Dailyatia odyssei Evans and Rowell, 1990

Betts, Marissa J., Claybourn, Thomas M., Brock, Glenn A., Jago, James B., Skovsted, Christian B. & Paterson, John R., 2019, Shelly fossils from the lower Cambrian White Point Conglomerate, Kangaroo Island, South Australia, Acta Palaeontologica Polonica 64 (3), pp. 489-522 : 512-513

Dailyatia odyssei Evans and Rowell, 1990

Fig. 14 .

1990 Dailyatia odyssei ; Evans and Rowell 1990: 696, figs. 7.1–7.8.

2007 Dailyatia sp. ; Skovsted and Brock in Paterson et al. 2007b: 141, fig. 4G–J.

2015 Dailyatia odyssei ; Skovsted et al. 2015a: 58, figs. 44–50.

2017 Dailyatia odyssei ; Betts et al. 2017b: 255, fig. 14A–I.

Material. —Two fragmentary A2 sclerites and a single fragmentary C2 sclerite ( SAM P57326–57328) from Clast 5. From the Dailyatia odyssei Zone, WPC, Kangaroo Island, South Australia.

Description.—See Skovsted et al. (2015a: 58).

Remarks.— Dailyatia odyssei is the only species of the genus known from both South Australia and Antarctica. In South Australia, it has a stratigraphic range (spanning most of Series 2, Stage 3) that is mutually exclusive of most other species of Dailyatia , such as D. ajax , D. macroptera , D. bacata , and D. helica . Hence, D. odyssei is an important age-diagnostic taxon in the South Australian early Cambrian biostratigraphic scheme developed by Betts et al. (2016, 2017b), and is the eponym for the youngest biozone.

Only three D. odyssei sclerites have been recovered from the WPC clasts. External ornament clearly distinguishes them from the co-occurring D. decobruta Betts sp. nov. Ornament on both the A2 and C2 sclerites is typical of D. odyssei ; both morphotypes exhibit low, closely set concentric ribs ( Fig. 14A 1 , B, C), unlike the extravagant pustules seen in D. decobruta Betts sp. nov. None of the specimens display the strong pseudoplicae seen in D. decobruta Betts sp. nov.

The A2 sclerites from the WPC are fragmentary, but exhibit a wide, poorly defined deltoid, and a weak lateral trough between the posterolateral and the first lateral plicae, as seen in specimens of D. odyssei from the Flinders Ranges ( Fig. 14A 1 , B; Skovsted et al. 2015a: fig. 46). The central plica of the C2 sclerite is well-developed, but not “wall-like”, as in the Flinders Ranges specimens ( Skovsted et al. 2015a: fig. 49), and the sclerite may only be weakly coiled ( Fig. 14C ).

Stratigraphic and geographic range. — Lower Cambrian of South Australia: Arrowie Basin ( D. odyssei Zone ); Andamooka Limestone, Stuart Shelf; Ajax Limestone, Mt Scott Range , northern Flinders Ranges; Mernmerna Formation and Nepabunna Siltstone, Arrowie Syncline, northeastern Flinders Ranges; Second Plain Creek Member of the Wilkawillina Limestone and Six Mile Bore, Linns Springs and Third Plain Creek of the Mernmerna Formation, Bunkers Graben, southern-central Flinders Ranges; Linns Springs and Third Plain Creek members of the Mernmerna Formation, central Flinders Ranges; Mernmerna Formation, Chambers Gorge area, eastern Flinders Ranges. Stansbury Basin ( D. odyssei Zone ); WPC clasts, Kangaroo Island. Antarctica: Shackleton Limestone, Churchill Range, Transantarctic Mountains.

Figures

Fig. 14. The camenellan tommotiid Dailyatia odyssei Evans and Rowell, 1990 from the lower Cambrian White Point Conglomerate, Kangaroo Island, South Australia. A. SAM P57326, A2 sclerite in apical view (A1); A2, detail of the double perforations in the apex. B. SAM P57327, A2 sclerite in apical view, tilted to show deltoid. C. SAM P57328, C2 sclerite in dorsal view.

Fig. 1. Map showing study area on northern Kangaroo Island, Australia. Dashed line indicates Stansbury Basin extent.