Devonian sharks from Antarctica 
293 
Figure 4 Antarclilamna teeth. A, B, WAM 92.3.62, in labial view. B, in basal view, from the top of Mt. Ritchie. C, 
WAM 92.3.68 from "Gorgon's Head", Cook Mountains, showing three intermediate cusps, labial view. D, a 
tooth from the holotype of Antarclilamna prisca (CPC 21187) previously illustrated by Young (1982, plate 89, 
figure 7), which shows two small intermediate cusps. Bar scales are all 1 mm. 
in advanced xenacanth teeth (e.g., Hampe 1988a: 
figure 1). The corresponding region in Phoebodus 
teeth is the 'labio-basal thickening' of Ginter and 
Ivanov (1992, figure 2). 
Stratigraphic occurrance 
Antarctilamm teeth are now known from the base 
of the Aztec Siltstone (A. prisca, askinae zone, with 
thelodonts) through to the youngest biozones 
(occurring with phyllolepids and Pambulaspis at 
Gorgon's Head), although the latter specimens may 
possibly belong in a different species. 
Portalodus gen. nov. 
Portalodus bradshawae sp. nov. 
Figures 5-7 
'tooth [which] resembles .... the diplodont teeth 
found in Xenacanthus', Ritchie, in McKelvey et 
at., 1972: 351. 
Xenacantheus sp. Young 1982: 833, figure 3E-G, 
plate 89, figures 1-4. 
Xenacantheus sp., Grande and Eastman 1986:121. 
'Xenacanthus' sp., xenacanth shark teeth. Young 
1988:13,14,16, figure 5. 
'Xeru)Cfl«f/u(s'sp.,Schneiderl988:71-2, figure 2 A-C. 
'xenacanth shark tooth'. Young 1989a: figure 4D. 
teethof Xemcanthus sp.', Young 1991: figure 15.6c, d. 
'xenacanthid gen. nov. 1', Young et at. 1993: 248. 
'xenacanth shark tooth', Vickers-Rich and Rich 
1993: 93, plate 82. 
'teeth identified as... Xenacanthus', Capetta et at. 
1993: 597. 
'xenacanthid indet.', Davis 1994: 60. 
'a new form of fossil shark's tooth...'. Long 1995b: 
p.69 (photo). 
Etymology 
From the type locality, Portal Mountain; and in 
honour of K221 expedition leader Margaret 
Bradshaw. 
Diagnosis 
Shark with large diplodont teeth, base to cusp 
apex length up to 2 cm in largest specimens. 
Principal cusps divergent, one about a third larger 
than the other, and twisted in different planes in 
occlusal view. Few sparse external striae may be 
developed on lingual surface, but labial surface 
smooth. Cusps almost rounded in cross-section, 
slightly compressed with cutting edges developed 
along mesial and marginal edges. Base normally 
broader than the height of the shorter cusp, with a 
prominent labial platform, and lacking a projection 
on lingual face. Underside of base simple, without 
