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Re: (origin of the palaeognathous palate)

From: David Marjanovic <david.marjanovic@gmx.at>
Reply-To: david.marjanovic@gmx.at
To: DML <dinosaur@usc.edu>
Subject: Re: (origin of the palaeognathous palate)
Date: Sun, 05 Sep 2004 20:34:52 +0200

> However, the rhea [...] DNA studies reveal that
> he is more closely related to the ostrich than the emu.

No longer.

Alan Cooper, Carles Lalueza-Fox, Simon Anderson, Andrew Rambaut, Jeremy
Austin & Ryk Ward: Complete mitochondrial genome sequences of two extinct
moas clarify ratite evolution, Nature 409, 704 -- 706 (8 February 2001)

With tinamous and chicken as outgroups:

  `--+--+--*Emeus* (a moa)
     |  `--*Dinornis* (another moa)
     `--+--*Struthio* (ostrich)
        `--+?--*Mullerornis* (Aepyornithidae)
           |--*Apteryx* (kiwi)
           `--+--*Casuarius* (cassowary)
              `--*Dromaius* (emu)

Thanks, good point. As expressed by your Cooper et al (2001): ?The tight clustering of dates and lack of phylogenetic resolution, despite the long sequences, also suggests that the derived ostrich, kiwi, and emu cassowary taxa speciated rapidly.? This probably explains why these DNA studies often disagree with each other. While Cooper et al 1992, and 2001, place the rhea as basal, Tuinen et al 1998 and 2000 group the ostrich, followed by the rhea as basal. The problem may be that the ratite lineages diverged a long time ago, and at nearly the same time, so resolution is uncertain.
The newest may actually be Haddrath and Baker (2001) which finds: ??the ratites are found to be monophlyletic, with moas basal, as in morphological trees. ?most of the major ratite lineages fit the vicariance biogeography hypothesis, the exceptions being the ostrich and the kiwi, which require dispersal to explain their present distribution.?

This sounds like support for Houde?s (1986) theory, based on palatal complexes, that the kiwi and ostrich descended directly from the Lithorn Cohort:

`--+--Green River Palaeognath
       |   `--Apteryx

I actually was looking at Dyke(2003), which is based mostly on characters used by Lee et al(1997):

|  |--Tinamidae
|  `--+--Lithornis
|      `--Ratites
|         |--+--Apteryx
|         |  `--Dinornis
|         `--+--Palaeotis
|             |--+--Casuarius
|             |  `--Dromaius
|             `--+--Rhea
|                 `--Struthio
   |  |--Anseriforms
   |  `--Galliforms`

As shown in this one, the rhea is typically grouped with the ostrich. But actually, I have no idea. Anyway, were getting off topic, the ratites all have a defineable PPC.
I believe that Dyke would place the ratites (struthioniforms) as follows:

Ornithurae(Ornithuromorpha) |--+--Patagopteryx |--Vorona `--+--Hesperornis `--+--Ambiortus |--Ichtyornis `--Neornithes Primitive Clades |--Palaeognathae | |--Struthioniforms | `--Tinamiforms `Neognathae |--Anseriforms |--Galliforms Neoaves |--Pelecaniformes |--Gruiforms Derived Clades

The palaeognathous palet is not the result of neotany, instead the Palaeognathae and Neognathae palets are two separate evolutionary solutions to the same problem (Gusseklo 2001, Gussekloo and Bout 2002). The Palaeognathous PPC can be defined as having a large processus basipterygoideus, a relatively short processus orbitalis quadrati, a broad and rostrally situated pterogoid-palet articulation, relatively broad pterygoids and a broad vomer. The common ancestor of both types would have had all of the elements needed to create either morphology: presence of a complete vomeral maxilary bar, a vomer, a processes basipterygoideus, and holorhinal nostril (See Gussekloo, S. W. S., Vosselman, M. G. & Bout, R. G. (2001), figures 1 and 2:

The Tinamou, they say meets this qualification, posessing: a complete Paleognathous PPC, a holorhinal nostril, and a complete lateral bar. However, the tinamou does not show up in the fossil record until the Miocene. Gussekloo suggests that the bifucation took place in the Cretaceous. Dyke suggests that only the most basal avian lineages existed in the Creataceous, and that radiations of more derived land birds occurred in the early Tertiary.
I believe that Dyke would place the struthioniforms as follows:

Ornithurae(Ornithuromorpha) |--+--Patagopteryx |--Vorona `--+--Hesperornis `--+--Ambiortus |--Ichtyornis `--Neornithes (Primitive Clades) |--Palaeognathae | |--Struthioniforms | `--Tinamiforms `Neognathae |--Anseriforms |--Galliforms Neoaves |--Pelecaniformes |--Gruiforms (Derived Clades)

Additional references:
Cooper et al. 1992. Independent Origins of the New Zealand Moas and Kiwis. Proc. Adal Sci Cad USA 8741-8744.

Cooper, Allen, Charles Lalueza-Fox, Simon Anderson, Andrew Rambaut, Jeremy Austin, and Ryk Ward. 2001. Complete mitochrondrial genome sequences of two extinct moas clarify ratite evolution. Nature 409, 704-707 (2001).

Dyke, G. J. 2001. The evolutionary radiation of modern birds: systematics and patterns of diversification. Geological Journal 36, 305-315.

Dyke, G. J. 2003. The fossil record and molecular clocks: basal radiations within Neornithes. In Smith, P. and Donoghue, P (eds) Telling the Evolutionary Time - Molecular Clocks and the Fossil Record. Taylor and Francis (London), pp. 263-278.

Haddrath, O. and Baker, A. J. 2001. Complete mitochondrial DNA genome sequences of extinct virds: ratite phylogenetics and the > vicariance biogeography hypothesis. _Proc. R. Soc. Lond. B_ 268 (1470), > 939-945.
(I do not have a copy of this, comment from the abstract)

Houde, P. 1988. Paleognathous birds from the Early Tertiary of the Northern Hemisphere. Publications of the Nuttall Ornithologoical Club, Vol 22. Cambridge, Mass: Nuttall Ornithological Club.

Houde, Peter. 1986. Ostrich Ancestors found in the Northern Hemisphere suggest new hypothosis of ratite origins. Nature Vol. 324. 11 December 1986.

Tuinen, Marcel, Charles G. Sibley, and S. Blair Hedges. 1998. Phylogeny and Biogeography of Ratite Birds Inferred from DNA Sequences of the Mitochondrial Riosomal Genes. Mol Biol. Evol. 15(4):370-376.


Evan Robinson

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