The Cambrian Lophotrochozoans of the Transantarctic Mountains, Antarctica

Home , Chancelloria, Churchill Mountains

The Cambrian lophotrochozoans of the Transantarctic Mountains, Antarctica

(image © Marissa Betts, used with permission)

THESIS FOR DEGREE OF FILOSOFIE LICENTIAT LEWIS BASSETT-BUTT 2015

Abstract

The origin of many lophotrochozoan groups can be traced to “small shelly fossil” (SSF) faunas of the Early Cambrian. Antarctica is a key region of study, due to the continent’s known close geographical proximity to well-stud- ied Australian and Indian basins in in the Cambrian. Few studies have focused on this region however, due to a paucity of data. Re-examination of camenellan sclerites from the Early Cambrian Shackleton Limestone of the Churchill Mountains of Antarctica has revealed a previously unidentified species of Dailyatia in the formation, co-occurring alongside previously described Dailyatia odyssei Evans and Rowell, 1990, as in the Arrowie Basin of Australia. Re-examination of material previously described as Kennardia sp. A and Kennardia sp. B has indicated that these taxa can likely be synonymized as a second species of Dailyatia. Dailyatia sclerites were also found in the temporally equivalent “Schneider Hills Limestone” formation, which crops out in the Argentina Range of Antarctica. These specimens appear to belong to a third species of Dailyatia, suggesting that the spatial distribution of tommotiids in the Early Cambrian was more complex than previously recognized, and that the group may be useful in future biostratigraphic studies. A study of the Middle Cambrian (Drumian Stage) Nelson Limestone Formation of the Neptune Range, Antarctica has revealed a moderately diverse brachiopod and trilobite fauna. The brachiopods have strong faunal links to taxa from South Australia and India, as well as other parts of the Antarctic province, fitting independent strong evidence for a united East Gondwanan region in the Mid- dle Cambrian. An unidentified camenellan tommotiid sclerite is also described from the Nelson Limestone. This extends the worldwide temporal range of the tommotiid clade into the Drumian Stage, and suggests that more basal members of the brachiopod stem-group survived to form part of a more diverse Middle Cambrian fauna.

Keywords: Brachiopoda, Dailyatia, Cambrian, Drumian, Middle Cambrian, Early Cambrian, Antarctica, tommotiid, camenellan, palaeobiology, small shelly fossils

Lewis Bassett-Butt, Uppsala University, Department of Earth Sciences, Pal- aeobiology, Villavägen 16, 752 36 Uppsala, Sweden

Acknowledgements

Many thanks to Lars Holmer (who has given me constant support and encour- agement), Graham Budd (for being incredibly supportive this year too), Mi- chael Streng (for bearing with the mishaps that seem to follow me in my trav- els from the acid lab to the photography room), Glenn Brock (for being really cool) and Christian Skovsted (for making my stay in the museum great). Many thanks to my other colleagues and friends from the department--Aodhán, Heda, Giannis, Illiam, Tim, Milos, Asa, Emma, Ralf, Linda, Luka, Sebastian and others. Your contributions are too huge to mention in full, and I'm sure I've forgotten someone important. Just like my doorkeys/keycard/passport I'll remember you when I've sent this in. Thanks too to people who have moved on (Francesco, Oskar, Steve, Haizhou and Allison)--our time together was short, but sweet. Unlike my succession of winter hats, I shan’t forget you all easily. Many thanks too to the "Macquarie Mob" who made Morocco 2014 incredibly memorable.

I'd also like to thank my liver, because I really need a stiff drink right about now.

Contents

Introduction ...... 9 Cambrian biomineralisation ...... 9 The Cambrian of Antarctica ...... 10 The Shackleton Limestone ...... 12 The Schneider Hills Limestone ...... 14 The Nelson Limestone ...... 15 Conclusions ...... 18 References ...... 18

Thesis produced for examination. It does not constitute a publication in the sense of the ICZN code.

List of papers

This thesis is based on the following papers, which are referred to in the text by their Roman numerals.

