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Acritarchs from the Duolbagáisá Formation (Cambrian Series 2, Miaolingian) on the Digermulen Peninsula, Finnmark, Arctic Norway: towards a high-resolution Cambrian chronostratigraphy

Published online by Cambridge University Press:  24 April 2020

Teodoro Palacios*
Affiliation:
Área de Paleontología, Facultad de Ciencias, Universidad de Extremadura, Avenida de Física s/n, 06006Badajoz, Spain
Anette E. S. Högström
Affiliation:
Arctic University Museum of Norway, UiT the Arctic University of Norway, 9037Tromsø, Norway
Jan Ove R. Ebbestad
Affiliation:
Museum of Evolution, Uppsala University, Norbyvägen 16, 752 36Uppsala, Sweden
Heda Agić
Affiliation:
Department of Earth Sciences, Uppsala University, 752 36Uppsala, Sweden Department of Earth Science, University of California at Santa Barbara, Santa Barbara, CA93106, USA
Magne Høyberget
Affiliation:
Magne Høyberget, Rennesveien 14, 4513Mandal, Norway
Sören Jensen
Affiliation:
Área de Paleontología, Facultad de Ciencias, Universidad de Extremadura, Avenida de Física s/n, 06006Badajoz, Spain
Guido Meinhold
Affiliation:
Department of Sedimentology & Environmental Geology, Geoscience Centre, University of Göttingen, Goldschmidtstraße 3, 37077Göttingen, Germany School of Geography, Geology and the Environment, Keele University, Keele, Staffordshire, ST5 5BG, UK
Wendy L. Taylor
Affiliation:
Department of Geological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
*
Author for correspondence: Teodoro Palacios, Email: [email protected]

Abstract

New information on acritarchs from the Duolbagáisá Formation, Digermulen Peninsula, Arctic Norway, enable recognition of the three Cambrian Series 2 acritarch-based zones: the Skiagia ornataFimbriaglomerella membranacea, Heliosphaeridium dissimilareSkiagia ciliosa and Volkovia dentiferaLiepaina plana Assemblage zones. Acritarchs of the Skiagia ornataFimbriaglomerella membranacea Zone (Cambrian Stage 3) appear near the base of the unit, close to an undetermined trilobite. In the Upper Member of the Duolbagáisá Formation, in levels with Kjerulfia n. sp. and Elliptocephala n. sp., appears an assemblage with abundant Skiagia ciliosa, indicative of the Heliosphaeridium dissimilareSkiagia ciliosa Zone. A few metres higher appear Liepaina plana, Heliosphaeridium notatum and Retisphaeridium dichamerum, which indicate the Volkovia dentiferaLiepaina plana Zone (Cambrian Stage 4). The transition between the Duolbagáisá Formation and the overlying Kistedalen Formation is marked by the appearance of Comasphaeridium longispinosum, Multiplicisphaeridium llynense and Eliasum llaniscum, diagnostic of the Miaolingian Series. This coincides with the disappearance of Skiagia; occurrences of Skiagia in Miaolingian strata consist of reworked material related to the Hawke Bay regression at the Cambrian Stage 4–Wuliuan transition. The absence of Skiagia in higher levels of the Duolbagáisá Formation and Kistedalen Formation suggests that no unconformity formed during the Hawke Bay regression in this area. The chronostratigraphical significance of the Skiagia ornataFimbriaglomerella membranacea, Heliosphaeridium dissimilareSkiagia ciliosa and Volkovia dentiferaLiepaina plana zones is critically analysed. Correlation of the Duolbagáisá Formation with peri-Gondwanan terrains of Avalonia and Iberia is established. The Digermulen Peninsula has great potential as a reference section for establishing a Cambrian chronostratigraphy based on acritarchs.

