Another several days and nights of more binge study trying to figure out
the topology of the crown birds recovers a slightly more parsimonious hypothesis of interrelationships in this subset of the large reptile tree (LRT, 1865+ taxa; Fig. 1). A few surprises were recovered (see below) and I’m starting to understand why paleontologists gave up studying phenomic traits in bird phylogeny and turned instead to genomic molecules for their cladograms. Earlier struggles with the clade of crown birds can be found here and here.
Problem number 1:
Most birds more or less fuse the premaxilla, maxilla and nasal bones. Cornified tissues (a keratinous beak) sometimes covers the anterior rostrum further obscuring underlying sutures. The extent of the premaxilla vs maxilla varies greatly among birds. Sometimes the two are laminated one atop the other. My bird palate data needed a closer look. Many corrections were made based on comparative anatomy.
Problem number 2.
Although the cladogram (Fig. 1) is fully resolved, the ‘backbone’ of the cladogram still needs to be further strengthened for higher Bootstrap/Jackknife scores. This is probably not the ‘most’ parsimonious tree possible, but a ‘more’ parsimonious tree than previous presentations.
Many surprises popped up,
resolving several issues:
Surprise number 1:
Mousebirds (Urocolius) + quetzals (Pharomachrus), neither of which have long legs, split off early from the rest of the Neognathae (non-ratites) along with tiny Cyrilavis and headless Palaeoglaux, both from the Eocene. Based on phylogenetic bracketing, I hope to find a long-legged mousebird ancestor someday.
Surprise number 2:
The long-legged wading ibis (Threskiornis) now nests with the short-legged grackle (Quiscalus) and the colorful hoopoe (Upupa, Fig. 2). Other workers nested the ibis with pelicans and the hoopoe with either hornbills or kingfishers.
Surprise number 3:
The extinct and flightless solitaire, Pezophaps, is related to the extant screamer (Chauna, Fig. 3), and both arise from more primitive pigeons (Columba). So these are giant pigeons with long legs, a reversal recalling traits from more primitive taxa.
Surprise number 4:
Pigeons now arise from the corn crake (Crex) via the sand grouse (Pterocles). Derived taxa include increasingly more plant matter in their diet. Screamers (Fig. 3) are herbivores, but will feed their young with small captured animals.
Don’t be surprised
to see future changes in the bird clade of the LRT. Based on past experience, the present cladogram (Fig. 1) still needs a bit of polishing. The weakness has never been in the LRT, only in my ability to process the subtle and sometimes barely visible data found in birds. Having a catalog of data for rapid and thorough comparative anatomy in the form of constantly updated images at ReptileEvolution.com has been the key to bringing this ongoing study more and more into focus. Apologies for earlier oversights. I’m learning as I go without much guidance, because there just isn’t that much guidance out there. And there’s lots of convergence.
Added a few days later: