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The Early Cambrian Fauna of North-East Greenland

Christian Skovsted

The Early fauna of North-East Dissertation presented at Uppsala University to be publicly examined in Lecture Theatre, building, Uppsala, Friday, January 16, 2004 at 13.00 for the degree of Doctor of Philosphy. The examination will be conducted in English.

Abstract Skovsted, C.B. 2003. The Early Cambrian fauna of North-East Greenland. 22 pp. Uppsala. ISBN 91-506-1731-1

Small shelly are common in sediments of Early Cambrian age, and include the earliest common representatives of metazoan with mineralized hard parts. The group include fossils of very different morphology, composition and ultrastructure, presumably representing skeletal remains of numerous groups, the biological affinity of which is sometimes unresolved. Although the of many small shelly fossils is obscure, the wide geographical range of many forms, yields a potential for enhancing biostratigraphic and palaeogeographic resolution in the Early Cambrian. Small shelly fossils have been studied extensively in many parts of the world, but our knowledge of their occurrence in Laurentia is still limited. The late Early Cambrian sequence of North-East Greenland has yielded a well preserved small shelly assemblage of more than 88 , representing a diversity which is unparalleled in Laurentian strata. The composition of the fauna, which also includes and , is indicative of a middle Dyeran (Botoman equivalent) age. The recovered fossils include a number of species that are known previously from other Early Cambrian palaeocontinents, and particularly strong ties to late Early Cambrian faunas of are documented. Among the widespread taxa are species belonging to very different animal groups such as brachiopods, molluscs, hyoliths, , coeloscleritophorans, eodiscid trilobites, bivalved and problematic fossils. These animals presumably had very different anatomical constructions, and their potential for dispersal in the Early Cambrian is suggestive of a close proximity of palaeocontinents in the Early Cambrian. The systematic affinity of many small shelly fossils is poorly understood, partly because of the fragmentary or disarticulated nature of many of the fossils. It has been suggested that the ornamented spines of Mongolitubulus were protoconodonts, but collections of Mongolitubulus from North and North-East Greenland exhibit characters better accommodated by an interpretation of the fossils as defensive spines of bivalved arthropods. Similarly, the problematic fossil Triplicatella has been interprested as a polyplacophoran shell but, in agreement with articulated specimens known from Australia, species of Triplicatella from Greenland show morphological features better explained by an opercular function. Morphological characters also suggest an affinity to orthothecid hyoliths. The early evolution of most extant animal groups is still not fully resolved, but new morphological and ultrastructural information in Early Cambrian fossil representatives helps elucidate the origin and evolution of major clades. Thus, the stem group from North-East Greenland combines characters of linguliform brachiopods and of , a non-bivalved problematic form from Australia with affinity. The combination strengthens arguments for a halkieriid ancestry of the brachiopod .

Keywords: Early Cambrian, Dyeran, Botoman, Biostratigraphy, Palaeogeography, Small Shelly Fossils, Brachiopoda, , , Trilobita.

Christian B. Skovsted, Department of Earth Science, Palaeobiology, Norbyvägen 22, SE-752 58 Uppsala, Sweden.

DISCLAIMER This manuscript is produced only for public examination as a doctoral thesis. It is not a publication in the sense of the International Code of Zoological Nomenclature.

©Christian Skovsted 2003

ISBN 91-506-1731-1

Printed in Sweden by Geotryckeriet, Uppsala 2003 Til Anne Mette, mit livs lys

List of Papers

I Skovsted, C.B. and Peel, J.S. 2001. The problematic fossil Mongolitubulus from the Lower Cambrian of Greenland. Bulletin of the Geological Society of Denmark, 48, 135- 147. II Holmer, L.E., Skovsted, C.B. and Williams, A. 2002. A stem group brachiopod from the Lower Cambrian – support for a Micrina (halkieriid) ancestry. Palaeontology, 45, 875- 882. III Skovsted, C.B. and Holmer, L.E. 2003. The Early Cambrian stem group brachiopod Mickwitzia from Northeast Greenland. Acta Palaeontologica Polonica, 48, 11-30. IV Skovsted, C.B. and Holmer, L.E. In press. Early Cambrian brachiopods from North-East Greenland. Accepted for publication in Palaeontology. V Skovsted, C.B. 2003. Mobergellans (Problematica) from the Cambrian of Greenland, and Kazakhstan. Paläontologische Zeitschrift, 77, 429-443. VI Gubanov, A., Skovsted, C.B. and Peel, J.S. In press. Anabarella australis (Mollusca, ) from the Lower Cambrian of Greenland. Accepted for publication in Geobios. VII Skovsted, C.B. Submitted. The mollusc fauna of the Early Cambrian Bastion Formation of North-East Greenland. Submitted to Bulletin of the Geological Society of Denmark. VIII Malinky, J. and Skovsted, C.B. Submitted. Hyoliths and small shelly fossils from the Lower Cambrian of North-East Greenland. Submitted to Acta Palaeontologica Polonica. IX Skovsted, C.B., Peel, J.S. and Atkins, C.J. Submitted. The problematic fossil Triplicatella from the Early Cambrian of Greenland, and Siberia. Submitted to Canadian Journal of Earth Science. X Peel, J.S. and Skovsted, C.B. Manuscript. Problematic cap-shaped fossils from the Lower Cambrian of North-East Greenland. XI Skovsted, C.B. Manuscript. Small shelly fauna from the late Early Cambrian of North- East Greenland.

Reproduction of papers I-VI was made with permission of the copyright holder. Paper I © 2001 by the Geological Society of Denmark, Copenhagen. Papers II and IV © 2002 by the Palaeontological Association, London. Paper III © 2003 by Instytut Paleobiologii PAN, Warsaw. Paper V © 2003 by E. Schweizerbartsche Verlagsbuchhandlung, Stuttgart. Paper VI © 2003 by Elsevier, Amsterdam. Papers VII-XI © 2003 by the authors. Contents

Den tidigkambriska faunan från Nordöstgrönland ...... 1 Tidig kambrium i Nordöstra Grönland och resten av världen...... 1 Djurlivets tidiga utveckling...... 2 Introduction...... 5 General introduction...... 5 Small Shelly Fossils...... 6 The Early Cambrian World...... 7 Timescale...... 7 Palaeogeography...... 7 The early evolution of animals...... 8 Cambrian fossils from North-East Greenland...... 9 Cambrian geology of North-East Greenland ...... 9 Composition of faunas...... 10 Correlations ...... 12 Summary of papers ...... 13 The spine-shaped Mongolitubulus...... 13 The stem group brachiopod Mickwitzia...... 14 Brachiopod fauna of North-East Greenland ...... 15 Mobergellans from Greenland and Asia...... 15 Molluscs and cap-shaped fossils of the Bastion Formation...... 16 Hyoliths and hyolith-like fossils from Greenland ...... 17 The shelly fauna of North-East Greenland ...... 18 Acknowledgements...... 19 References...... 19 Den tidigkambriska faunan från Nordöstgrönland

