Conodonts from the Cape Clay Formation (Lower ...

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Conodonts from the Cape Clay Formation (Lower Ordovician), southern Devon Islanc Arctic Archipelago

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ED LANDING'AND CHRISTOPHER R. BARNES' Department of Earth Sciences, University of Waterloo, Waterloo, Ont., Canada N2L 3G1 Received April 28, 1980 Revision accepted May 7, 1981

As part of a program involving the Ordovician conodont faunas of southern Devon Island, Northwest Territories, 22 samples were processed from the Cape Clay Formation and lowest Nadlo Point Formation near Dundas Harbour: The Cape Clay Formation is 85 m thick and composed of bluff-forming mottled limestone and dolomitic limestone. A small but diverse conodont fauna of 229 elements was recovered in which 23 form and multielement species are represented. Several new taxa are described in open nomenclature, and multielement Utahconus? bassleri (Furnish) is discussed. The fauna is considered to represent Fauna C of the North American Midcontinent Faunal Province and is indicative of a late Tremadocian age. This fauna, in a unit with few macrofossils, indicates correlation of the Cape Clay Formation near Dundas Harbour with the upper Turner Cliffs Formation of the Foxe Basin, with the upper Copes Bay and (or) lower Baumann Fiord formations of Cornwallis, northwest Devon, and Ellesmere Islands of the Canadian Arctic, and with some portion of Ross-Hintze trilobite Zones A - lower D of the Great Basin.

La prksente ktude fait partie d'un programme de recherche concernant les faunes h conodontes de l'ordovicien du sud de l'ile Devon, Temtoires du Nord-Ouest. Vingt-quatre Cchantillons provenant de la formation Cape Clay et de la base de la formation Nadlo Point ont kt6 trait& et examinks. La puissance de la formation Cape Clay est 85 m, elle constitue des falaises, et elle est composke de calcaire h tubulures de dolomite et de calcaire dolomitique. Une faune peu abondante mais variCe en conodontes comprenant 229 Clkments d'organismes, lesquels ont C t i rCcu@rks, et dont 23 esp&ces de formes et de multiClkments sont repksentks. Plusieurs nouveaux taxons sont dkcrits avec une nomenclature non dkfinitive et une discussion du multi6lCment Utahconus? bassleri (Furnish) est prCsentCe. La faune est considCr6e comrne repdsentant la Faune C de la Province du Mkdio-Continent de 1'ArnCrique du Nord et indique un Lge de la fin du TrCmadocien. Cette faune, et tant qu'uniti incluant quelques macrofossiles, 16vkle une corrklation de la formation Cape Clay prks de Dundas Harbour avec la formation Turner Cliffs du Foxe Basin, avec les formations Copes Bay supkrieure et (ou) Baumann Fiord infkrieure des iles Cornwallis, Devon (au nord-ouest) et Ellesmere dans 1'Arctique Canadien, et avec une partie des Zones Ross-Hintze I? trilobites A - D infkrieur du Great Basin. [Traduit par le journal] Can. I. Earth Sci., 18, 1609-1628 (1981)

Introduction The Middle cambrim to ~~l~ ordovician stratigraphy and p~eogeography of the canadian ti^ Archipelago are poorly known. Although recent stratigraphic studies have provided many valuable data, the strata of this interval are sparsely fossiliferous, and age and facies relationships of many formations remain obscure. This paper provides new conodont data for the Lower Ordovician Cape Clay Formation on southen Devon Island. The entire Ordovician sequence was collected for conodonts by D. M. Carson, F. van Soeren, and C. R. Barnes during July, 1978; the faunas from the higher stratigraphic units will be reported in later papers. The Cambrian-Ordovician succession on southern Devon Island has received little attention to date. Some data from a few localities are reported in the Operation

'present address: New York State Geological Survey, The State Education Department, ~ l b a n yNY , 12230, U.S.A. 'present address: Department of Geology, Memorial University of Newfoundland, St. John's, Nfld., Canada A l C 5S7.

Franklin volume (e.g ., Glenister 1963). The main study, based on field work in the Dundas Harbour area, is by Kurtz et al. (1952). Recent reconnaissance work by Christie (1977) is being amplified by a major mapping project by R. Thorsteinssonand U.M a ~ r othe f Geological Survey of Canada (GSC). This latter study will produce a major stratigraphic revision that will affect the introduced Kurtz et al(1952). On the advice of these workers and to conform with the GSC Paper in preparation (see also (kistie 1977)s we are adopting the term Cape Clay ~ ~ r m a t i o n for the upper, bluff-forming unit of the Mingo River Formation of Kurtz et al. (1952). heir other formational names will be retained here for discussion purPosesGeologic setting ~~~d~~ ~~~b~~~ area contains the best exposures On southem Devon Island for the basal part of the Cambrian-Ordovician succession (Figs. 1,2). Kurtz et al. (1952) and Christie (1977) reported that the Lower Cambrian Rabbit Point Formation, comprising nearly

0008-40771811101609-20$01.0010

01981 National Research Council of CanadalConseil national de recherches du Canada


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CAN. J. EARTH SCI. VOL. 18, 1981

Line 1 section

talus ONES SOUN

Om

Line 3

2-18 2-16, 2-15 2 -14

CLAY FM.

2-13 2-12 2- 11 2- 10 2-09 2- 08

FIG. 1. Location map showing Dundas Harbour locality of

2- 07

the Cape Clay Formation conodonts on southern Devon Island.

30 m of sandstone, unconformably overlies Precambrian metamorphic rocks. This is overlain by over 260 m of dolomitic limestone and subordinate quartz arenites of the Bear Point Formation of Middle Cambrian age. Most of the overlying sandstone, dolomitic limestone, and shale (180m) of the Ooyahgah Formation also appears to be of Middle Cambrian age, based on a brachiopod faunule from the upper part. Christie (1977) grouped the Bear Point and Ooyahgah as one unit with an estimated thickness of about 300 m. The age assignment of the Ooyahgah, together with an apparent disconformity between the Ooyahgah and the Cape Clay (= Mingo River of Kurtz et al. 1952). Formations and the presence of Early Ordovician trilobites (Symphsuri m and Hystricurus) and graptolites (Dendrograptus) in the latter unit, suggests that Upper Cambrian strata are absent. Kurtz et al. (1952) reported the Cape Clay Formation (= Mingo River) to be about 85m in thickness and composed primarily of bluff-forming limestone with more thinly bedded limestone and shale in the lower part. Overlying the Cape Clay Formation is the Nadlo Point Formation of Kurtz et al. (1952), about 85 m in thickness and formed predominantly of dolomitic limestone with a basal sandstone. The Nadlo Point Formation includes a lower 50m, largely covered, interval that may be equivalent to the Baumann Fiord Formation of Cornwallis and Ellesmere Islands and the Grinnell Peninsula, northwest Devon Island (see Kerr 1968 for review). Christie (1977) preferred to disregard the term Nadlo Point and referred the lower two thirds of this unit to "Unnamed Lower Ordovician carbonate beds" and the upper third to the overlying Eleanor River Formation. Kurtz et al. (1952) determined a probably late Canadian age for the Nadlo Point unit from fossil collections from the upper part. The extent of the Late Cambrian hiatus in the Canadian Arctic Archipelago may not be as great as

