PALEOBIOLOGY OF TRILOBITES- C. D. WALCOTT'S STUDIES: 1875–1881

Walcott's total college training was one week during the fall of 1873 with Louis Agassiz to whom he and W.P. Rust had sold a fossil collection. This inspired him to evolve from professional collector to paleontologist. He published four short papers on trilobites in 1875, from the Middle Ordovician rocks at Trenton Falls, NY. In 1874 or early 1875, within the thin Ceraurus limestone from the base of the famous trilobite quarry, he found indications of trilobite limbs associated with carapaces. During February, 1876, just after the death of his wife, he plunged into their study by cutting the rock and polishing sections, using some sort of homemade equipment. In November, 1876, Walcott moved to Albany as special assistant to James Hall and in December announced his discovery in a four page preprint. This was the first uncontested report of trilobite legs and equally the first proof that trilobites had jointed appendages and therefore were correctly assigned to the Arthropoda. He continued making sections, doing all work, except the actual cutting of limestone, after his official working hours. An 1877 preprint provided illustrations and a few more details; this was reprinted in several versions but the text was essentially unchanged. In 1879, Walcott, no longer employed by Hall, investigated a growth series of Triarthrus, the second such complete series after the pioneer work of J. Barrande. During 1881, Walcott, now with the U.S. Geological Survey, produced a comprehensive study of his investigations of trilobite limbs and it remained the standard reference for nearly four decades. His main error was in interpretation of the brachial structures.