Den kambriska perioden i Jordens historia var den första geologiska tidsperioden med ett rikt, diversifierat djurliv, och många av de organismgrupper (metazoer) som har dominerat jordytan under de senaste 540 årmiljonerna dök upp under denna tidsålder. Bevis för denna diversifiering av djurlivet, den “kambriska explosionen”, förekommer i sedimentära bergarter för första gången nära gränsen mellan ediakarium och kambrium, både som spår av organismernas livsaktiviteter och som direkta lämningar av organismerna själva. Vår förståelse av den tidigkambriska världen och dess djurliv har förändrats avsevärt under senare år med en förbättrad tidsskala (Landing et al. 1998) och en förbättrad förståelse av både de relativt fåtaliga ediakariska livsformerna och den uppsjö av metazoer som dök upp i kambrium. Inte minst har vår förståelse av den kambriska djurvärlden förbättrats genom studier av exeptionellt välbevarade kambriska faunor, Lagerstätten, som den mellankambriska från Kanada och de underkambriska från Grönland och Chenjiang från Kina. Dessa faunor innehåller väl bevarade fossil av djur utan mineraliserade skelettdelar och visar att en komplex ekologisk struktur etablerades redan tidigt i djurlivets historia (Conway Morris 1986; Hou och Bergström 2003). Lämningar av skalbärande organismer dominerar dock, under tidig kambrium precis som i alla senare delar av fanerozoikum, de allra flesta fossila faunor vi känner till. De allra första problematiska skalfossilen förekommer redan i ediakariska sediment (Cloudina och Namacalathus), men runt gränsen till kambrium dyker en rad nya fossil av skalbärande djur upp (Bengtson 1994). Under resterande delar av tidig kambrium ökar diversiteten bland skalbärande organismer snabbt och redan före periodens slut hade flera välkända djurgrupper, t.ex. brachiopoder (armfotingar) och trilobiter etablerats. Många av de tidiga fossilen är mycket små (en eller ett par millimeter), i engelskspråkig litteratur ofta benämda med den deskriptiva termen “small shelly fossils” (små skalfossil), och representerar en rad olika organismer. I vissa fall rör det sig om skal av millimeterstora djur, men ofta om mindre komponenter (skleriter) från större skelettstrukturer (skleritom). Dessa organismers släktskapsförhållande till nutida djurgrupper varierar, och även om många troligen representerar föregångare till dagens djurgrupper (t.ex. echinodermer, mollusker, brachiopoder etc.), är många andra mer problematiska och deras släktskapsförhållanden tills vidare oklara. Enstaka fossil som normalt hänförs till de så kallade “små skalfossilen” är kända sedan 1800-talet (t.ex. Billings 1871; Walcott 1886), men det moderna studiet av denna typ av fossil påbörjades i Sibirien av sovjetiska paleontologer på 1960-talet (t.ex. Rozanov et al. 1969). Senare arbeten har beskrivit faunor från Europa (Kerber 1986; Hinz 1987), Kina (Xing et al. 1983; Qian och Bengtson 1989) och Australien (Bengtson et al. 1990; Gravestock et al. 2001). Medan underkambriska trilobiter och andra leddjur från den laurentiska delen av Nordamerika är ganska väl kända, gäller det motsatta de flesta grupper av små skalfossil från denna region. Endast mindre faunor, särskilt från Appalacherna i östra USA och Kanada (Spencer 1980; Landing och Bartowski 1996; Landing et al. 2001) och från nordvästra Kanada (Nowlan et al. 1985; Voronova et al. 1987) är hittills kända. Det dubbla syftet med denna avhandling är dels att beskriva och analysera en ny, mycket välbevarad, fauna av små skalfossil från övre underkambrium i Nordöstgrönland, dels att i detalj studera enstaka fossil från denna fauna som är särskilt intressanta för vår förståelse av funktionen och den tidiga evolutionen av några viktiga djurgrupper. Det första syftet behandlas i de flesta av de elva artiklar som ingår i avhandlingen, som var och en beskriver utvalda delar av faunan, medan det andra syftet huvudsakligen avhandlas i fem artiklar som i detalj behandlar utvalda fossil eller fossilgrupper (Artikel I, II, III, IX, X).

Tidig kambrium i Nordöstra Grönland och resten av världen. Den kambriska lagerföljden i Nordöstgrönland består av en inledande transgressiv sekvens med avsättning av sandsten, siltsten och skiffer i nämnd ordning (Kløftelv- och Bastionformationerna) ovan 1 eroderade senproterozoiska bergarter. Efter Bastionformationen inleddes karbonatsedimentation i området med Ella Island-formationen. Både Bastion- och Ella Island-formationerna innehåller fossil från senare delen av tidig kambrium. Ovan Ella Island-formationen följer en dolomitsekvens som även om den i stort saknar fossil, troligen representar hela den resterande kambriska perioden (Hyolithus Creek- och Dolomite Point-formationerna). De kambriska, och överlagrande ordoviciska, bergarterna veckades och förkastades senare under den kaledoniska orogenesen, innan de utsattes för erosion och överlagring av devonska till tertiära bergarter (Cowie och Adams 1957; Peel 1982; Stouge et al. 2001). De fossil som studeras i denna avhandling härrör i huvudsak från de olösliga resterna efter etsning av kalkstensprov i ättikssyra. De prov som studerats kommer från den övre delen av Bastionformationen och från Ella Island-formationen, och innehåller (framför allt i Bastionformationen) en mycket rik och välbevarad fauna av små skalfossil. Vissa av dessa fossil består av primär kalciumfosfat medan andra, ursprungligen bestående av kalciumkarbonat, har bevarats genom diagenetisk utfällning av fosfat. Fosfat har i dessa fall antingen fyllt håligheter i fossilen (stenkärnor av t.ex. mollusker), eller täckt de ursprungliga kalkskalens ytor med en tunn fosfathinna, vilken motstått behandlig med syra (t.ex. hyolithoperkula). Ett stort antal djurgrupper finns representerade i faunan (88 olika arter enbart i Bastion Formationen), bland dem brachiopoder (Artikel II, III, IV), mollusker (Artikel VI, VII, X), hyolither (Artikel VIII, IX) och problematiska fossil (Artikel I, V, XI). Den rika fossilfaunan från Bastion- och Ella Island-formationerna kan hänföras till en informell, mellersta del av dyeranetagen (sensu Palmer 1998a; tidigare Bonnia- zonen) från senare delen av tidig kambrium i Laurentia. Korrelation mellan Bastionformationen och Browns Pond-formationen i den takoniska allochthonen (staten NewYork, USA) baseras på förekomsten av mycket likartade faunor av små skalfossil ( asaphoides-faunan; Landing och Bartowski 1996). Elliptocephala asaphoides-faunans ålder uppskattades av Landing och Bartowski som motsvarande sen tidig- eller tidig mellandyeran. Faunor från Forteauformationen i södra delen av Labrador och på västra delen av Newfoundland delar också de en del arter med Nordöstra Grönland (Spencer 1980; James och Kobluk 1978). Forteauformationen är dock troligen något yngre, åtminstone än Bastionformationen (James och Kobluk 1978). Ytterligare jämförelser av den nordöstgrönländska faunan inom den laurentiska paleokontinenten är svåra att göra på grund av att så få fossil, vid sidan om trilobiter, är kända från underkambrium i Laurentia. Internationell korrelation i tidig kambrium har länge ansetts besvärlig eftersom goda indexfossil i stort sett saknas under denna period (Palmer 1998b; Geyer och Shergold 2000). Många av de grupper som hänförs till de små skalfossilens skara, innerhåller dock arter som är mycket väl spridda över jorden under tidig kambrium (Brock et al. 2000; Gubanov 1998). Deras användbarhet för biostratigrafi hämmas dock av att många av dessa arter är mycket långlivade (Landing 1994; Gravestock et al. 2001). Framför allt faunan från Bastionformationen innehåller ett stort antal arter som är kända sedan tidigare från olika tidigkambriska paleokontinenter. Till dessa arter hör både brachiopoder, hyolither, mollusker och olika problematiska fossil. Tillsammans möjliggör de korrelation av Bastion- och troligen även Ella Island- formationerna med den tidiga delen av botomanetagen i Sibirien och dess motsvarigheter på andra paleokontinenter. Särskilt starka verkar banden till Australien vara, och ett stort antal arter från Bastion Formationen har beskrivits från Bemella communis / Halkieria parva biozonerna (Gravestock et al. 2001). Detta förhållande stärker tidigare framförda hypoteser angående ett nära geografiskt förhållande mellan Australien och Laurentia i sen proterozoikum / tidig kambrium (t.ex. Dalziel 1997; Moczydlowska-Vidal 1998; Smith 2000; Gubanov 2002; Budd och Jensen In press) och tyder på att separationen mellan dessa kontinentalblock under tidig kambrium inte var större än att många olika organismgrupper kunde överbrygga avståndet.