List of publications upon which this thesis is based

I BASSETT-BUTT, L. SUBMITTED. Systematics, biostratigraphic and biogeography of brachiopods and other fossils from the Middle Cambrian Nelson Limestone, Antarctica. Manuscript submitted to GFF. II BASSETT-BUTT, L & SKOVSTED, C. IN PRESS. Discovery of the youngest known tommotiid from the middle Cambrian (Drumian) Nelson Limestone of Antarctica. Manuscript for sub- mission to Bulletin of Geosciences. III BASSETT-BUTT, L & SKOVSTED, C. IN PRESS. Descrip- tion of camenellan tommotiids from the Early Cambrian of the Transantarctic Mountains, Antarctica. Manuscript for submis- sion to Palaeontology.

Thesis produced for examination. It does not constitute a publication in the sense of the ICZN code.

Introduction

The sudden diversification of metazoans in the Cambrian, known as the Cam- brian Explosion has been the subject of a huge amount of scientific research. A number of causes have been proposed, but a full consensus has yet to be reached. What is known however, is that the Early Cambrian contains the first unambiguous evidence of bilaterians in the fossil record, organisms which continued to diversify throughout the rest of the period. By the time of the Middle Cambrian Burgess Shale, typical marine faunas consisted of brachiopods, molluscs, annelids, arthropods and representatives of other enigmatic groups (Conway Morris, 1998). The development of stem- and crown- group concepts, first introduced by Henning (1981) and later refined by Budd and Jensen (2000), has allowed many of these ‘weird wonders’ of the Cambrian seas to be placed within the context of modern phyla.

Cambrian biomineralisation The evolution of biomineralised hard parts is crucial to understanding the evolution of bilaterian phyla. The first evidence of bilaterian biomineralisation comes from small shelly fossils—enigmatic fossils from the base of the Early Cambrian that are most often preserved in secondary calcium phosphate and with unclear links to modern phyla (Bengtson, 2004). Biomineralisation is currently understood to have evolved independently in many animal clades (Murdock and Donoghue, 2011), and, due to the biases against the preserva- tion of soft-bodied organisms, often the only evidence of an organism’s exist- ence in the fossil record is their biomineralised hard parts. Biomineralisation may have developed to counter increased predation in the Cambrian (Bengtson, 2002; Dzik, 2007) or to increase negative buoyancy and assist in burrowing (Cohen et al, 2003). Lophotrochozoans are believed to be among the first protostomes to bio- mineralise (Kouchinsky et al, 2012), and today represent a significant portion of total diversity in the marine realm (Pechenik, 2014). One major group of Palaeozoic lophotrochozoans were the brachiopods, a group which is still ex- tant, but with severely reduced diversity. The origin of this clade is still poorly understood, however recent theories suggest development from a phoronid- like ancestor. This ancestor is believed to be represented by the tommotiids, a

9 group of enigmatic small shelly fossils known mostly from disarticulated sclerites. This idea has been developed through the discoveries of articulated tommotiid specimens (Skovsted et al. 2008, 2009c, 2011), comparisons of shell secretion (Balthasar et al., 2009) and microstructure (Larsson et al., 2014) in brachiopods, tommotiids, and organisms with a suite of phoronid, tommotiid and brachiopod characteristics (Zhang et al., 2014).

Figure 1. Examples of different types of sclerites from the tommotiid Dailyatia ajax Bischoff, 1976 from the Flinders Range, South Australia (adapted from Skovsted et al., in review). A-B, Specimen SAMP A007, A sclerite: A, apical view, scale = 1 mm; B, right lateral view, scale = 1 mm. C-D, Specimen SAMP A003, dextral B1 sclerite: G, apical view, scale = 500 µm; H, supra-apical lateral view, scale = 500 µm. E, SAMP A054, central portion of broken dextral C sclerite, apical view, scale = 500 µm. F, SAMP A053, central portion of broken sinistral C sclerite, dorsal view, scale = 500 µm.

