All three dorsal-fin spines are long and robust and at least the
first two bear low serrations along the anterior and, especially
on the second spine, lateral edges. The distal end of the first
dorsal spine is missing, but based on the thickness and degree
of tapering of the basal region we estimate that the first spine
was only slightly longer (73% SL) than the second (63% SL),while by measurement the length of the third (42% SL) is
slightly more than half that of the second. The large rounded
base of the second dorsal spine does not appear to make close
contact with the posterior edge of the base of the first spine.
Therefore, we think it unlikely that the complex locking
mechanism of the first spine by the second spine as found in
Recent and fossil (as early as the Oligocene) balistids is
present. The origin of the spiny dorsal fin is at a level about half
way between the eye and the region of the gill slit and
pectoral-fin base, and the anterior end of its supporting basal
pterygiophores (which cannot be seen because of overlying
large scale plates) probably articulated with the posterodorsal
surface of the skull.
The base of the caudal fin is preserved and there appear to
have been 12 rays, but we cannot determine how many were
branched or unbranched because the distal part of the fin is only
a faint impression. There are no remains of the pectoral, soft
dorsal, or anal fins, and these are shown hypothetically by
dashed lines in the reconstruction (Figure 2). We presume that
there were no anal-fin spines because if such were present they
could be expected to be as easily visible as the dorsal-fin
spines, the rudimentary pelvic-fin spine and the carapace
spines.