Djurlivets tidiga utveckling. Som nämnts ovan är vår förståelse för många av de tidigaste djurens biologi och släktskapsförhållanden mycket begränsad. Ofta känner vi inte till hur de fossila rester vi hittar av de tidiga djuren förhåller sig till varandra i ett eventuellt skleritom, eller ens vilken funktion de ursprungligen hade. Som exempel kan nämnas det taggliknande fossilet Mongolitubulus (Artikel I). Detta fossil tolkades ursprungligen som en del av en tandapparat (protoconodont; Missarzhevsky 1977), men senare också som ett skyddande, taggliknande utskott på antingen ett skalbärande leddjur (bradoriid; se Artikel I nedan) eller en klomask (lobopod; Dzik 2003). Dessutom representerar de flesta av de tidiga djuren troligen tidiga stadier i den 2 utveckling som senare gav upphov till dagens djurgrupper (fyla). Vissa fossila organismer från tidig kambrium har föreslagits kombinera karaktärer från olika fyla (t.ex. Halkieria evangelista; Conway Morris och Peel 1995), och även när ett fossil visar släktskap till ett visst fylum, kan det ofta inte placeras inom detta fylums existerande fylogeni (den så kallade krongruppen). Dessa fossil kan istället föras till phylumets stamgrupp, en grupp som inkluderar besläktade organismer, vilka kombinerar primitiva drag med vissa av de karakteristika vi associerar med gruppens nulevande representanter (Budd och Jensen 2000). I den fauna från Nordöstgrönland som beskrivs i denna avhandling förekommer ett antal fossil vilkas morfologiska och ultrastrukturella egenskaper gör att de kan ge oss ny kunskap om några viktiga fossilgruppers tidiga utveckling. Först och främst rör det sig om det problematiska, tvåskaliga släktet Mickwitzia, tidigare bäst känt från underkambrium i Sverige, Estland och västra Nordamerika. Exemplar av Mickwitzia cf. occidens från Nordöstgrönland är aldrig kompletta, men de bevarade delarna, främst av ventralskalet, uppvisar ett antal karakteristika som påminner om de linguliforma brachiopoderna (bland annat larvalskalets morfologi, närvaron av en lingulidliknande pseudointerarea och follickelseta). Fossilen uppvisar samtidigt en skalstruktur som kombinerar strukturen hos vissa lingulida brachiopoder (acrotretiderna) med tuber genom skalet som (åtminstone på pseudointerarean) ursprungligen hyste seta (setigera tuber). Liknande strukturer förkommer i skleriter av släktet Micrina från Australien, ett släkte som tidigare föreslagits höra till halkieriiderna (snigelliknande kambriska organismer med ryggsidan täckt av ett stort antal taggliknande skleriter, kombinerat med ett större skal i vardera ändan, exemplifierade av Halkieria evangelista). Williams och Holmer (2002) föreslog att Micrina representerar ett tidigt stadium i brachiopodernas evolution, och kombinationen av karaktärer i Mickwitzia från Grönland stöder denna hypotes. Både Micrina och Mickwitzia hör således till brachiopodernas stamgrupp, om än Mickwitzia står de egentliga brachiopoderna närmare (Artikel II, III).

3 4 Introduction

General introduction The Early Cambrian was the period in Earth history that witnessed the emergence and early diversification of the animal groups that have dominated the planet for the last 540 Million years. Evidence for this biological event, the “”, can be studied in the sedimentary rock record, as traces of the activity of metazoan animals and remains of the animals themselves appear for the first time at, or near, the /Cambrian boundary (following a recent decision of the I.U.G.S. Subcommission on the terminal Proterozoic System, the name Ediacaran is now applied to the last Period of the Proterozoic). Our understanding of the Early Cambrian has changed greatly during the last few decades with the development of a refined timescale (Landing et al. 1998) and an improved understanding of the fossil record of both the sparse , and the prolific life-forms of the Cambrian itself. A remarkable diversity of soft-bodied animals is found in famous Cambrian Lagerstätten, such as the Middle Cambrian Burgess Shale of Canada, the Early Cambrian Sirius Passet fauna of North Greenland and the likewise Early Cambrian Chenjiang fauna of . These, and other similar faunas provide evidence for the utilisation of diverse niches, and the establishment of complex community structures early in the history of metazoan life (Conway Morris 1986; Hou and Bergström 2003). However, as in all subsequent geological periods, the absolute majority of fossils known from the Early Cambrian represent the skeletons of organisms secreting mineralised hard parts. The first shelly fossils are known from the Ediacaran (eg. Cloudina and Namacalathus), but at, or close to, the Ediacaran/Cambrian boundary the remains of diverse animal groups with mineralised hard parts appear for the first time. The diversity of shell-bearing animals increased rapidly during the remainder of the Early Cambrian, and many familiar fossil groups, such as brachiopods and trilobites, appeared during this interval. But many of the early shelly fossils are difficult to associate with later, fossil or extant, animal groups and are united only by their normally small size (up to a couple of millimeters). These fossils, representing a wide range of biological groups, are often termed “Small Shelly Fossils”. While some of these so-called small shelly fossils probably represent early representatives of animal groups well represented in later periods of the (eg. molluscs, , brachiopods, etc.), many other forms are more problematic and their biological affinities remain uncertain. Although elements of the Early Cambrian small shelly fossil assemblages have been known since the nineteenth century (eg. Billings 1871; Walcott 1886), modern studies of small shelly fossils were instigated by Soviet palaeontologists in the 1960-s (eg. Rozanov et al. 1969). Later workers have concentrated on Lower Cambrian sequences of Europe (eg. Kerber 1986; Hinz 1987), China (eg. Xing et al. 1983; Qian and Bengtson 1989) and Australia (eg. Bengtson et al. 1990; Gravestock et al. 2001). Although Early Cambrian trilobites and bivalved arthropods from Laurentia are relatively well documented (eg. Blaker and Peel 1997; Siveter and Williams 1997; Lieberman 1999), most of the fossil groups commonly included among small shelly fossils have not been extensively studied. Small assemblages from the Taconic Allochthon of the eastern United States and Quebec are known (eg. Landing and Bartowski 1996; Landing et al. 2002), and faunas from Labrador (Spencer 1980) and north- west Canada (Nowlan et al. 1985; Voronova et al. 1987) have also been described. The twofold aim of this thesis is first to document a new, well preserved and diverse fossil assemblage, dominated by small shelly fossils, from the late Early Cambrian of North-East Greenland, and to analyse its stratigraphical and palaeogeographical implications. The second objective is to study in greater detail fossils from North-East Greenland that are of particular interest for our understanding of the function and early evolution of major groups of animals. The first aim is addressed in most of the eleven papers presented in the thesis, each describing a portion of the total assemblage, while the second topic is the main theme in five of the papers, concentrating on selected fossils (Papers I, II, III, IX, X). 5 Small Shelly Fossils. Remains of the earliest animals secreting hard skeletons appear in the fossil record close to the base of the Lower Cambrian as small sclerites or shells, commonly not exceeding a couple of millimetres in size (Bengtson 1994). These remains, “small shelly fossils” are commonly described collectively (eg. Rozanov et al. 1969; Missarzhevsky 1989; Qian and Bengtson 1989; Bengtson et al. 1990; Gravestock et al. 2001), although they represent a wide variety of animals with diverse affinities within the animal kingdom (Bengtson 1994). Some of the fossils represent small animals in their own right, such as the univalved helcionelloid molluscs or the conchs and opercula of hyoliths, but many forms represent disarticulated components of multi- skeletons. Sclerites of a single scleritome may vary tremendously in morphology, requiring special attention in classification (Bengtson 1985). The phosphatic tommotiids and calcareous coeloscleritophorans are well known Cambrian examples. No fully