2 - 06 2-05 2 04 2-03

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2-02 2 -01

YAHGAH FM. FIG.2. Stratigraphic sections of the Cape Clay Formation at Dundas Harbour at Line 1 and Line 3 localities of Kurtz et al. (1952, Fig. 2). Position of conodont samples shown to the right of each column; faunas from samples are listed in Table 1.

previously considered. Lower Ordovician rocks are reported to lie disconformably on Middle Cambrian strata in southern Devon Island (Kurtz et al. 1952), the Bache Peninsula of eastern Ellesmere Island (Troelsen 1950; Christie 1967), and northwest Greenland (Cowie 1961). A greater hiatus appears to be present in northwest Baffin Island and the Foxe Basin (Trettin 1975), where the upper Lower Ordovician Ship Point Formation disconformably overlies the Middle Cambrian Admiralty Group. However, conodonts from the upper part of the Turner Cliffs Formation (upper Admiralty Group) identified by one of us (CRB) belong to Fauna B - lower Fauna C of Ethington and Clark (1971) (Mayr 1978, p. 49, Fig. 7) and indicate a correlation with the Cape Clay Formation. This possibility was recognized by Trettin (1975, Fig. 3). Recently, trilobites of probably Dresbachian (Late Cambrian) age have been identified from the subsurface of Cornwallis Island (Fritz, in Brideaux etal. 1975; and in Mayr 1978, p. 49). The occurrence of Proconodontus muelleri muelleri without other associated conodont species in the upper Panish Glacier Formation and in Member 1 of

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the Copes Bay Formation of Grinnell Peninsula, Devon Island, is indicative of a Late Cambrian age (Barnes et al. 1976; Nowlan 1976). Higher strata of Member 2 contain successively younger conodont zonal species (e.g ., Proconodontus notchpeakensis s.f., Cordylodus proavus s.f., C . rotundatus s.f.). Thus, on northwest Devon Island conodont Faunas A, B, and C of Ethington and Clark (1971) are present in sequence and there is little evidence of a complete Late Cambrian hiatus. Sparse conodont faunas from strata equivalent to the Cape Clay Formation elsewhere in the Canadian Arctic Archipelago have been reported by Barnes (1974) and Mayr et al. (1980).

Cape Clay Formation Kock (1929a, b) defined the Cape Clay Formation in Washington Land, Greenland, and the term has been applied on east-central Ellesmere Island (Christie 1967) and on southern Devon Island (Christie 1977). In all these areas it is represented by thickly bedded dolostone and dolomitic limestone bearing a sparse Early Ordovician fauna. Christie (1977) referred the more thinly bedded lower 12m of the Mingo River Formation of Kurtz et al. (1952) to the underlying Bear Point Ooyahgah unit, and assumed there was a hiatus beneath the upper bluff-forming, thickly bedded dolostones and limestones that he assigned to the Cape Clay Formation. Kurtz et al. (1952), however, indicated that the hiatus was below this 12 m interval and above a 3 m sandstone unit (Fig. 2). Christie (1977) discussed the lithology and megafauna of the Cape Clay Formation and its correlation across southern Devon Island. He noted a formational thickness varying from 37 to 70 m with about 70 m of section at Dundas Harbour. For the present study, the Cape Clay Formation was described, measured, and collected at two localities on the west side of Dundas Harbour (Figs. 1, 2). These localities are Lines 1 and 3 of Kurtz et al. (1952, see their Fig. 2 for detailed location). At the Line 3 section, south of Ooyahgah Pass, a 4 m sandstone is overlain by 11.5 m of thinly bedded, light gray, fine- to mediumgrained dolostone with intraclasts present at the base and in the middle of the unit. Above this, in the interval excluded from the Cape Clay Formation by Christie (1977), is 0.5 m of mottled limestone (sample 1-06, Fig. 2) overlain by 0.5 m of thinly bedded limestone (sample 1-07). The main bluff is composed of 13.5 m of medium brown-gray, fine-grained, dolomitic limestone (samples 1-08, 1-09) that is mottled and contains some white chert. This bluff-fonning interval is overlain by over 30 m of beds of similar lithology in a vertical cliff section. At the Line 1 section of Kurtz et al. (1952) in the Mingo River gorge on the north side of the river, the basal 9 m represents the dolostone unit that measured

11.5 m at the Line 3 section (Fig. 2). Samples 2-01 and 2-02 were taken at 2 and 5 m above the base. Above this, a 1 m mottled dolomitic limestone unit is overlain by 0.5m of argillaceous, dolomitic limestone (sample 2-03) that is probably the base of the shaly interval of previous authors. Upwards, 1.5 m of thickly bedded, medium gray-brown, mottled, fine-grained limestone is followed by 0.5 m of argillaceous, medium green and gray, mottled, fine-grained limestone (sample 2-04). The main cliff section above this is of rather uniform lithology and consists of massive to medium-bedded medium gray-brown, fine-grained, dolomitic limestone that is mottled (bioturbated?) throughout and becomes more calcareous towards the top. Samples 2-05 to 2-14 were taken from the upper part of the Cape Clay Formation. A 5 m recessive covered interval is overlain by lower units of the Nadlo Point Formation (Fig. 2): 0.5 m of white and pale gray, mottled dolostone (sample 2- 15); 1.5 m of laminated to thinly bedded pale gray dolomitic quartz arenite bearing some intraclasts (samples 2-16,2-17); a 5.0 m covered interval; and 1.Om of medium gray-green, fine-grained, sandy dolostone with intraclast-bearing lenses (sample 2-18). A major talus slope covers overlying units of the Nadlo Point Formation. Two samples were collected (2-01, 2-02) from the 11.5 m interval assigned to the lower Mingo River Formation by Kurtz et al. (1952) and assigned to the upper Bear Point - Ooyahgah by Christie (1977). The. Cape Clay Formation was sampled in 5 m intervals with closer spacing nearer the base (16 samples: 1-06 to 1-09, 2-03 to 2-14, with four samples (2-15 to 2-18) taken from the lower 13 m of the Nadlo Point Formation). Four samples taken from the lower part of the Bear Point Formation were barren of conodonts. The conodont distribution data (Table 1) clearly show that the conodont fauna from the lower 11.5 m dolomitic interval is the same as that in the Cape Clay Formation limestone and dolomitic limestone. Thus, if a hiatus is present between the Cape Clay and Ooyahgah Formations, it is probably at the level of the base of the formation selected by Kurtz et al. (1952) rather than at the higher level of Christie (1977) (see Fig. 2). The sparse fauna from the basal Nadlo Point Formation (Table 1, samples 2-15, 2-18) shows little difference from that of the underlying Cape Clay Formation and no evidence of a major hiatus is indicated by the conodont data.

Conodont faunas General . Conodonts are sparsely represented in samples (sample size 2.2-2.4kg) from the Cape Clay Formation, which yielded 229 elements representing 23 form and multielement species (Table 1). Conodont elements are

A s.f.

NOTE: Designation "el." refers to element.

U.?bassleri?

"Scolopodus"n.sp. A Asymmetrical el. Symmetrical el. Teridontus nakamurai Uirichodina? sp. A s.f. Utahconus? busslen Acodiform el. Acontidform el. Scolopodiform el.

"Scundodur" ssp.

Distacdiorm el. Oneotodus sp. A s.f. Protopandero$us? tricarinatus?

Acodiform el.