The Cambrian of Antarctica Understanding the palaeobiogeography of Antarctic forms will help us to un- derstand the evolution of bilaterians. Antarctica represents the last wilderness for fossil collection. Portions of varying size of the continent have been con- nected to Australia throughout most of Earth's history (Rogers, 1996; Cawood, 2005). By the time of the Cambrian ‘explosion’, Antarctica, Australia and India were conjoined in East Gondwana, which stretched from northern Australia to the Transantarctic Mountains of Antarctica and lay at equatorial latitudes within a region of shallow, warm seas (see Figure 2; Meert and Lieberman, 2008).

Figure 2. Approximate positions of the Churchill Mountains (square) and Argentina Range (circle) on the Cambrian East Antarctic Palaeo-Pacific margin. Adapted from Rode et al., 2003.

Recent discoveries of a diversity of brachiopod stem-group members from Australia, including the scleritomes of many tommotiids (Skovsted et al., 2008, 2009a, 2009b, 2011) as well as the more derived Mickwitzia (Skovsted et al., 2009b), and lingulate and calciate brachiopods (Holmer & Ushatinskaya in Gravestock et al 2001; Topper et al., 2013) suggests that Gondwana may represent the cradle of lophotrochozoan evolution. Major areas of observable Cambrian deposition in Antarctica occur in the Transantarctic Mountains (see Figure 3). The Transantarctic Mountains stretch from Northern Victoria Land to Coats Land, and divide the continent of Antarctica into west and east. These mountains contain the oldest sedimentary formations of interest to palaeontologists on the continent.

Figure 3. Map of Antarctica, indicating the fossil-bearing regions highlighted throughout the text. Adapted from Palmer and Rowell, 1995.

The Shackleton Limestone The Early Cambrian of Antarctica has been examined in the Shackleton Lime- stone and the overlying Holyoake and Starshot formations in the south of the Transantarctic Mountains, between Mt. Bowers and the Churchill Mountains (Laird, 1963; Myrow et al., 2002). The Shackleton Limestone records deposition on an Early Cambrian carbonate shelf (Evans and Rowell, 1990), from the Atdabanian, to possibly early Toyonian (Debrenne and Kruse, 1986; Ev- ans and Rowell, 1990; Palmer and Rowell, 1995). Detailed stratigraphic information that can be drawn from the formation is limited by its complex deformation (Myrow et al., 2002), however small shelly fossils (Evans and Rowell, 1990), trilobites (Rowell et al, 1988; Palmer and Rowell, 1995) and archaeocyaths (Rees et al., 1988; Debrenne and Kruse, 1986) have been described from the range (see Figure 4).

Figure 4. Fossils from the Early Cambrian (Botomian) of the Shackleton Lime- stone, East Antarctica. A-C, Eohadrotreta sp., D-E, Eoobolus priscus, F, Karathele yorkensis, G, Pelagiella sp., H, Parailsanella sp., I, Cambroclavus absonus, J, Yochelcionella sp., K, Dailyatia odyssei. Adapted from Holmer et al., 2014.

Close similarities have been noted with Lower Cambrian fossils described in Australia (Laurie, 1986; Kennard, 1991; Bengtson et al, 1990; Gravestock et al, 2001). In particular, the upper Shackleton Limestone can be directly corre- lated with the Mernmerna Formation in the Flinders Ranges (Arrowie Basin), South Australia and indicates a Botomian (Cambrian Series 2, Stages 3-4) age, whilst a δ13C excursion in the middle of the formation may tie to a globally recognised excursion in the upper Terreneuvian, Cambrian Stage 2 (Holmer et al., 2014). Herein, we redescribe tommotiid material collected from the Shackleton Limestone by Evans and Rowell (1990) over 30 years ago. Evans and Rowell (1990) described two species of Dailyatia: Dailyatia braddocki Evans and Rowell 1990 and Dailyatia odyssei Evans and Rowell 1990. Specimens that represent D. odyssei (Skovsted et al, in review) has also been discovered in glacial erratics from the King George Island, off the Antarctic Peninsula

