Records of the Western Australian Museum 17: 35-41 (1995). 
A new groenlandaspidid arthrodire (Pisces; Placodermi) from the Middle 
Devonian Aztec Siltstone, southern Victoria Land, Antarctica 
John A. Long 
Department of Earth and Planetary Sciences, Western Australian Museum, Francis Street, Perth, 
Western Australia 6000 
Abstract — Boomeraspis goujeti gen. et sp. nov is described from isolated 
trunk-shield plates found in the basal 30 metres of Aztec Siltstone exposed at 
Alligator Peak in the Boomerang Range of southern Victoria Land. 
Boomeraspis is characterised by its broad posterior dorsolateral plate (PDL) 
which has an inflected main lateral line canal and a strongly convex dorsal 
margin, and the posterior lateral plate (PL) features a strong lateral ridge. 
These features place Boomeraspis as a primitive member of the family 
Groenlandaspididae, distinguished from both Tiaraspis and Groenlandaspis 
by its proportionately longer PDL, strongly ridged and larger PL, and also 
by the long posterior division of the ventral lamina on the PVL plate. 
INTRODUCTION 
Devonian fossil fish remains were first collected 
from southern Victoria Land, Antarctica, in the 
summer of 1911-12 by Mr Frank Debenham, a 
member of Scott's "Terra Nova" expedition. His 
finds near Granite Harbour came from moraine 
material, and were later described by Woodward 
(1921), who correctly assigned a Devonian age to 
the small assemblage of fish scales, teeth and 
fragmentary bones. The first extensive collections 
were made in situ by B. M. Gunn and G. Warren 
during the 1955-1958 Transantarctic Expedition. 
More extensive collections of fossil fish were made 
in the summer of 1968-69 by members of the 
Victoria University of Wellington Antarctic 
Expeditions (VUWAE 13). Dr Alex Ritchie, of the 
Australian Museum, and Dr Gavin Young, 
Australian Geological Survey Organisation, made 
extensive collections of the Aztec Siltstone fishes 
over the summer of 1970-71 as part of VUWAE 15. 
White (1968) had described the fish remains 
collected by Gunn and Warren, and Ritchie (1972) 
summarised the distribution of the Aztec Siltstone 
fish faunas found on VUWAE 13, and later 
described the arthrodire Groenlandaspis antarcticus 
from the 1970-71 collection (Ritchie 1975). Young 
(1982,1988,1989a) has since described sharks, 
bothriolepid antiarchs and culmacanthid acan- 
thodians. Young et al. (1992) have monographed 
the crossopterygian fauna, and Turner and Young 
(1992) have described the thelodonts. The Aztec 
Siltstone is now known to contain over 30 species 
of fossil fishes, making it one of the most diverse 
freshwater fish faunas of its age, and a keystone to 
biostratigraphic correlations within the East 
Gondwana Province (Young 1989b,1993). 
During the 1988/89 season Woolfe et al. (1990) 
discovered fish-bearing Aztec Siltstone in the Cook 
Mountains, nearly 100 km south of the previously 
known sites. In the 1991/92 season the author 
joined M. Bradshaw, F. Harmsen and B. Staite in 
an expedition to collect fossil fish material from the 
Cook Mountains, and revisit known sites in the 
Skelton Neve region. It will be several years before 
the vast amount of new material collected from 
that expedition is prepared and ready for 
description. This paper describes a new 
groenlandaspidid arthrodire based on a few 
isolated plates recovered from the southeastern 
spur of the Alligator Ridge region of the 
Boomerang Range (site 21, of Young 1988, Fig. 1). 
Other undescribed phlyctaeniid arthrodires are 
known from the Aztec Siltstone (e.g. Young 1991) 
although the material described here can be readily 
distinguished from these forms by showing 
features characteristic of the family 
Groenlandaspididae. Although two scant fish 
faunas have been reported from the higher units in 
section 21, the material described herein came from 
a lower fish-bearing horizon within the basal 30 
metres of the Aztec Siltstone which may be 
identical with the fossiliferous horizon mentioned 
by Barrett and Webb (1973, section 3, as 
approximately 32 metres above the base of the unit) 
but not collected by them or by subsequent 
expeditions. All specimens are reposited in the 
collections of the Western Australian Museum 
(WAM). 
Abbreviations used in the text and figures are: 
ADL, anterior dorsolateral plate; AL, anterior 
lateral plate; AVL, anterior ventrolateral plate; 11c, 
main lateral-line canal groove; MD, median dorsal 
plate; ov.ADL, surface overlapped by ADL plate; 
ov.AL, area overlapped by AL plate; ov.MD, area 
overlapped by MD plate; ov.PL, area overlapped 
by PL plate; ov.PVL, area overlapped by PVL plate; 
PDL, posterior dorsolateral plate; PL, posterior 
lateral plate; PVL, posterior ventrolateral plate; ri. 