Juanognarhus? sp, A Acodifurm el. Distacodiform el. .I,sp. ?3

Homocurvatifom el. Su'betectiform el.

Drepanoisfodm? n.sp.

D.sp. A s.f.

D.homocurvam a.f.

Gracilifom el. Pipaform el.

C, prim s.f. Carnuodus longibasis Dfstacodus sp. A s.f. Drepanodus arcwhts

"Beldella" ap. s.f. C l a v o h u i w densus Cordylodus angularus s.f. C . intermedius s.f.

Acontiohs iawem's s.f.

TABLE1. Composition of conodont collections from the Cape Clay and lower Nadlo Point Formations, southern Devon Island



LANDING AND BARNES

thermally unaltered (color alteration index (CAI) = 1; see Epstein et al. 1977) in contrast to Early Ordovician conodonts (CAI = 4) from the subsurface of southern Ellesmere Island (Mayr et al. 1978). Surfaces of the elements are commonly strongly corroded and phosphatic crystallites stand out in relief (Pl. 2, fig. 3) or are coated with epitaxial apatite; which may show subhedral facets (Pl. 2, figs. 11, 12, 14). This diagenetic alteration has generally precluded observation of the original surface microsculpture.

Taxonomy Simple cone-like elements predominate in the Cape Clay Formation collections and represent a number of characteristic early Early Ordovician species of the North American Midcontinent Faunal Province (see "Correlation"). Conodont faunas of this age and faunal province are poorly documented, and application of multielement systematics to a limited fauna dominated by morphologically plastic cones is considered to be premature here. Juanognathus? sp. A, J.? sp. B, Utahconus? bassleri, and "Scolopodus" n.sp. A are represented by symmetry transition series in simple cones. It is unknown whether additional elements complement these albid striated elements. Additional problems in discussing these faunas are the taxonomic significance and constancy of development of white matter in conodont elements. Although Lindstrom (1970) regarded white matter as significant in suprageneric classification, the taxonomic implication of white matter and the regularity of its distribution in the elements of North American Early Ordovician conodont species are uncertain. For example, form species of Ulrichodina described by Furnish (1938) have white matter restricted to an axial zone. Ulrichodim? sp. A s.f. from the Cape Clay Formation is an enigmatic form species because many elements have an antero-basal ulrichodinan "notch" although all specimens have completely albid cusps.

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Correlation

Interregional correlation Faunas from samples 1-06 and 2-01 through 2-12 include, among other species, Acodus oneotensis s.f., Oistodus? triangularis s .f ., and Paltodus bassleri s .f . (= elements of multielement Utahconus? bassleri) with "Acontiodus" iowensis s.f., Clavohamulus densus, and Drepanodus homocurvatus s.f. Although the association of these forms with Cordylodus spp. s.f. is comparable to that originally reported by Ethington and Clark (1971) from the lower part of Early Ordovician conodont Fauna C of the North American carbonate platform, this fauna is not biostratigraphically diagnos-

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tic. Landing (1981) noted that conodont Fauna C, defined graphically by Ethington and Clark (1971, Fig. 2) as an assemblage of 13 associated form species, is present in the lower part of the Garden City Formation, Utah-Idaho. A fauna from the lowest beds of the Garden City with many, but not all, of the elements of Fauna C has been designated "upper Fauna B" (Landing 1981). Triangulodus? n.sp. A (= Oistodus sp. Ethington and Clark, 1971 (= Oistodus parallelus Lindstrom sensu Miiller 1973) + Acodus oneotensis Furnish sensu Miiller 1973) used to define the base of Fauna C in the Garden City Formation (Landing 1981) is not present in the Cape Clay Formation collections, and the faunas below horizons 1-08 and 2-07, with Clavohamulus densus (a characteristic Fauna C species), could be referred to upper Fauna B of Landing (198 1). However, it is probable that collections at least as low as 1-06 represent Fauna C. The element herein designated "Belodella" sp. s.f. is a rare form known from middle and upper Fauna C in the Garden City Formation (Landing, in preparation). Drepanoistodus? n. sp. from the Cape Clay Formation is also present in Fauna C of the Garden City Formation although it does range as low as the upper part of "upper Fauna B" of the Garden City Formation (Landing 1981, in preparation). The absence of cordylodids from upper conodont Fauna C assemblages has been reported from the lower El Paso Group, west Texas (Repetski 1975), from Arctic Canada (Nowlan 1976), and from the upper portion of "conodont complex 111" in Siberia (Abaimova 1975). However, recent work indicates that advanced Cordylodus form species are present in decreasing abundance to the top of Fauna C intervals in the House Limestone, western Utah (Ethington and Clark 1981) and the lower Garden City Formation, northern Utah and southwestern Idaho (Landing 1981, in preparation). The absence of cordylodids above sample 2-12 may not indicate a transition to upper Fauna C. Conodonts from this interval are rare and cordylodid absence may simply reflect this situation. Conodont Fauna C is present throughout Ross' (195 1) trilobite Zones A - lower D in the lower Garden City Formation of Utah-Idaho and undergoes little change in that interval (Landing 1981, in preparation). The lowdiversity Cape Clay Formation faunas lack such characteristic Fauna C taxa as Acanthodus, Chosonodina, and Loxodus. Conversely, Cape Clay Formation forms such as Juanognathus? sp. A., J.? sp. B, "Scolopodus?' n.sp. A s.f. are unknown in the Garden City. These faunal dissimilarities between the Cape Clay and Garden City Formations, the apparent homogeneity of conodont faunas from Garden City Fauna C, and generic-level identifications of lower Cape Clay Formation trilobites (Kurtz et al. 1952) preclude a precise Cape Clay -


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CAN. 1. EARTH SCI. VOL. 18, 1981

Garden City correlation. The apparent unconformity separating the Middle Cambrian Ooyahgah Formation from the Cape Clay Formation may include all or part of Ross (1951) - Hintze (1952) trilobite Zones A and B and possibly lower Zone C. Conodont Fauna C assemblages appear to bridge the biofacies differences shown by associated carbonate platform macrofaunas and are known from the Siberian Faunal Province ("conodont complex II" and "complex III"; Abaimova 1975). In addition, comparable conodont faunas are present in the Australasian Faunal Province in northern Iran (Assemblage Zones 6 and 7, upper Shirgesht Formation; Miiller 1973), western Queensland (= Cordylodus rotundatus - Cordylodus angulatus and Chosonodina he&rthi Assemblage Zones; Druce and Jones 1971), and the upper Pander Greensand and Claravale sequence, northwestern Australia (Jones 1971). The Cape Clay Formation fauna contains few of the species that are diagnostic of Baltoscandia; this situation reflects the severe Early Ordovician differentiation of the North American Midcontinent and North Atlantic conodont faunal provinces (Barnes et al. 1973; Lindstriim 1976). Only the Cordylodus form species of the Cape Clay Formation are geographically widespread and may prove to be useful in interprovincial correlations. However, only a few studies have been made of the Tremadocian conodonts of Baltoscandia, and the stratigraphicranges of C . angulatus s.f., C : intermedius s.f., and C . prion s.f. relative to one another on &and, Sweden, are unclear. These three form species are recognizable in reports on the upper Tremadocian Ceratopyge Limestone of Sweden (Lindstrom 1955;van Wamel 1974) and the Varangu member (AInv) of Estonia (Viira 1974). However, these form species also appear to range into older lower Tremadocian strata on 0land ( C . angulatus - C . prion and C . rotundatus Assemblage Zones of van Wamel 1974). Species similar or identical to Cornuodus longibasis and Drepanodus arcuatus are poorly represented in the Dundas Harbour sections in samples 2-08, 2-1 1, and 2- 18. These species are stratigraphicallylong-ranging in Baltoscandia (see Efgren 1978) and have their lowest known occurrences in the upper Trernadocian Varangu member (Viira 1974) and Ceratopyge Limestone (van Warnel 1974), respectively. These data and the presence of cordylodids suggest that the Cape Clay Formation at Dundas Harbour is tentatively equivalent to the upper Tremadocian of Baltoscandia. Arctic Canada correlation "Belodella" sp. s.f., Ulrichodina? n.sp. A s.f., Juanognathus? sp. A, J.? sp. B, Oneotodus? sp. A s.f., and "Scolopodus" n. sp. A s.f. have never been reported in North American sequences outside of Arctic Canada.

