Cambrian and Ordovician fossils from the Hardangervidda Group, Haukelifjell, southern Norway

DAVID L. BRUTON, DAVID A. T. HARPER, IVAR GUNBY & JOHAN NATERSTAD

Bruton, D. L., Harper, D. A. T., Gunby, l. & Naterstad, J. Cambrian and Ordovician fossils from the Hardangervidda Group, Haukelifjell, southern Norway. Norks Geologisk Tidsskrift, Vol. 64, pp. 313- 324. Oslo 1984. ISSN 0024-196X.

New finds of trilobites and brachiopods are described from two horizons in the autochthonous/parautoch­ thonous Hardangervidda Group. The occurrence of the trilobites Lejopyge armata (Linnarsson) and Andrarina costata (Angelin) indicates, for the first time, a late mid-Cambrian (Lejopyge /aevigata Zone) age for part of the 'Alum Shale' (Bjørno Member of the Låven Formation) on Hardangervidda. Brachiopods from the younger Bjørnaskalle Formation include orthides, a clitambonitide and Antigon­ ambonites of the p/anus species group of Opik and are indicative of a late Arenig- early Llanvirn age. Both faunas indicate the most westerly known extension of Cambrian and Ordovician rocks on the Baltic platform. But whilst the uniformity of the 'Alum Shale' facies across the platform is confirmed, the upper Arenig-lower Llanvirn rocks differ from coeval strata elsewhere in the autochthon.

D. L. Bruton, Paleontologisk Museum, Sars Gate l, Oslo 5, Norway. D.A. T. Harper, Department of Geology, The University, Dundee DDI 4HN, Scotland. Present address: Department of Geo/ogy, University College, Galway, Ire/and. l. Gunby, Institutt for Geo/ogy, University of Oslo, Blindern, Oslo 3, Norway. J. 230, 0277 2, Naterstad, Norges geologiske undersøkelse, Oslokonto�et, Drammensveien Oslo Norway.

Fossils are rare in the deformed rocks of the Although this new brachiopod material is not Scandinavian Caledonides, but where present well preserved and some specimens have suf­ they provide important constraints on develop­ fered intense tectonic deformation, the trilobites mental models for the fold belt. Two recently have undergone less distortion and are relatively discovered shelly faunas are reported, herein, well preserved. The trilobites indicate a correla­ from the autochthonous metasedimentary rocks tion of the base of the Bjørno Member of the of the Hardangervidda Group, Haukelifjell, on Låven Forma ti on with the uppermost zone of the Hardangervidda (Fig. 1). Cambrian trilobites Middle Cambrian, whilst the brachiopod fauna have been collected from the basal part of the suggests a correlation of the Bjørnaskalle Forma­ Låven Formation, whilst the Ordovician brachio­ tion with the upper part of the Lower Ordovician pods are from the Bjørnaskalle Formation. (high Arenig - low Llanvirn). These faunas The stratigraphy of the Hardangervidda therefore provide a means of correlation of parts Group has been described recently (Andresen of the Hardangervidda Group with coeval se­ 1978) and an important fossil find has been re­ quences elsewhere on the Baltic platform. And ported from these rocks (Andresen 1974). That although further evidence is provided of the lat­ fauna, from two Jocalities near Kvennsjøen, Iies eral persistence of the 'Alum Shale' facies in the within a crystalline limestone downfolded into Norden area (Martinsson 1974), at least patterns the underlying blue quartzite; it includes the of sedimentary facies in the lower Ordovician are brachiopod Orthis of the calliframma [sic] type, markedly different from those elsewhere in the the trilobite Ptychopyge sp., a planispire gastro­ autochthon (Bruton & Harper in press). pod and the actinoceroid cephalopod Ormo­ The faunal province affinities of the Hardan­ ceras? sp. It is probable that a horizon equivalent gervidda assemblages are with the Baltic and to that of the Bjørnaskalle Formation is repre­ therefore provide the minimum westward exten­ sented. Since Orthambonites calligramma is con­ sion of this province; further evidence from sidered to be a typical member of the genus more fossil occurrences is necessary in order to Orthambonites (see Bassett 1981, p. 652), An­ describe in detail the western margin of the Bal­ dresen's record of Orthis of the calligramma type tie province and its associated biofacies. It is probably refers to a species similar or conspecific hoped that this paper may provide a further with orthid gen. et sp. l, herein. stimulus to researchers to sustain the search for 314 D. L. Bruton et al. NORSK GEOLOGISK TIDSSKRIFT4 (1984)

e� � � - � � - � - - - � � - + + Sketch maps showing the � - � - - � � � - � - - � - - � + ���� ���� �� � � --- �---- + locations of new fossil finds � � � � � + + + + at Haukelifjell, Southwest + + + + + .:!:::::��::;:t__;lt./ +

+ + + + + + + + + + + + + + + + + + r=--J.r--,..,.' + + + + + + +

+ '-'-'-'- Thrust zone

Fig. l. Locality map showing position of Ordovician brachiopod find (A) and Cambrian trilobite find (B).

