Abstract

A new data set of appendicular skeletal characters
in a representative sample of fin- and limb-bearing taxa
spanning the fish–tetrapod transition is used to test the phylogenetic
utility of both girdle and paired appendage data. A
cladistic analysis retrieves most traditional taxonomic
groups, highlighting only partial conflict along internal
branches that sit deep in the phylogeny, and good to moderate
support for within-group branching sequences. Most of
the conflict affects stem tetrapods from the Devonian, with
Ichthyostega, Hynerpeton and the Catskill humerus as particularly
unstable taxa. Phylogenetic constraints that reflect
recent hypotheses of relationships do not entail significant
differences (in terms of character fit) from the shortest trees.
The data set is subjected to an analysis of trait compatibility.
Results show that predefined character partitions (i.e. shoulder
girdle, pelvic girdle, anterior paired appendages, posterior
paired appendages and autopodium plus general
features) do not reveal strong within-set correlation or any
correlation with global character compatibilities. In addition,
character clusters exhibit little logical and ⁄ or functional
interdependence.