13 (Wrona, 2004). These erratics were presumably originally derived from the Transantarctic Mountains, and possibly rocks of the same age as the Shackle- ton Limestone. Skovsted et al. (in review) suggested that the Shackleton Limestone Dai- lyatia specimens showed evidence of micro-ornamentation that had not been previously noted by Evans and Rowell (1990), and we can confirm this find- ing. In addition, we find evidence of a third species of Dailyatia in the Shack- leton Limestone, which co-occurs with D. odyssei in some locations. Material is too meagre to fully describe the species, however it is identical to unidentified Dailyatia specimens from the Arrowie Basin of Australia, which also co- occur alongside D. odyssei (Skovsted et al., in review). Two species of Kennardia were also identified by Evans and Rowell (1990) in the Shackleton Limestone, but due to a small number of specimens they could not be examined in detail. A closer examination of a larger number of similar sclerites has shown shared ornamentation features; therefore we con- sider these two species to be synonymous. The sclerites do not resemble Ken- nardia specimens from Australia, instead the specimens bear strong similarities to the sclerites of Dailyatia ajax Bischoff 1976, but contain morphological features which have not been previously observed in any Dailyatia species (Skovsted et al., in review). They therefore likely represent a new Dailyatia species.

The Schneider Hills Limestone Lower Cambrian fossils have also been found in the informally named “Schneider Hills limestone” in the Argentina Range (Rode et al., 2003). It has been suggested that the hills are part of the same carbonate shelf that the Shackleton Limestone was deposited on (Rowell et al., 1992). New stratigraphic data has also implied that the Schneider Hills are the shallow-water equivalents of the deeper-water Hannah Ridge Formation, which underlies the Nelson Limestone (see Figure 5; Rowell et al., 2001).

Figure 5. Proposed stratigraphic relationship of the major rock units of the Neptune and Argentina ranges. Adapted from Rowell et al., 2001.

Archaeocyaths from an unknown location in the Schneider Hills were dated to the Botomian (Konyushkov and Shulyatin, 1980), however Rowell (1992)

14 also noted the presence of Dailyatia sclerites in the upper beds of the Schnei- der Hills limestone. A close examination of these sclerites has revealed that they can be divided into several separate forms. There are morphological similarities to other species of Dailyatia, but the specimens are distinct enough to be considered a new species. Differences between the Dailyatia sclerites of the Schneider Hills and the Shackleton Limestone suggests that temporal or spatial factors may have been involved in the separation of the species. At present these factors cannot be readily distinguished due to the limited data available on the age of the Argentina Range, but the almost 1200km distance between the Ar- gentina Range and the central Churchill Mountains suggests a strong spatial element (Rowell et al., 1992).

The Nelson Limestone The Nelson Limestone is one of the most pronounced fossiliferous Middle Cambrian deposits of the Transantarctic Mountains, located in the Neptune Range of the Pensacola Mountains (see Figure 3 and Figure 5). Important contributions to the paleobiogeography understanding of this area were conducted by Palmer and Gatehouse (1972). Lieberman (2004) refined these results in the Nelson Limestone, and showed close links to Aus- tralia in the Middle Cambrian and dated the Nelson Limestone to Drumian in age. The formation records a general eustatic sea rise and the formation of a carbonate shelf deposit, with three subsequences recording smaller scale fluc- tuations in relative sea level (Evans et al., 1995). Two separate trilobite bi- ozones have been recognised, dividing the formation into upper and lower segments (Lieberman, 2004). Archaeocyaths (Wood et al., 1992) were recognised from the Nelson Limestone. A small fauna of brachiopods have also been documented (Evans et al., 1995; Lieberman, 2004). A close examination of this fauna shows it is comprised of Oepikites haimantensis Reed 1910, Prototreta millsi Brock and Percival 2006, Acro- thele sp. cf. vertex Reed 1910, Micromitra sp. cf. nerranubawu Kruse 1990, Diraphora dyunyin Kruse, 1990 and Dictyonina australis Roberts, 1990 (see Figure 6; Bassett-Butt, submitted). Trilobites representative of forms described by Palmer and Gatehouse (1972) and Lieberman (2004) were also described. There appears little differentiation in faunal assemblages between the upper and lower parts of the formation.

