Mergellus

{{Short description|Genus of duck}}

{{Automatic taxobox

| image = Male Smew on the pond.jpg

| image_caption = Smew (Mergellus albellus)

| taxon = Mergellus

| authority = Selby, 1840

| subdivision_ranks = Species

| subdivision =

• Mergellus albellus
• †Mergellus mochanovi

}}

Mergellus is a genus of duck. The smew (Mergellus albellus) is the only living species, but an extinct species known as Mergellus mochanovi has also been described from Late Pleistocene deposits in the Yakutia region of Russia.{{cite journal |last1=Zelenkov |first1=N. |title=Two New Waterfowl Species (Aves: Anseriformes) from the Upper Pleistocene of Yakutia: The First Extinct Species of Quaternary Birds from Russia |journal=Paleontological Journal |date=2014 |volume=48 |issue=6 |pages=645–654 |doi=10.1134/S0031030114060161 |bibcode=2014PalJ...48..645Z |s2cid=85286257 |url=https://www.researchgate.net/publication/268143312}}

An unnamed fossil seaduck, known from a humerus found in the Middle Miocene Sajóvölgyi Formation (Late Badenian, 13–12 million years ago) of Hungary was assigned to Mergus.{{cite journal|author1=Erika, G. |author2=János, H. |author3=Eugen, K. |author4=József, K. |author5=Lukács, M. |author6=Márton, V. |title= The Middle Miocene fossils of Mátraszőlős 1. (a short synopsis) |url=https://www.researchgate.net/publication/270506958_The_Middle_Miocene_fossils_of_Matraszolos_1_a_short_synopsis |journal= Nógrád Megyei Múzeumok Évkönyve |date=1999|volume=23|pages=41-48}} However, the authors included the smew therein, and consequently, the bone is more properly assigned to Mergellus—especially as it was more similar to a smew's than to the Bucephala remains also found at the site.{{Citation needed|date=March 2025}} It is sometimes argued{{cite book |last=Mlíkovský |first=Jiří |year=2002 |title=Cenozoic Birds of the World, Part 1: Europe |publisher=Ninox Press |location=Prague |id={{Listed Invalid ISBN |80-901105-3-8}} |url=http://www.nm.cz/download/JML-18-2002-CBE.pdf|archive-url=https://web.archive.org/web/20160411215341/http://www.nm.cz/download/JML-18-2002-CBE.pdf|archive-date=11 April 2016 |page=123}} that the Mátraszõlõs fossil is too old to represent any of the modern seaduck genera, but apparently these were all well-distinct even back then.{{cite journal |last=Gál |first=Erika |author2=Hír, János |author3=Kessler, Eugén |author4=Kókay, József |date=1998–99 |title=Középsõ-miocén õsmaradványok, a Mátraszõlõs, Rákóczi-kápolna alatti útbevágásból. I. A Mátraszõlõs 1. lelõhely |trans-title=Middle Miocene fossils from the sections at the Rákóczi chapel at Mátraszőlős. Locality Mátraszõlõs I. |journal=Folia Historico Naturalia Musei Matraensis |volume=23 |pages=33–78 |language=Hungarian, English |url=http://www.matramuzeum.hu/Personal/folia/23/03MATSZOLOS.PDF |access-date=2008-08-05 |archive-url=https://web.archive.org/web/20110721111701/http://www.matramuzeum.hu/Personal/folia/23/03MATSZOLOS.PDF |archive-date=2011-07-21 |url-status=dead }}