New Mexico Geological Society Annual Spring Meeting — Abstracts

Two Puercan faunal zones have been recognized in the early Paleocene Nacimiento Formation. These are known as the “Hemithlaeus kowalevskianus zone” (=”Ectoconus zone”) and the “Taeniolabis zone.” The mammalian faunas from these zones form the primary basis for the recognition of the Pu2 and Pu3 interval zones, respectively. Pu3 is distinguished from Pu2 primarily on the absence of several taxa including the periptychid condylarths Hemithlaeus kowalevskianus and Conacodon entoconus as well as the presence of the multituberculate Taeniolabistoaensis. The two interval zones are also distinguished by the presence/absence of other taxa, especially those that are rare. Reported here is the first record of the triisodontid Eocondongaudrianus from the Taeniolabistoaensis zone.

E. gaudrianus is an uncommon component of the “H.kowalevskianus zone.” It is represented in the “Taeniolabis zone” by a single specimen, United States National Museum (USNM) 405671, a crushed and distorted m1 and an associated partial left dentary with m2 recovered from “Upper Puerco, Barrel Springs Arroyo.” The specimen falls within the size range of E. gaudrianus from the “H.kowalevskianus zone” and possess the high trigonids with the protoconids and metaconids merging above the trigonid basin that is characteristic of the taxon.