Pliocene (latest Hemphillian and Blancan) vertebrate fossils from the Mangas Basin, southwestern New Mexico

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Andrew B. Heckert Ph.D., Professor (Creator)
Appalachian State University (ASU )
Web Site:

Abstract: Two vertebrate faunas of Pliocene age, the Walnut Canyon and Buckhorn local faunas, are described from sediments of the Gila Group in the Mangas basin in northern Grant County, southwestern New Mexico. Stratigraphic sections and lithologic descriptions are provided for the three unnamed formations in the upper part of the Gila Group that produced these two faunas. The Walnut Canyon local fauna includes one major locality, the Walnut Canyon Horse Quarry, and three smaller sites located 5 km southeast of Gila. The fauna is composed of 12 species of mammals, including one lagomorph, one rodent, two carnivores, two horses, one peccary, three camels, one cervid, and one antilocaprid. The most common members of the fauna are the equids Astrohippus stockii and Dinohippus mexicanus and two genera of camelids (Hemiauchenia and Alforjas). The remaining species in the fauna are represented by very small samples. A. stockii, D. mexicanus, the canid Vulpes stenognathus, the tayassuid d. Catagonus brachydontus, and the camelid Alforjas are typical of late Hemphillian (late Miocene and early Pliocene) faunas. Furthermore, the presence of A. stockii, D. mexicanus, and a true cervid are indicative of latest Hemphillian faunas. Two correlative latest Hemphillian faunas, the Yepomera fauna from Chihuahua in northern Mexico and the Palmetto fauna from the Bone Valley Formation in Florida, are earliest Pliocene in age (5.2- 4.5 Ma). The Buckhorn local fauna incorporates 14 sites located between 3 and 10 km northwest of Buckhorn. The fauna is composed of 27 species of vertebrates, including one fish, one frog, one salamander, two snakes, six birds, one lagomorph, four rodents, four carnivores, two horses, one peccary, two camels, one ruminant, and one proboscidean. The abundance of aquatic vertebrates in several of the Buckhorn sites, in particular frogs (Rana) and birds, including a flamingo (Phoenicopterus), rails, and ducks, as well as the lithology of the sediments, suggest a lacustrine depositional environment. The mammals from the Buckhorn local fauna are clearly indicative of a Blancan (Pliocene) age, and several species permit a more precise placement within the Blancan. The presence of the small hipparionine horse Nannippus and a primitive species of the arvicoline rodent Mimomys and the absence of Neotropical immigrants, suggest a pre-late Blancan age (older than 2.5 Ma). The occurrence of the horse Equus (Dolichohippus) simplicidens and a large species of Mimomys (subgenus Ogmodontomys) excludes very early Blancan faunas. The evolutionary stage of the rodents Mimomys (Ogmodontomys) d. M. poaphagus and Repomys d. R. panacaensis is most consistent with a late early or early middle Blancan age (4.0-3.0 Ma) for the Buckhorn local fauna. Broadly correlative early or middle Blancan faunas are Cuchillo Negro Creek and Truth or Consequences in New Mexico, Clarkdale and Verde in Arizona, Rexroad in Kansas, and Panaca in Nevada.

Additional Information

Morgan, G.S., Sealey, P.L., Lucas, S.G., and Heckert, A.B., (1997) Pliocene (latest Hemphillian and Blancan) vertebrate fossils from the Mangas Basin, southwestern New Mexico. New Mexico Bulletin of Natural History and Science Bulletin 11, p. 97-128. (ISSN 1524-4156) Archived in NC DOCKS with permission of the editor. The version of record is available at:
Language: English
Date: 1997

Email this document to