Description after BASS et al. 1976 [#131]:
The teeth of a western North Atlantic specimen are well illustrated by Bigelow and Schroeder (1948, fig. 99).
Isistius brasiliensis fig. 99 Bigelow & Schroeder
Tooth counts vary from 12 - 1 - 12 to 15 - 1 - 15 in the lower jaws and from 15 - 1 - 15 to 18 - 1 - 18 in the upper jaws (that of the holotype of I. plutodus is 14 - 1 - 14/ 9 - 1 - 9.
Bigelow and Schroeder (1948) stated that there was an increase in tooth count with growth but Strasburg (1963) found the number to remain constant or possibly even to decrease with growth. Hubbs et al. (1967) point out that the number of tooth rows is unlikely to change because the outermost tooth row on each side is distinctly specialized. The most notable feature of the teeth as compared to those of other dalatiids is that the cusps of the lower teeth are erect or, if at all oblique, point to the symphysis rather than outwards.
Material: female, 44 cm TL, collection: Jaws International, Gordon Hubbell, Florida
Images: © Ross Robertson, Smithsonian Tropical Research Institute, Panama, images shows the correct position of the teeth
Material: female, 41 cm TL, off Senegal
Images: © Jacques Herman, Beigem (Grimbergen), Belgique, images shows the correct position of the teeth
Material: female, 24 cm TL, Atlantic