Pennsylvanian trilobites from the Madera Formation, Cedro Canyon, New Mexico
— Barry S. Kues

Fossils have been known from Pennsylvanian strata east of Albuquerque since 1853, when Jules Marcou, a member of the Whipple Expedition, collected numerous brachiopods, corals, and nautiloids from the Sandia Mountains and Tijeras Canyon (Marcou, 1858). Studies of the Madera Formation (or Group, see Myers, 1973) in the Sandia, Manzanita, and Manzano mountains since then have revealed that marine invertebrates are abundant and diverse; plants and vertebrate re- mains are also present in some of the nonmarine parts of the Madera. Of the more than 300 reported species of invertebrates, most are brachiopods, corals, foraminifers, bryozoans, pelecypods, gastropods, and crinoid stems (Northrop, in Kelley and Northrop, 1975). Many of these are similar or identical to forms found elsewhere in the Pennsylvanian strata of New Mexico, and indeed, in Pennsylvanian rocks throughout the midcontinent and east-central parts of the United States.

 

Trilobites are uncommon elements of Pennsylvanian marine faunas of North America, and their occurrence in the Madera Formation and equivalent units in northern New Mexico is limited generally to occasional isolated pygidia, cephalon fragments, and rare complete spec- imens. A single locality in Cedro Canyon, however, over the years has yielded hundreds of trilobites, including many complete individuals. The purpose of this paper is to describe, discuss, and illustrate these trilobites and to examine some aspects of their paleoecology.