It is unclear whether these forms (1) represent an Early Ordovician conodont biofacies, (2) represent an interval of time that is presently undocumented elsewhere in North America, or (3) indicate subprovincialisrn of North American faunas. Nowlan (1976) recovered several of these species on Ellesmere Island and northern Devon Island. Drepanoistodus? n.sp. and Oneotodus? sp. A s.f. are associated with Cordylodus spp. s.f. in the upper Copes Bay Formation (Member 3) in lower Fauna C assemblages. Barnes (in Mayr 1978, p. 49) also identified C . angulatus s.f. from the upper Copes Bay Formation in the subsurface of Cornwallis Island. Nowlan (1976) recovered Juanognathus? sp. A and "Scolopodus"sp. A s.f. in upper Fauna C collections from the overlying Baumann Fiord Formation. These species were designated (in nomen nudum) and were used in a proposed zonation of upper Fauna C. However, new data from this study indicate that these three forms co-occur with Cordylodus spp. s.f. in Fauna C assemblages from the Cape Clay Formation. Conodont faunas from the Cape Clay Formation at Dundas Harbour consequently do not permit a highly resolved correlation with Ellesmere and northwest Devon Islands, and correlative faunal assemblages may be present either in the upper Copes Bay or in the Baumann Fiord Formations.

Systematic paleontology The following taxa, listed in Table 1 and illustrated, occur in insufficient numbers to allow new taxonomic interpretation and are not discussed further in this section: "Acontiodus" iowensis Furnish s.f. (Pl. 4, figs. 7, 11-14, 16, 18-21; Fig. 3-21, -22) Clavohamulus densus Furnish (Pl. 2, figs. 11- 14) Cordylodus angulatus Pander s.f. (Pl. 3, fig. 11; Fig. 3-4) C . intermedius Furnish s.f. (Pl. 2, fig. 19; Fig. 3-5) C . prion Lindstrom s.f. (Pl. 2, fig. 16; Fig. 3-6) Cornuodus longibasis (Lindstrom) (Pl. 2, fig. 6) Drepanodus arcuatus Pander (Pl. 2, figs. 17, 20) D . homocurvatus Lindstrijm s.f. (PI. 2, fig. 10; Fig. 3-26) Teridontus nakamurai (Nogami) (Pl. 1, figs. 15- 17, 20; Fig. 3-16) All type and figured specimens are in the repository of the National Type Fossil Collection, Geological Survey of Canada (GSC), Ottawa. Designations in parentheses following repository number, e.g., (2- 12), indicate section and sample, respectively. The suffix s.f. (sensu formo) is used to distinguish form species from multielement species. Genus Acontiodus Pander, 1856 s. f.

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Type species Acontiodus latus Pander, 1856 s.f. Remarks Furnish's (1938) type specimens of Acontiodus iowensis s.f. and A . propinquus s.f. are elements with albid cusps, which were recovered from the Oneota Dolostone, whereas A. staufferi Furnish, 1938 s.f. has a hyaline cusp with a growth axis and was originally described from the overlying Prairie du Chien Group. Form element morphologies comparable to and intermediate between A. iowensis s .f. and A. propinquus s .f. are present in the large collections from the lower Garden City Formation, northern Utah and southeastern Idaho, and are associated with an albid element superficially similar to A. staufferi s. f. (see PI. 4, figs. 7, 11, 16,18,20,21; Fig. 3-21). Landing (198l)referredthese acontiodiform elements to Semiacontiodus iowensis (Furnish) and associated A. staufferi s.f., Ulrichodina deflexus Furnish s .f. , and Scolopodus quadraplicatus Branson and Mehl s.f. in one apparatus (Landing, in preparation). Genus Belodella Ethington s.f. Type species Belodus devonicus Stauffer, 1940 s. f. "Belodella" sp. s. f. P1. 1, fig. 2; Fig. 3-28

Description Strongly laterally flattened, recurved element with sharp oral and posterior edges. Concave anterior margin flanked by two antero-lateral costae. Cusp albid above deep basal cavity.

Distacodus sp. A. s.f. P1. 3, figs. 7, 12; Fig. 3-31 Description Proclined, albid elements with costae reaching aboral margin. Tip of basal cavity located slightly anterior of midline of element. Element laterally compressed at base and slightly antero-posteriorly compressed toward tip. Comparison The specimens resemble tetracostate elements of Utahconus? bassleri but are larger and have rounded costae that reach the aboral margin. Hypotypes GSC 62042 (1-07), 62043 (2-18).

Genus Drepanodus Pander, 1856 Emended Lindstrom, 1971 Type species Drepanodus arcuatus Pander, 1856 s.f. Drepanodus sp. A s.f. P1. 4, fig. 17; Fig. 3-3 Drepanodus cf. cyranoicus Lindstrom. (Abaimova 1975, p. 60, 61, P1. 3, fig. 10; Fig. 6-21.) Description Strongly laterally flattened element with sharply keeled, albid cusp slightly proclined over large base. Shallow base cavity has concave profile anterior and posterior to medially located basal tip. A smooth arc is made by the intersection of the oral edge and posterior keel of the cusp.

Remarks Hypotype Serpagli (1967) regarded the Belodella apparatus as a GSC 62048 (1-07). symmetry transition series involving posteriorly denticGenus Drepanoistodus Lindstrom, 1971 ulate elements. Early species of Belodella appear to Emended van Wamel, 1974 include both denticulate and non-denticulate elements (Barnes and Poplawski 1973; Nowlan 1976; Barnes Type species 1977; Lofgren 1978). Oistodiform elements have been Oistodus forceps Lindstrom, 1955 s.f. considered to complement the apparatus (Nowlan 1976; Drepanoistodus? n. sp. Barnes et al. 1979). P1. 2, figs. 1, 2, 5, 7, 8; Fig. 3-23, -25 The systematic affinity of "Belodella" sp. s.f. from the Cape Clay Formation is uncertain. Completely Description Homocurvatiform element with slightly laterally flatcomparableelements are known from the middle portion of Fauna C in the Garden City Formation and are tened cusp reclined over long, weakly expanded base. associated with elements with a keeled anterior margin Basal cavity deep with anterior located basal tip. Suberectiform element laterally flattened with relawith or without bordering antero-lateral costae. tively deep basal cavity. Basal tip slightly anterior to Hypotrpe midline of element. GSC 62097 (1-06). White matter originates at tip of basal cavity and fills the cusp. Genus Distacodus Hinde, 1879 s.f. Type species Machairodus incurvus Pander, 1856 s. f.

