While researching fossil parrots,
in preparation for tomorrow’s post on a giant parrot, I found a paper by Ksepka, Clarke and Grande 2011 describing a Green River “stem parrot.” Cyrilavis colburnorum (early Eocene, Figs. 1–3), turns out to be a barbet, very similar to the extant Psilopogon (Fig. 4) and the coeval Septencoracias, all more closely related to toucans and hornbills, than to parrots (Fig. 5), as we learned here. Like the two tested barbets, the posterior maxilla extends lateral to and below the jawline and terminates without narrowing to a point or suturing to other bones. It just hangs out there (Fig. 4). And that’s just the first of many traits (I don’t want to pull a Larry Martin here, especially since he found the generic type).
Originally the skull was crudely traced
with an outline that failed to identify several bones and misidentified others (Fig. 2). Here (Fig. 2) the bones are colored for identification and reconstruction using DGS.
The Ksepka team also failed to include
barbets in their phylogenetic analysis, only parrots and the outgroups passeriformes, falconidae, and mouse birds in order of increasing distance. They assumed their inclusion set incorrectly. So, once again, taxon exclusion messed up their results. It doesn’t matter if you view the subjects first hand or not, if you don’t include their closest sister taxa.
Type specimen: FMNH PA 754, a skeleton (Figs. 1, 2). Referred specimen: (FMNH PA 722, a complete skull and cervicals (Fig. 3).
I have not tested
the type specimen for the genus, Cyrilavis olsoni (Feduccia and Martin 1976), but the mandible in ventral view is short, straight and sharply tipped, unlike that of parrots, but similar to barbets.
And lest we forget,
like parrots, barbets likewise have a zygodactyl (pedal digit 4 oriented posteriorly) pes (Fig. 5).
The authors discuss the clade, Halcyornithidae,
a clade within Pan-Psittaiformes. The authors report, “All character states potentially supporting halcyornithid monophyly are reconstructed as ambiguous synapomorphies due to the unresolved polytomy containing the five sampled taxa.”
It would probably be interesting
to reconstruct and test other members of the Halcyornithidae to see if they also nest elsewhere in the LRT. We’ll save that for later.
Feduccia A and Martin LD 1976. The Eocene zygodactyl birds of North America (Aves: Piciformes). Smithsonian Contributions to Paleontology, 27:101–110.
Ksepka DK, Clarke JA, and Grande L 2011. Stem parrots (Aves, Halcyornithidae) from the Green River Formation and a combined phylogeny of Pan-Psittaciformes. Journal of Paleontology 85:835-854