View source for Sciurini

{{Short description|Tribe of rodents}}
{{Automatic taxobox
| fossil_range = {{Fossil range|Late Eocene|present|ref=<ref name=EK775/>}}
| image = Eastern Gray Squirrel 800.jpg
| image_caption = [[Eastern gray squirrel]] (''Sciurus carolinensis'')
| taxon = Sciurini
| authority = [[Gotthelf Fischer|G. Fischer]], 1817
| type_genus = ''[[Sciurus]]''
| type_genus_authority = [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]
| subdivision_ranks = [[Genus|Genera]]
| subdivision = 
*?''[[Douglassciurus]]'' (extinct)
*?''[[Freudenthalia]]'' (extinct)
*''[[Microsciurus]]''
*''[[Miosciurus]]'' (extinct)
*''[[Plesiosciurus]]'' (extinct)
*''[[Rheithrosciurus]]''
*''[[Sciurus]]''
*''[[Syntheosciurus]]''
*''[[Pine squirrel|Tamiasciurus]]''
| diversity_link = 
| diversity_ref = <ref name=TH754/>
| diversity = Five living genera and about forty species.
}}

'''Sciurini''' ({{IPAc-en|s|I|'|j|u:|r|I|n|i:}}) is a [[tribe (taxonomy)|tribe]] that includes about forty species of [[squirrel]]s,<ref name=TH754>Thorington and Hoffmann, 2005, p.&nbsp;754</ref> mostly from the Americas. It includes five living genera—the American dwarf squirrels, ''[[Microsciurus]]''; the Bornean ''[[Rheithrosciurus]]''; the widespread American and Eurasian tree squirrels of the genus ''[[Sciurus]]'', which includes some of the best known squirrel species; the Central American ''[[Syntheosciurus]]''; and the American pine squirrels, ''[[Pine squirrel|Tamiasciurus]]''. Like other [[arboreal]] squirrels, they are sometimes referred to as [[tree squirrel]]s.<ref>Thorington and Ferrell, 2006, p.&nbsp;18</ref>

==Taxonomy==
The name "Sciurini" was first employed by [[Hermann Burmeister]] in 1854, who used it for the entire squirrel family.<ref>Burmeister, 1854, p.&nbsp;145; McKenna and Bell, 1997, p.&nbsp;122</ref> In his influential 1945 classification of mammals, [[George Gaylord Simpson]] included four [[genus|genera]] of squirrels in Sciurini, which he recognized as one of eight [[tribe (taxonomy)|tribes]] within the subfamily Sciurinae (including all squirrels except the [[flying squirrel]]s): ''[[Sciurus]]'', ''[[Syntheosciurus]]'', ''[[Microsciurus]]'', and ''[[Sciurillus]]''. He also classified ''[[Rheithrosciurus]]'' as "?Sciurini ''[[incertae sedis]]''" (of uncertain placement).<ref name=S78>Simpson, 1945, p.&nbsp;78</ref> This grouping derives from [[Reginald Innes Pocock]], who united these squirrels in 1923 as the subfamily Sciurinae.<ref name=M177>Moore, 1959, p.&nbsp;177</ref>

In 1959, [[Joseph Curtis Moore]] published a review of the interrelationships of the squirrels. His definition of Sciurini was similar to Simpson's, but he no longer considered ''Rheithrosciurus'' to be ''incertae sedis''. He noted that the members of Sciurini were united only by the possession of a special type of [[baculum]] (penis bone).<ref>Moore, 1959, pp.&nbsp;177–178</ref> He also divided the tribe into [[subtribe]]s, producing the following classification:<ref>Moore, 1959, pp.&nbsp;177–180</ref>
*Tribe '''Sciurini'''
**Subtribe Sciurina
***Genus ''[[Sciurus]]''
***Genus ''[[Guerlinguetus]]'' (currently included in ''Sciurus'')<ref name=TH758>Thorington and Hoffmann, 2005, p.&nbsp;758</ref>
***Genus ''[[Rheithrosciurus]]''
**Subtribe Microsciurina
***Genus ''[[Microsciurus]]''
***Genus ''[[Syntheosciurus]]'' 
**Subtribe Sciurillina
***Genus ''[[Sciurillus]]''