fossils in the uncompromising rocks of the moun­ ous Cambrian-Ordovician meta-sedimentary tain belt. rocks; the succession here is disturbed by faults but is presumed continuous. The fauna, which indicates a late Mid-Cambrian age for this part of the sequence, occurs a few metres above the Stratigraphy and locality data local basal quartzite (Haremo pers. comm. 10 The stratigraphy of the Hardangervidda Group is Oct. 1984). Although within the outlier thrust summarised in Fig. 2 and follows closely that of zones and imbricate basement slices occur, the Andresen (1978). The new fossils have been col­ rocks are locally less deformed than those at lected from two localities. Middle Cambrian tri­ Hermodsholtjønn. Moreover, whilst the rocks lobites have been collected from near the base of are intensely folded, with axes trending NW-SE, the Bjømo Member of the Låven Formation at the late Caledonian crenulation cleavage, which Nasatjønn whilst Lower Ordovician brachio­ dips SE and is common as far SE as Haukeli­ pods, bryozoans and trilobites dominate a fauna sæter, is not developed at Nasatjønn. collected from the Bjømaskalle Formation at Hermodsholtjønn. Hermodsho/tjønn The shelly fauna was collected from fallen blocks Nasatjønn of calcareous sandstone immediately below ex­ The trilobites were collected from a black carbo­ posures of this unit, 3.5 km SE of Haukelisæter naceous shale, presumably the Alum Shale, in a (Grid Ref. for the locality MM 016 314; see also road cutting about 4 km from Edland (Grid Ref. Fig. 1). These rocks overlie quartzites, whilst of locality MM163 256 see also Fig. 1). The rocks phyllites occur both above and below. This se­ crop out in a down-faulted outlier of autochthon- quence has been folded about axes which trend NORSK GEOLOGISK TIDSSKRIFT 4 (1984) Cambrian and Ordovician fossils 315

HARDANGERVIDDA (south east part) Significance of the faunas (Andresen 1978) The Cambrian trilobites Holmasjø Fm. (25-250m) Until now, only the age of the top of the 'Alum Shale' succession on Hardangervidda has been known from the occurrence of the Tremadoc dendroid Dictyonemaflabelliforme (Dahll 1861, Brøgger 1893, Rekstad 1905, Størmer 1941). The Langenu Mb. (>150m) present record of Lejopyge armata (short spine form) and of Andrarina costata from a leve l a few Solnut Fm. (200m) metres above the local Precambrian basement r indicates that here the Bjørno Member of the Låven Formation belongs to the topmost zone (1dB, Lejopyge laevigata Zone) of the Middle Cambrian. This same zone is represented on Vardahaug Mb. (15m) Bornholm (but not Gotland), in all districts of Llanvirn Svartaberg Mb. ( 15m) 5 southern and central Sweden (Martinsson 1974), B T6CP7 Bjørnaskalle Fm.(<\-6m) in the Oslo Region (Strand 1929, Henningsmoen Holberg Quartzite & (100-150m) in Strand Henningsmoen 1960) and in various districts along the Caledonian front west of Lake Buanut Mb. Tremadoc (10-60m) Mjøsa, including Etnedal (Brøgger 1876) and to OROOVICIAN Låven Fm. (90-100m) 1929 , 326). Bjørno Mb. (30-40m) the east in Rendalen (Strand p. Study CAM BRIAN J of material from these areas confirms the identi­ � � fication of the present specimens which are fig­ Precambrian Basement ured and discussed aiong with better preserved comparative material. The zone has so far not Fig. 2. The Stratigraphy of the Hardangervidda Group and been identified along the Caledonian front from location of fossils in the section on Hardangervidda. Modified from Andresen (1978). Footnotes: T =trilobite, Gr= grapto­ Jamtland and northwards. Iite, Tf=trace fossil, B =brachiopod, Cp=cephalopod, Cr = crinoid stem. l. Lower Cambrian fauna recorded from basal The Ordovician brachiopods conglomerate at Ustaoset (Størmer 1925). 2. Late Middle Cambrian trilobites described herein. 3. Dictyonema flabelli­ The age of the Bjørnaskalle Formation is based forme at several localities (Dahll 1861, Rekstad 1905, Størmer 1941, Andresen 1974, Erdtmann 1982). 4. 'Tube-like' struc­ principally on the occurrence of the Antigonam­ tures (Andresen 1978). 5-7. Brachiopod, trilobite and cephalo­ bonites of the p/anus species group. The genus pod faunas consistent with a late Arenig-early Llanvirn age for Antigonambonites is restricted to rocks of B11 and the formation and suggest correlation with the 'Orthoceras Bm age (the Volkhov and Kunda stages of the Limestone' of the Oslo Region (Andresen 1974, also this pa­ O per). 8. Crinoid stems, Middle Ordovician or younger (Bocke­ land Series in the Baltic terminology). The Iie in Andresen 1978). p/anus species group is further restricted to the higher Bu strata and the lowest part of Bm (Opik 1934, p. 73). These rocks are equivalent to the Upper Arenig and lowest Llanvirn of the stand­ ard British Ordovician succession. Antigonam­ NW-SE, whilst the quartzite and calcareous bonites is an important element of the bland sandstone is surrounded by slices of highly tec­ faunas of the Baltic province. An unnamed spe­ tonised gneiss which is separated from the typical eies of Antigonambonites has been described basement rocks by black shale. The extent of the from the late Arenig rocks of Virgin Arm, New­ thrusting is not known but the tectonised gneiss foundland which contain a diverse brachiopod is considered to be of local origin. fauna (Neuman 1976) currently assigned to the The fossils, although commonly highly de­ adjacent peri-insular Celtic province (Neuman formed, indicate a correlation with the high Low­ 1976, Neuman & Bates 1978, Bruton & Harper er Ordovician for the Bjørnaskalle Formation. 1984). Neuman (1976, p. 28) indicated his spe­ Fossils have recently been described from a stra­ eies may belong to the maekulaensis species tigraphically similar level, by Andresen (1974), group; however, it could not be compared with farther north on Hardangervidda. an y members of that group. Moreover, denticles