Remarks This association of elements, with the characteristic


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distribution of white matter noted above, is present in anterior surface, distally convex and adapically concave lower Fauna C of the upper Copes Bay Formation, posterior surface of cusp, and convex oral surface. Ellesmere Island (Nowlan 1976), and upper Fauna B Aboral margin is a slightly laterally compessed ellipse in and lower Fauna C of the Garden City Formation, distacodiform elements to a strongly antero-posteriorly compressed slit in acodiform elements. Basal cavity Utah-Idaho (Landing 1981). The homocurvatiform element differs from that in does not extend above level of oral edge and has concave such species as Drepanoistodus suberectus (Branson or straight anterior margin. Basal tip near anterior face and Mehl) and D. forceps (Lindstrom) in the anterior of element. Lateral costae extend to tip of element and terminate with rounded ends at aboral margin. location of basal cavity. Generic assignment It is possible that D.? n.sp. does not have an oistodiform element and would not be a species of Drepanoistodus sensu stricto.

Remarks Two elements are only doubtfully brought to the species. One specimen (Pl. 4, fig. lo), with a long, antero-posteriorly flattened base, may represent a symmetrical element. The second specimen (Pl. 4, fig. 9) Hypotypes Homocurvatiform elements GSC 62047 (1-06), may be a strongly asymmetrical acodiform element with 62050 (1-07), 6205 1 (2-03), 62 100 (1-06); suberecti- two low carinae developed on the posterior surface of the element. form element 62052 (1-06). Genus Juanognathus Serpagli, 1974 Type species Juanognathus variabilis Serpagli, 1974. Juanognathus? sp. A P1. 3, figs. 13, 16; P1. 4, figs. 1-6, 8, 9(?), lo(?); Fig. 3-32, -33, -35, -36, -38, -39 Aff. Scolopodus staufferi (Furnish). (Jones 1971, p. 67, P1. 6, figs. 7a-c.) ?Acodina navicula Abaimova, 1975 (pp. 36, 37, P1. 1, figs. 15a-16b; Fig. 6-5, -6). Description A symmetry transition series involving albid, striated, proclined elements with two lateral keel-like costae. Elements with broadly carinate or rounded

Comparison The species is represented by a small number of distacodiform (symmetrical) and acodiform (asyrnrnetrical) elements. Nowlan (1976) recovered comparable elements in association with non-costate drepanodiform elements from the lower Baumann Fiord Formation (lower Fauna C) on Ellesmere and Devon Islands. Acodina navicula Abaimova s.f. from lower Fauna C of Siberia may represent a distacodiform element of Juanognathus? sp. A. Generic assignment Juanognathus is defined as a symmetry transition of bicostate elements (Serpagli 1974), and Nowlan's (1976) recovery of drepanodiform elements makes the generic assignment questionable.

FIG. 3. Outline drawings of conodonts from the Cape Clay and lower Nadlo Point Formations, Devon Island. (1, 2)

"Scolopodus" n.sp. A, GSC 62096, x 80, and GSC 62099, x 50, respectively. (3) Drepanodus sp. B s.f., GSC 62048, X 60. (4) Cordylodus angulatus Pander s.f., GSC 62038, x 35. (5) Cordylodus intermedius Furnish s.f., GSC 62039, x 50. (6) Cordylodusprion Lindstrom s.f., GSC 62040, x 45. (7,8,10-15,24,37,40,41) Utahconus? bassleri (Furnish): (7) tricostate acodiform element with secondarily trifid posterior costa, GSC 62082, X 30; (8) tricostate acodiform element, GSC 62083, x 30; (10) acontiodiform element, GSC 62077, x 35; (1 1) scolopodiform element, GSC 62085, X 35; (12) tricostate acodiform element, GSC 62079, x 40; (13) tricostate acodiform element, GSC 62084, X 40; (14) unicostate acodiform element, GSC 62069, X 45; (15) acontiodiform element, GSC 62070, X 35; (24) unicostate acodiform element, GSC 62049, x 30; (37) sharply costate acontiodiform element, GSC 62090, x 70; (40) tricostate acodiform element, GSC 62092, X 100; (41) sharply costate scolopodiform element, GSC 62093, x 80. (9) Utahconus? bassleri? (Furnish), GSC 62098, X 45. (16) Teridontus nakamurai (Nogami), GSC 62065, x 35. (17-19) Juanognathus sp. B: (17) distacodiform element, GSC 62061, x 75; (18) distacodiformelement, GSC 62062, x 40;(19) acodifonn element, GSC 62064, X 65. (20) "Scandodus" sp. A s.f., GSC 62087, X 55. (21,22) "Acontiodus" iowensis Furnish: (21) GSC 62032, X 30; (22) GSC 62033, X 60. (23,25,27) Drepanoistodus? n.sp.: (23) suberectiform element, GSC 62052, x 50; (25) homocurvatiform element, GSC 62051, X 35; homocurvatiform element, GSC 62047, x 35. (26) Drepanodus homocurvatus Lindstrom s.f., GSC 62046, X 40. (28) "Belodella" sp. s.f., GSC 62097, X 50. (29,34) Ulrichodina? sp. s.f.: (29) GSC 62073, X 60; (34) GSC 62074, X 70. (30) Oneotodus? sp. A s.f., GSC 62101, X 90. (31) Distacodus sp. A s.f., GSC 62043, x 35. (32, 33, 35, 36, 38, 39) Juanognathus? sp. A: (32) acodiform element, GSC 62056, x 80; (33) acodifonn element, GSC 62057, X 100; (35) distacodiform element, GSC 62053, x 70; (36) distacodiform element, GSC 62055, x 100; (38) acodiform element, GSC 62058, x 60; (39) distacodiform element, GSC 62094, X 130.

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Hypotypes Distacodiform elements GSC 62053 (2-03), 62054 (1-07), 62055 (1-08), 62089 (1-07), 62094 (1-07); acodiform elements GSC 62056 (1-06), 62057 (1-07), 62058 (2-12), 62059 (2-04). Juanognathus? sp. B P1. 3, figs. 1, 2, 4-6, 8-10; Fig. 3-17-19 ?Acodus deltatus Lindstrom. (Abaimova 1975, pp. 42,43, P1. 1, figs. 17, 18.)

have never been reported in studies of Early Ordovician conodonts. Abaimova's (1975) illustrated Acodus deltatus s.f. element from lower Fauna C of Siberia may represent an acodiform element. Juanognathus? sp. A of this report has elements with shallower, anteriorly located basal cavities. Hypotypes Distacodiform elements GSC 62060 (1-O8), 62061 (1-08), 62062 (1-09); asymmetrical elements GSC 62063, 62064 (2-07).

