Editing Loon (section)

===Fossil record===
{{Cladogram|caption=Cladogram of the ''Gavia'' species with the inclusion of fossil species.<ref name="Olson&Rasmussen2001">{{Cite journal |last1=Olson |first1=S. L. |last2=Rasmussen |first2= P. C. |year=2001 |title=Miocene and Pliocene birds from the Lee Creek Mine, North Carolina. |journal=Smithsonian Contributions to Paleobiology |volume = 90 |issue = |pages = 233–365|doi=10.5479/si.00810266.90.233 |url=https://www.biodiversitylibrary.org/part/351988 }}</ref>
|clades=
{{clade
|1={{clade
   |1={{clade
      |1=†''Gavia egeriana''
      |2={{clade
         |1=†''G. schultzi''
         |2={{clade
            |1={{clade
               |1=†''G. howardae''
               |2=''G. stellata'' }}
            |2={{clade
               |1=†''G. brodkorbi''
               |2=†''G. paradoxa''
               |3={{clade
                  |1={{clade
                     |1=†''G. moldavica''
                     |2={{clade
                        |1=†''G. concinna''
                        |2={{clade
                           |1=''G. arctica''
                           |2=''G. pacifica'' }} }} }}
                  |2={{clade
                     |1=†''G. fortis''
                     |2={{clade
                        |1=''G. adamsii''
                        |2=''G. immer''}} }} }} }}
}}
}}
}}
}}
}}
}}

Nearly ten prehistoric species have been named to date in the genus ''Gavia'', and about as many undescribed ones await further study. The genus is known from the Early Miocene onwards, and the oldest members are rather small (some are smaller than the [[red-throated loon]]). Throughout the late [[Neogene]], the genus by and large follows [[Cope's Rule]] (that population lineages tend to increase in body size over evolutionary time). [[File:Gavia fossil Vienna.jpg|thumb|Fossil of ''[[Gavia schultzi|G. schultzi]]'' in Vienna]] 

'''List of fossil ''Gavia'' species'''
* †''[[Gavia brodkorbi|G. brodkorbi]]'' <small>Howard, 1978</small> (Late Miocene of Orange County, United States)
* †''G. concinna'' <small>[[Alexander Wetmore|Wetmore]], 1940</small> (Late Miocene/Early Pliocene of west and east United States)
* †''[[Gavia egeriana|G. egeriana]]'' <small>Švec, 1982</small> (Early Miocene of Czechoslovakia ?and Cheswold, Delaware, United States –? Yorktown Early Pliocene of Lee Creek Mine, North Carolina, United States)<ref>A small loon, smaller than ''G. howardae'': [[#Olson|Olson (1985: pp. 213–214)]], [[#Rasmussen|Rasmussen (1998)]], [[#Mlikovsky|Mlíkovský (2002: p. 63)]]</ref>
* †''[[Gavia fortis|G. fortis]]'' <small>[[Storrs Olson|Olson]] & [[Pamela C. Rasmussen|Rasmussen]], 2001</small> (Yorktown Early Pliocene of Lee Creek Mine, North Carolina, United States)<ref name="Olson&Rasmussen2001"/>
* †''[[Gavia howardae|G. howardae]]'' <small>[[Pierce Brodkorb|Brodkorb]], 1953</small> ([[San Diego Formation]], California<ref name="Brodkorb1953">{{Cite journal |last1=Brodkorb |first1=P. |year=1953 |title=A review of the Pliocene loons. |journal=The Condor |volume = 54 |issue = 4 |pages = 211–214|doi=10.2307/1364769 |jstor=1364769 }}</ref> and Yorktown Formation, North Carolina<ref name="Olson&Rasmussen2001"/>
* †''[[Gavia moldavica|G. moldavica]]'' <small>Kessler, 1984</small> (Late Miocene of Chişinău, Moldova)<ref name = milkovsky2002-64>[[#Mlikovsky|Mlíkovský (2002: p. 64)]]</ref>
* †''G. palaeodytes'' <small>Wetmore, 1943</small> (Bone Valley Early/Middle Pliocene of Pierce, Florida, United States)<ref>Known from a few limb bones. Roughly similar in size to [[Pacific loon]], but proportions seem to differ and apparently not close to any living species except maybe [[red-throated loon]]: [[#Brodkorb1953|Brodkorb (1953)]].</ref>
* †''G. paradoxa'' <small>Umanska, 1981</small> (Late Miocene of Čebotarevka, Ukraine)<ref name = milkovsky2002-64/>
* †''[[Gavia schultzi|G. schultzi]]'' <small>Mlíkovský, 1998</small> (Middle Miocene of Sankt Margarethen, Austria)<ref name=M98>{{Cite journal|last1=Mlíkovský|first1=Jiří|year=1998|title=A new loon (Aves: Gaviidae) from the middle Miocene of Austria|url=http://verlag.nhm-wien.ac.at/pdfs/99A_331339_Mlikovsky.pdf|journal=Annalen des Naturhistorischen Museums in Wien, Serie A|pages=331–339}}</ref>

