Systematics
- For genera sometimes split from Vanellus, see there.
While authorities generally agree that there about 25 species of Vanellinae, classifications within the subfamily remain confused. At one extreme, Peters recognised no less than 20 different genera for the birds listed in 2 genera here; other workers have gone so far as to group all the "true" lapwings (except the Red-kneed Dotterel) into the single genus Vanellus. Current consensus favors a more moderate position, but it is unclear which genera to split. The Handbook of Birds of the World provisionally lumps all Vanellinae into Vanellus except the Red-kneed Dotterel, which is in the monotypic Erythrogonys. Its plesiomorphic habitus resembles that of plovers, but details like the missing hallux (hind toe) are like those of lapwings: it is still not entirely clear whether it is better considered the basalmost plover or lapwing.
Many coloration details of the Red-kneed Dotterel also occur here and there among the living members of the main lapwing clade. Its position as the most basal of the living Vanellinae or just immediately outside it thus means that their last common ancestor - or even the last common ancestor of plovers and lapwings - almost certainly was a plover-sized bird with a black crown and breast-band, a white feather patch at the wrist, no hallux, and a lipochromic (probably red) bill with a black tip. Its legs were most likely black or the color of the bill's base.
Read more about this topic: Lapwing