Type
Original Article
Copyright
© Cambridge University Press 2020

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References

Agić, H, Högström, AES, Jensen, S, Ebbestad, JOR, Meinhold, G, Palacios, T, Taylor, WL and Høyberget, M (2018) Life through the ‘Varanger Ice Ages’: microfossil record of late Neoproterozoic glacial-interglacial units from Arctic Norway. Geological Society of America, Abstracts with Programs 50, doi: 10.1130/abs/2018AM-322291.CrossRefGoogle Scholar
Agić, H, Högström, AES, Moczydłowska, M, Jensen, S, Palacios, T, Meinhold, G, Ebbestad, JOR, Taylor, WL and Høyberget, M (2019) Organically-preserved multicellular eukaryote from the early Ediacaran Nyborg Formation, Arctic Norway. Scientific Reports 9, 14659, doi: 10.1038/s41598-019-50650-x.CrossRefGoogle ScholarPubMed
Ahn, SY and Zhu, M (2017) Lowermost Cambrian acritarchs from the Yanjiahe Formation, South China: implications for defining the base of the Cambrian in the Yangtze Platform. Geological Magazine 154, 1217–31.CrossRefGoogle Scholar
Banks, NL (1970) Trace fossils from the late Precambrian and Lower Cambrian of Finnmark, Norway. In Trace Fossils (eds Crimes, TP and Harper, JC), pp. 1934. Geological Journal Special Issue 3. Liverpool: Seel House Press.Google Scholar
Banks, NL (1973) Tide-dominated offshore sedimentation, Lower Cambrian, northern Norway. Sedimentology 20, 213–28.CrossRefGoogle Scholar
Banks, NL, Edwards, MB, Geddes, WP, Hobday, DK and Reading, HG (1971) Late Precambrian and Cambro-Ordovician sedimentation in East Finnmark. Norges Geologiske Undersøkelse 269, 197236.Google Scholar
Cohen, KM, Finney, SC, Gibbard, PL and Fan, JX (2013; updated 2019/5) The ICS International Chronostratigraphic Chart. Episodes 36, 199204.Google Scholar
Crimes, TP and McIlroy, D (1999) A biota of Ediacaran aspect from Lower Cambrian strata on the Digermulen Peninsula, Arctic Norway. Geological Magazine 136, 633–42.CrossRefGoogle Scholar
Díez Balda, MA and Fournier Vinas, C (1981) Hallazgo de acritarcos en el Complejo Esquisto-Grauváquico al Sur de Salamanca. Acta Geológica Hispánica 16, 131–4.Google Scholar
Downie, C (1982) Lower Cambrian acritarchs from Scotland, Norway, Greenland and Canada. Transactions of the Royal Society of Edinburgh: Earth Sciences 72, 257–85.CrossRefGoogle Scholar
Ebbestad, JOR, Høyberget, M, Högström, AES, Palacios, T, Jensen, S, Taylor, WL and Meinhold, G (2017) Holmiid trilobites from the lower Cambrian of the Digermulen Peninsula, Arctic Norway. In Abstracts, 6th International Conference on Trilobites and their Relatives. Tallinn, Estonia, 7–10 July 2017 (ed. Pärnaste, H), pp. 1516. Tallinn: Abstracts Libris Est OÜ.Google Scholar
Ebbestad, JOR, Högström, AES, Palacios, T, Jensen, S, Meinhold, G, Høyberget, M, Agić, H, and Taylor, WL (2018) Biostratigraphy and palaeontology of the lower Cambrian Duolbagáisá Formation on the Digermulen Peninsula, Arctic Norway. In Session Abstracts, International Conference on Arctic Margins VIII, Stockholm, Sweden, 11–14 June 2018.Google Scholar
Eklund, C (1990) Lower Cambrian acritarch stratigraphy of the Bårstad 2 core, Östergötland, Sweden. Geologiska Föreningens i Stockholm Förhandlingar 112, 1944CrossRefGoogle Scholar
Føyn, S (1937) The Eo-Cambrian series of the Tana district, northern Norway. Norges Geologiske Undersøkelse 17, 65161.Google Scholar
Grazhdankin, DV, Marusin, VV, Izokh, OP, Karlova, GA, Kochnev, BB, Markov, GE, Nagovitsin, KE, Sarsembaev, Z, Peek, S, Cui, H and Kaufman, AJ (2020) Quo vadis, Tommotian? Geological Magazine 157, 2234.CrossRefGoogle Scholar
