Approximately 35% (241) of the ichthyoliths came from 52 of the 1,025 outcrop samples, 59% (404) from 300 of the 2,152 Shell Canada well samples, and 6% (42) from five samples in the END-76B-6 core. A total of 687 specimens representing 99 different species, subtypes, or forms of ichthyoliths were recovered from approximately 11% (357 of 3,184) of the outcrop and offshore Tofino Basin samples. Tofino Basin upper Eocene-Pliocene ichthyoliths are typically in situ and diverse but few in finer grained (e.g., shale) bathyal environment strata. In three coarse-grained outcrop samples (BC-74 spot checks 7, 8, and 15) ichthyoliths were common (103 specimens), diverse (e.g., 6 Squalomorphii forms, 11 named ichthyolith subtypes, and 16 different rare-coded, undescribed, or unidentified ichthyoliths), and represent (in part) reworked Upper Cretaceous/lower Cenozoic ichthyoliths that were transported from structural highs and deposited in upper Eocene and lower Oligocene structural lows (bathyal environments, Narayan et al., 2005).

Most of the Tofino Basin ichthyoliths (45%) are cone teeth (actinopterigians, probably teleosts) and elasmobranch teeth and dermal denticles (31%). Teeth with canals, flanged or flexed teeth, and other ichthyoliths are 13%, 8%, and 3% (the affinity of these ichthyoliths is unknown). Elasmobranch teeth and dermal denticles, teeth with canals, and flexed teeth (90%) were commonly deposited in Oligocene and upper Eocene strata, whereas cone teeth (88%) were mainly deposited in Miocene and Pliocene strata.

Upper Eocene outcrop surface samples from the Hesquiat Formation and some samples near the base of the Pluto I-87 well contain rare ichthyoliths. The reason for this paucity is not well understood but the distal bathyal environment indicated by foraminifers in fine-grained shale samples (Cameron 1980) may not have been a suitable environment for many fishes. Also during the Eocene, tectonism, accretion, faulting and uplift contributed to much of the British Columbia coastal and inland topographic relief (e.g., Mathews 1991; Hyndman et al. 1990; Hyndman et al. 1994; Hyndman 1995). Both distal and proximal Tofino Basin environments are indicated during the middle to upper Eocene and Oligocene. A tectonically active margin is further indicated with an unconformity above lower Eocene volcanic rocks in the Zeus D-14 and Prometheus H-68 Shell Canada wells (Shouldice 1971), in faulted (slickensided) upper Eocene and Oligocene strata in the basal Pluto I-87 well (e.g., Shell Canada report 1967). Cameron (1980) interpreted rapid facies changes and reworked older macro- and micro-faunas within the Escalante and Hesquiat formations.

Ichthyoliths in distal Tofino Basin sediments continued to be rare into the lower Oligocene until near the boundary of the Turrilina alsatica and Bulimina cf. alsatica foraminifer zones by Cameron 1980. At this level in the Hesquiat Formation and in the Pluto I-87 subsurface samples, faunas indicate a more proximal environment, and strata are coarser grained, contain shell and wood fragments, and locally disturbed. Ichthyoliths in these samples are common and diverse. Some of these ichthyoliths may have been concentrated in the sediments through a winnowing effect under turbid conditions (Cameron 1980), through transport and into graded beds, or by reworking. The ichthyoliths are dominated by potentially reworked Cretaceous to middle Eocene elasmobranch teeth (e.g., Superorder Squalomorphii forms) and dermal denticles (e.g., pointed and skirted Doyle et al. 1978; kite-shaped longitudinal line Doyle et al. 1974; three peaks forked median ridge new subtype; and several rare elasmobranch dermal denticles).

Ichthyoliths interpreted to be approximately in situ in the upper Eocene and Oligocene Tofino Basin strata are short side peaks differentiated margin, Doyle et al. 1974, triangular teeth with canals (angled cone and basal canals, flanged triangle with canals, centrally inflated triangle with canals – three new subtypes) triangle one canal above Doyle et al. 1974); triangular flanged teeth (triangle double flex Doyle et al. 1974; wide triangle double flex Gupta 1991); and one cone tooth new subtype, dome-top triangle bowed inline.

In upper Oligocene and lower Miocene intervals (possibly middle Miocene) a transitional ichthyolith fauna is observed in the Pluto I-87 well and in the Zeus D-14 and Prometheus H-68 wells just above the Eocene volcanic rocks and an unconformable surface. This transitional fauna contains: 1) Oligocene ichthyoliths observed in the Pluto I-87 well and the marine Hesquiat Formation; 2) cf. triangle curved margin ends Doyle and Riedel 1985b and curved triangle striated inline new subtype; and 3) a variety of other new "cone tooth" ichthyoliths which occur later in the Miocene. Further upsection, cone teeth are the dominant forms. These cone teeth include subtypes similar to narrow curved triangle Doyle et al. 1974; short triangle stepped margin Doyle et al. 1974; triangle small top Ramsey et al. 1976; and 11 new cone tooth subtypes (Table 2) dominated by angled cone and bulbous base, curved triangle parallel-sided inline, curved triangle wide inline, narrow tall triangle inflated inline apex, narrow tall triangle cone inline, and narrow tall triangle irregular threaded inline. These changes in faunas are significant in the Tofino Basin region because they mark the replacement of teeth with canals and many elasmobranch dermal denticles and teeth (flattened teeth with a cutting edge) by actinopterygians - mainly teleosts (with cone teeth that do not have a cutting edge and are circular in cross-section). The faunal change corresponds to an apparent lower Miocene transgression in this region (Shouldice 1971) that is indicated by fine-grained deeper water bathyal sediments and foraminifers (Narayan et al., 2005) observed at certain intervals in the Shell Canada Zeus D-14, Prometheus H-68, Apollo J-14, and Pluto I-87 wells. Also, pollen data from northwestern Canada and Alaska (White et al. 1997) show a warmer early to middle Miocene climate that peaked at 15 Ma followed by temperature declines before the onset of the Pliocene-Pleistocene glaciations.

In the upper Miocene and Pliocene, earlier common and diverse Miocene cone tooth ichthyoliths show a decrease in diversity and abundance. New cone tooth subtypes appear (e.g. shadowed curved blunt triangle and shadowed high inline cone) and a form similar to the deep-sea core subtype long triangle stepped margin Doyle et al. 1974. Only rare ichthyoliths are recovered from sediments above the upper Pliocene, an interval when glacial cooling (Fulton 1984; Clague 1991; Mathews 1991; White et al. 1997) would have significantly effected the environment in this region.

In summary, these patterns of ichthyolith occurrence correspond to regional tectonic activity in the Tofino Basin (e.g., Hyndman et al. 1990; Hyndman et al. 1994; Hyndman 1995; Yorath et al. 1999), apparent higher sea levels in the late Eocene/early Oligocene, early to middle Miocene, and early Pliocene indicated by deeper water bathyal environments (Narayan et al., 2005) and a climate cooling trend from the Oligocene through the Pleistocene (e.g., Clague 1991; Zachos et al., 1994, 1996, 1997; Hilary et al., 2000; Prothero 2003).