21 - Geologisk Tidsskr. 4/84 316 D. L. Bruton et al. NORSK GEOLOGISK TIDSSKRIFT 4 (1984) NORSK GEOLOGISK TIDSSKRIFT 4 (1984) Cambrian and Ordovician fossils 317

which characterise the hinge line of the Baltic plete nature of the material, firm generic place­ members of the genus are not reported for the ments are not possible. Canadian form. The remaining elements of the brachiopod fauna are not in themselves definitive but, taken l together, are compatible with a late early Ordo­ Orthid gen. et sp. indet. Fig. 3A, B, D, E; Fig. 4C vician age and a position within the Baltic prov­

ince. Remarks. - Approximately ten specimens are assigned to this species. Before distortion the valves appear to have been ventribiconvex with Systematic palaeontology elongate, rounded subquadrate outlines. The ex­ All figured and additional material has been de­ terna! ornament comprises coarse costae with posited in the Paleontologisk Museum, Oslo wavelengths of about l mm medianly at the 10 (hereafter abbreviated PMO). Prepared speci­ mm growth stage. A fine radial ornament of mens were firstcoated with a matt black prepara­ capillae is developed on the ribs and in the inter­ tion and then ammonium chloride sublimate be­ spaces; both the ribs and interspaces have evenly fore photography. Because the material is de­ rounded profiles. A fine concentric ornament is formed, measurements are not given in the dis­ occasionally preserved. The ventral interarea is cussion of taxa. The magnifications given on the relatively long, flat and anacline whilst the del­ figure explanations are accurate to within 5 %. thyrium is wide and open. The strong teeth bear denticles on their dorsal faces, which may indi­ cate the individual (Fig. 3A, D) to be gerontic, and are supported by thin dental plates which Brachiopoda converge towards the floor of the valve. The David A. T. Harper ventral muscle scar is elongately oval and is con­ fined to the umbonal cavity. Although the majority of the specimens assigned The ornament and shape of the valves together to the Brachiopoda are broken, poorly preserved with the features of the ventral interior suggest and have suffered some tectonic deformation, at an assignation to either Orthambonites (s.s.) !east six different forms are present in the sample Pander or Paralenorthis. Havlicek & Branisa of about 30 valves studied. Therefore the rela­ (1980, p. 16) considered that the anteriorly diver­ tively high diversity of the present small sample gent proximal parts of the ventral vascula media suggests that further collecting may markedly of species which they placed in the latter require increase the multiformity of the brachiopod fau­ separate generic status from Pander' s genus. Suf­ na. ficient detail of the vascular markings of the Hardangervidda species is lacking and thus a Order ORTHIDA Schuchert and generic placement of this material based on such Cooper, 1932 criteria is not presently possible. Suborder ORTHIDINA Schuchert and Cooper, 1932 Superfamily ORTHACEA Woodward, 1852 Orthid gen. et sp. indet. 2 Family ORTHIDAE Woodward, 1852 Fig. 3F

Three separate species are assigned here. How­ Remarks. - Two specimens are included in this ever, due to the poor preservation and incom- category. In contrast to the previous form, the

