Dalmanitidae, Vodges, 1890

Sandford, Andrew C. & Holloway, David J., 2006, Early Silurian phacopide trilobites from central Victoria, Australia, Memoirs of Museum Victoria 63 (2), pp. 215-255 : 249

Dalmanitidae indet.

Figure 17B

Dalmanitina sp. cf. Dalmanitina (Eudolatites) aborigenum .— Öpik, 1953: 28, pl. 10, fig. 92.

Trilobita indet.— Talent, 1964: 51 (pars).

Material. NMV P127957 (incomplete thorax) from old Costerfield Antimony Mine, Costerfield. Costerfield Siltstone. Locality marked Thomas (1941).

Remarks. This poorly preserved thorax with seven or possibly eight segments distinguishable is the only fossil recorded from the Costerfield Siltstone. Based on its large size (about 60 mm wide) and the form of the pleural furrows, Öpik (1953, p. 29) suggested that it probably belongs to Dalmanitina , a genus then interpreted more broadly than now, and that it may be related to his species ʻ Dalmanitina (Eudolatites)ʼ aborigenum from beds higher in the sequence. However, Talent (1964), regarded the specimen as too poorly preserved for identification even to family level.

We agree with Öpik that the specimen probably belongs to the Dalmanitidae , and that the short (exsag.), sharply incised pleural furrows preclude assignment to Dalmanites or its close allies. However, the holotype of ʻ Dalmanitina (Eudolatites)ʼ aborigenum , the species to which he thought it may be related, belongs to Dalmanites athamas (see above), and the fragmentary pygidium also included in aborigenum by Öpik is here assigned to Struveria sp. 2 . In size, the abaxially subquadrate outline of the axial rings and the form of the pleural furrows, the poorly preserved thorax from Costerfield is not unlike Struveria ? plithourgos described above, and it is possible that the two forms are related.

Figures

Figure 17. A, C, Struveria sp. 2, from PL206, Wallan. A, NMV P138209, pygidium, × 2. C, NMV P139337, cranidium,× 5.5.B, Dalmanitidae indet., NMV P127957, partial view of incomplete thorax, × 0.9, from old Costerfield Antimony Mine, Costerfield. D–F, Bessazoon sp. D, NMV P147769, pygidium (fragment), × 1.8, from PL256, Wallan. E, NMV P312817, cranidium (fragment), × 2.2, from PL6361, Springfield. F, NMV P147770, pygidium (fragment), × 2.4, from PL256, Wallan.