Figure 6. Fossils from the Middle Cambrian (Drumian) of the Nelson Limestone. A, Micromitra cf. nerranubawu ventral valve exterior, scale = 500 µm. B, Dictyonina australis, dorsal valve exterior, scale = 500 µm. C, Acrothele cf. vertex, oblique view of ventral valve exterior, scale = 500 µm. D, Prototreta millsi, view of ventral pseudointerarea, scale = 500 µm. E, Prototreta millsi, oblique view of dorsal valve interior, scale = 500 µm. F, Oepikites haimantensis, internal view of dorsal valve, scale = 500 µm. G, Diraphora dyunyin, dorsal view of calcified dorsal valve exterior, scale = 5 mm. H, ?Peronopsis sp., dorsal view of cephalon, scale = 500 µm. I, ?Chancelloria sp., oblique view, scale = 500 µm.

The Nelson Limestone brachiopod fauna is closest in similarity to forms from the rest of the Cambrian East Gondwanan margin. Acrotretids are similar to species described from the Bowers Group, of North Victoria Land, Antarctica, whilst lingulid and acrothelid forms are shared with the Indian Parahio For- mation (Popov et al., in press.). The closest similarities in Australia are found with Stage 4 to Stage 5 specimens from southern Australian basins, described by Roberts and Jell (1990) and Brock and Percival (2006). These basins formed on the eastern margin of Gondwana (Percival and Kruse, 2014; see Figure 7). Fewer similarities are found with specimens from intracratonic basins from the north and central Australia (e.g.: Rowell and Henderson, 1978; Kruse, 1990, 1991, 1998; Percival and Kruse, 2014; Smith et al., 2014) or with

16 basins formed on island arcs east of the margin (e.g.: Henderson and MacKin- non, 1981; Brock et al., 2000; Fergusson et al., 2013; Percival and Kruse, 2014). Detailed biogeographic studies have revealed a complex picture of trilobite distribution throughout East Gondwana in the Middle Cambrian (Hally and Paterson, 2014), and this appears to be the case for the brachiopods as well. However, there is a paucity of studies concerning Drumian deposits of Australia, reducing the clarity of biogeographical information that can be dis- cerned.

Figure 7. Australasian basins associated with Cambrian deposition. Red areas indicate intracratonic basins, green areas indicate basins associated with the East Gond- wanan margin, and blue areas indicate deposition on the flanks of islands offshore to the margin. Adapted from Percival and Kruse, 2014.

A possible new genus of tommotiid is also presented from the Nelson Lime- stone, based on the morphology of a single sclerite. The sclerite has an ex- panding tubular shape, with lateral compression and the characteristic orna- ment of the raised, closely spaced co-marginal ribs which makes the specimen very similar to sclerites of certain camenellan tommotiids. Because the Nelson Limestone has been dated to the Drumian (Lieberman, 2004), this would im- ply that this Antarctic specimen is the world’s youngest, and would indicate the clade survived for longer than previously known.

17 Conclusions In conclusion, these areas can greatly contribute to our understanding of Ant- arctic geology. However, to complete our understanding of the paleobiogeography of various biomineralised taxa, further studies of Antarctic material are required.

