*Actually the genus Gyps (Griffin vultures) seems to be the long-necked "vulture" archetype. Ever notice how in cartoons taking place in the American West the vultures are all Griffins? Vultures most certainly are not limited to deserts either, by the way. Aegypiine vultures have some interesting forms and classification controversies, they might get discussed later.
**According to Amadon 1977, at least one authority called the whole group "condors".
Some sources such as Mikko's phylogeny put cathartidae and vulturidae as synonyms. Curiously I've noticed that papers on condors (e.g. Vultur) classify them as vulturids but just about everything else calls them cathartids (e.g. Cathartes aura, the turkey vulture).
But here's the problem: cathartids aren't ciconiiformes either. Popular literature is often outdated and/or a simplification of controversial issues. As a layman, the world of bird phylogeny seems ludicrously confusing and unsettled. A 2006 paper by Ericson et al places them closer to falconiformes (and near-passerines, apparently) than ciconiiformes, although their split apparently took place slightly before the K/T event. Slack et al in a 2007 paper places them in a super-group called the Cracrafti/Conglomerati, although they are positioned in an unstable area in between the falcon/buzzard, gull/oystercatcher, and albatross/loon/stork/penguin lineages. Another paper by Gibb et al in 2007 again with more species included it the synonymous "water-carnivore" super-group and interestingly placed cathartids closer to the seabirds/shorebirds than anything. However, they are still clearly quite isolated. The phylogenetic trees also demonstrates a surprising distance between falcons and buzzards making falconiformes apparently paraphyletic; and demonstrated storks and pelicans grouping rather than with herons, making the traditional ciconiiformes polyphyletic. With more species getting studied, it seems like birds phylogeny is going to need a radical overhaul. Cathartids are now apparently an incertae sedis, although I have seen a proposal for the creation of the order cathartiformes. I've seen this used in a recent Spanish-language publication (here), although widespread acceptance is lacking.
Despite taxonomic upheavals galore the extinct family teratornithidae is still attached to cathartids in recent publications (e.g. Chatterjee 2007). Mikko's phylogeny page places both groups in an encompassing group called vulturides. Usage of that group appears exceedingly rare in publications and I am not certain if it could be synonymous with cathartiformes or not. Despite traditionally being portrayed as super-condors (such as here) tetatorns are now believed to be predatory and distinctive. Given their size (bigger than even super-marabous) they might just be present in the final post of some trilogy.
Let us now discuss cathartids proper, the extinct ones. The reason I don't call cathartids "New World vultures" is that they were certainly present in the Eocene-Oligocene of Europe. To make matters worse, aegypiine vultures are known from both Old and New Worlds from the lower Miocene to Pleistocene, obscuring their "world" of origin (Fedduccia 1974). That's a tale for another day though. Cracraft & Rich in their 1972 paper discuss how for years possible remains of Old World cathartids were discounted or ignored due to their problematic nature (the vice versa was true as well interestingly). Despite their outwards similarity to aegypiines, cathartids are very distinctive from a skeletal standpoint, particularly the shape of the tarsometatarsus and to a lesser degree the tibiotarsus. They named four genera, one of which (Amphiserpentarius) was apparently re-classified as a secretary bird, but according to Mikko's the rest still stand up. [[Edit: Peer editing has revealed to me that the alleged smallest crow-sized cathartid, Plesiocathartes, is a leptosomid. The paper is unfortunately unavailable to me, but see comments]]. The authors raise the remarkable possibility that cathartids in fact originated in Europe in between the late Cretaceous and Eocene and branched out to the New World in the Early Eocene. This was presented as an alternate hypothesis and not a replacement. I haven't seen much more discussion on this, but it should be noted that they used the non-cathartid Neocathartes in their theory. This was alleged to be a "walking turkey vulture" of sorts, but turned out not to be. Sorry for not being able to find the actual paper for that one.
I hope that this was an adequate prelude to the cathartids. There are still some fossil forms that I'll probably cover some time in the future, but I'd like to talk more about extant species. Perhaps I can do a cathartid-of-the-random-time-interval sort of feature. Or maybe not, I like to focus on obscurity...
Oh, I'm not done just yet.
Some free, some not.
Amadon, Dean. 1977. Note on the Taxonomy of Vultures. The Condor. 79: 413-416. Available: Here
Chatterjee, Sankar & Templin, R. Jack & Campbell, Kenneth E. 2007. The aerodynamics of Argentavis, the world's largest flying bird from the Miocene of Argentina. Proceedings of the National Academy of Sciences. Published online (for free) Here
Cracraft, Joel & Rich, Pat Vickers. 1972. The Systematics and Evolution of the Cathartidae in the Old World Tertiary. The Condor. 74: 272-283. Available: Here
Ericson, G.P. et al. 2006. Diversification of Neoaves: integration of molecular sequence data and fossils. Biology Letters. 2: 543-547. Available: Here
Fedduccia, A. 1974. Another Old World vulture from the New World. Wilson Bull. 86: 251-255. Available online Here (for free)
Gibb, Gillian C. et al. 2007. Mitochondrial Genomes and Avian Phylogeny: Complex Characters and Resolvability without Explosive Radiations. Mol Biol Evol. 24: 269-280. Available: Here
Slack, Kerryn E. et al. 2007. Resolving the root of the avian mitogenomic tree by breaking up long branches. Molecular Phylogenetics and Evolution. 42: 1-14. Available: Here