And the osprey,
Pandion haliaetus (Linneaus 1758) joins the large reptile tree (LRT, 1124 taxa) at the base of (owls + swifts) + (Old World vultures + falcons). The secretary bird, Sagittarius, and the terror birds are proximal outgroups.
So the osprey is a basal
short-legged, arboreal birds-of-prey.
“The osprey differs in several respects from other diurnal birds of prey. Its toes are of equal length, its tarsi are reticulate, and its talons are rounded, rather than grooved. The osprey and owls are the only raptors whose outer toe is reversible, allowing them to grasp their prey with two toes in front and two behind. It has always presented something of a riddle to taxonomists, but here it is treated as the sole living member of the family Pandionidae, and the family listed in its traditional place as part of the order Falconiformes.”
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.