298 
J.A. Long, G.C. Young 
A 
Figure 9 Aztecodus harmsmae gen. et sp. nov. A, B, WAM 92.3.58, labial and ventral views. C, WAM 92.3.59, labial 
view; D-G, holotype WAM 92.3.61, in D, lingual, E, labial, F, dorsal, and G, ventral views; H, WAM 92.3.71, 
labial view. I, WAM 92.3.69, from Fault Bluff, ("fish hotel" B horizon) x4. J, CPC 21229, labial view 
(previously illustrated by Young, 1982, figure 3FI, plate 88, figure 4). All bar scales are 1 mm. 
There is also a resemblance to Mcmurdodus in the 
shape of the base in ventral view, as subsequently 
described by Turner and Young (1987: figure 4B). 
However, the main differences lie in the larger 
number of cusps and absence of a lower crenulated 
cutting ridge in the central part of the Mcmurdodus 
tooth, where instead the largest cusps are situated, 
the lack of the ventral groove on the base, and the 
fact that the minor cusps at either end are directed 
almost horizontally in that form. 
Holotype 
WAM 92.3.61 (Figures 8A-E, 9D-G), from the 
section LA, site LA-2, Lashly Mountains, about 200 
metres south of Mt Crean, from the second fish 
horizon (LA2) about 70-80 m above the base of the 
section. 
Material 
Six other teeth. CPC 21229, from Mt Ritchie, 
section A4 near units 61, 62 (figured Young 1982, 
text-figure 3H, plate 88, figure 4); WAM 94.2.17, 
from LA-2 (type locality); WAM 92.3.58, from site 
20 (scree); 92.3.59, from Alligator Peak, locality 20 
(top horizon); WAM 92.3.70, 92.3.71, from Fish 
Hotel site B, Cook Mountains. 
Description 
These teeth range in size from about 5 mm 
(92.3.70) to 16 mm across the cusps (WAM 92.3.59, 
Figures 8H, 8C), being considerably wider than 
high, and with a distinctive almost rectangular base 
when viewed dorsally or ventrally (Figures 8D, E, 
9B, F G). The holotype (WAM 92.3.61, Figures 8 A- 
E, 9D-G) was extracted from in situ, and although 
the main cusps are damaged it shows the 
distinctive crenulated mesial edge, a feature not 
seen on any other Devonian sharks tooth. In this 
specimen there are approximately twelve small 
ridges forming the crenulated mesial edge which is 
gently curved, being weakly convex when viewed 
labially. The enameloid-root boundary is well 
defined and gently curved on the labial face. The 
two prominent main cusps have a strong lingual 
curvature and are relatively broad and flat, 
tapering mesially to form a sharp cutting edge 
before the crenulations develop (e.g.. Figures 8H, I, 
9 A-C). The basal view (Figures 8D, 9 B, G) shows 
the root with an anterior thickening and a few 
rostrocaudal ridges and weak grooves, but lacking 
any foramina. Two well defined nutritive foramina 
pass through the tooth from labial to lingual side at 
the level of the ventral margin of the base (e.g.. 
Figure 9A, D, E, H). Other specimens show the 
same proportions as the holotype (Young 1982, 
text-figure 3H; Figures 8F, 9H). 
Two specimens have slightly different 
morphologies, and come from the top of the Aztec 
Silstone at site 20 in Alligator Ridge, within the 
phyllolepid biozone of Young (1988). WAM 92.3.59 
and 92.3.58 are slightly larger than the other 