In their 1997 update to Simpson's classification, McKenna and Bell retained a similar definition for Sciurini, but also included several extinct genera, as follows:<ref name=MC122>McKenna and Bell, 1997, p.&nbsp;122</ref>
*Tribe '''Sciurini'''
**''[[Freudenthalia]]'' (fossil, early [[Miocene]] of Europe; assignment to Sciurini "uncertain")<ref name=MC122/>
**''[[Rheithrosciurus]]''
**''[[Plesiosciurus]]'' (fossil, middle Miocene of Asia)
**Subtribe Sciurina
***''[[Douglassciurus]]'' (fossil, late [[Eocene]] of North America; McKenna and Bell used ''[[Douglassia]]'', a [[preoccupied name]] replaced by ''Douglassciurus'')<ref name=EK400>Emry and Korth, 2001</ref>
***''[[Protosciurus]]'' (fossil, early [[Oligocene]] to early Miocene of North America)
***''[[Miosciurus]]'' (fossil, early Miocene of North America)
***''[[Sciurus]]'' (including ''Syntheosciurus'')
***''[[Microsciurus]]''
**Subtribe Sciurillina
***''[[Sciurillus]]''
{{cladogram|caption=Phylogeny of the squirrels.<ref name=MR-Sea>Mercer and Roth, 2003; Steppan et al., 2004</ref>
|clades=
{{clade|label1=[[Sciuridae]]
  |1={{clade
     |1=''[[Sciurillus]]''
     |2=''[[Ratufa]]''
     |label3=&nbsp;&nbsp;
     |3={{clade
        |1=[[Callosciurinae]]
        |2=[[Xerinae]]
        |label3=[[Sciurinae]]
        |3={{clade
           |1=[[Pteromyini]]
           |label2='''Sciurini'''
           |2={{clade|1=''[[Tamiasciurus]]''|2=''[[Sciurus]]''{{#tag:ref|''[[Syntheosciurus]]'', ''[[Rheithrosciurus]]'', and ''[[Microsciurus]]'' appear among the species of ''Sciurus''.<ref name=MR-Sea/>|group=fn}}
              }}
           }}
        }}
     }}
}}
}}
In the early 2000s, several studies were published using DNA sequences to study the interrelationships of squirrels. Two, published in 2003 and 2004 and both based on several different genes, produced largely concordant results, concluding that ''Sciurillus'' is not related to other Sciurini, but rather forms one of the most distinctive lineages of all squirrels; that ''[[Tamiasciurus]]'' is the closest relative to the other Sciurini; and that the group of ''Tamiasciurus'' and the other Sciurini is most closely related to the [[flying squirrel]]s.<ref name=MR-Sea/> The authors of the 2004 study formalized these results into a revised classification of squirrels. They removed ''Sciurillus'' from Sciurini, placed ''Tamiasciurus'' in it, and classified Sciurini with the flying squirrels (tribe Pteromyini) in a subfamily Sciurinae.<ref name=Sea715>Steppan et al., 2004, p.&nbsp;715</ref> Their classification was adopted in the 2005 third edition of ''[[Mammal Species of the World]]''<ref name=TH754/> and remains current.

