2.59. Cylindrical vertical to oblique borings.
Diagnosis.—Included in Trypanites are simple unbranched vertical to sinuous borings with a single opening to the surface; with or without a flared entrance. Circular in cross section; generally isodiametric throughout the entire length but may terminate in a small cupulate chamber.
Discussion. —Pouch-shaped borings excluding those characteristic of acrothoracican cirripeds and bivalves. From a single entrance, the boring may extend as a long cylindrical tube with a circular cross section. Borings in all substrates are included, with no restriction to geological age. Bromley (1972) revised the nomenclature of Trypanites, which involved the grouping of seven different ichnogenera (Teredolites Leymerie, Gastrochaenolites Leymerie, Nygmites Mägdefrau, Specus Stephenson, Martesites Vitalis, Vermiforichnus Cameron, and Conchifera Muller) into synonymy. This scheme, however, was far-reaching and has gained little following. Subsequently, Bromley and D'Alessandro (1983) included single entranced borings with flattened cross sections in the ichnogenus Caulostrepsis Clarke. This included the forms Polydorites Douville, Dodecaceria Voigt (non Orstead), and Ramosulcichnus Hillmer and Schulz, which were placed in synonymy with Trypanites by both Bromley (1972) and Pemberton et al. (1980). Likewise, Kelly and Bromley (1984) removed Gastrochaenolites and Teredolites (including Martesites) from Trypanites, restricting them to pouch-shaped borings of bivalve origin in lithic and xylic substrates, respectively. Included in the above synonymy of Trypanites are forms designated as Spiracavites by Chiplonkar and Ghare (1977) and Cylindrocavites by Ghare (1982). These forms are similar in most respects to Trypanites.
Diagnosis– (Modified after Bromley & D’Alessandro, 1987, p. 403.) Single entrance, cylindrical or sub-cylindrical, unbranched boring in lithic or biogenic substrates having circular cross-section throughout length. The axes of the boring may be straight, curved or irregular.
Remark: Cylindrical, unbranched boring; length up to 50 times width. Some Ordovician examples described by Kobluk and Nemcsok (1982) contain scolecodonts suggesting that the borings were made by polychaete worms.