Journal of Mammalian Evolution

, Volume 23, Issue 3, pp 309–317 | Cite as

When Cotton Rats Grasp Like Pandas

  • Juan AbellaEmail author
  • Francisco J. Ruiz-Sánchez
  • Alberto Valenciano
  • Daniel Hontecillas
  • Alejandro Pérez-Ramos
  • Douglas Vera
  • Jonathan A. Santana-Cabrera
  • María H. Cornejo
  • Plinio Montoya
  • Jorge Morales
Original Paper


The panda’s false thumb is an iconic structure, described as one of the most shocking cases of anatomical convergence, and has been studied in many essays about evolution. However, in a recent paper in which we evaluated this feature within the Carnivora, we concluded that the developed radial sesamoid could be taken as a plesiomorphic character for at least the Arctoidea, rather than an anatomical convergence of the pandas (both red and giant). Following this argument, in this research we describe the action of a radial sesamoid as a real false thumb for the first time outside the mammalian carnivorans. The cricetid Sigmodon peruanus shows a very similar radial sesamoid compared to that of the giant panda (Ailuropoda melanoleuca) but somehow relatively even more developed, compared to the other bones of the manus than in the latter, showing that the use of this structure as a opposable pincer is much more expanded in mammals than thought previously.


False thumb Sigmodon Cricetidae Santa Elena Ecuador 



This study was supported by the Spanish Ministerio de Economía y Competitividad (CGL2011-25754, CGL2011-28681 and CGL2012-37866), the Generalitat de Catalunya (2014 SGR 416 GRC) and the Universidad Complutense de Madrid (BSCH-UCM910607). J.A. and F.J.R thank the “Proyecto Prometeo” of the “Secretaria de Educación Superior, Ciencia Tecnología e Innovación,” Republic of Ecuador. A.V. is researcher in formation in the CSIC program JAE-PRE_CP2011 (CSIC program “Junta para la ampliación de estudios”), co-funded by the European Social Fund. D.H. is researcher in formation in the FPU 2013 program granted for the Ministerio de Educación, Cultura y Deporte, Spain. We thank Jorge Brito, José Luis Román-Carrión, and Pablo Moreno for their help finding new specimens of this species in their collections. We are also indebted to many colleague workers of UPSE (Universidad Estatal Península de Santa Elena) that have supported our investigation. Finally, we would like to thank an anonymous reviewer and the editor-in-chief for their comments and valuable suggestions.


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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • Juan Abella
    • 1
    • 2
    Email author
  • Francisco J. Ruiz-Sánchez
    • 1
    • 3
  • Alberto Valenciano
    • 4
    • 5
  • Daniel Hontecillas
    • 6
  • Alejandro Pérez-Ramos
    • 7
  • Douglas Vera
    • 1
  • Jonathan A. Santana-Cabrera
    • 1
    • 8
  • María H. Cornejo
    • 1
  • Plinio Montoya
    • 9
  • Jorge Morales
    • 6
  1. 1.Universidad Estatal Península de Santa ElenaLa LibertadEcuador
  2. 2.Institut Català de Paleontologia Miquel CrusafontUniversitat Autònoma de Barcelona, Edifici ICTA-ICP, Carrer de les Columnes s/n, Campus de la UABCerdanyola del VallèsSpain
  3. 3.Xarxa de Museus de Paleontologia (XMP), Departament de GeologiaUniversitat de ValènciaBurjassot, ValènciaSpain
  4. 4.Departamento de Geología Sedimentaria y Cambio MedioambientalInstituto de Geociencias, IGEO (CSIC, UCM)MadridSpain
  5. 5.Departamento de PaleontologíaUniversidad Complutense de MadridMadridSpain
  6. 6.Museo Nacional de Ciencias Naturales (MNCN-CSIC)MadridSpain
  7. 7.Departamento de Ecología y Geología, Facultad de CienciasUniversidad de MalagaMalagaSpain
  8. 8.Grupo TARHA. Departamento de Ciencias HistóricasUniversidad de Las Palmas de Gran CanariaLas PalmasSpain
  9. 9.Departament de GeologiaUniversitat de ValènciaBurjassot, ValènciaSpain

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