Fig. 3. Orthid gen. et sp. indet. 1: A, D. Internat mould and latex east of pedicle valve, PMO 111.405, x2. B. External mould of pedicle valve, PMO 111.486, x2. E. External mould of brachial valve, PMO 111.487, x2. Orthid gen. et sp. indet. 2: F. Latex east of external mould of brachial valve and adjacent, smaller pedicle (?) valve, PMO 111.488, x2. Orthid gen. et sp. indet. 3: G. Latex east of external mould of pedicle (?) valve, PMO 111.489, x2. Antigonambonites of the p/anus species group, Opik 1934: I, K. Internat mould and latex east of brachial valve, PMO 111.490, x2. J, L. Internat mould and la tex east of pedicle valve, PMO 111.491, x2. Clitambonitid indet.: C, H. Internat mould and latex east of pedicle valve, PMO 111.492, x2. All P. Haremo Coll. 318 D. L. Bruton et al. NORSK GEOLOGISK TIDSSKRIFT 4 (1984) radial ornament is characterised by angular pro­ line probably reflects tectonic strain. It is not files whilst the wavelengths of ribs, medianly at certain how the relatively short spondylium is the 10 mm growth stage, are less than 0.5 mm. A supported although there are indications of later­ concentric ornament of fine but well-defined al septa; this may suggest the presence of a spon­ concentric growth lines is well developed. Due to dylium triplex, a feature characteristic of the severe distortion of the specimens, little can be gonambonitacean brachiopods. confidently noted regarding the shape of the valves; the brachial valve, however possesses a weU-marked sulcus. Superfamily GONAMBONITACEA Schuchert and Cooper, The ornament of this species is similar to that 1931 of species of Panderina Schuchert & Cooper, Family GONAMBONITIDAE Schuchert and Cooper, 1931 Subfamily GONAMBONITINAE Schuchert and Cooper, 1931 1931 which are present in rocks of B1 and Bn age in the eastern Baltic (see e.g. Rubel 196 1). Much Genus Antigonambonites Opik, 1934 more information regarding this form is needed befare a confident generic assignement can be Type species. - By original designation, Gonam­ made. bonites plana Pander, 1830; from the Lower Or­ dovician of Estonia.

Orthid gen. et sp. indet. 3 Fig. 3G Antigonambon��es of the planus species group, Opik, 1934 Remarks. - The third species of orthid is repre­ Fig. 31-L; Fig. 4A, B, D, G sented by four poorly preserved valve exteriors

which have all suffered tectonic deformation. Remarks. - Ten valves are assigned to this form Nevertheless the ornament of this form consists and although the majority are broken a few are of rounded costae and costellae which number relatively well preserved. The valves are subpyr­ about 5 per 2 mm at the 10 mm growth stage amidal in shape with an alate hinge line. The medianly and have wavelengths of 0.5 mm at the brachial valve is essentially flat whilst the pedicle same position on the valve. The concentric orna­ valve is resupinate; the ornament is of fine costae ment is restricted to rarely thickened growth and costellae numbering· about five per 2 mm lines. The ornament of this species clearly differs medianly at the 10 mm growth stage, cancellated from those of the previous two, but the inade­ by fine weU-marked concentric growth lines. quacy of the material prevents further comment. Ventral interarea long, apsacline with the delth­ yrium covered by convex pseudodeltidium. The hinge line is denticulate whilst the spondylium triplex is supported laterally by at !east two pairs Suborder Clitambonitidina Opik, of septa. The teeth are small and other features 1934 of the ventral interior are unclear. The dorsal Two distinct forms of this suborder are present. interior possesses a simple cardinal process which Specimens of Antigonambonites of the p/anus is thickened posteriorly adjacent to the minute, species group are relatively well preserved and convex chilidium. The socket ridges are widely permit a confident correlation of the Hjørna­ divergent and extend anteriorly from a pair of skalle Formation with the high Lower Ordovi­ swollen ridges which mark the margins of the cian of the eastern Baltic. Only one deformed notothyrium. The dorsal interarea is short, flat specimen of the second form is available for and anacline whilst the dorsal musculature is fee­ study; however it is sufficiently distinct as not to bly impressed. be confused with the Antigonambonites. Opik (1934 , p. 148 ) considered the members of Antigonambonites in terms of three species groups (see also Neuman 1976 , p. 28 ). The Har­ dangervidda specimens are most similar to those Clitambonitidinid indet. of Opik's p/anus group in that they have stropho­ Fig. 3C, H menoid profiles and a feebly impressed dorsal Remarks. -The pedicle valve is large and appar­ musculature.The p/anus species group comprises ently flat although the somewhat elongate out- p/anus itself and A. costatus Opik, 1934 ; the NORSK GEOLOGISK TIDSSKRII'T 4 (1984) Cambrian and Ordovician fossils 319

Fig. 4. Antigonambonites of the p/anus species group, Opik 1934: A, B. External mould and latex east of pedicle valve, PMO 111.493, C, G. Fragment of external mould and latex east of indeterminate valve, PMO 111.494, x2. Orthid gen. et sp. indet. 1: D. Latex east of pedicle valve exterior, PMO 111.495, x2. Articulate brachiopod indet.: E, F. Internal mould and latex east of pedicle valve, PMO 111.496, x2. All P. Haremo Coll. H, J-M. Lejopyge armata (Linnarsson, 1869). H, complete individual with damaged segments, internal mould. PMO 111.507, X4. I. pygidium, internal mould. PMO 111.508, x7. J. cephalon with postero-lateral spines. K. pygidium. PMO 111.506, x7. L. cephalon. PMO 111.505, X7. M. pygidium. PMO 111.504, x5. All specimens latex casts from external moulds. Upper Middle Cambrian, Låven Fm., (Bjørno Mb.), Nasatjønn, Haukelifjell. Coll. D. L. Bruton.

