Haplomys and its bearing on the origin of the aplodontoid rodents

Rensberger, J

Analysis of recently discovered Haplomys teeth and comparison with related groups for consistent classification. See Oligo-Miocene Geographic location:JODA (John Day Fossil Beds National Monument), John Day Formation. Recently discovered mandibular teeth of Haplomys, a late Oligocene aplodontid rodent, more strongly resemble the dental patterns in the Prosciurinae than those of Eohaplomys, an Eocene genus generally regarded as ancestral to the aplodontids. Eohaplomys is dentally more specialized than the Prosciurinae and therefore did not likely give rise to them. An origin of the aplodontids from the prosciurines, which now seems probable, eliminates the Oligocene discontinuity of the succession under the older interpretation. To make the classification consistent with this relationship, the Prosciurinae are transferred from the Ischyromyidae or Paramyidae of authors to the Aplodontidae, and the aplodontid taxa, which fall into three equally distinct groups, are segregated as the Prosciurinae (an early to middle Oligocene radiation), the Allomyinae (an Oligo-Miocene radiation), and the Aplodontinae (a later Miocene radiation).

Haplomys and its bearing on the origin of the aplodontoid rodents

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