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Palaeognath monophyly

Darren Naish asked me to forward this to the DML.


The implication that belief in a polyphyletic Palaeognathae
is widespread in ornithology seems a rather odd thing to
argue in view of the technical literature on this area - and
there is an awful lot of it, too much to summarise here.

For the record, 'ratite' is not synonymous with
'palaeognath'. Palaeognathae as presently conceived =
Tinamiformes/Tinamidae + Ratitae (plus some ostensible
basal palaeognaths that I won't discuss here; see Kurochkin,
1999, Hope, 2002).

While it has been proposed various times that ratites may
have descended from specific neognaths (e.g., Olson,
Feduccia and others have proposed that ostriches were
ergilornithid gruiform derivatives; Olson suggested that
kiwis might be derived ibises; both Olson and Feduccia
have at times intimated that moa may be derived from
anseriforms), little more than wishy-washy arm waving has
been proposed in defence of this view. All recent studies
that have examined ratite affinities find them to be
monophyletic. Among the more important of these works
include; Bock (1963) on cranial anatomy, Stapel et al.
(1984) on amino acid sequences of eye lens proteins,
Cracraft (1974), Bledsoe (1988) and Mayr and Clarke
(2003) on morphology, Cooper and Penny (1997) and van
Tuinen et al. (1998) on DNA, and Lee et al. (1997) on both
molecular and morphological data. Notably, even certain
authors who have hinted at a non-monophyletic
Palaeognathae regard ratite monophyly as sound. Houde
and Haubold (1987) for example (and it should be clear
from this thread that Houde is one of the few workers who
has argued strongly that tinamiforms might in some way be
allied with neognaths) strongly supported ratite monophyly
in their study of _Palaeotis weigelti_...

We do not concur with the idea that the paleognathous
[sic] palate is homoplastic because palaeognathous [sic]
birds are generally alike each other and differ from
neognathous birds in a plethora of non-osteological
characters: myology (Hofer 1950, McGowan 1982),
rhamphothecal grooves (Parkes and Clark 1966), plumage
as chicks (Pycraft 1900, Jehl 1971), pterylography (Parker
1864, Chandler 1916), spermatozoa (McFarlane 1971),
gonads (Meier 1979), Bursa of Fabricius (Berens von
Rautenfeld and Budras 1982), ocular pectin (Seemba and
Mathers MS), cardiovascular system (Glenny 1965, Baumel
1968), osseous microvascularization (Amprino and Godina
1944, Zavatarri and Cellini 1956), cortical neuroanatomy
(Craige 1935a, b, 1940a, b, Pearson 1972), Eustachian tubes
(Hopkin 1906), coelomic cavities (Duncker 1979), proteins
(Sibley 1960, Wilson et al. 1964, Miller and Feeney 1964,
Kaplan 1965, Fitch and Margoliash 1967, Osuga and
Feeney 1968, Feeney and Alison 1969, Gysels 1970, Sibley
and Ahlquist 1972, Sibley and Frelin 1972, Krampitz et al.
1974, Ho et al. 1976, Prager et al. 1976, Stapel et al. 1984),
DNA (Takagi et al. 1972, Takagi and Sasaki 1974, de Boer
1980, Sibley and Ahlquist 1981, 1985), behavior (Meise
1963), and parasites (Kellogg 1913). (p. 37).

While, therefore, it's been fun to suggest that different
ratites arose from different assorted neognaths, the evidence
is strongly against it. As for claims that ratites look so
different from one another (especially in pelvic anatomy)
that they simply must be polyphyletic, this isn't much of a
valid criticism (compare the diversity in ratite pelvic
anatomy with, e.g., piciform or passeriform cranial anatomy
[the point being that ratites don't look so different from one
another at all]), and it's countered by the twenty or so
derived characters that unite ratites and support their
monophyly (for which see, e.g., Lee et al., 1997).

Unfortunately the question of palaeognath monophyly is
often confused with the issue of ratite paedomorphism.
Ratites probably do exhibit heterochrony (some of their
features can be interpreted as peramorphic: they don't just
exhibit paedomorphosis - see Elzanowski, 1989, for a good
response to the paedomorphic argument), but claims that
this process horribly masks their morphology or muddies
any interpretation of their affinities are naïve given that they
still exhibit plenty of good characters that can be evaluated

The idea that tinamous might be allied to galliforms, rather
than to ratites, is old - Lesson in 1831 was one of the first
authors to propose this and it was later favoured by
Seebohm, Goodchild, Chandler, Dubinin and Verheyen.
Even Huxley (1867) placed tinamous within his Carinatae
(though he did admit that they were 'the most struthious of
all carinate birds' (p. 426)). However, the view that
tinamous are closer to ratites, and that any similarities with
galliforms are either convergent or not indicative of a
special affinity, is also old and, historically, equally as
popular - if not more so. Pycraft (1900) was the first to
include tinamous within Palaeognathae, and he placed them
closer to rheids, dinornithids and aepyornithids than to other
ratites; Stresemann in 1927 attributed similarities between
tinamous and galliforms to convergence; Oliver in the
1940s regarded tinamous as volant kin of ratites; McDowell
in 1948 treated tinamous as close relatives of rheids within a
palaeognath clade; Zavattari and Cellini in 1956 regarded
tinamous as close to ratites; Tyler and Simkiss in 1959
found exclusive egg shell similarities between tinamous and
ratites. and so on.