latter species has a coarse radial ornament of sub­ 1934, pl. 31, figs. 2, 3a-c; pl. 34, figs. 2a, b) and angular costae and costellae and a pronounced both have fine radial ornaments of costae and concentric ornament. A. p/anus (Pander, 1830) costellae cancellated by fine growth lines. Mate­ is the type species of Antigonambonites and rial which may be assigned to the p/anus species the most common fossil in the limestones of group has been documented from the Expansus Bn age in the east Baltic whilst persisting into Shale of the Oslo Region (Opik 1939); further strata of Bm age (Opik 1934, p. 155). The Nor­ specimens are present in the collections of the wegian material is similar to Pander's species; as Paleontologisk Museum (Harper, unpublished far as can be judged the ventral and dorsal interi­ data). But pending the discovery of more com­ ors of both forms are comparable (see Opik plete and better preserved material of the Har- 320 D. L. Bruton et al. NORSK GEOLOGISK TIDSSKR!Ff 4 (1984) NORSK GEOLOGISK TIDSSKRIIT 4 (1984) Cambrian and Ordovician fossils 321 dangervidda form and redescription of the Ex­ and the pseudospondylium, though small, have pansus Shale species, a detailed comparison of similarities to members of the Alimbellidae. both is not warranted.

Trilobita Articulate brachiopod indet. David L. Bruton Fig. 4E, F Family AGNOSTIDAE MeCoy, 1849 Remarks. - One internal mould of a pedicle Subfamily PTYCHAGNOSTINAE Kobayashi, 1939 valve cannot be readily assigned to any described & genus of Ordovician brachiopod. The val ve has a Genus Lejopyge Hawle Corda, long flat interarea, anaclinal and with a wide 1847 open delthyrium. Both the anterior and lateral Type species. - Battus laevigatus Dalman, 1828, profiles are strongly convex and the anterior from the L. laevigata Zone, Honsater, Kinne­ commissure was probably rectimarginate. Al­ kulle, Vastergotland, Sweden. though the teeth are broken, dental plates are Discussion. - Opik (1979, p. 157-158) used the absent. A posterior pair of muscle scars are situ­ speiling Leiopyge, maintaining that in the trans­ ated on a small thickened callus of shell occupy­ lation into Latin from the classical Greek, 'i' ing the posterior part of the umbonal cavity. A (iota) cannot be expressed by ' j', which is un­ median septum separates two large elongate de­ known in both alphabets. While this is correct, pressions which apparently fade near the mid­ the speiling Lejopyge has been used without valve length. change since its inception, so there is a strong Information rearding the morphology, noted argument for conservation. above, is too sparse to permit confident specula­ tion concerning the precise affinities of this ar­ ticulate brachiopod. Nonetheless the features of (Linnarsson, 1869) the ventral interior suggest links with the Alim­ Lejopyge armata Fig. 4H-M bellidae. Andreeva (1960, p. 292) erected the farnily to include Alimbella Andreeva and Mede­ Discussion. - This form was originally named sia Andreeva from the Tremadoc rocks of the Agnostus laevigata var. armata, and Westergård Urals. Both she and Biernat (1965, p. H530) (1946, p. 89) considered it a subspecies of laevi­ considered the alimbellids to be aberrant porani­ gata. The two are clearly related, but the pres­ bonitaceans; however, Williams (1974, p. 68) re­ ence of postero-lateral spines on the cephalon cognised the orthoid features of the family and (Fig. 4J, L) and the pygidium of L. armata are assigned it, including his new genus Astraborthis characteristic, and I follow Opik (1979, p. 161) in from the upper Arenig Mytton Flags of the considering armata a separate species because of Shelve inlier, to the Orthacea. Although the this spinosity. The pygidial spines are very short valve from Hardangervidda is not sulcate, the and pygidia of the present material (Fig. 4K, M) details of the interarea, the Jack of dental plates resemble the two specimens figured by Wester-

Fig. 5. A, B, C-F, J. Andrarina costata (Angelin, 1854). A. Dorsal.view of part internat mould of moult stage. B. Latex east of external mould of same specimen. PMO 111.503, x2. Upper Middle Cambrian, Låven Fm., (Bjørno Mb.), Nasatjørin, Haukeli­ fjell. Coll. P. Haremo. C. Pygidium, dorsal view. PMO 111.502, X4. Upper Middle Cambrian (1dB), Ringsaker. Colt. s, Skjeseth. D. Thorax of 12 segments and pygidium, dorsal view, internat mould. PMO 26097, x3.5. Speeimen figured by Strand 1929, pl. 2, fig. 7. Upper Middle Cambrian (1dB), Stange. Coll. Th. Kjerulf. E. Cranidium, partly exfoliated, dorsal view. PMO 111.501, x3. Same horizon and locality as E. Specimen associated with Lejopyge laevigata. F. Cranidium, oblique anterior view, latex east of external mould. PMO 111.500, x3. Upper Middle Cambrian (1dB), associated with Lejopyge laevigata, north west of Aurå, Rendalen. Coll. Getz, 1883. J. Free eheek, dorsal view. PMO 26084, x4. Speeimen figured by Strand 1929, pl. 2, fig. 10. Same horizon and loeality as D. Coll. W. C. Brøgger. G-1, K, L. Groenwallia microphthalma (Angelin, 1851). G. Cranidium, dorsal view, flattened in shale. PMO 28792, x2. Upper

