420 
A.M. De Pomeroy 
extending beyond base posteriorly, ornamented 
with parallel or slightly radiating rounded ribs, 
usually only on anterior part of crown. Neck low, 
clearly separated from both base and crown, with 
small canal openings on front and back. Base 
convex, usually extends anterior to crown, 
concentrically striated. Mesodentine crown, with 
Stranggewebe in posterior half, has concentric, 
radial and ascending vascular canals. Tubules on 
top of the crown grouped into tufts in the furrows, 
with side branches extending into the ridges. Base 
of cellular bone. 
Cheiracanthoides comptus Wells, 1944 
Figure 3A-D 
Material 
280 scales (QMF 31819, 20 + 278 others). 
Localities 
SD15/59.1-113m, SD128/54.3-201.5m, SD130/ 
32.5-73.lm, SD131/92.1m, SD146/418m, SD164/ 
117.7-124.lm, SD170/710m, SD192/0-50m, SD193 
(spot sample), SD204/115.9-120m, SD210/69.7- 
132.3m, SD216/26.7-95.3m, and SAG/26.8-121.9m; 
Lomandra, Stanley, Spanner and Chinaman Creek 
limestones, and Papilio Formation. 
Stratigraphic range 
Eifelian (kockelianus Zone) to earliest Frasnian 
{asymmetricus Zone). 
Remarks 
The scales have the flat or slightly convex crown 
with posteriorly converging ridges, the low 
indented neck, and convex base, described by both 
Wells (1944) in the original diagnosis, and by 
Denison (1979) as being typical of this genus. The 
Broken River scales are a similar size to those of 
Wells (1944). 
Description 
The scales have four to eleven radiating or 
subparallel rounded ridges on the anterior part of 
the crown. The anterior edge of the crown has a 
distinct rim (Figures 3A, C) that separates the flat 
crown from the indented neck, and connects the 
front edge of the coronal ridges; this is particularly 
visible in side view (Figure 3B). All specimens have 
a diamond-shaped, convex base. The crown 
extends posteriorly beyond the base, in some 
specimens further (Figure 3D) than in others 
(Figure 3B). In most of the scales, the crown length 
and width is approximately equal, while the scale 
height is approximately one-third to one-half of the 
length/width measurement. The size range of the 
scales is 0.5-0.9 mm long, 0.4-1 mm wide, and 0.2- 
0.5 mm high. Thin sections reveal the typical 
Nostolepis- type histology, with a pyramid-shaped 
base of cellular bone showing concentric growth 
zones, and a crown with ascending and concentric 
vascular canals (Denison 1979, figures 9A-C and 
10B), however preservation is insufficient in the 
prepared thin sections to reveal whether tubules 
are grouped into tufts in the furrows, a feature 
distinguishing this genus from Nostolepis (Denison 
1979). 
Discussion 
Wells (1944) separated scales of this 
morphological type into six species in two genera. 
These were subsequently amalgamated into the 
single species C. comptus by Gross (1973), who 
considered the morphological differences intra¬ 
specific. 
The anterior coronal rim found on all Broken 
River specimens is not specified by Wells (1944) as 
a character of the genus, but his illustrations 
(figures 4a-k, 5a-e, and especially the side view in 
figure 4c) show a clear delineation between the flat 
crown and deeply indented neck. Some later 
illustrations of C. comptus also show the rim (e.g. 
Gross 1973, plate 26 figures 24-26; Vieth-Schreiner 
1983, plate 4 figures 32-33; Valiukevicius 1985, 
plate 8 figures 4-5). In contrast, other specimens 
have the coronal ridges running down the anterior 
edge of the scale to where the neck area joins the 
base (e.g. Giffin 1980, figure 5; Gross 1973, plate 27 
figure 2c; and Cheiracanthoides cf. comptus 
illustrated by Boucot et al. 1989, text-figure 19). In 
these latter two examples the crown, in side view, 
appears thicker than the crown of specimens with 
the anterior rim. It is possible that this type of scale, 
without the anterior coronal rim, belongs to a 
different taxon, or at least occurs on a different 
region of the body. 
An acanthodian scale with some morphological 
similarity to the Broken River specimens, including 
the anterior rim on the crown, has been figured 
and described as ?Gomphonchus sp. by Long et al. 
(1988, figure 2F, G). Those authors discuss 
the differences between Comphonchus and 
Cheiracanthoides, and these differences are sufficient 
to separate Comphonchus and the Broken River 
material. 
Scales assigned here to C. comptus Wells, 1944 are 
the most common acanthodian microvertebrates in 
the Broken River material occurring in horizons 
from Eifelian ( kockelianus Zone) to earliest Frasnian 
(asymmetricus Zone). Specimens from Australian 
localities are figured by Giffin (1980 figure 5) and 
Turner (1991, plate 2A, F, plate 5C). The 
cosmopolitan genus has been reported elsewhere 
from the Early and Middle Devonian, particularly 
the Emsian and Eifelian (e.g. Wells 1944; Vieth 
1980; Valiukevicius 1979, 1985), and also from the 
lowermost Givetian ( hemiansatus Zone - Vieth- 