References ALEXANDER, E., J. JAGO, A. ROZANOV, AND A. ZHURAVLEV. 2001. The Cambrian biostratigraphy of the Stansbury Basin, South Australia. 282 pp. Nauka, Transactions of the Palaeontological Institute, Moscow. BALTHASAR, U., SKOVSTED, C.B., HOLMER, L.E. & BROCK, G. A., 2009. Homologous skeletal secretion in tommotiids and brachiopods.Geology 37, 1143–1146. BASSETT-BUTT, L. SUBMITTED. Systematics, biostratigraphic and biogeography of brachiopods and other fossils from the Middle Cambrian Nelson Limestone, Antarc- tica. GFF. BENGTSON, S., 2004. Early skeletal fossils. Paleontological Society Papers 10, 67–77. BENGTSON, S., 2002. Origins and early evolution of predation. Paleontological Society Papers 8, 289–318. BENGTSON, S., MORRIS, S.C. & COOPER, B.J., 1990. Early Cambrian fossils from south Australia. Memoirs of the Association of Australasian Palaeontologists 9, 1–364. BISCHOFF, G.C.O., 1976. Dailyatia, a new genus of the Tommotiidae from Cambrian strata of SE Australia (Crustacea, Cirripedia). Senckenbergiana lethaea 57, 1–33. BROCK, G., ENGELBRETSEN, M., JAGO, J., KRUSE, P., LAURIE, J., SHERGOLD, J., SHI, G. & SORAUF, J., 2000. Palaeobiogeographic afﬁnities of Australian Cambrian faunas. Memoir-Association of Australasian Palaeontologists 23, 1–61. BROCK, G. & PERCIVAL, I., 2006. Cambrian stratigraphy and faunas at Mount Ar- rowsmith, northwestern New South Wales. Memoirs of the Association of Aus- tralasian Palaeontologists 32, 75–101. BUDD, G.E. & JENSEN, S., 2000. A critical reappraisal of the fossil record of the bilaterian phyla. Biological Reviews of the Cambridge Philosophical Society 75, 253– 295. CAWOOD, P. A., 2005. Rodinia breakup and development of the Pacific and Iapetus margins of Gondwana during the Neoproterozoic and Paleozoic.Earth-Science Reviews 69, 249–279. COHEN, B., HOLMER, L. & LÜTER, C., 2003. The brachiopod fold: a neglected body plan hypothesis. Palaeontology 46, 59–65. CONWAY MORRIS, S., 1998. The crucible of creation: the Burgess Shale and the rise of animals. 242 pp. Oxford University Press, UK. DEBRENNE, F. & KRUSE, P.D., 1986. Shackleton Limestone archaeocyaths. Alcheringa: An Australasian Journal of Palaeontology 10, 235–278. DZIK, J., 2007. The Verdun Syndrome: simultaneous origin of protective armour and infaunal shelters at the Precambrian Cambrian transition. Geological Society, London, Special Publications 286, 405–414. EVANS, K. & ROWELL, A., 1990. Small shelly fossils from Antarctica: an Early Cam- brian faunal connection with Australia. Journal of Paleontology 64, 692–700.