Figure 1 Small shelly fossils from the late Early Cambrian of North-East Greenland. All scalebars except D, F and I equal 0.5 mm. A. Hyolithellus micans (Billings, 1871), a phosphatic, tubular shell of unknown affinity. B. Conotheca australiensis Bengtson in Bengtson et al., 1990, a calcareous tubular shell related to orthothecid hyoliths. C. Parkula bounites Bengtson in Bengtson et al., 1990, the operculum of a hyolithid hyolith. D. Bradoriid sp., left valve of a bivalved , scalebar = 200 µm. E. ossicle of uncertain affinity. F. Hadimopanella apicata Wrona, 1982, a dermal sclerite of a palaeoscolecid worm, scalebar = 20 µm. G. Chancelloria sp., a composite sclerite (calcareous) of a coeloscleritophoran animal. H. Lapworthella shodakensis Lochman, 1956, an asymmetrical, phosphatic sclerite of a tommotiid. I. Microdictyon sp., a fragmentary specimen of a phosphatic sclerite of a lobopod, scalebar = 200 µm. articulated specimens of the Early to Middle Cambrian tommotiids are known, but a multi-sclerite reconstruction is inferred from ontogenetically fused specimens as well as morphological and distributional data (Bengtson 1970, Landing 1984). The coeloscleritophorans on the other hand, although also mainly known from disarticulated material (spanning most of the Cambrian period in age), are

6 known from articulated specimens. Well-preserved specimens of the superficially -like chanelloriids are known from a number of Early and Middle Cambrian localities, such as the famous Burgess Shale (Walcott 1920), while articulated specimens of the -like are known only from the Early Cambrian Sirius Passet Fauna of North Greenland (Conway Morris and Peel 1995). Small shelly fossils are common in Early Cambrian sediments and, as the fossils are often easily extracted by standard techniques used for conodont studies, can possibly serve well for biostratigraphical zonation and correlation in the Early Cambrian. However, the situation is complicated by the highly divergent employed by various workers, based on poorly preserved or misunderstood material (discussion in Qian and Bengtson 1989), as well as the apparently very long stratigraphical range of many taxa (Palmer 1998b; Gravestock et al. 2001; Landing et al. 2002). The advantage of small shelly fossils in biostratigraphy on the other hand is the wide palaeogeographical distribution of many species. Among other Early Cambrian fossil groups, the well known archaeocyathids appear to be highly endemic (Debrenne et al. 1999), and although some species and genera occur on different continents, high levels of endemism are also apparent among trilobites in the Early Cambrian (Geyer and Shergold 2000). It has become increasingly apparent that the distribution of small shelly fossils in the Early Cambrian can be used as a tool both for correlation between the Cambrian palaeocontinents, and for reconstructions of Cambrian palaeogeography itself (Brock et al. 2000; Gubanov 1998, 2002; Budd and Jensen In press).

The Early Cambrian World.

Timescale The Early Cambrian constitutes the majority of Cambrian time, spanning more than 30 million years (543 to about 510 Ma; Landing et al. 1998). Although the base of the Cambrian (and thus the Phanerozoic) has been defined at the base of the Trichophycus pedum zone at Fortune Head, eastern Newfoundland (Landing 1994), no international Stage-scale divisions have been defined for the period. In the meantime, the most commonly used strategy is to use the well known Early Cambrian Stages of the Siberian platform (Nemakit-Daldynian, Tommotian, Adtabanian, Botoman, Toyonian) as a standard, although it is not clear that the boundaries between these Stages have any meaning outside Siberia, or that even the Early/Middle Cambrian boundary as defined on different palaeocontinents can be easily correlated (Geyer and Palmer 1995; Palmer 1998b). A Stage-scale division for the Upper and Middle Cambrian of Laurentia was extended into the Early Cambrian by Palmer (1998a). The trilobite-bearing Early Cambrian is divided into two Stages, the Montezuman Stage (corresponding to the Fallotaspis and Nevadella zones of older usage) and the Dyeran Stage (Bonnia-Olenellus zone). No formal division of these Stages into zones has been put forward, but an informal threefold division of the Dyeran Stage, based on the presence of the trilobite in a middle unit, has been suggested (Theokritoff 1985; Palmer and Repina 1993; Landing and Bartowski 1996). The concept of the genus Wanneria was substantially altered by Lieberman (1999) in a recent monograph on the taxonomy of olenellid trilobites. However, the suggestions of Lieberman are controversial (M. Webster and A.R. Palmer pers. com. 2003), and the consequences for stratigraphy as yet unclear. If the presence of Wanneria (as conventionally defined) can be used as a biostratigraphic indication, both the Bastion and Ella Island Formations of North-East Greenland can be assigned to this informal, middle part of the Dyeran Stage. Another fossil, the problematic, disc-shaped Discinella has been suggested to be diagnostic of the middle Dyeran based on its co-occurrence with Wanneria at many localities (Palmer and Repina 1993), but this may range into the latest Early Cambrian of Quebec (Landing et al. 2002). Similar arguments apply to the problematic cone-shaped fossil Salterella, suggested to be diagnostic of the middle part of the Dyeran Stage (Fritz and Yochelson 1988), but an occurrence of the genus in North Greenland (Peel and Yochelson 1982) appears to be latest Early Cambrian in age (discussion in Skovsted 2003).

Palaeogeography It is generally agreed that the distribution of continents in the Early Cambrian was the result of the break- up of a Late Proterozoic supercontinent. However, neither the exact configuration of the supercontinent in 7 question, nor the timing of break-up and subsequent separation of continents, are agreed upon (eg. Dalziel 1997 contra Piper 2000). The Early Cambrian has previously been interpreted as a period characterised by largely endemic fossil faunas (eg. Palmer 1998b), and as mentioned above, this appears to be true for arcahaeocyathids and to a lesser extent for trilobites. Among other groups of shelly fossils the opposite situation is apparent, and many species in the small shelly fossil assemblage from North-East Greenland discussed in this thesis are already known from other palaeocontinents. In many palaeogeographical reconstructions for the Early Cambrian the main regions have been reconstructed as isolated continents separated by wide oceans (eg. McKerrow et al. 1992). More recent data, both derived from palaeomagnetic and palaeontological studies, indicate that the continents in the Early Cambrian were more closely arranged than previously thought (Dalziel 1997; Moczydlowska-Vidal 1998; Smith 2000; Gubanov 2002; Budd and Jensen In press). Although continental break-up may have started already in the Late Proterozoic, the final separation of continents appears not to have been substantial until relatively late in the Early Cambrian (Gubanov 2002). The late Early Cambrian faunas of North-East Greenland described herein provide abundant new evidence in support of such an interpretation (Papers I, IV, VI, VII, VIII, IX, X, XI).

