New primitive paromomyid from the clarkforkian of wyoming and dental eruption in plesiadapiformes

Published

Journal Article

Clarkforkian late Paleocene freshwater limestone from the Clarks Fork Basin, Wyoming, has yielded four specimens of the plesiadapiform paromomyid, Acidomomys hebeticus gen. et sp. nov. A. hebeticus has a strong metaconid on p4, a small double-rooted p3, and a very diminutive i2. Presence of p3 and i2 is primitive, and their retention in A. hebeticus suggests that this taxon is part of a previously unknown lineage that diverged from other paromomyids by the early or middle Paleocene. Acidomomys hebeticus is represented by virtually complete upper and lower dentitions, all from less than fully mature individuals, with teeth at one of three stages of development. The dental eruption sequence differs from that of other plesiadapiforms in having p3 erupt before p4 (p3 erupts after p4 in microsyopids, and p3 and p4 erupt simultaneously in plesiadapids). A. hebeticus differs from Plesiadapis and primitive primates, in which the premolars erupt after m3 is in place, in having p3/P3 erupt before or at the same time as that of m3/M3. It is similar to Plesiadapis in having p4 erupt after the molars are in place, a condition considered primitive in primates. While these differences in dental eruption sequence between representatives of Paromomyidae, Microsyopidae, and Plesiadapidae could be phylogenetically significant, they may instead reflect adaptive differences in dental morphology, facial architecture, or life history. © 2002 by the Society of Vertebrate Paleontology.

Full Text

Duke Authors

Cited Authors

  • Bloch, JI; Boyer, DM; Gingerich, PD; Gunnell, GF

Published Date

  • January 1, 2002

Published In

Volume / Issue

  • 22 / 2

Start / End Page

  • 366 - 379

Electronic International Standard Serial Number (EISSN)

  • 1937-2809

International Standard Serial Number (ISSN)

  • 0272-4634

Digital Object Identifier (DOI)

  • 10.1671/0272-4634(2002)022[0366:NPPFTC]2.0.CO;2

Citation Source

  • Scopus