18 EVANS, K., ROWELL, A. & REES, M., 1995. Sea-level changes and stratigraphy of the Nelson Limestone (Middle Cambrian), Neptune Range, Antarctica. Journal of Sedimentary Research B65, 32–43. FERGUSSON, C., NUTMAN, A., KAMIICHI, T. & HIDAKA, H., 2013. Evolution of a Cam- brian active continental margin: the Delamerian–Lachlan connection in south- eastern Australia from a zircon perspective. Gondwana Research 24, 1051–1066. HALLY, L. A. & PATERSON, J.R., 2014. Biodiversity, biofacies and biogeography of middle Cambrian (Series 3) arthropods (Trilobita and Agnostida) on the East Gondwana margin. Gondwana Research 26, 654–674. HENNIG, W., 1981. Insect phylogeny. 514pp. John Wiley & Sons Ltd, UK HOLMER, L.E., BROCK, G.A., SKOVSTED, C.B., TOPPER, T.P, BASSETT-BUTT, L., STEM- MERIK, L. & MYROW, P., 2014. The Early Cambrian of Antarctica: Faunas and che- mostratigraphy of the Shackleton Limestone. Presented at the International ISCS/ISES Joint Conference in Ouarzazate, Morocco. KENNARD, J.M., 1991. Lower Cambrian archaeocyathan buildups, Todd River Dolo- mite, northeast Amadeus Basin, Central Australia: sedimentology and diagenesis. Geological and Geophysical Studies in the Amadeus Basin, Central Australia, Bulletin 236 1, 195–225. KONYUSHKOV, K.N. & SHULYATIN, O.G., 1980. Ob arkheotsiatakhd Antarktidy I ikh sopostavlenii s arkheotsiatami Sibiri (On the archaeocyaths of Antarctica and their comparison with the archaeocyaths of Siberia). Kembriy Altae—Sayanskoy Skladchatoy Oblasti. Nauka, Moscow, 143–150. KOUCHINSKY, A., BENGTSON, S., RUNNEGAR, B., SKOVSTED, C., STEINER, M. & VEN- DRASCO, M., 2011. Chronology of early Cambrian biomineralization. Geological Magazine 149, 221–251. KRUSE, P., 1991. Cambrian fauna of the Top Springs Limestone, Georgina Basin. The Beagle: Records of the Museums and Art Galleries of the Northern Territory 8, 169–188. KRUSE, P., 1990. Cambrian palaeontology of the Daly basin. Northern Territory Geo- logical Survey Report 7, 1–58. KRUSE, P.D., 1998. Cambrian palaeontology of the eastern Wiso and western Georgina Basins. Northern Territory Geological Survey Report 9, 1–68. LAIRD, M.G., 1963. Geomorphology and stratigraphy of the nimrod glacier–beaumont bay region, Southern Victoria land, Antarctica.New Zealand Journal of Geology and Geophysics 6, 465–484. LARSSON, C.M., SKOVSTED, C.B., BROCK, G. A., BALTHASAR, U., TOPPER, T.P. & HOLMER, L.E., 2014. Paterimitra pyramidalis from South Australia: scleritome, shell structure and evolution of a lower Cambrian stem group brachiopod. Palae- ontology 57, 417–446. LAURIE, J., 1986. Phosphatic fauna of the Early Cambrian Todd River Dolomite, Amadeus Basin, central Australia. Alcheringa, 431–454. LIEBERMAN, B.S., 2004. Revised Biostratigraphy, Systematics, and Paleobiogeogra- phy of the Trilobites from the Middle Cambrian Nelson Limestone. The Univer- sity of Kansas Paleontological Contributions 14, 1–23. MEERT, J.G. & LIEBERMAN, B.S., 2008. The Neoproterozoic assembly of Gondwana and its relationship to the Ediacaran–Cambrian radiation. Gondwana Research 14, 5–21. MURDOCK, D.J.E. & DONOGHUE, P.C.J., 2011. Evolutionary origins of animal skeletal biomineralization. Cells, tissues, organs 194, 98–102.

19 MYROW, P. & POPE, M., 2002. Depositional history of pre-Devonian strata and timing of Ross orogenic tectonism in the central Transantarctic Mountains, Antarctica. Geological Society of America Bulletin 114, 1070–1088. PALMER, A. & GATEHOUSE, C., 1972. Early and middle Cambrian trilobites from Ant- arctica. U.S Geological Survery Professional Paper 456-D, 1–36. PECHENIK, J.A., 2014. Biology of the Invertebrates, 624 pp. McGraw-Hill Higher Ed- ucation, United States. PERCIVAL, I. & KRUSE, P., 2014. Biostratigraphy and biogeographic affinities of middle to late Cambrian linguliformean brachiopods from Australasia, in IGCP Pro- ject 591 Field Workshop, p. 109–116. POPOV, L. E., HOLMER, L. E., HUGHES, N. C., GHOBADI, P. M. & MYROW, P. M. IN PRESS. Himalayan Cambrian Brachiopods. Papers in Palaeontology. REED, F.R.C., 1910. The Cambrian fossils of Spiti. 76 pp. Memoirs of the geological Survey of India, Palaeontologia Indica, India. REES, M., PRATT, B. & ROWELL, A., 1989. early Cambrian reefs, reef complexes, and associated lithofacies of the Shackleton Limestone, Transantarctic Mountains. Sedimentology 36, 341–361. ROBERTS, J. & JELL, P. A., 1990. Early Middle Cambrian (Ordian) brachiopods of the Coonigan Formation, western New South Wales. Alcheringa: An Australasian Journal of Palaeontology 14, 257–309. RODE, A., LIEBERMAN, B. & ROWELL, A., 2003. A new early Cambrian bradoriid (Ar- thropoda) from East Antarctica. Journal of Paleontology 77, 691–697. ROGERS, J., 1996. A history of continents in the past three billion years. The Journal of Geology 104, 91–107. ROWELL, A., EVANS, K. & REES, M., 1988. Fauna of the Shackleton Limestone. Antarc- tic Journal of the United States 20, 5–6. ROWELL, A. & HENDERSON, R., 1978. New genera of acrotretids from the Cambrian of Australia and the United States. The University of Kansas Paleontological Con- tributions 93, 1–12. ROWELL, A.J., REES, M.N., COOPER, R. A. & PRATT, B.R., 1988. Early paleozoic history of the central transantarctic mountains: evidence from the Holyoake Range, Ant- arctica. New Zealand Journal of Geology and Geophysics 31, 397–404. ROWELL, A.J., REES, M.N. & EVANS, K.R., 1990. Depositional setting of the Lower and Middle Cambrian in the Pensacola Mountains.: Antarctic Journal of the United States 25, 40–42. ROWELL, A., REES, M. & EVANS, K., 1992. Evidence of major Middle Cambrian deformation in the Ross orogen, Antarctica. Geology 20, 31–34. ROWELL, A. J., VAN SCHMUS, W.R., STOREY, B.C., FETTER, A. H. & EVANS, K.R., 2001. Latest Neoproterozoic to Mid-Cambrian age for the main deformation phases of the Transantarctic Mountains: new stratigraphic and isotopic constraints from the Pensacola Mountains, Antarctica. Journal of the Geological Society 158, 295– 308. SKOVSTED, C.B., BALTHASAR, U., BROCK, G. A. & PATERSON, J.R., 2009. The tommotiid Camenella reticulosa from the Early Cambrian of South Australia: morphology, scleritome reconstruction, and phylogeny. Acta Palaeontologica Polonica 54, 525–540. SKOVSTED, C.B., BROCK, G. A., HOLMER, L.E. & PATERSON, J.R., 2009. First report of the early Cambrian stem group brachiopod Mickwitzia from East Gondwana. Gondwana Research 16, 145–150.

