290 
J.A. Long, G.C. Young 
preserved as 3-D impressions (McLoughlin and 
Long 1994). 
Mt Gudmundson 
Approximately 93 m of Aztec Siltstone is 
exposed here in continuous outcrop, conformably 
resting upon a thick exposure of Beacon Heights 
Orthoquartzite and unconformably topped by 
Darwin Tillite. The stratigraphic section was 
measured and described by J. Long. At least six 
different fish bearing horizons identified: site "1", 
about 2.5 m above the base, with isolated fish 
plates preserved in black siltstones; site "2", a 
boulder scree resting on a table of quartzite, about 
10 m from base, with rare isolated fish plates; site 
"3", contains fish fragments about 2 metres higher 
than previous site in similar lithology; site "4", 
about 21 m above the base, has isolated fish plates 
in clean, white medium-grained quartz arenite; site 
"5" about 54 m above the base, a rich bonebed of 
fish plates in a pebbly, gritty coarse sandstone- 
conglomerate, and site "6", about 90 m above the 
base in the highest exposure of flat-lying 
sandstones of the Aztec Siltstone, also a gritty layer 
with abundant fish bones. Some scree material 
containing fish fossils in a coarse sandstone was 
found in between sites 5 and 6 and labelled as site 
"5.5". 
Southern Warren Range 
Site 23 (Young 1988) 
Section A5, west of Mount Ritchie (70/71). The 
shark tooth illustrated by Young (1982, plate 88, 
figure 4) came from the vicinity of section A5 of 
Askin et al. (1971). The precise horizon is uncertain, 
but was interpreted by Young (1988, text-figure 5) 
to lie within the range of "Xenacanthus" sp. 
(described herein as Portalodus bradshawae gen. et 
sp. nov.). 
Site 24 (Young 1988) 
Section A4, Mount Ritchie (70/71). Arthrodire, 
Gorgons Head” Fault Bluff 1 Fish Hotel site Mt. Gudmundson 
BIOZONES 
Figure 2 Comparisons of stratigraphic sections from four new localities of Aztec Siltstone fish fauna in the Cook 
Mountains. Biozonation modified from Young (1988). An, Antarctilamna prisca ; Ar, Anareodus gen. nov., Az, 
Aztecodus gen. nov., Bv, Bothriolepis vuwae ; Gy, Gryracanlhides warreni; No, Notorhizodon mackelveyi; Pa, 
Pambulaspis antarctica; Ph, phyllolepids common; Po, Portalodus bradshawae. Other numbers and 
abbreviations refer to field localities of fish-bearing horizons. 