Habib, D, Eshet, Y and van Pelt, R (1994) Palynology of sedimentary cycles. In Sedimentation of Organic Particles (ed. Traverse, A), pp. 311–35. Cambridge: Cambridge University Press.CrossRefGoogle Scholar
Hagenfeldt, SE (1989) Lower Cambrian acritarchs from the Baltic Depression and south-central Sweden, taxonomy and biostratigraphy. Stockholm Contributions in Geology 41, 1176.Google Scholar
Hayes, JM, Kaplan, LR and Wedeking, W (1983) Precambrian organic geochemistry, preservation of the record. In Earth’s Earliest Biosphere (ed. Schopf, JW), pp. 93134. Princeton: Princeton University Press.Google Scholar
Högström, AES, Jensen, S, Palacios, T and Ebbestad, JOR (2013) New information on the Ediacaran–Cambrian transition in the Vestertana Group, Finnmark, northern Norway, from trace fossils and organic-walled microfossils. Norwegian Journal of Geology 93, 95106.Google Scholar
Howell, BF (1925) The faunas of the Cambrian Paradoxides beds at Manuels, Newfoundland. Bulletin of American Paleontology 11, 1149Google Scholar
Jachowicz-Zdanowska, M (2013) Cambrian phytoplankton of the Brunovistulicum–taxonomy and biostratigraphy. Polish Geological Institute Special Papers 28, 1150.Google Scholar
Jankauskas, T (2002) Cambrian Stratigraphy of Lithuania. Vilnius: Institute of Geology of Lithuania, 256 pp.Google Scholar
Jensen, S, Högström, AES, Almond, J, Taylor, WL, Meinhold, G, Høyberget, M, Ebbestad, JOR, Agić, H and Palacios, T (2018) Scratch circles from the Ediacaran and Cambrian of Arctic Norway and southern Africa, with a review of scratch circle occurrences. Bulletin of Geosciences 93, 287304.CrossRefGoogle Scholar
Jensen, S, Palacios, T and Martí Mus, M (2010) Revised biochronology of the Lower Cambrian of the Central Iberian zone, southern Iberian massif, Spain. Geological Magazine 147, 690703.CrossRefGoogle Scholar
Landing, E, Geyer, G, Brasier, MD and Bowring, SA (2013) Cambrian evolutionary radiation: context, correlation, and chronostratigraphy-overcoming deficiencies of the first appearance datum (FAD) concept. Earth‐Science Reviews 123, 133–72.CrossRefGoogle Scholar
Liñán, E, Gámez Vintaned, JA and Gozalo, R (2015) The middle lower Cambrian (Ovetian) Lunagraulos n. gen. from Spain and the oldest trilobite records. Geological Magazine 152, 1729.CrossRefGoogle Scholar
Liñán, E, Gozalo, R, Palacios, T, Gámez Vintaned, JA, Ugidos, JM and Mayoral, E (2002) Cambrian. In The Geology of Spain (eds Gibbons, W and Moreno, T), pp. 1729. London: The Geological Society of London.CrossRefGoogle Scholar
Lopes, G, Pereira, Z, Fernandes, P, Wicander, R, Matos, JX, Rosa, D and Oliveira, JT (2014) Significance of reworked palynomorphs (middle Cambrian to Tournaisian) in the Visean Toca da Moura Complex (South Portugal). Implications for the geodynamic evolution of Ossa Morena Zone. Review of Palaeobotany and Palynology 200, 123.CrossRefGoogle Scholar
Martin, F and Dean, WT (1983) Late Early Cambrian and Early Middle Cambrian acritarchs from Manuels River, eastern Newfoundland. Current Research, Part B. Geological Survey of Canada, Paper 83-1B, 353–63.Google Scholar
Martin, F and Dean, WT (1984) Middle Cambrian acritarchs from the Chamberlains Brook and Manuels River Formations at Randon Island, eastern Newfoundland. Current Research, Part A. Geological Survey of Canada, Paper 84-1A, 429–40.Google Scholar
Martin, F and Dean, WT (1988) Middle and Upper Cambrian acritarch and trilobite Zonation at Manuels River and Random Island, eastern Newfoundland. Geological Survey of Canada Bulletin 381, 191.Google Scholar