Figure 2 One example of a palaeogeographical reconstruction placing the major continental blocks in close proximity in the Early Cambrian. Modified from Gubanov 2002.

The early evolution of animals. The systematic affinities of Early Cambrian fossils are often obscured by our incomplete understanding of how the fossils should be reconstructed (eg. the ornamented spine-shaped fossil Mongolitubulus could be a component of a jaw apparatus [Missarzhevsky 1977], a defensive spine on the carapace of a bradoriid arthropod [Paper I herein] or a lobopod [Dzik 2003]), but, at least in principle, also by their basal position within the major animal groups known from later in the Phanerozoic (Budd and Jensen 2000). Early Cambrian fossils in general (including many small shelly fossils) often show combinations of morphological traits reminiscent of different modern groups. The peculiar organisation of the halkieriid animal, for example, has been suggested to combine characters associated with both brachiopods and molluscs, and has also been compared to the problematic, cone-shaped hyoliths (Conway Morris and Peel 1995). Even when fossils appear to be more closely related to a specific phylum than to any other modern animal group, the Early Cambrian examples often can not be placed within the taxonomic framework of that group (the so-called ), and are instead best described as members of the stem group to that phylum (Budd and Jensen 2000). The Early Cambrian faunas of the Bastion and Ella Island Formations are rich in small shelly fossils with potential bearing on the early evolution of high ranking animal groups. Among the molluscs of the Bastion Formation, for example, several forms occur that can not be placed easily within the existing taxonomy of that phylum, even if extinct groupings such as helcionellids are also considered (Paper X). But within two major groups, the Brachiopoda (Papers II, III) and the Hyolitha (Papers VIII, IX), the 8 North-East Greenland faunas have their greatest potential to help elucidate the early pathways of evolution.

Cambrian fossils from North-East Greenland

Cambrian geology of North-East Greenland Outcrops of Cambrian rocks have been known in the Caledonian region of North-East Greenland for more than 70 years. In an early study, Christian Poulsen (1932) described brachiopods, hyoliths, trilobites and a few problematic Early Cambrian taxa. Although acritarchs (Vidal 1979) and trace fossils (Pickerill and Peel 1991) have subsequently been described, little palaeontological work on the shelly faunas of North-East Greenland has been published since Poulsen’s (1932) work. Cambrian rocks in North-East Greenland rests unconformably on late Proterozoic sediments and consists of a deepening upwards clastic sequence (Kløftelv and Bastion Formations) followed by carbonate shelf sedimentation, continuing through to the (Ella Island, Hyolithus Creek and Dolomite Point Formations; Cowie and Adams 1957; Peel 1982; Stouge et al. 2001). Cambrian and Ordovician rocks were folded and faulted in the Caledonian orogeny and are today exposed in a narrow north-south trending band in central North-East Greenland, between the late Proterozoic in the west and overlying to Tertiary rocks to the east. Cambrian shelly fossils are known from the shale- dominated Upper Bastion Formation and the overlying clastic carbonates of the Ella Island Formation, both late Early Cambrian in age. The rest of the Cambrian sequence (Hyolithus Creek and Dolomite Point Formations) is dominated by essentially unfossiliferous dolomites, although Salterella is known from the lower part of the Hyolithus Creek Formation (Peel and Yochelson 1982). Fossils described in this thesis were derived from residues of limestone samples, digested in 10%, buffered acetic acid, collected from the Upper Bastion and Ella Island Formations by J.S. Peel and M.P. Smith during fieldwork in North-East Greenland for the Geological Survey of Greenland (GGU, now a part of the Geological Survey of Denmark and Greenland). Specimens in matrix from the collections of Poulsen (1932) and Cowie and Adams (1957), complementing the acid-isolated material, were also included. The Upper Bastion Formation contains the most diverse shelly fauna known from Laurentia, including 88 species of shelly fossils. The fauna of the overlying Ella Island Formations shares many of its components with the Bastion Formation, but is less diverse (see Table 1). The Upper Bastion Formation has been interpreted to represent a distal shelf environment with deposition below the fair weather wave base (H. Tirsgaard in Pickerill and Peel 1991). With the exception of one trilobite species, all shelly fossils from the Upper Bastion Formation were derived from thin limestone layers and nodules within the otherwise shale dominated sequence. The limestones are largely composed of shell material, sometimes approaching a coquina (Cowie and Adams 1957), and probably represent material transported onto the distal shelf from more shallow water environments, possibly by storm events (J.S. Peel, pers. com.). Transport and hydrodynamic sorting of fossils have resulted in large numbers of well preserved cap-shaped fossils in acid residues, while elongated forms (eg. hyolith conchs and other tubular problematica) are less numerous and, when present, frequently fragmented. The preservation of the fauna is generally very good, with many originally calcareous fossils from the Bastion Formation preserved by diagenetic phosphate, either as internal moulds or as thin coatings of shell surfaces. Phosphate replacement of shell material is observed in some taxa, and appears to be related to shell structure (Paper III). Secondary phosphate is largely confined to echinoderm ossicles in samples from the Ella Island Formation, and the fauna of acid-residues from this formation is dominated by originally phosphatic taxa (Paper IV, XI).

9 Figure 3 Map of North America with localities discussed in the text marked. A. North-East Greenland. On insert map are marked Cambrian–Ordovician outcrops (in black) and localities with Early Cambrian fossils. Below: simplified Cambrian stratigraphy for North-East Greenland. B. Southern Labrador and western Newfoundland (Forteau Formation). C. Taconic region of New York State (Browns Pond Formation).

Composition of faunas The diverse fauna of the Bastion Formation includes at least 88 species of shelly fossils. Brachiopods are represented by five different species (Papers II, III, IV) and molluscs by 19 species (Papers VI, VII, X). 25 hyoliths and hyolith-like taxa are also present (Papers VIII, IX), as well as four trilobites and 35 additional shelly fossils (Paper XI). The latter include problematic forms such as Mongolitubulus (Paper I) and Discinella (Paper V). Most of the taxa (86 species) are present in acid-resistant residues (Table 1), but two species, the trilobite Olenellus roddyi? and the hyolithid Similotheca similis (Walcott, 1886) are only known from hand specimens collected by Cowie and Adams (1957) and Poulsen (1932) respectively (additional hyolith taxa were described by Poulsen, but are based on undiagnostic material; Paper VIII). Although Poulsen (1932) also described trilobites and other shelly fossils from the overlying Ella Island Formation, the fauna recovered in acid-resistant residues from this formation (Table 1) is less diverse than that of the Bastion Formation. Most of the sparse shelly fauna is shared with the Bastion Formation (Papers III, IV, XI).