The same studies also provided insights into the interrelationships of genera within Sciurini. ''Microsciurus'', ''Syntheosciurus'', and ''Rheithrosciurus'' all appear among the various species of ''Sciurus'' included, making the latter genus [[paraphyly|paraphyletic]]; additionally, the two species of ''Microsciurus'' included in Mercer and Roth's 2003 study did not cluster with each other.<ref name=MR-Sea/> A [[morphology (biology)|morphological]] study of [[Central America]]n Sciurini also found that ''Microsciurus'' and ''Syntheosciurus'' are part of the ''Sciurus'' radiation, and suggested that ''Syntheosciurus'' be lumped into ''Sciurus'' while further work is needed on ''Microsciurus''.<ref name=VCR>Villalobos and Cervantes-Reza, 2007</ref> In a 2008 monograph on [[Brazil]]ian rodents, Bonvicino and others considered ''[[Guerlinguetus]]'' and ''[[Urosciurus]]'', conventionally placed in ''Sciurus'', as separate genera.<ref>Bonvicino et al., 2008, pp.&nbsp;15–16, 18</ref>

===Fossil history===
''[[Douglassciurus]]'', a fossil from the late [[Eocene]] (about 36 million years ago) of [[Wyoming]], [[Montana]], and [[Saskatchewan]], is so similar to living ''Sciurus'' that the latter has been considered a [[living fossil]].<ref>Mercer and Roth, 2003, p.&nbsp;1569; Emry and Korth, 1996, p.&nbsp;775</ref> but some exclude this animal from the squirrel family because of several primitive characters.<ref>Thorington and Ferrell, 2006, p.&nbsp;23</ref> Emry and Korth, who re-described the animal in 1996, classified it within Sciurini<ref name=EK775>Emry and Korth, 1996, p.&nbsp;775</ref> and speculated that other squirrels may have evolved from animals similar to Sciurini squirrels.<ref name=EK778>Emry and Korth, 1996, p.&nbsp;778</ref> The [[Oligocene]] to early [[Miocene]] North American genera ''[[Protosciurus]]'' and ''[[Miosciurus]]'' are classified in Sciurini and may have given rise to the earliest known member of ''Sciurus'', ''[[Sciurus olsoni|S.&nbsp;olsoni]]'' from the early late Miocene (about 10 million years ago) of [[Nevada]]. In [[Europe]], ''Sciurus'' first appears early in the [[Pliocene]]. The 2005 discovery of ''S.&nbsp;olsoni'' provided evidence that the origin of the Sciurini lies in North America.<ref name=Eea235>Emry et al., 2005, p.&nbsp;235</ref>

A Miocene squirrel from [[France]] and [[Spain]], ''[[Freudenthalia]]'', has been tentatively placed in Sciurini.<ref>Cuenca Bescós, 1988, p.&nbsp;92; Aguilar, 2002, p.&nbsp;388</ref> ''[[Plesiosciurus]]'' from the Miocene of [[China]] has been interpreted as a member of Sciurini, but is unlikely to belong to the tribe.<ref name=Eea228>Emry et al., 2005, p.&nbsp;228</ref>