Description A possible symmetry transition series of laterally Genus Oneotodus Lindstriim, 1955 s.f. unicostate, striated, albid elements with concave poster- Type species ior face of cusps. Basal cavity deep with medially Distacodus? simplex Furnish, 1938 s.f. located basal tip extending as high as or above level of Oneotodus? sp. A s.f. oral edge. Anterior margin of basal cavity convex, P1. 1, fig. 6; Fig. 3-30 straight, or slightly concave; posterior margin distally concave. Description Distacodiform (subsymmetrical) elements with cusps Strongly proclined, gently curved, albid elements reclined over large, laterally flattened bases. Slight with circular cross section throughout. Basal cavity asymmetry results from one costa being more anteriorly slender and anteriorly located. located on base (compare P1. 3, figs. 4, 5). Costae become gradually obsolescent (Pl. 3, figs, 4,5) or have Remarks rounded terminations (Pl. 3, figs. 1,2) anterior to aboral Nowlan (1976) recovered closely similar elements margin. from lower Fauna C of the Copes Bay Formation, Acodiform (asymmetrical) elements are delta-shaped Ellesmere and Devon Islands. Nowlan's specimens in lateral view with slightly reclined cusp. Cusp with differ by having a centrally located basal cavity. It is deeply concave postero-lateral surface lying between probable that Nowlan's small collection (seven elepostero-lateral costa and anteriorly displaced lateral ments) is not representative of the range of morphologic costa. variability in the basal cavity of the form. Remarks Comparison Similarity in basal cavity shape, cusp colour, and Oneotodus? sp. A s. f. and Nowlan's specimens are reclination, and mutual association suggest that the more elongate than Scolopodus filosus Ethington and acodiform and distacodiform elements represent a symClark s.f. Although no surface detail is preserved in the metry transition series. Cam Clay Formation specimens, Nowlan (personal corhmunication, 1979) noted that his elements &e more Comparison Forms comparable to the distacodiform elements finely striated than those of S. filosus s.f. PLATE1

FIGS.1, 5. "Scolopodus" n.sp. A s.f.: (1) lateral and slightly posterior view showing weakly concave posterior surface of cusp, GSC 62096, x 140; (5) lateral view, asymmetrical element, GSC 62099, x 80. FIG.2. Belodella? sp. s.f. Lateral and slightly antero-aboral view, GSC 62097, x 95. FIGS.3, 4, 7-14, 18-22. Utahconus? bassleri (Furnish): (3, 4) surface microsculpture and posterior views of tricostate acodiform element with low secondary costae on posterior costa, GSC 62082, X 195 and X 50, respectively; (7) posterior view of acontiodiform element showing slight asymmetry and bifid posterior costa, GSC 62078, X 70; (8) lateral view of tricostate acodiform element with sharp costae, GSC 62084, x 70; (9) lateral view of acontiodoform element with rounded costae, GSC 62077, x 60; (10) lateral view of tricostate acodiform element with sharp costae, GSC 62083, X 45; (11) tricostate acodiform element with large base and subdued costae, GSC 62079, X70; (12) proclined unicostate acodiform element, GSC 62068, x 110; (13) tricostate acodiform element with large base, GSC 62081, X 55; (14) tricostate acodiform element with sharp costae, GSC 62080, x 55; (18) scolopodiform (tetracostate) element with rounded costae, GSC 62085, X 65; (19) acontiodiform element with long base, GSC 62070, x 70; (21) unicostate acodiform element with antero-lateral costa, GSC 62069, x 80; (22) short-based acontiodiform element, GSC 62071, X 70. FIG.6. Oneotodus? sp. A s.f., GSC 62101, X 200. FIGS.15-17, 20. Teridontus nakamurai (N,ogami): (15) proclined element, GSC 62066, X 115; (16, 20) lateral view and surface microsculpture, GSC 62067, x 100 and x 560, respectively; (17) GSC 62065, X 90. Specimens from 1-06.


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Hypotype GSC 62101 (1-09).

basal cavity are concave. Cusp is albid above basal cavity.

Discussion Repetski (1975) recovered similar elements, which are gently proclined to erect, from Faunas C and D of the El Paso Formation, west Texas. Scandodus, as emended by Lindstrom, has a hygine Protopanderodus? tricarinatus? Barnes and Poplawski apparatus and the albid Cape Clay Formation specimen P1. 2, fig. 18 ?Protopanderodus tricarinatus Barnes and Poplaw- is only provisionally referable to the genus in a form sense. ski, 1973 (Pl. 1, fig. 5; Fig. 2B). Hypotype Remarks GSC 62087 (1-06). An elongate, antero-posteriorly compressed aconGenus Scolopodus Pander, 1856 s.f. tiodiform element with sharp lateral costae, a gently curved, albid cusp, and an anteriorly located basal Type species cavity is closely similar to elements recovered from Scolopodus sublaevis Pander, 1856 s. f. lower Arenigian boulders from the Mystic Formation, "Scolopodus" n. sp. A s .f. Quebec. The basal cavity extends into the bases of the P1. 1, figs. 1, 5; Fig. 3-1, -2 costae at the aboral margin. ?Scolopodus triangularis Ethington and Clark. (AbThe generic assignment of Protopanderodus? tricarinatus? is questionable because the nature of the aimova 1975, pp. 104, 105, P1. 9, fig. 16; Fig. 8-20.) apparatus is unknown and the surfaces of the Mystic Description Formation and Cape Clay Formation elements are corSlightly procliied to erect, small, laterally comroded. pressed elements with grooved posterior margin on anteriorly tapering cusp. Basal cavity very shallow with Hypotype anteriorly directed tip located anterior to midline of GSC 62086 (2- 13). element. Anterior and posterior stretches of basal cavity Genus Scandodus Lindstrom, 1955 are, respectively, concave and convex. Cusp is opaque Emended Lindstriim, 1971 white above the basal cavity. Type species Remarks Scandodus furnishi Lindstrom, 1955 s .f. Nowlan (1976) recovered five symmetrical, shortcusped elements from the lower Baumann Fiord Forma"Scandodus" sp. A s.f . tion (lower Fauna C), southern Ellesmere Island. An P1. 2, fig. 15; Fig. 3-20 asymmetrical, long-cusped element recovered in this Description study (Pl. 1, fig. 5) has a basal cavity comparable to that Laterally compressed, gently laterally and posteriorly present in the short-cusped elements and is included in curved, proclined element with sharp anterior and "Scolopodus" n.sp. A. The later specimen is similar to posterior edges. Tip of the shallow basal cavity is an albid element incorrectly figured by Abaimova medially located and interior and posterior margins of (1975) as Scolopodus triangularis s.f. from Siberia. Genus Protopanderodus Lindstrijm, 1971 Type species Acontiodus rectus Lindstriim, 1955 s.f.

PLATE2

FIGS.1 , 2 , 5 , 7 , 8 . Drepanoistodus? n.sp.: (2,5,7) homocu~atiformelements, GSC 62047, X 55; (2) GSC 62050, X 70; (5) GSC 62100, x 110; (7) GSC 62051, X 65; (8) suberectifom element, GSC 62052, X 85. FIGS.3 , 4 , 9. Ulrichodim? sp. s.f.: (3) lateral and slightly aboral view, GSC 62074, X 100; (4) lateral and slightly anterior view, GSC, 62075, X 80; (9) lateral and slightly aboral view, GSC 62076, X 70. FIG.6. Cornuodus longibasis (Lindstrom, 1955), GSC 62041, x 100. Specimen from sample 2-1 1. FIG. 10. Drepanodus homocurvatus Lindstrom, 1955 s.f., GSC 62046, x 70. Sample 2-08. Frcrs. 11-14. Clavohamulusdensus Furnish, 1938 s.f.: (1 1, 14) lateral andoral views, GSC 62036, X 90; (12, 13) lateral and anterior views, GSC 62037, X 100. Samples 1-08, 2-07. FIG. 15. "Scandodus" sp. A s.f., GSC 62087, x 95. FIG. 16. Cordylodusprion Lindstrijm, 1955 s.f., GSC 62040, x 85. Sample 2-02. FIGS.17,20. Drepanodus arcuatus Pander, 1856: (17) graciliform element, GSC 62044, X 50; (20) pipaform element, GSC 62045, x 45. Specimens from 2-18. FIG. 18. Protopanderodus? tricarinatus? Barnes and Poplawski, 1973. Lateral and aboral view, GSC 62086, x 65. FIG.19. Cordylodus intermedius Furnish, 1938 s.f., GSC 62039, X 90. Sample 1-06.


