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PALEONTOLOGICAL SOCIETY PAPERS, V. 8, 2002borings of the type made by muricid gastropods.Drill holes of at least two distinctive typesoccur in middle to late Paleozoic shells (Ausichand Gurrola, 1979). These were termed Type A andType B boreholes and they are morphologicallysimilar to the later muricid and naticid gastropoddrill holes, respectively (see Figs. 4.3, 4.4). TypeA drill holes (Figs. 5.1, 5.2) are smaller, cylindrical,and may penetrate shells from below; they mayFIGURE 4—Traces of predation, in fossil and Recentshells. 1—Shell of Devonian gastropodPalaeozygopleura with sublethal healed fracture ofthe outer lip. 2—Permian bivalve shell with healedcrescentic fractures along valve margin; probably theresult of attempted predation by a fish. 3—Incompletebore hole of Polinices duplicata; note raised boss atcenter. 4—Complete drill hole of Natica severa; notebeveled outer margin. Redrawn from photographsin the following sources: 1, Brett and Cottrell (1982),2, Boyd and Newell (1972); 3, 4, Carriker andYochelson (1968). Figure modified from Brett (1992).record attacks by parasitic organisms (Ausich andGurrola, 1979). However, Type A drill holes occuras a single drill hole per shell and display a nonrandomstereotyped pattern characteristic ofcarnivores (Fig. 5.6) (Smith et al., 1985; Leighton,2001a, b). Cylindrical holes are known from LateOrdovician (Cincinnatian) brachiopods (Bucher,1938; Cameron, 1967). Some of these have provento be domichnial borings (Trypanites) made in deadshells (Carriker and Yochelson, 1969; Richards andShabica, 1969). But Kaplan and Baumiller (2000)argued recently that at least some of these holesshow non-random positioning, and hence wereprobably produced by predatory organisms.Rohr (1976) observed prey and site selectivityof small boreholes in Silurian orthid brachiopods.Liljedal (1985) also noted Type A borings insilicified Silurian bivalves. Similarly, Type Aborings occur in about 11% of the Early Devonianbrachiopod Discomyorthis and show evidence ofsize and site selectivity on the prey shells (Sheehanand Lespérance, 1978). Buehler (1969) reported alow frequency (2.25%) of cylindrical borings inMiddle Devonian shells, as did Rodriguez andGutschick (1970). However, the jury is still out onthe issue of whether these were predatory or merelyparasitic in nature (Leighton, 2001a, b).Type B boreholes are parabolic, 1–3 mm indiameter, and display a chamfer or bevel;incomplete boreholes possess a central raised knobor boss (see Figs. 4.3–5.5). These most closelyresemble drillings of modern naticid gastropods.These boreholes first become common in Devonianbrachiopods (Fenton and Fenton, 1931, 1932;Smith et al., 1985; Kowalewski et al., 1998); earlierpossible examples are known from Ordovicianbrachiopods (S. Felton, pers. comm.) but have notbeen documented in the literature. Brunton (1966)reports frequencies of up to 30% of brachiopodsdrilled with this type of hole in assemblages of lateCarboniferous age. Relatively few typical Type Bborings are reported from the Upper Carboniferousto Permian (see Kowalewski et al., 2000).However, a series of papers document small (< 2mm) boreholes with chamfering, which shouldperhaps be assigned to a third category; these occur100