==Footnotes==
{{Reflist|group=fn}}

==References==
{{Reflist|colwidth=30em}}

===Literature cited===
{{Commons category|Sciurini}}
*Aguilar, J.-P. 2002. [http://linkinghub.elsevier.com/retrieve/pii/S0016699502000335 Les sciuridés des gisements karstiques du Miocène inférieur à moyen du sud de la France : nouvelles espèces, phylogénie, paléoenvironnement] (subscription required). Geobios 35:375–394 (in French).
*Bonvicino,  C.R., Oliveira, J.A. and D'Andrea, P.S. 2008. [https://web.archive.org/web/20110706161213/http://bvs1.panaftosa.org.br/local/File/textoc/Roedores_2008.pdf Guia dos Roedores do Brasil, com chaves para gêneros baseadas em characteres externos]. Série de Manuais Técnicos 11:1–120. Rio de Janeiro: Centro Pan-Americano de Febre Aftosa – OPAS/OMS (in Portuguese).
*Burmeister, H. 1854. [https://www.biodiversitylibrary.org/bibliography/13607 Systematische Uebersicht der Thiere Brasiliens, welche während einer Reise durch die Provinzen von Rio de Janeiro und Minas geraës gesammelt oder beobachtet wurden. Erster Theil. Säugethiere (Mammalia)]. Berlin: G. Reimer (in German).
*Cuenca Bescós, G. 1988. [http://www.repository.naturalis.nl/record/317448 Revisión de los Sciuridae del Aragoniense y del Rambliense en la fosa de Calatayud-Montalbán]. Scripta Geologica 87:1–116 (in Spanish).
*Emry, R.J. and Korth, W.W. 1996. [https://www.jstor.org/pss/4523775 The Chadronian ''"Sciurus" jeffersoni'' Douglass, 1901: a new generic name, new material, and its bearing on the early evolution of Sciuridae (Rodentia)]. Journal of Vertebrate Paleontology 16:775–780.
*Emry, R.J. and Korth, W.V. 2001. [http://www.bioone.org/doi/abs/10.1671/0272-4634%282001%29021%5B0400%3ADNNFDE%5D2.0.CO%3B2 ''Douglassciurus'', new name for ''Douglassia'' Emry and Korth, 1996, not ''Douglassia'' Bartsch, 1934] (subscription required). Journal of Vertebrate Paleontology 21(5):400.
*Emry, R.J., Korth, W.W. and Bell, M.A. 2005. [https://www.jstor.org/stable/4524432 A tree squirrel (Rodentia, Sciuridae, Sciurini) from the Late Miocene (Clarendonian) of Nevada] (subscription required). Journal of Vertebrate Paleontology 25(1):228–235.
*McKenna, M.C. and Bell, S.K. 1997. Classification of Mammals: Above the species level. New York: Columbia University Press, 631&nbsp;pp.&nbsp;{{ISBN|978-0-231-11013-6}}
*Mercer, J.M. and Roth, V.L. 2003. [http://sciencemag.org/cgi/content/abstract/299/5612/1568 The effects of Cenozoic global change on squirrel phylogeny] (subscription required). Science 299:1568–1572.
*Moore, J.C. 1959. [http://hdl.handle.net/2246/1265 Relationships among the living squirrels of the Sciurinae]. Bulletin of the American Museum of Natural History 118:157–206.
*Simpson, G.G. 1945. [http://hdl.handle.net/2246/1104 The principles of classification and a classification of mammals]. Bulletin of the American Museum Natural History 85:1–350.
*Steppan, S.J., Storz, B.L. and Hoffmann, R.S. 2004. [http://www.bio.fsu.edu/~steppan/Steppan_et_al_Sciuridae.pdf Nuclear DNA phylogeny of the squirrels (Mammalia: Rodentia) and the evolution of arboreality from c-myc and RAG1]. Molecular Phylogenetics and Evolution 30:703–719.
*Thorington,  R.W. Jr. and Hoffmann, R.S. 2005. Family Sciuridae. Pp.&nbsp;754–818 in Wilson, D.E. and  Reeder, D.M. (eds.). [http://www.bucknell.edu/msw3 Mammal Species of the World: a taxonomic and  geographic reference. 3rd ed].  Baltimore: The Johns Hopkins University Press, 2 vols., 2142 pp.&nbsp;{{ISBN|978-0-8018-8221-0}}
*Thorington, R.W. and Ferrell, K. 2006. [https://books.google.com/books?id=Y7cuEWCWpLMC Squirrels: the animal answer guide]. Johns Hopkins University Press, 183 pp.&nbsp;{{ISBN|978-0-8018-8402-3}}
*Villalobos, F. and Cervantes-Reza, F. 2007. [http://www.mapress.com/zootaxa/2007f/z01525p040f.pdf Phylogenetic relationships of Mesoamerican species of the genus ''Sciurus'' (Rodentia: Sciuridae)]. Zootaxa 1525:31–40.

{{S. Sciurinae1 nav}}
{{Taxonbar|from=Q2294121}}

[[Category:Tree squirrels|*]]
[[Category:Mammal tribes]]
[[Category:Extant Eocene first appearances]]
[[Category:Taxa named by Gotthelf Fischer von Waldheim]]