Editing Pygmy marmoset (section)

== Evolution and taxonomy ==

Debate has arisen among primatologists concerning the proper genus in which to place the pygmy marmoset. An examination of the interstitial [[retinol binding protein]] nuclear gene (''IRBP'') in three marmoset species showed that ''[[Callithrix]]'' as constructed in the 1990s also needed to include ''C. pygmaea'' to be [[monophyletic]], and that the times of separation of ''pygmaea'' and the ''argentata'' and ''jacchus'' species groups from one another are less than 5 million years ago, as might be expected for species of the same genus.<ref name="Barroso_etal1997">{{Cite journal | last1 = Barroso | first1 = C. M. L. | last2 = Schneider | first2 = H. | last3 = Schneider | first3 = M. P. C. | last4 = Sampaio | first4 = I. | last5 = Harada | first5 = M. L. | last6 = Czelusniak | first6 = J. | last7 = Goodman | first7 = M. | title = Update on the phylogenetic systematics of New World monkeys: Further DNA evidence for placing the pygmy marmoset (''Cebuella'') within the genus ''Callithrix''| journal = International Journal of Primatology | volume = 18 | issue = 4 | pages = 651–674| year = 1997 | doi = 10.1023/A:1026371408379 | s2cid = 24741900 }}</ref> However, subsequent separation of the ''argentata'' and ''jacchus'' species groups into different genera (the ''argentata'' group having been moved to ''Mico'') justifies maintaining a separate genus for the pygmy marmosets, as ''Callithrix'' is no longer [[paraphyletic]].<ref name="IUCN">{{cite iucn |author=Rylands, A.B. |author2=de la Torre, S. |year=2008 |title=''Cebuella pygmaea'' ssp. ''pygmaea'' |page=e.T136926A4350391 |doi=10.2305/IUCN.UK.2008.RLTS.T136926A4350391.en}}</ref>

The two species described of the pygmy marmoset are:<ref name="MSW3" /><ref name=SAP />
{{Species table |genus=[[Cebuella]] |authority-name= [[John Edward Gray|Gray]] |authority-year=1866 |species-count=two|no-note=y|narrow-percent=75}}
{{Species table/row
|name=Western pygmy marmoset |binomial=[[Cebuella pygmaea]]
|image=File:Pygmy Marmoset (5336773146).jpg |image-size=180px |image-alt=
|authority-name=Spix  |authority-year=1823 |authority-not-original=yes
|range= Bolivia, Brazil, Colombia, Ecuador and Peru
|range-image=
|range-image-size=180px
|size=
|habitat=
|hunting=
|iucn-status= VU
|population=
|direction=
}}
{{Species table/row
|name=Eastern pygmy marmoset |binomial=[[Cebuella niveiventris]]
|image=File:Pygmy Marmoset (19012690354).jpg |image-size=180px |image-alt=
|authority-name=Lönnberg |authority-year=1940 
|range= Peru, Brazil, Ecuador and Bolivia.
|range-image=
|range-image-size=180px
|size=
|habitat= 
|hunting=
|iucn-status= VU
|population=
|direction=
}}
{{Species table/end}}

Few morphological differences occur between these species, as they may differ only slightly in color, and they are separated only by geographical barriers, including large rivers in South America.<ref>{{cite book|last=Groves|first=Colin P.|title=Primate Taxonomy|year=2001|publisher=Smithsonian}}</ref>

The evolution of this genus diverged in terms of body mass from typical primates, with a high rate of body-mass reduction. This involves large decreases in prenatal and postnatal growth rates, furthering the thought that progenesis played a role in the evolution of this animal.<ref>{{cite journal | last1 = Montgomery | first1 = S. H. | last2 = Mundy | first2 = N. I. | year = 2013 | title = Parallel episodes of phyletic dwarfism in callitrichid and cheirogaleid primates | journal = Journal of Evolutionary Biology | volume = 26 | issue = 4| pages = 810–819 | doi = 10.1111/jeb.12097 | pmid=23442013| doi-access = free }}</ref>