Many thousands of species of trilobites have been described in the paleontological literature. Species were first named & described starting in the late 1760s, but trilobites were discussed in the literature long before this.
The oldest known reference to trilobite fossils in the literature is a 4th century A.D. Chinese book by Guo Po (276-324 A.D.). This book mentions trilobite-bearing fossiliferous limestones that have been called “batstones” by the Chinese for many centuries.
Drepanura premesnili pygidium (2.9 cm across at its widest) - this trilobite pygidium (tail) is in a fossiliferous wackestone from the Kushan Formation (~uppermost Middle Cambrian) of Shandong Province, northeastern China. Kushan limestones contain a relatively diverse trilobite fauna. The most distinctive trilobite in Kushan rocks is Drepanura premesnili Bergeron, 1899 (Arthropoda, Trilobita, Polymerida, Damesellidae). The pygidia of Drepanura have strikingly large anterolateral spines. When portions of the pygidia are covered in matrix, these Drepanura tails resemble flying bats (see below) - hence “batstones”.
Batstone from the Kushan Formation (Cambrian) of Shandong, China. Note the flying bat shape of the pygidium at upper right (from Chang, 1921).
Drepanura premesnili pygidium in the logo of the Geological Survey of China
(from cover of Sun, 1935 - Palæontologia Sinica, Series B 7(2)).
Drepanura premesnili tails dominate the surfaces of these Kushan Formation batstones from Shandong, China.
(left: James St. John collection; right: Nanjing Institute of Geology and Palaeontology collection)
Drepanura premesnili tails in fossiliferous limestone (above & below), details of a large batstone slab from the Kushan Formation (Cambrian) of Shandong, China.
FMNH 13897 (Field Museum of Natural History, Chicago, Illinois, USA). Centimeter scale.
Chang, H.T. 1921. Lapidarium sinicum, a study of the rocks, minerals, fossils and metals as known in Chinese literature. Memoir of the Geological Survey of China, Series B, number 2. 348 pp. 11 pls. [in Chinese; English preface] [2nd edition published 1927: 432 pp., 20 pls., 1 chart]