10 Table 1 Fossils recovered from acid residues of samples from Albert Heim Bjerge and C.H. Ostenfeld Nunatak.

11 Correlations The age of the Upper Bastion Formation and overlying Ella Island Formation can be established as Dyeran (late Early Cambrian), based on the presence of Olenellus and a large number of other taxa known from this interval in other parts of Laurentia. The genera Wanneria, Salterella and Discinella occur in both the Bastion and Ella Island Formations. While the stratigraphic utility of all three can be questioned, all have been suggested to be diagnostic of an informal middle unit of the Dyeran Stage (see discussion above). The most striking similarities of the North-East Greenland assemblages are to faunas of the Taconic Allochthon of the of the eastern United States and Quebec (Walcott 1886; Lochman 1956) and adjoining parts of the Appalachian region of eastern North America. The fauna of the Bastion Formation in particular is closely comparable to an Elliptocephala asaphoides assemblage from the upper Browns Pond Formation of the Taconic Allochthon in New York State described by Landing and Bartowski (1996). A late early or early middle Dyeran age of this fauna was suggested by Landing and Bartowski, but this interpretation was mainly based on the absence of Wanneria in the Browns Pond Formation. A similar, late early or early middle Dyeran age is considered likely for the Bastion Formation, although fragments of Wanneria? may suggest the later part of this interval. The fauna of the Forteau Formation of Labrador and western Newfoundland includes a number of late Early Cambrian taxa also present in North-East Greenland (Spencer 1980; James and Kobluk 1978; Skovsted 2003) and may be of a similar age, although evidence from trilobites suggests a slightly younger, middle-late Dyeran age (James and Kobluk 1978). Correlation of the Bastion and Ella Island Formations into other parts of Laurentia is complicated by the poor knowledge of non-trilobite taxa in the Laurentian Early Cambrian, but brachiopods from North-East Greenland occur in the Mackenzie Mountains of northwest Canada (Voronova et al. 1987), and possibly in Nevada (Rowell, 1977). Interregional correlation of the Bastion and Ella Island Formation is facilitated by surprisingly strong faunal similarities to late Early Cambrian (Botoman) assemblages from different parts of the world. Particularly strong affinity to faunas from South and Central Australia, described by Bengtson et al. (1990) and Gravestock et al. (2001), has been documented, and more than 15 species and many additional genera are common to both areas (Papers I, IV, VI, VII, VIII, X, XI). Although many of the fossils occurring in both regions are long ranging (Gravestock et al. 2001), the fauna of the Bastion Formation shares the highest number of taxa with the Bemella communis mollusc Biozone (Early Botoman equivalent) or the Halkieria parva small shelly fossil Biozone (Botoman equivalent), as defined by Gravestock et al. (2001). Similarities to faunas of the Botoman Stage in Siberia exist among brachiopods, molluscs and hyoliths, and correlation into the late Early Cambrian of North China is based on the occurrence of similar mollusc and hyolith faunas (Zhou and Xiao 1984; Duan 1984). Late Early Cambrian faunas from England (Hinz 1987) and eastern Germany (Elicki 1994) also share a number of fossils with North-East Greenland. The strong ties of the North-East Greenland faunas to Australia are compelling evidence for faunal interchange between these palaeocontinents in the late Early Cambrian. This interpretation reinforces earlier suggestions based on brachiopods and other fossils for an Australia-Laurentia connection throughouth the Cambrian Period (Brock et al. 2000), and is in agreement with palaeogeographic reconstructions with these plates juxtaposed in the Late Proterozoic-Early Cambrian interval (Rodina models, eg. Dalziel 1997). Faunal connections to other parts of the world are less strong, but strengthen earlier suggestions that most palaeocontinents produced by the break up of the Late Proterozoic supercontinent were still relatively closely juxtaposed during the Early Cambrian, allowing easy migration of many different organisms (Gubanov 2002; Budd and Jensen In press).

12 Summary of papers

The spine-shaped Mongolitubulus

The problematic fossil Mongolitubulus from the Lower Cambrian of Greenland. Skovsted, C.B. and Peel, J.S. 2001. Bulletin of the Geological Society of Denmark, 48, 135-147. (Paper I).

The phosphatic, ornamented spines of Mongolitubulus Missarzhevsky, 1977 are known from a number of Early and Middle Cambrian localities (Mongolia, Kazakhstan, Siberia, , Australia, Greenland). Well preserved spines with an outer ornamentation of triangular or rounded scales from the Henson Gletscher Formation of North Greenland are very close to the type material of Mongolitubulus squamifer Missarzhevsky, 1977, and the presence of more than 150 specimens allows a more detailed description of this taxon. New morphological information includes the pointed tip of the spine and extensive variation in surface ornamentation. A two-layered ultrastructure with an outer, compact hyaline layer and a thinner inner layer composed of longitudinal fibres is also described. Extensive collections of Mongolitubulus henrikseni sp. nov. from the Bastion Formation of North-East Greenland demonstrate the presence of a previously unknown widely flaring base for the spine. Mongolitubulus was originally thought to be a protoconodont (Missarzhevsky 1977), but a grasping function appears improbable since the raised elements of the ornamentation are directed towards the tip of the fossil, hindering grasping but favouring defence. Melnikova (2000) associated spines of Mongolitubulus from the Middle Cambrian of Siberia with a bivalved (bradoriid) arthropod, and the morphology of the basal part of Mongolitubulus from North-East Greenland strengthens this interpretation. Although no complete shell of the proposed carapace bearing Mongolitubulus spines has been found in North-East Greenland, fragmentary material of possible juvenile specimens with multiple spine-bases co-occurs with the spines. However, the lack of Mongolitubulus-type ornamentation on the spine-bases makes assignment to the same taxon uncertain.

Figure 4 Mongolitubulus henrikseni Skovsted and Peel, 2001, Bastion Formation. All scalebars except F = 200 µm. A. Spine fragment with pointed tip. B. Spine fragment with outer shell layer partly exfoliated. C. Gently curved spine fragment with partly subdued ornamentation. D. Spine fragment with flaring basal portion. E. Large spine fragment with widely flaring base. F. Possible juvenile Mongolitubulus carapace fragment with multiple spine-bases preserved, scalebar = 100 µm.

13 The stem group brachiopod Mickwitzia

A stem group brachiopod from the Lower Cambrian – support for a Micrina (halkieriid) ancestry. Holmer, L.E., Skovsted, C.B. and Williams, A. 2002. Palaeontology, 45, 875-882. (Paper II)

The Early Cambrian stem group brachiopod Mickwitzia from Northeast Greenland. Skovsted, C.B. and Holmer, L.E. 2003. Acta Palaeontologica Polonica, 48, 11-30. (Paper III)

The exclusively Early Cambrian, bivalved genus Mickwitzia is mainly known from the Baltic region and from the North American Cordillera. The type species of the genus, M. monilifera (Linnarsson, 1869) is poorly known due to heavy recrystallisation of the type material, and species described from North America are not much better preserved (Walcott 1908; McMenamin 1992). Although Mickwitzia was previously referred to the paterinate brachiopods, the genus has recently been excluded from the phylum Brachiopoda by Laurie (2000). New material of Mickwitzia from the Bastion and Ella Island Formations of North-East Greenland is referred to Mickwitzia cf. occidens, a species known previously only from the Lower Cambrian of Nevada. The material from Greenland shows a variety of new morphological details, such as the presence of a ventral pseudointerarea, marginal (follicle) setae and a larval shell, suggesting an affinity to linguliform brachiopods. However, the shell structure of M. cf. occidens from North-East Greenland is peculiar, combining columnar lamellae (closely comparable to those of acrotretid linguliform brachiopods) with vertical and, on the ventral pseudointerarea, horizontal tubular structures perforating the shell. The latter, at least on the pseudointerarea, were open to the exterior and probably contained setae (setigerous tubes).

Figure 5 Mickwitzia cf. occidens Walcott, 1908 from the Bastion (A) and Ella Island Formations (B-F). A. Oblique exterior view of ventral valve with larval shell, radiating traces of follicle setae (nickpoints) and partly dissolved, weakly phosphatised shell regions, scalebar = 0.5mm. B. interior view of ventral valve with lingulid-like pseudointerarea, scalebar = 0.5mm. C. Oblique posterior view of ventral pseudointerarea with numerous openings of setigerous tubes, scalebar = 100µm. D. Section through primary and secondary shell layers with vertical tube through primary shell layer and acrotretid-like columnar laminae in secondary shell, scalebar = 20µm. E. Oblique view of secondary layer with numerous acrotretid-type columns and a single vertical tube, scalebar = 20µm. F. Close-up of setigerous tube (on ventral pseudointerarea) with striated interior surface (imprints of microvilli), scalebar = 10µm.