McIlroy, D and Brasier, MD (2017) Ichnological evidence for the Cambrian explosion in the Ediacaran to Cambrian succession of Tanafjord, Finnmark, northern Norway. In Earth System Evolution and Early Life: A Celebration of the Work of Martin Brasier (eds Brasier, AT, McIlroy, D and McLoughlin, N), pp. 351–68. Geological Society of London, Special Publication no. 448.Google Scholar
McIlroy, D, Green, OR and Brasier, MD (2001) Palaeobiology and evolution of the earliest agglutinated Foraminifera: Platysolenites, Spirosolenites and related forms. Lethaia 34, 1329.CrossRefGoogle Scholar
Moczydłowska, M (1991) Acritarch Biostratigraphy of the Lower Cambrian and the Precambrian–Cambrian Boundary in Southeastern Poland. Fossils and Strata no. 29. Oslo: Universitetsforlaget, 127 pp.Google Scholar
Moczydłowska, M (1998) Cambrian Acritarchs from Upper Silesia, Poland – Biochronology and Tectonic Implications. Fossils and Strata no. 46, Oslo: Scandinavian University Press, 121 pp.Google Scholar
Moczydłowska, M (2010) Life cycle of early Cambrian microalgae from the Skiagia-plexus acritarchs. Journal of Paleontology 84, 216–30.CrossRefGoogle Scholar
Moczydłowska, M (2011) The early Cambrian phytoplankton radiation: acritarch evidence from the Lükati Formation, Estonia. Palynology 35, 103–45CrossRefGoogle Scholar
Moczydłowska, M and Zang, WL (2006) The Early Cambrian acritarchs Skiagia and its significance for global correlation. Palaeoworld 15, 328–47.CrossRefGoogle Scholar
Molyneux, SG, Le Hérissé, A and Wicander, R (1996) Paleozoic phytoplankton. In Palynology: Principles and Applications (eds Jansonius, J and McGregor, DC), pp. 493529. College Station, Texas: American Association of Stratigraphic Palynologists Foundation.Google Scholar
Nielsen, AT and Schovsbo, NH (2015) The regressive Early-Mid Cambrian ‘Hawke Bay Event’ in Baltoscandia: epeirogenic uplift in concert with eustasy. Earth-Science Reviews 151, 288350CrossRefGoogle Scholar
Nikolaisen, F and Henningsmoen, G (1985) Upper Cambrian and Lower Tremadoc olenid trilobites from the Digermul Peninsula, Finnmark, N.-Norway. Norges Geologiske Undersøkelse Bulletin 400, 149.Google Scholar
Nikolaisen, F and Henningsmoen, G (1990) Lower and Middle Cambrian trilobites from the Digermulen peninsula, Finnmark, northern Norway. Norges Geologiske Undersøkelse Bulletin 419, 5595.Google Scholar
Nowak, H, Servais, T, Monnet, C, Molyneux, SG and Vandenbroucke, TR (2015) Phytoplankton dynamics from the Cambrian Explosion to the onset of the Great Ordovician Biodiversification Event: a review of Cambrian acritarch diversity. Earth-Science Reviews 151, 117–31.CrossRefGoogle Scholar
Palacios, T (2015) Acritarch assemblages from the Oville and Barrios Formations, northern Spain: a pilot proposal of a middle Cambrian (Series 3) acritarch biozonation in northwestern Gondwana. Review of Palaeobotany and Palynology 219, 71105.CrossRefGoogle Scholar
Palacios, T, Högström, A, Ebbestad, JOR, Jensen, S, Høyberget, M, Meinhold, G and Taylor, WL (2015) Acritarchs from the Duolbagáisá and Kistedalen formations (Cambrian Series 2-3), Digermulen Peninsula, northern Norway. In Abstract Book, CIMP Meeting 2015, University of Bergen, Bergen, Norway, 17–18 September 2015 (eds Mangerud, G, Lopes, G, Vecoli, M and Wicander, R), p. 32.Google Scholar
Palacios, T, Jensen, S and Apalategui, O (2006) Biostratigrafía de acritarcos en el Cámbrico Inferior y Medio del margen septentrional de Gondwana (Área de Zafra, Suroeste de la Península Ibérica). In XXII Jornadas de la Sociedad Española de Paleontología, Libro de Resúmenes (ed. Fernández-Martínez, E), pp. 156–61. León: Universidad de León.Google Scholar
