Robert M. Schoch

The Eocene biostratigraphy of New Mexico

The San Jose, Galisteo, and Baca Formations are continental deposits in New Mexico containing Eocene vertebrate fossils. The Almagre and Largo local faunas of the San Jose Formation in the San Juan basin are Lysitean (middle Wasatchian). The Cerrillos local fauna of the Galisteo Formation also is Wasatchian, possibly Lysitean. Strata of the Baca Formation in south-central New Mexico contain the titanotheres Palaeosyops sp. and cf. Manteoceras sp. and are the only Bridgerian strata known in New Mexico. The Tonque local fauna of the Galisteo Formation and fossil vertebrates from the Baca Formation in west-central New Mexico are correlatives of the Lapoint (Utah), Pearson Ranch (California), and Porvenir (Texas) local faunas and are Duchesnean. Precise placement of the Paleocene-Eocene and Eocene-Oligocene boundaries in New Mexico using vertebrate biostratigraphy is impossible because of a lack of fossils at critical horizons. The near absence of Bridgerian and total absence of Uintan fossils in New Mexico may result from a lack of collecting, particularly in parts of the Baca Formation.

New Conoryctines (Mammalia: Taeniodonta) from the Middle Paleocene (Torrejonian) of Western North America

A new genus and species of conoryctine taeniodont is described from two skulls and associated lower jaw fragments from middle Paleocene-aged (Torrejonian) strata of the Nacimiento Formation, San Juan Basin, New Mexico. A second new species, known from a lower jaw from Torrejonian-aged strata of the Polecat Bench Formation, Big Horn Basin, Wyoming, also is described. Among the conoryctines, the new genus most closely resembles Conoryctes , but differs from it in having a relatively molarized P3, prominent mesostyles on M1–2, and relatively prominent paraconids and paracristids on the lower molars. “ Triisodon heilprinianus ” Cope 1882, recently referred to Conoryctes comma , tentatively is referred to the new genus and is considered a nomen dubium at the specific level.

The systematics of Stylinodon, an Eocene taeniodont (Mammalia) from western North America

ABSTRACT Stylinodon, the latest taeniodont, is known from the late Wasatchian and Bridgerian of Colorado and Wyoming, Uintan of Utah, and Bridgerian or Uintan of western Texas. Two species, S. mirus Marsh, 1874, and S. inexplicatus, new species, are here considered valid. A large gliriform tooth from the late Eocene of Shandong, China, formerly referred to “?Stylinodon”, is here referred to the Tillodontia. Recently discovered specimens indicate that the dental formula of Stylinodon is l2 1 C1 1 P4 4 M3 3. Thus, contrary to previous opinions, Ectoganus (dental formula I1 1 C1 1 P4 4 M3 3) can be excluded from the direct ancestry of Stylinodon.

Annotated Bibliography of the Eocene Paleontology and Stratigraphy of New Mexico

This bibliography is not comprehensive, but it includes all major, and most minor, references on the stratigraphy and paleontology of the Eocene formations in New Mexico. Papers discussing the following formations are included: Baca, Blanco. Basin, Cub Mountain, El Rito, Espinaso, Galisteo, Love Ranch, McRae, Orejon, Palm Park, and San Jose. Although the Blanca Basin, Cub Mountain, El Rito, Espinaso, Love Ranch, McRae, and Orejon Formations are not demonstrably Eocene, their assignment, to that epoch by various workers, past and present, justifies their inclusion here.