Ageleodus sp.

Roelofs, Brett, Barham, Milo, Mory, Arthur J. & Trinajstic, Kate, 2016, Late Devonian and Early Carboniferous chondrichthyans from the Fairfield Group, Canning Basin, Western Australia, Palaeontologia Electronica (Barking, Essex: 1987) 262, pp. 1-28 : 6

Ageleodus sp.

Figure 3.1-4

Material. Four incomplete teeth: one tooth from sample 198404, and three teeth from TS-1, Laurel Formation, Laurel Downs, Tournaisian.

Description. Labio-lingually compressed crown that is slightly arched along the occlusal margin ( Figure 3.1-3 ). The crown comprises a single row of four to five unornamented triangular cusps, decreasing in size distally ( Figure 3.1 ). Most teeth bear cusp apices with a slight lingual inclination that are typically worn flat or slightly rounded ( Figure 3.2-3 ). One specimen, WAM 15.6.33, ( Figure 3.4 ) preserves three pointed triangular cusps with little wear. Shallow, vertical grooves originating at the juncture of the cusps are present on the top half of both crown faces. On one tooth (WAM 15.6.34, Figure 3.2 ), the crown is labio-lingually convex between the base of the cusps and the crown base interface. The lateral sides of the crown are rounded and taper mesially to a shallow depression along the crown-base interface ( Figure 3.1-3 ). The labio-lingually flattened base is short and bears small foramina and longitudinal furrows. Remarks. Due to the high level of heterodonty previously recorded for Ageleodus pectinatus Agassiz, 1838 and the absence of multiple complete teeth from the samples, species determination is not possible. The teeth do share similarities with other known Ageleodus species. One partial tooth crown (WAM 15.6.33, Figure 3.4 ) possesses the pointed triangular cusps typical of the Late Devonian Ageleodus pectinatus Downs and Daeschler, 2001 and the Ageleodus teeth described by Lebedev (1996, figure 13). The rounded apicies on one tooth (WAM 15.6.23, Figure 3.1 ) are similar to Ageleodus altus Garvey and Turner, 2006 from the Carboniferous of Victoria, Australia. As cusp morphology appears to diagnose different species of Ageleodus , it is possible more than one species inhabited the Canning Basin at this time. However, given the large amount of variation in the small sample size, it is more likely physical wear has contributed to the cusp shape than species specific morphology.

Figures

FIGURE 3. Late Devonian and Early Carboniferous shark teeth from the Lennard Shelf, Canning Basin, Western Australia. 1-4, Ageleodus sp., WAM 15.6.23, sample 198404, in lingual view (1), WAM 15.6.34, sample TS-1, in labial (2) and lingual (3) views, and WAM 15.6.33, sample TS-1, in lingual view (4); 5-7, Phoebodus cf. turnerae, WAM 15.6.28, sample OH-4, in occlusal (5), labial (6) and lateral (7) views; 8-11, Thrinacodus ferox, WAM 15.6.32, sample LG-1, in occlusal view (8), WAM 15.6.8, sample 198404, in occlusal view (9), WAM 15.6.11, sample 198404, in lateral view (10), and WAM 15.6.9, sample 198404, in occlusal view (11); 12-16, Stethacanthus? sp., WAM 15.6.6, sample 198404, in occlusal view (12), and WAM 15.6.7, sample 198404, in basal (13), lingual (14), occlusal (15) and labial (16) views. Scale bar length: 1-4, 1 mm; 5-7, 0.5 mm; 8-11, 0.25 mm; 12, 0.5 mm; 13-16, 0.5 mm.

FIGURE 4. Ctenacanthiform teeth from the Lower Carboniferous Laurel Formation, Laurel Downs, Lennard Shelf, Canning Basin, Western Australia. 1-7, Cladodus thomasi, WAM 15.6.50, sample 198404, in lingual view (1), WAM 15.6.25, sample 198404, in occlusal view (2), WAM 15.6.12, sample 198404, in lingual (3) and labial views (4), WAM 15.6.19, sample 198404, partial platform and crown in lingual view (5), and WAM 15.6.13, sample TS-1, in occlusal (6) and labial (7) views; 8-12, Cladodoides cf. wildungensis, WAM 15.6.15, sample 198404, in lingual (8), occlusal (9) and labial (10) views, WAM 15.6.16, sample 198404, in labial (11) and lingual (12) views. Scale bar length: 1-7, 1 mm; 8-10, 0.25 mm; 11-12, 0.5 mm.