Palacios, T, Jensen, S, Barr, SM and White, CE (2009) Acritarchs from the MacLean Brook Formation, southeastern Cape Breton Island, Nova Scotia, Canada: new data on Middle Cambrian–Lower Furongian acritarch zonation. Palaeogeography, Palaeoclimatology, Palaeoecology 273, 123–41.CrossRefGoogle Scholar
Palacios, T, Jensen, S, Barr, SM, White, CE and Myrow, PM (2018) Organic-walled microfossils from the Ediacaran–Cambrian boundary stratotype section, Chapel Island and Random formations, Burin Peninsula, Newfoundland, Canada: global correlation and significance for the evolution of early complex ecosystems. Geological Journal 53, 1728–42.CrossRefGoogle Scholar
Palacios, T, Jensen, S, Cortijo Sánchez, I and Martí Mus, M (2014) First Lower Cambrian record of Wiwaxia from north-west Gondwana: small carbonaceous fossils from the Láncara Formation, Cantabrian Mountains, northern Spain. In Programme, Abstracts and AGM Papers, 58th Annual Meeting of the Palaeontological Association, University of Leeds, Leeds, UK, 16–19 December 2014, p. 90.Google Scholar
Palacios, T, Jensen, S, White, CE and Barr, SM (2011) New biostratigraphical constraints on the lower Cambrian Ratcliffe Brook Formation, southern New Brunswick, Canada, from organic-walled microfossils. Stratigraphy 8, 4560.Google Scholar
Palacios, T, Jensen, S, White, CE and Barr, SM (2012) Cambrian acritarchs from the Bourinot belt, Cape Breton Island, Nova Scotia: age and stratigraphic implications. Canadian Journal of Earth Sciences 49, 289307.CrossRefGoogle Scholar
Palacios, T, Jensen, S, White, CE and Barr, SM (2016) Organic-walled microfossils from the Ediacaran-Cambrian Global boundary stratotype section, Chapel Island, Random, and Brigus formations, southeastern Newfoundland, Canada. Geological Society of America Abstracts with Programs 48, doi: 10.1130/abs/2016NE-271964Google Scholar
Palacios, T, Jensen, S., White, CE, Barr, SM and Miller, R (2017a) Acritarchs from the Hanford Brook Formation, New Brunswick, Canada: new biochronological constraints on the Protolenus elegans Zone and the Cambrian Series 2–3 transition. Geological Magazine 154, 571–90.CrossRefGoogle Scholar
Palacios, T and Moczydłowska, M (1998) Acritarch biostratigraphy of the Lower–Middle Cambrian boundary in the Iberian Chains, province of Soria, northeastern Spain. Revista Española de Paleontología, Numero Extraordinario, Homenaje al Prof. Gonzalo Vidal, 6582.Google Scholar
Palacios, T, Ou, Z, Agić, H, Högström, AES, Jensen, S, Høyberget, M, Meinhold, G, Taylor, WL and Ebbestad, JOR (2017b) Organic-walled microfossils and organic fossils across the Ediacaran–Cambrian boundary on the Digermulen Peninsula, Arctic Norway. In Abstract Volume, International Symposium on the Ediacaran–Cambrian Transition (ISECT) 2017, Saint John’s, Newfoundland, Canada, 20–22 June 2017 (ed. McIlroy, D), p. 91.Google Scholar
Palacios, T and Vidal, G (1992) Lower Cambrian acritarchs from northern Spain: the Precambrian–Cambrian boundary and biostratigraphic implications. Geological Magazine 129, 421–36.CrossRefGoogle Scholar
Pu, JP, Bowring, SA, Ramezani, J, Myrow, P, Raub, TD and Landing, E (2016) Dodging snowballs: geochronology of the Gaskiers glaciation and the first appearance of the Ediacaran biota. Geology 44, 955–8.CrossRefGoogle Scholar
Reading, HG (1965) Eocambrian and Lower Palaeozoic geology of the Digermulen Peninsula, Tanafjord, Finnmark. Norges Geologiske Undersøkelse 367, 77104.Google Scholar
