Journal of Mammalian Evolution

, Volume 2, Issue 2, pp 117–131 | Cite as

On the systematic position ofChaetomys subspinosus (Rodentia: Caviomorpha) based on evidence from the incisor enamel microstructure

  • Thomas Martin


We have studied the incisor enamel microstructure ofChaetomys subspinosus and other possibly closely related caviomorph rodents.Chaetomys subspinosus lacks the important synapomorphy of the Octodontoidea, reactangular plate-like interprismatic matrix (IPM) in the portio interna (PI) of the incisor Schmelzmuster. Therefore its transfer from the Erethizontidae to the Echimyidae, as proposed by Patterson and Wood (Bull. Mus. Comp. Zool. 149, 371–543, 1982) based on retention of dP4, is contested. The parallel to acute angular IPM in the PI ofChaetomys and the Erethizontidae is a symplesiomorphy and does not indicate close relationship. Contrary to previous claims, a posterior carotid foramen is also retained inChaetomys. Chaetomys is characterized by an unusual thin enamel which is considered primitive after outgroup comparison. Therefore, it is proposed to leaveChaetomys in the monospecific erethizontid subfamily Chaetomyinae, until additional information on the species is available.

Key Words

enamel microstructure evolution Chaetomys incisors Caviomorpha 


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Copyright information

© Plenum Publishing Corporation 1994

Authors and Affiliations

  • Thomas Martin
    • 1
  1. 1.Institut für PaläontologieFreie UniversitätBerlinGermany

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