The origin of hummingbirds from sea gulls, part 2

I was looking for a small seagull,
as a transitional taxon leading toward hummingbirds, but I could not find one better than Eocypelus (Fig. 1) from the Eocene. Then I looked for a giant hummingbird. That’s when I found Patagona gigas (Fig. 1).

Earlier, with 100 fewer taxa,
the large reptile tree (LRT, 1227 taxa) nested hummingbirds with Chroicocephalus, the extant seagull (Fig. 1) here.

Phylogenetic miniaturization
(also called the Lilliput effect), is a key driver in the genesis of new clades. This neotonous trend also brought us hummingbirds… and tiny hummingbirds, including the smallest of all birds, the bee hummingbird (genus: Mellisuga, Fig. 1). Eocypselus more clearly represents phylogenetic miniaturization due to its short rostrum. Thereafter the descendants of Eocypselus leading toward hummingbirds developed a longer rostrum, like that of Patagona. Otherwise their skulls are about the same size. Perhaps this was the transition point leading to nectar feeding, rather than sea dipping.

Patagona has a relatively slow wing beat
while hovering, only 15 wing beats per second. According to Wikipedia, “Hummingbird muscle fibres are filled with mitochondria (50% by volume) enabling high frequency wing beats to be sustained over extended periods using oxidative energy.” The range of this genus extends along the Pacific side of the Andes from Ecuador to mid-Chile.

The Andean gull (Chroicocephalus serranus) has a similar range and, unusual for a gull, breeds inland in mountain areas and can be found around rivers, lakes, marshes and pasturelands. It is an insectivore, sometimes aerially and otherwise on fields and grasslands. Distinct from hummingbirds, the Andean gull swims like a duck. But hummingbirds do like bird baths.

References

wiki/Hummingbird
wiki/Archilochus
wki/Eocypselus_rowei
wiki/Patagona
wiki/Mellisuga
wiki/Black-headed_gull