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?Scolopodus bassleri (Furnish). (Druce and Jones 1971, pp. 91,92, P1. 17, figs. la-4d; Fig. 30b; Jones 1971, pp. 62,63, PI. 5, figs. 3 a-c, 6 a-c; P1. 9, figs. Genus Utahconus Miller, 1980 2a-3c; Druce and Jones 1971 illustrate hyaline elements.) Type species Drepanodus acutus Pander. (Druce and Jones 1971, Paltodus utahensis Miller, 1969 s .f. p. 73, P1. 20, figs. 5a-7c; Fig. 24a.) Utahconus? bassleri (Furnish, 1938) Acodus housensis Miller. (Jones 1971, p. 43, P1. 3, P1. 1, figs. 3, 4, 7-14, 18-22; P1. 3, figs. 14, 15, fig. 6 a-c.) 17-21; P1. 4, fig. 15; Fig. 3-7, -8, -10-15, -24, -37, Drepanodus tenuis Moskalenko. (Jones 1971, p. 55, -40, -41 P1. 3, figs. 3a-4b; P1. 8, fig. 9 a-c.) ?Paltodus spurius Ethington and Clark. (Greggs and Acodus oneotensis Furnish, 1938 (p. 325, P1. 42, figs. 26-29; Fig. 1N; ?Mound 1968, p. 406, P1. 1, fig. 4; Bond 1971, p. 1468, P1. 2, figs. 1-2a.) Acontiodus kha&ni Abaimova, 1975 (p. 49, P1. Ethington and Clark 1971, P1. 1, figs. 3, 6, 8; Jones 1971, p. 44, P1. 1, fig. 5a-c; P1. 1, figs. 6a-7c; P1. 8, 2, figs. 13, 15; Fig. 6-18a, -18b). Acontiodus rectus Lindstrijm. (Abaimova 1975, pp. fig. 1 a-c = new genus A new species A Repetski, 1975). 50, 51, P1. 2, fig. 11; Fig. 6-15.) Paltodus distortus Branson and Mehl. (Abaimova Oistodus? triangularis Furnish, 1938 (pp. 330, 33 1, P1.42, fig. 22; Fig. 1P; Ethington and Clark 1971, P1. 1, 1975, pp. 90, 91, P1. 8, fig. 7 a , b; Fig. 7-47.) Paltodus kullerudensis (Hamar). (Abaimova 1975, figs. 18, 22, 23). Paltodus bassleri Furnish, 1938 (p. 33 1, P1. 42, fig. pp. 89, 90, P1. 8, figs. 3-5; Fig. 7-47.) Scolopodus bassleri (Furnish). (Fiihraeus and Now1; Ethington and Clark'1971, P1. 2, figs. 2, 4, 6) Repetski and Ethington 1977, P1. 1, fig. 1). lan 1978, p. 468, P1. 1, figs. 18, 19.) Paltodus variabilis Furnish, 1938 (p. 331, P1. 42, Non Paltodus basserli Furnish. (Miller and Melby figs. 9,lO; Fig. 1E; Graves and Ellison 1941, p. 5, P1.2, 1971, P1.2, figs. 10- 12 (= "Paltodus" utahensis Miller fig. 17; Mound 1968, p. 415, P1. 4, figs. 18-38). s.f.).) Scolopodus sulcatus Furnish, 1938 (p. 334, P1. 41, Acontiodus staufferi Furnish. (Abaimova 1975, pp. figs. 14, 15; Fig. 11). 51, 52, P1. 2, figs. 8, 9; Fig. 6-14, -17.) Non Paltodus variabilis Furnish. (Graves and Ellison Paltodus(?) bassleri Furnish. (Abaimova 1975, pp, 1941, P1. 2, fig. 17.) 88, 89, P1. 7, figs. 14, 15, 17-19; Fig. 7-41, -42, Distacodus sp. B Sando, 1958 (p. 840, P1.2, fig. 22). -44-46.) Non Acodus oneotensis? Furnish. (Muller 1964, pp. Pahodus(?) variabilis Furnish. (Abaimova 1975, pp. 95,96, PI. 13, figs. 1-8.) 92, 93, P1. 7, figs. 12, 16; Fig. 8-2, -3.) ?Acodus sp. Miiller, 1964 (p. 96, P1. 212, figs. a , b, Remarks g). The elements recovered in this study are a completely Scandodus rectus Lindstrom. (Muller 1964, p. 98, P1. 12, figs. 1, 6, 10.) intergradational series of simple cone-like elements to Non Paltodus variabilis Furnish. (Lee 1970, p. 33 1, which a number of form species names have been applied in the older literature. Symmetrical tricostate P1. 7, fig. 31). Hypotypes GSC 62096 (2-09), 62099 (2-12).

-

-

PLATE3

FIGS.1,2,4-6,8- 10. Juanognathus? sp. B: (1) distacodiform (subsymmetrical) element, GSC 62060, x 125;(2,lO) lateral and surface microsculpture views, distacodiform (subsymmetrical) element, GSC 62061, X 135 and X 735, respectively; (4,s) lateral views showing slight asymmetry of subsymmetrical element due to higher (4) and lower (5) course of lateral costae on opposite sides of base, GSC 62062, X 70; (6) outer lateral view of acodiform (asymmetrical) element, GSC 62063, x 95; (8,9) outer and inner lateral views of acodiform element, GSC 62064, x 105. FIG. 3. Utahconus? bassleri? (Furnish), GSC 62098, x 65. FIGS.7, 12. Distacodus sp. A s.f., GSC 62043 and GSC 62042, X 70 and X 40, respectively. FIG. 11. Cordylodus angulatus Pander s f . , GSC 62038, x 60. Sample 2-03. FIGS.13, 16. Juanog~thus?sp. A: (13) postero-lateral view of long-based distacodiform element, GSC 62089, x 90; (16) postero-lateral view of distacodiform element, GSC 62094, X 130. FIGS.14, 15, 17-21. Utahconus? bassleri (Furnish): (14) short-based acontiodiform element, GSC 62090, x 100; (15) short-based acontiodiformelement, GSC 62091, X 95; (17) long-based, tricostate acodiform element, GSC 62088, x 85; (18) long-based, tricostate acodiform element with low secondary costa between anterior and postero-lateral costa, GSC 62092, x 150; (19,20) lateral and surface microsculpture views of scolopodiform element, GSC 62095, X 110 and X 570, respectively; (21) short-based, tricostate acodiform element, GSC 62093, X 120.