Recent studies on palaeognath affinities support an
affiliation of tinamous with ratites, and not with any
neognath group. Among the more significant of these
include Prager et al. (1976), Lee et al. (1997) and Mayr and
Clarke (2003). Groth and Barrowclough (1999) on the
nuclear RAG-1 gene - the study that led Ericson et al.
(2001) to reject their hypothesis of non-monophyly of
Galloanseres - found support for a monophyletic
Palaeognathae. This work is also significant in recovering
the palaeognath-neognath split as the basal dichotomy
within Neornithes, something not recovered in all molecular
studies (e.g., Mindell et al., 1997, Harlid and Arnason,
1999); the latter (and I am talking about the studies in which
passeriforms are found to be most basal neornithines) is
widely thought due to inadequate taxon sampling and long-
branch attraction. Bock (1963) and Starck (1995) concluded
from skull anatomy that tinamous and ratites formed a
clade, McGowan (1984) supported affiliation of tinamous
with ratites based on tarsal morphology and Gussekloo and
colleagues, while questioning the validity of some of the
morphological evidence supporting palaeognath distinction
(Gussekloo and Zweers, 1999, Gussekloo et al., 2001), still
find that palaeognaths are distinct from neognaths, more
basal than neognaths, and that 'the Tinamidae are the
closest relatives of the ratites' (Gussekloo and Zweers,
1999, p. 39). Palaeognath monophyly has also been upheld
and supported by Elzanowski (1995), Kurochkin (1995,
1999), van Tuinen et al. (2000), Dyke (2001, 2003),
Livezey and Zusi (2001), Cracraft (1981, 1988, 2001),
Cracraft and Clarke (2001), Ericson et al. (2001), Bock
(2002) and others. Despite his apparent championing of
palaeognath non-monophyly, Feduccia has repeatedly
published a phylogram in which palaeognath monophly is
unambiguously supported (Feduccia, 1994, p. 180;
Feduccia, 1995, p. 637; Feduccia, 1996, p. 172; Feduccia
2003, p. 173). I therefore conclude that even he supports
palaeognath monophyly on at least some days of the week.

As for lithornithids, Houde's work was extensively revised
and revisited by Dyke during his tenure at the AMNH under
Cracraft. Dyke (2003) included tinamous, ratites and
lithornithids in an analysis based mostly on the characters
used by Lee et al. (1997). The results: Palaeognathae is
monophyletic, and lithornithids are not 'proto-tinamous', at
least four characters show that they are more derived than
tinamous, being closer to ratites within Palaeognathae.
Houde's features, used by him to support an affinity with
galliforms, are convergent.

Contrary to the idea that palaeognath polyphyly is popular,
well supported, or thriving then, palaeognath monophyly -
specifically, the existence of a neornithine clade that
includes tinamous and ratites to the exclusion of other
neornithines - is well corroborated and, in fact, the
consensus view. More below on the latter point. Virtually
all recent work on palaeognath relationships has not
supported Houde's contention that Palaeognathae is non-
monophyletic and that tinamous are allied to any specific
neognath group (viz, galliforms).

Finally, I would like to make an important point: I've made
it several times before but I don't know whether anyone has
been listening or not. As is clear from the above discussion,
the concept of palaeognath non-
monophyly/paraphyly/polyphyly really is not popular
among working ornithologists. Why then would anyone
think that it is? The answer: the concept of palaeognath
non-monophyly/paraphyly/polyphyly has been well
publicised and well disseminated by a key minority group
of vocal researchers - the same researchers who are known
to hold other 'non-consensus' views on aspects of avian
phylogeny, but the only palaeornithologists that produce
important holistic works on avian phylogeny nonetheless.
Alan Feduccia would probably be the first to admit that the
views he favours are not those supported by most other
working ornithologists, so it is highly ironic that he is the
only person who produces books on neornithine evolution.

Those acquainted with research on bird origins are of course
familiar with the fact that the Feducciaries hold, errr,
heterodox ideas on bird origins. Less appreciated is that
these are exactly the same authors who also maintain views
strongly disputed by most other ornithologists. Examples?
The origin of feathers, the monophyly of palaeognaths, the
timing of the radiation of Neornithes, the monophyly of
Galloanseres, the pattern of character acquisition in
anseriforms and the position of screamers and magpie
geese, the position of presbyornithids, the affinities of
flamingos, the affinities of the shoebill, falconiform
monophyly, the affinities and monophyly of piciforms, the
relationships among gruiforms, the position of turnicids,
coraciiform phylogeny, the origin of passerines, and so on.

And, for the record, we do not uphold views such as the
theropod origin of birds, the monophyly of palaeognaths, or
the anatoid affinities of _Presbyornis_ because we
necessarily 'like' these ideas the most, or think that they are
the coolest, but because they are the ideas that are best
supported by the data.

Refs - -

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Darren Naish
School of Earth & Environmental Sciences
University of Portsmouth UK, PO1 3QL

email: darren.naish@port.ac.uk
tel: 023 92846045


Mickey Mortimer