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The lake duck grows to 36–46 centimetres (14–18 in). Females weigh 510–700 grams (18–25 oz) and males 600–850 grams (21–30 oz). Males can be distinguished from Andean duck (Oxyura ferruginea), a similar species, by being smaller and having a flatter head. [2] Female ducks have an anti-corkscrew vagina made for difficult penetration.
It resembled a small ruddy duck or, even more, an Argentine blue-bill. A larger Middle Pleistocene fossil form from the southwestern United States was described as Oxyura bessomi; it was probably quite close to the ruddy duck. "Oxyura" doksana from the Early Miocene of Dolnice (Czech Republic) cannot be assigned to any anatine subfamily with ...
Lake duck, O. vittata The black-headed duck of Heteronetta is indisputably quite basal , looking more like a typical duck-like Anatidae with a short tail and normal bill. The masked duck of Nomonyx has a more intermediate position; it probably diverged from the lineage leading to the main radiation some time after Heteronetta .
[5] [6] This genus has been separated into 2 groups: the Old World ducks consist of O. maccoa, O. leucocephala (white-headed duck), and O. australis (blue-billed duck), and the New World ducks are O. vittata (lake duck) and O. ferruginea (andean duck). [5] The exact relationships between the different species of Oxyura are still undetermined. [5]
This is a list of the native mammal species recorded in Argentina. As of January 2020, the list contains 402 mammal species from Argentina , of which one is extinct, seven are critically endangered, seventeen are endangered, sixteen are vulnerable, and thirty are near threatened.
The rufous hornero is the national bird of Argentina. This is a list of the bird species recorded in Argentina. The avifauna of Argentina has 1044 confirmed species, of which 18 are endemic, nine have been introduced by humans, 69 are rare or vagrants, two are thought to be extinct, and four and possibly a fifth have been extirpated. An ...
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The only member of the genus Nomonyx, it is intermediate between the rather primitive black-headed duck (Heteronetta) and the very apomorphic true stiff-tailed ducks. It is sometimes included with the latter in the genus Oxyura, but the masked ducks are now considered the descendants of a missing link in the Oxyurini evolution, having changed little for millions of years.