Middle Cambrian ( = Zone of Jincella brachymetopa), Krekling. Co li. W. C. Brøgger 1877. H. Moult stage of eomplete individual, external mould, flattenedin shale. PMO H2658, xl. Specimen the original of Brøgger 1878; pl. 3, fig. l. Upper Middle Cambrian,

Krekling. Coll. Wille and Brøgger 1877. l. Cranidium, dorsal view, flattened in shale. PMO 28770. K. Moulted pygidium and posterior thoracic segments, dorsal view. PMO 58611, Xl.5. Same locality and collection as G. L. Incomplete cephalon, ventral view, external mould with hypostome. PMO 28627, x2. Upper Middle Cambrian, Krekling. Colt. Unknown. 322 D. L. Bruton et al. NORSK GEOLOGISK TIDSSKRIFT 4 (1984) gård (1946, pl. 13, figs. 30, 31) from the upper that of the left side being inverted. The crani­ part of the L. laevigata Zone in Vastergotland. dium, an interna! mould, is poorly preserved, but Effacement of the pygidial rachis varies, the ra­ it is possible to distinguish the apparently broad chis of the specimen illustrated as Fig. 41 being sub-parallel-sided glabella and the long, straight well defined posteriorly and resembling the sec­ course of the posterior facial suture and broad ond pygidium figured by Westergård and a vari­ postocular cheek. This feature and details of the ety calledforfex by Brøgger (1878, pl. S, fig. 6a). suture are more clearly seen on two uncom­ I have examined the latter (PMO 28897), which pressed cranidia (Fig. SE, F) preserved in lime­ does not have as deep rachial furrows as stone (stinkstone), and figured for comparison. Brøgger's illustration suggests (see also remarks Westergård (1948, p. 14) has drawn attention to by Westergård 1946, p. 88, 89). The specimen is the similarity between Andrarina and the youn­ somewhat compressed and appears to have a ger olenids, and these similarities extend to de­ much wider doublure than material figured here­ tails of the occipital furrow, shape of gla beila, in, and the border Jacks the small spines. In my eye ridges and shape of the pre-glabellar field view, Brøgger's variety forfex falls within the and border (cf. Figs. SE, F and species of Proto­ range of variation known for Lejopyge laevigata. peltura in Henningsmoen 19S7, pl. 23). The di­ The present material of L. armata does not seem verging anterior facial sutures in Andrarina cos­ to have a median node on the rachis which is fata were thought by Westergård to be essentially present on both Swedish and Australian speci­ a non-olenid feature, though it is clear that the mens. However, this may be a result of the poor Olenidae as presently interpreted (see Fortey preservation of the Norwegian specimens. The 1974, p. 9-10) include forms with strongly di­ thoracic segments on the only complete individu­ verging anterior sutures. al (Fig. 4H) are not well preserved, but a fulcral Andrarina costata and Groenwallia microphth­ spine is visible on the second segment and this is alma (Angelin, 18S1) (Fig. SG, H, l, K, L) were characteristic for L. armata and not L. lejopyge. considered by Westergård (19S3, p. 31) to be similar and the latter was tentatively assigned to Family ANDRARINIDAE Raymond, 1937 the Andrarinidae. The differences between Groenwallia and Andrarina, however, were not Genus Andrarina Raymond, 1937 made clear. The type species of Groenwallia (Liostracus platyrrhinus Gronwall, 1902) is re­ Type species. - Liostracus costatus Angelin, corded together with G. microphthalma from the 18S4, from the uppermost Middle Cambrian Jincella brachymetopa Zone (Andrarum Lime­ Zone of Lejopyge laevigata, Honsater, Kinne­ stone and equivalents) in Sweden, whereas in kulle, Vastergotland. Norway, G. microphthalma is known from Kre­ kling together with Lejopyge laevigata and ele­ Andrarina costata (Angelin, 1854) ments of the older zone (Brøgger 1878). There are several complete specimens of G. microphth­ Fig. 5A -F,J . - alma in the collections of the Paleontologisk Mu­ Discussion. - Westergård (1948) provided new seum, Oslo, and study of these shows that they figures of Swedish material including the origi­ are clearly different from A. costata. Two speci­ nals of Angelin from which a pygidium (Wester­ mens (Fig. SH, K) show a characteristic moulting gård 1948, pl. 3, fig. 23) was chosen as lectotype .. whereby the thorax is separated into distinct sec­ Strand (1929) gave a complete description of tions with a sinuous axial line. The free cheeks material from the Zone of L. laevigata in the are in place, suggesting that the ventral doub­ Mjøsa district of Norway. His figured complete lures were attached and the hypostome Iies thorax and attached pygidium and a free cheek slightly displaced under the glabeila. The present are refigured herein (Fig. SD, J). Details of the material confirms Strand's (1929, p. 3S4) obser­ thorax, consisting of 12 segments, the pygidium vation that the thorax possessed 13 segments and with narrow, well-defined border and furrowed the 9th carries a macropleural spine. The glabella pleural areas, and the free cheek with short genal tapers more strongly forwards and is more spine, are identical with the one new specimen rounded anteriorly than in A. costata and there is from Hardangervidda (Fig. SA, B). This speci­ a broad, concave pre-glabellar field and a flat men, preserved in shale, is of a moult stage in curved anterior border narrowing towards the which both free cheeks Iie beneath the thorax, anterior corner. On larger, well preserved speci- NORSK GEOLOGISK TIDSSKRIFT 4 (1984) Cambrian and Ordovician fossils 323 mens (Fig. 51), there is a caecal pattem on the Brøgger, W. C. 1878. Om Paradoxidesskifrence ved Krekling. pre-glabellar field. The pygidium of G. mi­ Nyt. Mag. fur Naturv., 24, 18-80. Brøgger, W. C. 1893. Lagfølgen pa Hardangervidda og den crophthalma differs from that of A. costata in såkaldte 'højfields-kvarts'. Nor. geo/. unders. 