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elements with weakly to strongly developed anterolateral costae and a more broadly rounded posterior surface are Paltodus bassleri s.f. Similar elements with sharp posterior and antero-lateral costae (pl. 3, fig. 14) are also present. Asymmetrical tricostate elements in which one of the antero-lateral costae is lateral and the posterior surface has shifted to a postero-lateral position represent P . variabilis s.f. The latter type of element with sharp costae and deep sulcae is Acodus oneotensis s.f. Paltodus variabilis s.f. elements grade into Oistodus? triangularis s. f. with the obsolescence of the postero-lateral sulcus and the restriction of the anterolateral sulcus to the base of the element. A second symmetrical variant is a scolopodiform element with antero-lateral and postero-lateral costae separated by sulcae; this type of element is simply a symmetrical tricostate element with a posterior sulcus. Scolopodiform elements (Pl. 1, fig. 18) are superficially identical to Scolopodus quadraplicatus Branson and Mehl s.f. However, type specimens of the latter form species have white matter restricted to the axial portion of the cusp (Branson and Mehl1933) and do not have the completely albid cusps of Utahconus? bassleri elements. Scolopodiform elements of U.? bassleri from the Cape Clay Formation represent a variant of Scolopodus sulcatus s.f., an element that is also considered to be part of multielement U.? bassleri.

triangularis s .f. were associated in one apparatus (Sweet and Bergstrom 1972;Lindstrtim in Zeigler 1977). Lindstrom (in Ziegler 1977, pp. 429-431) also proposed that an oistodiform element variously identified as Oistodus inclinatus Branson and Mehl s.f. sensu Furnish (1938), 0 . inclinatus Pander s.f. sensu Druce and Jones (1971), and 0 . sp. s.f. Ethington and Clark (1971) was associated with P . bassleri s.f. However, current work suggests that an oistodiform element is not associated with P. bassleri s.f. and its symmetry variants. 0 . inclinatus s.f. sensu Furnish is part of a Scolopdus-like apparatus (Landing, in preparation), whereas the latter two oistodiforms are associated in a prioniodiform-like apparatus with Acodus oneotensis s.f. sensu Miiller (1973).

Variation In addition to variation in the number and strength of of the costae and in of Utahconus? bassleri differ in curvature. Elements grade from recurved? to erect, to proclined.

HYP~WP~~ Acontiodiform elements GSC 62070 (2-09), 62071 (1-06), 62077 (1-06), 62078 (2-07), 62090 (1-07), 62091 (1-09); acodiform elements GSC 62049 (2-09), 62079 -06), 62080 ( 6208 ( 62082

Generic assignment Miller (1980) defined Utahconus as a bielemental apparatus consisting of albid simple cones with one lateral costa or a lateral plus an antero-lateral costa. It is significant that the bicostate elements also include symmetrical variants (Miller 1980, p. 35) because this means that most of the elemental variants, with the exception of the scolopodiform element, are present in both U . utahensis (Miller) and U.? bassleri. The apparatuses in both species comprise albid and finely longitudinally striated elements (Landing 1979).

(1-071, 62083 (1-061, 62084 (2-03), 62088 (1-09), 62069 (2- 13), 62092 (1-07), 62093 (1-07); scolopodiform GSC 62095 (2-06).

Discussion The Cape Clay Formation collections, as well as Utahconus? bassleri? (Furnish) collections from the lower part of the Garden City P1. 3, fig. 3; Fig. 3-9 Formation, Utah-Idaho (Landing 1981, in preparation), support the suggestion that Acodus oneotensis s.f., Description Large-based, laterally compressed element with Paltodus bassleri s.f., P . variabilis s.f., and O.? PLATE4

FIGS.1-6, 8,9?, lo?. Juanognathus? sp. A: (1, 3) postero-lateral and lateral views, distacodiform element, GSC 62053, x 105; (2,4) surface microsculpture and inner lateral views, acodiform element, GSC 62057, X 1000and X 160, respectively; (5) outer lateral view, acodiform element, GSC 62059, x 85; (6) inner lateral view of acodiform element, GSC 62056, x 115; (8) lateral view distacodiform element, GSC 62054, x 90; (9?) postero-lateral view, modified acodiform element with posterior, two postero-lateral, and anterolateral costae, GSC 62058, x 85; (lo?) oblique lateral view of long-baseddistacodiformelement, GSC 62055, X 145. FIGS.7, 11- 14, 16, 18-21. "Acontiodus" iowensis Furnish s.f.: (7, 11) lateral and posterior views, GSC 62034, x 75, of element with bifid posterior costa resembling A. staufferi s f . , sample 2-12; (12, 13) elements with weakly defined costae (= Oneotodus erectus Druce and Jones s.f.), GSC 62072, x 90, and GSC 62073, x 105; (14, 19) posterior view and surface microsculpture, GSC 62033, x 90 and x 480, respectively, sample 2-12; (16,20) lateral and posterior views, GSC 62032, x 65, sample 2-03; (18, 21) lateral and posterior views, GSC 62035, X 60, of element resembling A. staufferi s.f., sample 2-15. FIG. 15. Utahconus? bassleri (Furnish). Unicostate acodiform element, GSC 62049, x 55. FIG. 17. Drepanodus sp. B. s.f., GSC 62048, X 105.


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rounded anterior and posterior margins and lateral costa on albid, blunt, proclined cusp. Basal cavity located in medial portion of element.

Remarks The specimen may be simply an aberrant acodiform element of multielement Utahconus? bassleri.

Hypotype GSC 62098 (1-06). Genus Ulrichodina Furnish, 1938

Type species Ulrichodinaprima Furnish, 1938 s.f. (= Acontiodus abnormalis Branson and Mehl, 1933 s.f.). Ulrichodina? sp. s. f. P1. 2, figs. 3, 4, 9; Fig. 3-29, -34 Description Strongly proclined, albid elements with shallow basal cavity with axially to anteriorly located basal tip. Broad, low antero-lateral costae on base extend onto lower portion of cusp; cusp circular in cross section distally. Anterior margin of oral edge between the antero-lateral costae extends a short distance below the plane of the oral margin and may or may not be depressed.

Discussion Furnish's (1938) form species of Ulrichodina are hyaline elements with an albid growth axis. The affinity of the completely albid elements from the Cape Clay Formation with Ulrichodina s. f. lies in the presence of an ulrichodinan " n o t c h on the antero-basal edge of some of the elements.

Hypotypes GSC 62074-62076 from 2-12.

Acknowledgements Sincere thanks are extended to D. M. Carson and F. van Soeren (University of Waterloo) and to R. Thorsteinsson and U. Mayr (Institute of Sedimentary and Petroleum Geology) for their help in field work and Arctic logistics. J. Martin and M. Maziarz kindly assisted with the photography and drafting, respectively. C. R. Barnes gratefully acknowledges financial aid for this project from the Geological Survey of Canada and the Natural Sciences and Engineering Research Council of Canada. ABAIMOVA, G. P. 1975. Ranneordovikskie konodonty srednego techeniya r. Leny. Trudy Sibirskogo Geofiziki i Mineralogii, Syrya (SNIGGIMS),Novosibirsk, 207. 129p. BARNES, C. R. 1974. Ordovician conodont biostratigraphy of the Canadian Arctic. In Geology of the Canadian Arctic. Edited by J. D. Aitken and D. J. Glass. Geological

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