The Scleritome of Paterimitra: an Early Cambrian Stem Group Brachiopod From

The scleritome of Paterimitra: an early Cambrian stem group brachiopod from

South Australia

Christian B. Skovsted1*, Lars E. Holmer1, Cecilia M. Larsson1, Anette E.S. Högström1, Glenn A. Brock2, Timothy P. Topper2, Uwe Balthasar1, Sandra Petterson Stolk1 & John R. Paterson3

Electronic Supporting Material

MATERIAL AND LOCALITIES

Isolated sclerites of Paterimitra are abundant in acid macerated limestone samples from lower Cambrian outcrops in the FlindersRanges, South Australia. Specimens illustrated here were recovered from samples collected from three broadly synchronous (late Atdabanian-early Botoman) carbonate dominated units.

1. Wilkawillina Limestone. Specimens are derived from two main stratigraphic sections: The type section (WILK) of the Wilkawillina Limestone in Wilkawillina Gorge (Pararaia tatei trilobite Zone)originally collected by the late Brian Daily in the early 1970s. Figured specimens come from sampled horizons WILK I, Q, Rwhich are located 49.46 m, 65.00 m and 66.83 m, respectively, above the base of the section. The base of the type section is located at the iron rich microstromatolitic “reddened” horizon which equates with the regionally significant Flinders Unconformity (James Gravestock 1990; Gravestock Cowley 1995) (co-ordinates: 31° 15.7’ S; 138° 53.5’ E map datum: UTM54J).The second locality is situated near the top of the Wilkawillina Limestone just below the “reddened” microstromatolitic horizon at sample horizon MMF/0.0 (Abadiella huoi trilobite Zone). This stratigraphic level conforms with the base of the MMF section and is located approximately 1 km south of Balcoracana Creek on the eastern side of the Bunkers Range (coordinates: 31°11’38.4”S, 138°52’28.7”E; map datum: WGS84). This horizon has also yielded articulated specimens of the tommotiid Eccentrotheca (Skovsted et al. 2008). Paterson & Brock (2007) provide detailed discussion of sedimentology and biostratigraphy of this locality.

2. Ajax Limestone, MountScottRange.Material is derived from horizons from two separate stratigraphic sections that equate with the Abadiella huoi trilobite Zone: Section AJX-M is a 277 m (true thickness) section and specimens come from sample horizons AJX-M/256 and 262.7which are 143.15 m and 146.9 m (true thickness), respectively, above the base of the section at 30°35′49.020′′S, 138°19′59.448′′E. Section AJX-N is 257 m thick and specimens come from horizon AJX-N/213, 122 m (true thickness) above the base of section at 30°35′07.3′′S, 138° 18′56.5′′E).

3. Wirrapowie Limestone, DruidRange.One specimen showing sclerite fusion was recovered from flat lying exposures of the upper Wirrapowie Limestone (?Abadiella huoi trilobite Zone) collected from a spot locality on the northern slope of theDruidRange (co-ordinates: 31°46′23.488′′S, 138°35′44.448′′E). Specimen numbers (prefix SAMP) refer to the paleontological collection of the SouthAustralianMuseum, Adelaide.

REFERENCES

Gravestock, D.I., Cowley, W. M. 1995 ArrowieBasin. In J. F. Drexel and W. V. Priess (eds), The geology of South Australia, Volume 2: The Phanerozoic. Mines and Energy, South Australia, Bulletin 54,20-31.

James, N.P. &Gravestock, D.I.. 1990 Lower Cambrian shelf and shelf margin build-ups, Flinders Ranges, South Australia. Sedimentology 37, 455-480.

Paterson, J.R. & Brock, G.A. 2007 Early Cambrian trilobites from Angorichina, Flinders Ranges, South Australia, with a new assemblage from the Pararaia bunyerooensis Zone. Journal of Paleontology 81, 116-142.

Skovsted, C.B., Brock, G.A., Paterson, J.R., Holmer, L.E. Budd, G.E. 2008 The scleritome of Eccentrotheca from the Lower Cambrian of South Australia: lophophorate affinities and implications for tommotiid phylogeny. Geology36, 171–174. doi: 10.1130/G24385A.1