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RE: likelyhood for these avian clades?




From: "Brian Lauret" <zthemanvirus@hotmail.com>
Reply-To: zthemanvirus@hotmail.com
To: dinosaur@usc.edu
Subject: likelyhood for these avian clades?
Date: Thu, 20 May 2004 18:58:25 +0200

There are a certain number of clades I've seen proposed on the net and I wondered if these are really likely, or perhaps likely in a somewhat altered form:


clade (Staethornithidae(Trogonidae))


This most interesting hypothesis stems from Mayr (2003b) and was recovered by Mayr & Clarke (2003). Trogons have been traditionally considered to be coraciiform birds, with which they share a number of traits including the morphology of the stapes (Feduccia 1975a, 1977d, 1979c, 1980, 1996) and details of pelvic limb myology (Maurer & Raikow 1981). Sibley & Ahlquist (1990) also recovered a similar topology in their DNA-DNA hybridization studies. Mayr (2003b) disputed that characters used in these analyses and analysis of complete cytochrome b and ribosomal RNA sequence data in Espinosa de los Monteros (2000) also failed to recover a trogon/coraciiform relationship. Johansson et al. (2001), however, did find a sister group relationship between trogons and a melange of coraciiform and piciform birds, while arguing that Steatornithidae was the sister clade thereto. Mayr & Clarke (2003) supported an oilbird/trogon nexus with the following characters:

1. Distinct naso-frontal hinge present in skull
2. Internasal septum largely ossified
3. Palatinum pars lateralis small or absent (this might be a plesiomorphic attribute)
4. Palatines completely fused along midline
5. Columella with large hollow, bulbous basal and footplate area which exhibits large fenestra on one side.
6. Fossa for M. brachii deep and sharply defined

Given the conflicting evidence I would regard the position of Trogonidae vis-a-vis Steatornithidae contentious as of yet, with either the coraciiform affinities of Trogonidae or the model favored by Mayr (2003b) equally plausible. Further systematic comparison of Steatornithidae with Strigiformes (as suggested by Mayr 2002a) would be useful in determining the phylogenetic relationships of oilbirds.

JGK

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