11, 1-142. being more rectangular with a smooth to faintly Bruton, D. L. & Harper, D.A. T. in press. Arenig-Liandovery furrowed pleural area and a doublure that is stratigraphy and faunas across the Scandinavian Caledon­ broad anterolaterally, narrowing medially where ides. Geo/. Soc. Lond. DahU, T. 1861. Om Telemarkens geologie. Nyt. Mag. Naturvi­ there is a notch in the posterior border behind densk. 11, 137-172. the rachis. Dalman, J. W. 1828. Nya Svenska Palaeader Årsberattelse om The type species of Groenwallia has an occipi­ nyart Zoologiske Arbeten och Upptackter lill Kong/. Vet.­ tal spine, whereas Swedish material of G. mi­ Akad. 134-135. Erdtmann, B.-D. 1982. Palaeobiogeography and environments crophthalma (cf. Westergård 1953, pl. 7, figs. 13 of planktic dictyonemid graptolites during the earliest Ordo­ and 19) has a small node-like swelling. No such vician. Pp. 9-27. In Bassett, M. G. & Dean, W. T. (Eds). node is present on Norwegian material which I The Cambrian-Ordovician boundary: Sections, fossil distri­ have studied, and I do not consider the absence butions, and correlations. 227 pp. National Museum of Wales, Geological Series 3. of a spine sufficiently important to exclude mi­ Fortey, R. A. 1974. The Ordovician trilobites of Spitsbergen l. crophthalma from Groenwallia. However, it Olenidae. Norsk. Polarinst. Skrift. 160, 1-129. seems doubtful whether Groenwallia should be Gronwall, K. A.· 1902. Bornholms Paradoxideslag og deres retained in the Andrarinidae, though like An­ fauna. Dan. Geo[. Unders. 2(13) i-xi, 1-23. Havlieek, V. & Branisa, L. 1980. Ordovician brachiopods of drarina it possesses several olenid-like features. Bolivia. Rozpr. Cesk. Akad. Ved. 90, 1-54, pls. 1-{i. Certainly the hypostome is olenid-like and was Hawle, l. & Corda, A. J. C. 1847. Prodrom einer Monographie probably attached to a ventral membrane of the der Bohmischen Trilobiten. 1-136. cephalon and not the doublure, in a manner Henningsmoen, G. 1957. The trilobite family Olenidae. Skr. Norske Vid. Akad. Oslo, I. Mat.-Nat. Kl. 1957 l, 1-303. similar to those olenids (Balnibarbiinae Fortey, Kobayashi, T. 1939. On the agnostids (pt. 1). J. Fac. Sei. Jmp. 1974) which have a long pre-glabellar area. Univ. Tokyo 2, 5, 60-108. Linnarsson, J. G. O. 1869. Om Vestergotlands Cambriska och Acknowledgements. - We thank Dr. A. W. Owen and Mr. F. Siluriska aflagringar. Kong/. Svensk. Vet. -A kad. Forh. 8, 1- Nikolaisen for reading the manuscript and Jenny Orr for her 89. accurate typing. Bruton acknowledges finance from Norges Martinsson, A. 1974. The Cambrian of Norden. In Holland, C. Almenvitenskapelige Forskningsråd, whilst Harper thanks H. (Ed.) Cambrian of the British Isles, Norden and Spitsber­ N.E.R.C., N.A.V.F. and the Paleontologisk Museum, Oslo gen, 185-283. for financial support. Neuman, R. B. 1976. Early Ordovician (late Arenig) brachio­ Manuscript received pods from Virgin Arm, New World Island, Newfoundland. October 1984 Bull. Geo/. Surv. Canada 261, 11-{il. . Neuman, R. B. & Bates, D. E. B. 1978. Reassessment of Arenig and Llanvirn age (Early Ordovician) brachiopods from Anglesey, north-west Wales. Palaeontology 21, 571- 613. References Opik, A. A. 1934. Ober Klitamboniten. Acta Comment. Univ. Tartu. 17, 1-262, 22 pls. Andreeva, O. N. 1960. In Markowskii, B. P. (Ed.) [New Opik, A. A. 1939. Brachiopoden und Ostrakoden aus dem species of ancient plants and invertebrates of the U.S.S.R.] Expansusschiefer Norwegens. Nor. Geo/. Tidsskr. 19, 117- 288pp, 73pls., Moscow (in Russian). 142, pls. 1-{i. Andresen, A. 1974. New fossil finds from the Cambro-Silurian Opik, A. A. 1979. Middle Cambrian agnostids: Systematics metasediments on Hardangervidda. Nor. geo/. unders. 304, and biostratigraphy. Bull. Bureau Min. Resources 172, Vol. 55-{i(). l (text), Vol. 2 (plates). Andresen, A. 1978. Lithostratigraphy of the authochthonous/ Pander, C. H. 1830. Beitriige zur Geognosie des Russischen parautochthonous Lower Palaeozoic metasediments on Har­ Reiches. 165 pp. 31 pls. St Petersburg. dangervidda, south Norway. Nor. geo/. unders. 338, 59-69. Raymond, P. E. 1937. Upper Cambrian and Lower Ordovician Angelin, N. P. 1851. Palaeontologia Svecica. P.l. Inconogra­ trilobita and ostracoda from Vermont. Bull. Geo/. Soc. Am. phia crustaceorum formationis transitionis. Fase. l. Lundae. 48, 1079-1146. Angelin, N. P. 1854. Palaeonto/ogia Scandinavica. P.l. Crusta­ Rekstad, J. 1905. Fra Høifjeldstrøget mellem Haukeli og cea formationis transitionis. Fase. Il. Lipsiae (T. O. Weigel] Hemsedalsfjeldene Nor. geo/. unders. 36, 1-54. (Lundae). Rubel, M. P. 1961. (Lower Ordovician brachiopods of the Bassett, M. G. 1981. The Ordovician brachiopods of Cornwall. Superfamilies Orthacea, Dalmanellacea and Syntrophiacea Geo/. Mag. 118, 647-{;64, pls. 1-4. of the Eastern Baltic.) Akad. Nauk. ESSR, Inst. Geo/. Trudy Biemat, G. 1965. Suborder Syntrophiidina Ulrich & Cooper, 6, 141-226, pls. 1-27 [in Russian & Estonian]. 1936./n Moore,R. C. (Ed.): Treatiseon invertebrate paleon­ Schuchert, C. & Cooper, G. A. 1931. Synopsis of the brachio­ tology, part H, Brachiopoda, H526-H536. Geo/. Soc. Am. & pod genera of the suborders Orthoidea and Pentameroidea, Univ. Kansas Press. Lawrence, Kansas. with notes on the Telotremata. Am. J. Sei. 20, 265-288, pls. Brøgger, W. C. 1876. 'Andrarums-kalk' ved Breidengen i 1-3. Valders. Geo/. For. i Stockh. Forh. 3, 1-{i. Schuchert, C. & Cooper, G. A. 1932. Brachiopod genera of

