Updated November 17, 2020
with new data nesting the stilt, Himanopterus, with hummingbirds, both descending from Eocene Eocypselus.
Hummingbirds are the tiniest of living birds.
They are famous for hovering with wings beating so rapidly they essentially blur from view. Today hummingbirds live only in the New World.
Prum et al. 2015
based on DNA, nested hummingbirds with swifts and these nested with the nocturnal nightjars. That is the traditional nesting.
In the LRT 2015
based on morphology, hummingbirds nest with the extinct Eocypselus (Fig. 4, 50 mya) and the sea gull, Chroicocephalus (Figs. 1, 3; extant). Mayr 2004 reported on an Old World hummingbird, Eurotrochilus inexpectatus (Fig. 4; 30 mya), from the early Oligocene. Elsewhere on the cladogram, swifts nest with owls and owlets in the large reptile tree (LRT, 1129 taxa then, 1760+ taxa now).
It should be noted
that swifts do not feed while hovering. They speed through the air snatching insects in flight. On the other hand, gulls do hover (Figs. 1, 2). Gulls appear to hover only in a breeze, which is often present at shorelines. Thus gulls represent the awkward origin of hummingbird hovering, which improved with faster wingbeats. a deeper sternum and a smaller size. Stilts probe mud like hummingbirds probe flowers with their long slender beak.
Fossils tell us
that hummingbird-sized specimens, like Eocypselus (Figs. 3, 4), lived 50 mya and probably originated much earlier. One-sixth the size of the small gull, like Hydrocoloeus (Figs. 2, 3), Eocypselus had a relatively short, small beak and shorter legs, though still longer than the wings.
Of course, small size is key to hummingbird evolution.
At this point, I’m not aware of any gulls smaller than Hydrocoloeus, whether extant or in the fossil record. Stilts are taller, but that is due to those extreme legs and feet.
The fossil Eutrochilus
(Fig. 4, Mayr 2004) bridges the time gap between Eocypselus and extant hummingbirds and would appear to be a complete and fully realized hummingbird itself, living some 30 mya, while originating much earlier. Eocypselus (Fig. was not much different in size or morphology.
Old World vs. New World
So, based on Eutrochilus, hummingbirds used to be in Europe. Now they are restricted to the New World. Why? There is a long list of hummingbird eaters online here. Something killed European hummingbirds in the Old World.
Mayr G 2004. Old World fossil record of modern-type hummingbirds. Science 304:861–864,
Ksepka DT, Clarke JA, Nesbitt SJ, Kulp FB and Grande L. 2013. Fossil evidence of wing shape in a stem relative of swifts and hummingbirds (Aves, Pan-Apodiformes). Proceedings of the Royal Society B: Biological Sciences 280 (1761): 20130580. doi:10.1098/rspb.2013.0580. Supplementary materials here.
McGuire JA et al. (7 coauthors) 2014. Molecular Phylogenetics and the Diversification of Hummingbirds. Current Biology, 2014; DOI: 10.1016/j.cub.2014.03.016
Zhang Z, Feduccia A and James HF 2012. A Late Miocene Accipitrid (Aves: Accipitriformes) from Nebraska and Its Implications for the Divergence of Old World Vultures. PLoS ONE7(11): e48842. https://doi.org/10.1371/journal.pone.0048842