Journal of Mammalian Evolution

, Volume 20, Issue 3, pp 249–261 | Cite as

A New Early Miocene Chinchilloid Hystricognath Rodent; an Approach to the Understanding of the Early Chinchillid Dental Evolution

  • Alejandro G. Kramarz
  • María G. Vucetich
  • Michelle Arnal
Original Paper


Chinchilloidea is an emblematical group of caviomorph rodents characterized by euhypsodont, laminated cheek teeth. Recent molecular analyses proposed that the extant Dinomys (and implicitly its fossil allies) is also part of this group. Their relationships with fossil caviomorphs with less derived dental features are still obscured by the deficiency of the fossil record documenting its early dental evolution. The new genus and species Garridomys curunuquem, from the early Miocene deposits of the Cerro Bandera Formation, northern Patagonia, is here described. It is represented by numerous mandible and maxillary remains with dentition. This species has protohypsodont cheek teeth with three transverse crests in all ontogenetic stages arranged in a transitory S-shaped pattern, resembling putative early dinomyids. Garridomys curunuquem is here interpreted as the sister group of the clade including the living and fossil chinchillids; both chinchillas and viscaccias would have diverged from a Garridomys-like ancestor and acquired hypsodonty independently. Garridomys and other chinchilloids would have diverged from the lineage leading to chinchillids in pre-Oligocene times, suggesting a very early, still poorly documented chinchilloid radiation.


Caviomorpha Chinchillidae Early Miocene Patagonia Cerro Bandera Formation 



We thank A. Garrido (MOZ), A. Forasiepi (Museo de Historia Natural de San Rafael, Mendoza), L. Filippi, S. Saldivia (Museo Carmen Funes, Neuquén), A. Martinelli, and G. Aguirrezabala for their help during the fieldtrips; C. Deschamps for help editing the manuscript; R. Coria (Museo Carmen Funes, Neuquén) and Dirección Provincial de Minería de la Provincia del Neuquén for technical support during fieldworks; and D. Flores (División Mastozoología, MACN) for access to specimens under his care. Special thanks to M. E. Pérez (MEF) for providing electronic photos of UCMP specimens, and F. Tricárico for helping us with the SEM photographs. Two anonymous reviewers improved this work by providing very constructive critical reviews. This work is a contribution to the projects PIP CONICET 6018/05 and 0276/2011, PICT 38112, and UNLP N/568.

Supplementary material

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ESM 1 (DOC 165 kb)


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Copyright information

© Springer Science+Business Media New York 2012

Authors and Affiliations

  • Alejandro G. Kramarz
    • 1
  • María G. Vucetich
    • 2
  • Michelle Arnal
    • 2
  1. 1.CONICET. Sección Paleontología de Vertebrados. Museo Argentino de Ciencias Naturales Bernardino RivadaviaBuenos AiresArgentina
  2. 2.CONICET. Departamento. Científico Paleontología VertebradosLa PlataArgentina

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