22 - Geologisk Tidsskr. 4/84 324 D. L. Bruton et al. NORSK GEOLOGISK TIDSSKRIFT 4 (1984)

the suborders Orthoidea and Pentameroidea. Peabody Mu· Westergård, A. H. 1948. Non-agnostidean trilobites of the seum Nat. History Mem. 4, 1-270, pls. A and 1-29. Middle Cambrian of Sweden. l. Sver. geo/. unders. C 498, Størmer, L. 1925. On a Lower Cambrian fauna at Ustaoset. 1-32. Fennia 45, 12-22. Westergård, A. H. 1953. Non-agnostidean trilobites of the Størmer, L. 1941. Dictyonema shales outside the Oslo Region. Middle Cambrian of Sweden. Ill. Sver. geo/. unders. C 526, Nor. Geo/. Tidsskr. 20, 161-169. 1-58. Strand, T. 1929. The Cambrian beds of the Mjøsen district in Williams, A. 1974. Ordovician Brachiopoda from the Shelve Norway. Nor. Geo/. Tidsskr. JO, 305-366. district, Shropshire. Bull. Br. Mus. Nat. Hist. (Geo/.) Suppl. Strand, T. & Henningsmoen, G. 1960. Cambro-Silurian strati­ Il, 1-163. graphy. Nor. geo/. unders. 208, 128-169. Westergård, A. H. 1946. Agnostidae of the Middle Cambrian of Sweden. Sver. geo/. unders. C 477, 1-140.