Beecher's Trilobite Bed:
for the Other Half of the Trilobite
THE ORDOVICIAN UTICA AND LORRAINE FORMATIONS OF New York State are composed of shales, siltstones, and limestones that have yielded a considerable amount of remarkable fossils, including large articulated eurypterids. Parts of these formations might be considered as Lagerstätten by themselves, but it is a very thin layer within the Frankfort Shales of the Utica Formation that has attracted much attention and has become world famous: the so-called Beecher's Trilobite Bed. This layer has become especially well known for the preservation of pyritized trilobites, which show not only perfectly articulated exoskeletons, but preservation of soft parts, including legs and antennae, muscles, and parts of the digestive tract. Sedimentological evidence indicates that Beecher's Trilobite Bed formed as a consequence of a sudden influx of sediment, carrying bottom-dwelling animals for some distance before burying them under a cover of fine siltstone. Beecher's Trilobite Bed is thus a classic example of an obrution deposit.
The first trilobites with preserved appendages were discovered in 1884 by the amateur collector William S. Valiant in loose blocks along Six Mile Creek near Rome, in upstate New York (Whiteley 1998, 2000). It was not until 1892, however, that he was able to locate the trilobite bed in outcrop. This exciting discovery, first published in 1893 (Matthew 1893), quickly drew the attention of Charles Emerson Beecher, a paleontologist at Yale University. Beecher started excavating the locality in 1893, but by 1895 the trilobite bed was thought to be mined out, and quarrying ceased (Briggs and Edgecombe 1992, 1993). Beecher's sampling efforts yielded