Brachiopods are very abundant throughout the Trenton Group, but have not been as well studied as other groups, such as the Trenton trilobites and crinoids. They were recognized as components of the Trenton strata very early and are mentioned by John Sherman in his description of Trenton Falls in 1844. James Hall later described many of the common species of brachiopods in some of his publications on the paleontology of New York State (Hall, 1847, 1866a, 1872; Hall and Clarke, 1892). Since Hall's early publications few of the Trenton brachiopods have been studied in detail and redescribed.
Orthids and Strophomenids seem to dominate the fauna with Rafinesquina trentonensis being the most abundant species seen in outcrop within Trenton Gorge and the surrounding areas. The brachiopod fauna of the of the Trenton Group, as represented in the Museum of Comparative Zoology (MCZ) collections, consists of 13 lingulid species, one acrotretid, one siphonotretid, one craniid, four strophomenids, three orthids, one rhychonellid, and two atrypids. The specimens illustrated here were collected by Charles Doolittle Walcott and William P. Rust in the late 1800s.