20 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: Lo- phophorate affinities and implications for tommotiid phylogeny. Geology 36, 171. SKOVSTED, C.B., BROCK, G. A., TOPPER, T.P., PATERSON, J.R. & HOLMER, L.E., 2011. Scleritome construction, biofacies, biostratigraphy and systematics of the tommotiid Eccentrotheca helenia sp. nov. from the Early Cambrian of South Aus- tralia. Palaeontology 54, 253–286. SKOVSTED, C.B., HOLMER, L.E., LARSSON, C.M., HÖGSTRÖM, A.E.S., BROCK, G. A, TOP- PER, T.P., BALTHASAR, U., STOLK, S.P. & PATERSON, J.R., 2009. The scleritome of Paterimitra: an Early Cambrian stem group brachiopod from South Australia. Proceedings of the Royal Society B 276, 1651–6. SKOVSTED, C.B., BETTS, M.J., TOPPER, T.P. & BROCK, G.A. IN REVIEW. The early Cambrian tommotiid genus Dailyatia from South Australia. Memoirs of the Association of Australasian Palaeontologists. SMITH, P., BROCK, G., PATERSON, J. & TOPPER, T., 2014. New bradoriid arthropods from the Giles Creek Dolostone (Cambrian Series 3, Stage 5; Templetonian), Amadeus Basin, central Australia. Memoirs of the Association of Australasian Palaeontol- ogists 45, 233–248. TOPPER, T.P., HOLMER, L.E., SKOVSTED, C.E., BROCK, G. A., BALTHASAR, U., LARSSON, C.M., PETTERSSON STOLK, S. & HARPER, D. A. T., 2013. The oldest brachiopods from the lower Cambrian of South Australia. Acta Palaeontologica Polonica 58, 93–109. WOOD, R., EVANS, K. & ZHURAVLEV, A., 1992. A new post-early Cambrian archaeocy- ath from Antarctica. Geological Magazine 129, 491–495. WRONA, R., 2004. Cambrian microfossils from glacial erratics of King George Island, Antarctica. Acta Palaeontologica Polonica 49, 13–56. ZHANG, Z., LI, G.-X., HOLMER, L. & BROCK, G., 2014. An early Cambrian agglutinated tubular lophophorate with brachiopod characters. Scientific reports Nature Scien- tific report 4, 1–7.