14 The shell structure of Mickwitzia cf. occidens, particularly the presence of setigerous tubes, recalls sclerites of the problematic Micrina from the Lower Cambrian of Australia. These sclerites were recently interpreted as closely related to halkieriids (supposedly homologous to the anterior and posterior shells of Halkieria evangelista). The combination of characters seen in Mickwitzia is intermediate between the non-bivalved Micrina and the lingulate brachiopods, strengthening earlier suggestions for a halkieriid ancestry of the phylum Brachiopoda (Williams and Holmer 2002), and placing Mickwitzia itself in the as yet little known brachiopod stem group.

Brachiopod fauna of North-East Greenland

Early Cambrian brachiopods from North-East Greenland. Skovsted, C.B. and Holmer, L.E. In press. Accepted for publication in Palaeontology. (Paper IV)

Brachiopods are important constituents of the Early Cambrian faunas of North-East Greenland, beeing represented by nine species. In the Bastion Formation Eoobolus priscus (Poulsen, 1932), Botsfordia caelata (Hall, 1847), Obolella crassa (Hall, 1847), craniopsid gen. et sp. ind. and the stem group brachiopod Mickwitzia cf. occidens Walcott, 1908 are present, while Mickwitzia cf. occidens occurs together with Micromitra bella (Billings, 1872), Kutorgina reticulata Poulsen, 1932, Vandalotreta sp. and an unidentified chileiid species in the overlying Ella Island Formation. This diverse fauna suggests that all three extant brachiopod subphyla (Linguliformea, Caniiformea and Rhynchnelliformea) had diverged already by the Late Early Cambrian. The fauna also has biostratigraphic utility; O. crassa, B. caelata and M. bella are widespread in the Lower Cambrian of Laurentia, and the species E. priscus and B. caelata facilitate correlation of the North-East Greenland succession with the Botoman Stage of Australia and Siberia.

Mobergellans from Greenland and Asia

Mobergellans (Problematica) from the Cambrian of Greenland, Siberia and Kazakhstan. Skovsted, C.B. 2003. Paläontologische Zeitschrift, 77, 429-443. (Paper V)

Disc-shaped mobergellans are problematic, phosphatic fossils found exclusively in Early Cambrian sediments and are characterised by 10 to 14 paired muscle scars on the ventral surface. A handful of genera and species belonging to this group is distributed over several Early Cambrian palaeocontinents, and has been used for biostratigraphical correlations (eg. Gubanov 2002). Poulsen (1932) described two mobergellans from North-East Greenland: Discinella micans (Billings, 1871) known from several localities in the eastern United States and Canada, but also a new species; Discinella brastadi Poulsen 1932. The latter was thought to be distinguishable from D. micans by having twelve rather than ten muscle scars, and was later designated as the type species of the genus Brastadella Missarzhevsky 1989. Restudy of the type material of Discinella brastadi from North-East Greenland shows that all specimens are identical to D. micans. About 800 additional specimens of D. micans from acid resistant residues from both the Bastion and Ella Island Formations testify to the high variability of this species, but no specimen exhibits twelve muscle scars. It is concluded that the morphologically similar genera Discinella Hall, 1872 and Mobergella Hedström, 1923 can only be separated by the surface structure of the muscle scars, rather than the mere number of scars (contra Hedström 1930; Missarzhevsky 1989). Mobergellans from the Tommotian and Atdabanian of Siberia, previously assigned to Discinella brastadi (eg. Rozanov et al. 1969) and Mobergella radiolata Bengtson, 1968 (eg. Missarzhevsky 1989) are all assigned to the genus Mobergella, based on the pitted surface structure of the muscle scars. Specimens from the late Tommotian with 13 or 14 muscle scars are assigned to M. sibirica n. sp. and specimens from the early Atdabanian with eleven or twelve scars are referred to M. hexactina n. sp.

15 Figure 6 Mobergellans from Greenland, Siberia and Kazakhstan. A,B. Discinella micans (Billings, 1871), scalebars = 0.5 mm; A, dorsal surface; B, ventral surface. C, D. Mobergella sibirica Skovsted, 2003, scalebars = 0.25 mm; C, dorsal view; D, ventral view. E, F. Aktugaia triangula Missarzhevsky, 1976, scalebars = 0.25 mm; E, dorsal view; F, ventral view. G, H. Mobergella hexactina Skovsted, 2003, scalebars = 100 µm; G, dorsal view; H, ventral view.

The cap-shaped mobergellan Aktugaia triangula Missarzhevsky, 1976 from the Botoman of Kazakhstan is shown to have twelve muscle scars in a configuration closely comparable to that of the little known Thorslundella duodecifoliata Nyers, 1984 from Sweden. The surface structure of the muscle scars in Aktugaia resembles that of Discinella, but the fossils differ in the arrangement of the muscle scars and in their mode of growth.

Molluscs and cap-shaped fossils of the Bastion Formation

Anabarella australis (Mollusca, Helcionelloida) from the Lower Cambrian of Greenland. Gubanov, A., Skovsted, C.B. and Peel, J.S. In press. Accepted for publication in Geobios. (Paper VI)

The mollusc fauna of the Early Cambrian Bastion Formation of North-East Greenland. Skovsted, C.B. Submitted to Bulletin of the Geological Society of Denmark. (Paper VII)

Problematic cap-shaped fossils from the Lower Cambrian of North-East Greenland. Peel, J.S. and Skovsted, C.B. Manuscript. (Paper X)

Shells of helcionelloid molluscs are among the first calcareous fossils to appear in the fossil record and, together with minute bivalves, continued to form an important component in Small Shelly Fossil assemblages throughout the Early and Middle Cambrian. In North-East Greenland a rich assemblage of small molluscs, including 13 helcionelloid taxa and two bivalves (Papers VI, VII), as well as four species of the problematic genera Xianfengella He and Yang, 1982 and Ocruranus Liu, 1979 (Paper X) occur together. Although molluscs from the early Early Cambrian are known to be very widespread (eg. Gubanov 1998), less is known about the distribution of late Early Cambrian forms. Many of the molluscs from the Bastion Formation have previously been described from other parts of Laurentia and from other palaeocontinents, testifying to the wide geographical distribution of many early molluscs. The most marked similarity is to the assemblage of the Bemella communis zone (early Botoman equivalent; Gravestock et al. 2001) of Australia, but strong ties to late Early Cambrian faunas of North China, Germany and Siberia are also documented. Faunal ties between palaeocontinents support previous suggestions of close proximity of continents in the Early Cambrian. 16 Figure 7 Molluscs from the Bastion Formation. All scalebars = 0.5 mm. A. Mackinnonia rostrata (Zhou and Xiao, 1984), internal mould, lateral view. B. Mackinnonia taconica (Landing and Bartowski, 1996), internal mould, lateral view. C. Anabarella australis Runnegar in Bengtson et al., 1990, internal mould with phosphatic coating, lateral view. D. Asperconella troyensis (Resser, 1938), internal mould, dorsal view. E. Pelagiella subangulata (Tate, 1892), phosphatic coating, oblique dorsal view. F,G. Pojetaia runnegari Jell, 1980; F, phosphatic coating, right lateral view; G, internal mould, posterior view.