Rice, AHN, Edwards, MB, Hansen, TA, Arnaud, E and Halverson, GP (2011) Glaciogenic rocks of the Neoproterozoic Smalfjord and Mortensnes formations, Vestertana Group, E. Finnmark, Norway. In The Geological Record of Neoproterozoic Glaciations (eds Arnaud, E, Halverson, GP and Shields-Zhou, G), pp. 593602. Geological Society of London, Memoirs no. 36.Google Scholar
Rushton, AWA and Molyneux, SG (2011) Welsh Basin. In A Revised Correlation of the Cambrian Rocks in the British Isles (eds Rushton, AWA, Brück, PM, Molyneux, SG, Williams, M and Woodcock, NH), pp. 21–7. Geological Society of London, Special Report no. 25.CrossRefGoogle Scholar
Staplin, FL, Jansonius, J and Pocock, SAJ (1965) Evaluation of some acritarchous hystrichosphere genera. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 123, 167201.Google Scholar
Stover, LE, Brinkhuis, H, Damassa, SP, de Verteuil, L, Helby, RJ, Monteil, E, Partridge, AD, Powell, AJ, Riding, JB, Smelror, M and Williams, GL (1996) Mesozoic–Tertiary dinoflagellates, acritarchs and prasinophytes. In Palynology: Principles and Applications, vol 2 (eds Jansonius, J and McGregor, DC), pp. 641750. Dallas: American Association of Stratigraphic Palynologists Foundation.Google Scholar
Vidal, G (1981) Micropaleontology and biostratigraphy of the Upper Proterozoic and Lower Cambrian sequence in east Finnmark, northern Norway. Norges Geologiske Undersøkelse 362, 153.Google Scholar
Vidal, G and Moczydłowska-Vidal, M (1997) Biodiversity, speciation and extinction trends of Proterozoic and Cambrian phytoplankton. Paleobiology 23, 230–46.CrossRefGoogle Scholar
Vidal, G, Moczydłowska, M and Rudavskaya, V (1995) Constraints on the early Cambrian radiation and correlation of the Tommotian and Nemakit-Daldynian regional stages of eastern Siberia. Journal of the Geological Society, London 152, 499510.CrossRefGoogle Scholar
Vidal, G, Palacios, T, Díez Balda, MA, Gámez Vintaned, JA and Grant, SWF (1994) Neoproterozoic–early Cambrian geology and palaeontology of Iberia. Geological Magazine 131, 729–65.Google Scholar
Vidal, G and Peel, JS (1993) Acritarchs from the Lower Cambrian Buen Formation in North Greenland. Grønlands Geologiske Undersøgelse Bulletin 164, 135.Google Scholar
Volkova, NA (1969) Acritarchs of the north-west Russian Platform. In Tommotian Stage and the Cambrian Lower Boundary Problem (eds Yu Rozanov, A, Missarzhevsky, VV, Volkova, NA, Voronova, LG, Krylov, IN, Keller, BM, Korolyuk, IK, Lenzion, K, Michniak, R, Pykhova, NG and Sidorov, AD), pp. 224–36. Trudy Geologicheskogo Instituta Akademii Nauk SSSR, no. 206 (in Russian).Google Scholar
Volkova, NA, Kirjanov, VV, Piscun, LV, Paškevičienė, LT and Jankauskas, TV (1983) Plant microfossils. In Upper Precambrian and Cambrian Palaeontology of the East-European Platform (eds Urbanek, A and Yu Rozanov, A), pp. 746. Warszawa: Wydawnictwa Geologiczne.Google Scholar
Welsch, M (1986) Die Acritarchen der höheren Digermul-Gruppe, Mittelkambrium bis Tremadoc, Ost-Finnmark, Nord-Norwegen. Palaeontographica, Abteilung B 201, 1109.Google Scholar
Zhang, X, Ahlberg, P, Babcock, LE, Choi, DK, Geyer, G, Gozalo, R, Stewart, J, Hollingsworth, SH, Li, G, Naimark, EB, Pegel, T, Steiner, M, Wotte, T and Zhang, Z (2017) Challenges in defining the base of Cambrian Series 2 and Stage 3. Earth-Science Reviews 172, 124–39.CrossRefGoogle Scholar
Zang, WL, Moczydłowska, M and Jago, JB (2007) Early Cambrian acritarch assemblage zones in South Australia and global correlation. In South Australia 2006 – Papers from the XI International Conference of the Cambrian Stage Subdivision Working Group (eds Laurie, JR, Paterson, JR and Jago, JB), pp. 141–77. Memoirs of the Association of Australasian Palaeontologists no. 33.Google Scholar