (3) cassowaries, emus, and kiwis. The three groups seem to have separated over a short period of time. The next question is which of the three groups separated first?

Currently, this has not been conclusively resolved. However, it appears that it is either the rheas or the tinamou/moa clade (see J.V. Smith et al., 2013). Many analyses (e.g., Harshman et al., 2008; Phillips et al., 2009; J.V. Smith et al., 2013) favor putting the rheas first. However, when Haddrath and Baker (2012) considered retroposons, the balance shifted to the tinamaou/moa clade, and that is the topology we will follow here.

This topology implies that flightlessness has evolved at least 3 times in the Paleognathae: in ostriches, in moas, and at least once among the rheas, emus, cassowaries, and kiwis. Indeed, if the chronogram in Haddrath and Baker (2012) is correct, both the split of the rheas and Austalasian ratites and the split between the kiwis and emus/cassowaries occurred about 80 million years ago (mya). This timing is consistent with the kiwis originating due to the separation of Australia and New Zealand and with the ancestral rheas walking their way across the then-temperate Antarctica to South America.

There is further relevant DNA evidence indicating that the extinct elephant birds of Madagascar are the closest relatives of the kiwis (Mitchell et al., 2014b), with a common ancestor perhaps 50 mya. This is a problem for vicariance theories because Madagascar (and India) likely separated from Gondwana considerably earlier, perhaps 120 mya. In that case, the ancestor of the elephant birds would have had to fly, and we can infer that flight was indpendently lost in the rheas, emu/cassorwary, elephant bird, and kiwi lineages, a total of 6 losses of flight. This is not an unreasonable number. One only has to consider all of the flightless rails to see that.

The fossil evidence considered by Johnston (2011) suggests that the long-extinct Lithornithiformes were close relatives of the tinamous.

The Paleognathae are divided into several orders in recognition of the great antiquity of the various branches, some probably dating back to the Cretaceous period. Phillips et al. (2009) estimate the ostriches diverged from the rest of the Paleognathae about 60-95 mya, while Chojnowski et al. (2008) date this divergence around 64±22 mya, near the K/T (=K/Pg) boundary. Haddrath and Baker (2012) put it at 73-119 mya. Finally, mapping Jarvis et al. (2014) onto the phylogeny used here suggests that the split was about 84 mya (interval 58-96 mya).

The Cassowaries and Emus seem much more closely related than the other paleognath families, and so are placed in a single order: Casuariiformes. In fact, the molecular dates in Phillips et al. and in Haddrath and Baker suggest they are so closely related that they could be treated as a single family. Although the Moas and Elephant Birds are not part of the main TiF list, a genus-level phylogeny of both is given in the tree diagram. The Moa tree is based on Bunce et al. (2009).

STRUTHIONIFORMES Latham, 1790

Struthionidae: Ostriches Vigors, 1825

The authors for family-group names are mostly based on Bock (1994), while the authors for order-group names are primarily based on the series by Brodkorb (1963-1978). In both cases, additional sources have been consulted (e.g., Livezey and Zusi (2007)). In a number of cases, I have managed to examine the original (thank you Google Books!). The ICZN does not regulate order-group names. However, for parvorders (-ida), infraorders (-ides), suborders (-i), orders (-iformes), and superorders (-imorphae), I am attempting to follow similar rules. In particular, they are based on priority and the orginal use must been at an ordinal level and must be based on an included genus name (type genus) actually used by that author. The endings have been adjusted to modern usage.

1 genus, 2 species HBW-1

RHEIFORMES Forbes, 1884

Rheidae: Rheas Bonaparte, 1849

1 genus, 2 species HBW-1

CASUARIIFORMES P.L. Sclater 1880

Dromaiidae: Emus Huxley, 1868

1 genus, 1 species HBW-1

Heupink et al. (2011) argue that the extinct King Island Emu, Dromaius ater, was quite closely related to the extinct Tasmanian subspecies of the Emu, and is best considered a dwarf subspecies of Dromaius novaehollandiae. The Kangaroo Island Emu, D. baudinianus, seems likely to have been no more different from the Emu than the King Island Emu was, so I am also considering it a subspecies of the Emu, D. novaehollandiae.

Casuariidae: Cassowaries Kaup, 1847

1 genus, 3 species HBW-1

APTERYGIFORMES Haeckel 1866

The order of the Kiwis reflects the phylogeny in Burbidge et al. (2003) and Shepherd et al. (2012). Burbidge et al. also provide evidence for recognizing 3 extant species of brown kiwi, as is done here. Shepherd et al. found evidence of an extinct northern clade of Little Spotted Kiwi that may deserve recognition as a separate species. The DNA samples of this potential species are from bones of unknown age.

Apterygidae: Kiwis G.R. Gray, 1840

1 genus, 5 species HBW-1

TINAMIFORMES Huxley, 1872

Tinamidae tree

The Tinamiformes are the other branch of the Paleognathae. There is only one family. The taxonomy here is based on Bertelli and Porzecanski (2004) and SACC.

The Tinamidae are sometimes divided into two subfamilies: Rynchotinae and Tinaminae. This is consistent with the phylogeny shown, although there is some uncertainty about whether Nothocercus really groups with Tinamus and Crypturellus.

Tinamidae: Tinamous G.R. Gray, 1840

9 genera, 47 species HBW-1

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