'''List of fossil ''Gavia'' specimens'''
* ''Gavia'' sp. (Early-Middle Miocene of eastern United States)<ref>A tiny loon, smaller and more delicate than even the [[sympatric]] contemporary ''G. egeriana''-like birds. Probably a distinct species – [[sexual dimorphism]] in loons is not very pronounced: [[#Rasmussen|Rasmussen (1998)]].</ref>
* ''Gavia'' sp. (Calvert Middle Miocene ?or Pleistocene of Maryland, United States) – same as ''Gavia'' cf. ''immer'' below?<ref>[[USNM]] 16612, [[Anatomical terms of location#Proximal and distal|distal]] right [[tibiotarsus]]. Smaller than [[common loon]]; the polished-bone look and large size of the specimen makes a Miocene origin rather unlikely: Wetmore (1941), [[#Olson|Olson (1985: p. 214)]].</ref>
* ''Gavia'' spp. (Middle Miocene of Steinheim, Germany) – three species<ref name = milkovsky2002-64/>
* ''Gavia'' sp. (Early Pliocene of Empoli, Italy)<ref>Known from a skull very similar to the [[black-throated loon]]. Initially assigned to ''G. concinna'', but this is not very likely: [[#Mlikovsky|Mlíkovský (2002: p. 64)]], and see also at ''"Gavia" portisi''.</ref>
* ''Gavia'' sp. (Early Pliocene of Kerč Peninsula, Ukraine)<ref name=milkovsky2002-64/>
* ''Gavia'' cf. ''concinna'' (San Diego Middle/Late<ref name=":0">{{Cite web|url=https://sora.unm.edu/sites/default/files/journals/condor/v055n04/p0211-p0214.pdf|title=A REVIEW OF THE PLIOCENE LOONS|last=BRODKORB|first=PIERCE|date=July 1953|website=Searchable Ornothological Research Archive}}</ref><!-- only Late? --> Pliocene of San Diego, California, United States) – two species?<ref>Initially in part (specimens [[LACM]] 2110, 2142) assigned to ''G. concinna'', but apparently one or two undescribed smaller species, about the size of the [[Pacific loon]]: [[#Brodkorb1953|Brodkorb (1953)]], [[#Mlikovsky|Mlíkovský (2002: p. 64)]].</ref>
* ''Gavia'' sp. (Early Pleistocene of Kairy, Ukraine)<ref name=milkovsky2002-64/>
* ''Gavia'' cf. ''immer'' (Pleistocene of California and Florida, United States) – possibly a ''G. immer'' [[paleosubspecies]]<ref name=b53>[[#Brodkorb1953|Brodkorb (1953)]]</ref>

''"Gavia" portisi'' from the [[Late Pliocene]] of [[Orciano Pisano]], [[Italy]], is known from a [[cervical vertebra]] that may or may not have been from a loon. If so, it was from a bird slightly smaller than the [[common loon]]. Older authors were quite sure the bone was indeed from a ''Gavia'' and even considered ''G. concinna'' a possibly [[junior synonym]] of it. This is now regarded as rather unlikely due to the quite distinct range and age. The [[Early Pliocene]] ''Gavia'' skull from [[Empoli]] (Italy) was referred to ''G. concinna'', and thus could conceivably have been of ''"G." portisi'' if that was indeed a loon. The [[holotype]] vertebra may now be lost, which would make ''"G." portisi'' a ''[[nomen dubium]]''.<ref name=b53/><ref>[[#Brodkorb1963|Brodkorb (1963: p. 224)]], [[#Mlikovsky|Mlíkovský (2002: pp. 64, 256–57)]]</ref>