The mollusc assemblages from the two main study areas in North-East Greenland, the Albert Heim Bjerge region and C.H. Ostenfeld Nunatak, contain approximately the same taxa, but differ in relative abundance of helcionelloid species. This difference is related to the morphology of the shell, with laterally flattened and openly coiled or erect forms dominating in samples from Albert Heim Bjerge and more strongly coiled forms dominating in samples from C.H. Ostenfeld Nunatak. The sedimentary sequence of the Upper Bastion Formation of the C.H. Ostenfeld Nunatak area indicates deposition in deeper water than the Albert Heim Bjerge sequence, and the documented morphological differences may be related to water depth. Cap-shaped shells of Ocruranus and Xianfengella are known from the earliest Meishucunian Stage in China (Qian and Bengtson 1989), but similar fossils also occur in the Bastion Formation of late Early Cambrian age (Paper X). The affinity of these fossils to helcionelloids or other mollusc groups is uncertain (Qian and Bengtson 1989), and Oruranus has been considered as possibly forming part of a coeloscleritophoran scleritome (Bengtson 1992). Conclusive evidence as to the affinities of either Ocruranus or Xianfengella is lacking.

Hyoliths and hyolith-like fossils from Greenland

Hyoliths and small shelly fossils from the Lower Cambrian of North-East Greenland. Malinky, J. and Skovsted, C.B. Submitted to Acta Palaeontologica Polonica. (Paper VIII)

The problematic fossil Triplicatella from the Early Cambrian of Greenland, Canada and Siberia. Skovsted, C.B., Peel, J.S. and Atkins, C.J. Submitted to Canadian Journal of Earth Science. (Paper IX)

Abundant hyoliths and hyolith-like fossils occur in the Bastion Formation of North-East Greenland. Many taxa are represented by well preserved opercula, while the co-occurring conchs are often fragmentary and difficult to diagnose, probably as a result of transport and sorting before final deposition. In consequence, the taxonomies of conchs and opercula are largely independent. Ten species can be attributed to hyolithids and three to orthothecids (Paper VIII). Eight species are more difficult to place 17 within the existing taxonomy of the Hyolitha, and probably testify to the early morphological diversity and evolution of the group (Papers VIII, IX). The hyolith fauna of the Bastion Formation shows a strong affinity to previously described faunas from other palaeocontinents and, as have been documented for molluscs, particularly strong faunal ties to late Early Cambrian faunas of Australia are observed. Faunal elements are also shared with Siberia and North China (Paper VIII). Species of the genus Triplicatella Conway Morris in Bengtson et al., 1990, previously known only from Australia, are described from the Early Cambrian of North and North-East Greenland, from western Newfoundland and Siberia (Paper IX). The affinity of Triplicatella to orthothecid hyoliths is discussed and the functional morphology of the marginal folds characteristic of the genus is outlined. Triplicatella lacks clavicles and cardinal processes, features commonly associated with hyolith opercula. However in at least one species from North and North-East Greenland, the well developed marginal folds may have had a function analogous to that of the cardinal processes in typical hyoliths.

The shelly fauna of North-East Greenland

Small shelly fauna from the late Early Cambrian of North-East Greenland. Skovsted, C.B. Manuscript. (Paper XI)

Although several components of the shelly faunas of the Bastion and Ella Island Formations have been described separately (Papers I-X), many fossils remain. The composition of the entire fauna of shelly fossils from North-East Greenland is summarised and the fossil content of all investigated samples is presented. A total of 39 species of shelly fossils from the Bastion Formation are described for the first time, together with 13 taxa from the Ella Island Formation. Notable among these fossils are trilobites, bradoriid arthropods, coeloscleritophorans and various problematic taxa such as Lapworthella Cobbold, 1921, Hyolithellus Billings, 1872 and Apistoconcha Conway Morris in Bengtson et al., 1990. The trilobite Olenellus cf. roddyi Resser and Howell, 1938, from the collections of J.W. Cowie and P.J. Adams is the only fossil to be described from the shales of the Upper Bastion Formation, but the eodiscids Calodiscus laboatus (Hall, 1847) and Ekwipagetia sp. occur in acid residues together with fragments of Wanneria? sp.

Figure 8 Trilobites from the Bastion Formation. All scalebars = 200 µm except A . A. Olenellus cf. roddyi Resser and Howell, 1938, dorsal view of specimen in shale, scalebar = 5 mm. B, C. Calodiscus lobatus (Hall, 1847), phosphatised specimens from acid residues; B, cephalon in dorsal view; C, pygidium in dorsal view. D. Ekwipagetia sp., pygidium with broken axial spine in lateral view. E. fragment of Wanneria? sp.

The middle Dyeran age of both the Bastion and Ella Island Formations is established by strong faunal ties to equivalent assemblages in the eastern United States and Canada. This interval is interpreted to 18 correspond approximately to the early Botoman Stage in Siberia and its equivalents. The observed faunal similarities to faunas from Siberia, China and Europe, but most notably to Australia, demonstrated by a range of fossil groups, are interpreted as a strong indication that the continents were still closely juxtaposed in the late Early Cambrian.

Acknowledgements. This thesis was made possible by the help and support I have received from many people over the years. I am very grateful to my supervisors, John Peel and Lars Holmer, both of whom has always been eager to discuss various matters and offer their help; their doors have always been open. John Peel offered me the opportunity to work on the material from North-East Greenland in the first instance, and has been a great source of knowledge and encouragement. I would also like to thank him for his understanding of the difficulties of combining the life of a research student with parenthood. My fellow doctorands and the other staff (past and present) of the former program for Historical Geology and Palaeontology in Uppsala have been a continuous source of encouragement and many worthwhile discussions, social as well as scientific. Special thanks go to Graham Budd and Alexander Gubanov who have discussed and explained many current ideas and problems in biology and palaeontology. Artiom Kouchinsky, Anna Lindström, Jan-Ove Ebbestad, Ole Hoel, and Malgorzata Moczydlowska-Vidal are also thanked for their help. Alexander Gubanov, Artiom Kouchinsky, Tatiana Tolmachova, Michael Streng and Malgorzata Moczydlowska-Vidal helped with translations, while Ulf Sturesson, Gudrun Söderman and Birgit Jansson assisted with various practical matters. Gary Wife and Stefan Gunnarsson (Evolutionary Biology Centre, Uppsala) guided me in working the SEM. Access to material from Siberia and Kazakhstan was given by Artiom Kouchinsky and Stefan Bengtson (Stockholm), and material from Labrador and Newfoundland by A.R. “Pete” Palmer (Boulder), who also offered me his hospitality during a vistit to Colorado. Gerd Geyer (Würtzburg) helped arrange a visit to the New York State Museum in Albany, and Ed Landing (Albany) provided access to collections from New York State. The work has been financed by a university research scholarship and by grants (through John Peel and Lars Holmer) from the Swedish Research Council (VR). Two travel grants from the Swedish Polar Research Council (YMER-80) made visits to Boulder, Colorado and Albany, New York possible. I have had the pleasure of writing several of the papers in this thesis together with different co- workers: John Peel, Lars Holmer, Alexander Gubanov, John Malinky, Alwyn Williams and Christian Atkins have all generously shared their knowledge and given their support. I also owe thanks to Pete Palmer, John Hollingsworth, Uwe Balthasar, Mark Webster, Li Guoxiang and Jakob Meyersson for important information and interesting discussions. Lastly, but not least, I would like to express my gratitude towards my family and friends for making my years in Uppsala a memorable time indeed. In particular, my children Ida and Johanna have been a constant source of joy. When my mind was troubled they always showed me what is most important in life. And finally I thank my wife, Anne Mette, who always supported and comforted me. I owe her everything.

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