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Ameghiniana

versión impresa ISSN 0002-7014

Ameghiniana vol.46 no.2 Buenos Aires abr./jun. 2009

 

ARTÍCULOS ORIGINALES

Conodont fauna of the Machari Formation (Middle and Upper Cambrian), Yeongweol area, Gangweon Province, Korea

Byung-Su Lee1, Yong Il Lee2, James F. Miller3, and Heon Jeong4

1Department of Earth Science Education, Chonbuk National University, Jeonju 561-756, Korea <geodbslee@hanmail.net>
2School of Earth and Environmental Sciences, Seoul National University, 151-742, Korea <lee2602@plaza.snu.ac.kr>
3Department of Geography, Geology, and Planning, Missouri State University, Springfield, Missouri 65897, USA. <JimMiller@MissouriState.edu>

4Korea National Oil Corporation, 1588-14 Gwanyang-dong, Dong-gu, Anyang 431-711, Korea <jeongheon@knoc.co.kr>

Abstract. A diverse conodont fauna from the Machari Formation in the Yeongweol area of Gangweon (formerly Kangweon) Province, Korea, includes protoconodonts, paraconodonts, and euconodonts. Protoconodonts (assigned to Phylum Chaetognatha Leuckart and to Order Protoconodontida Landing) include Gapparodus Abaimova, Gumella Müller and Hinz, Hertzina Müller, and Phakelodus Miller. Paraconodonts (assigned to Phylum Chordata Bateson, to Superclass Conodonta Pander, and to Class Paraconodontida Müller) include species of Furnishina Müller, Muellerodus Miller, Proacodus Müller, Proacontiodus An, Prooneotodus Müller and Nogami, Prosagittodontus Müller and Nogami, and Westergaardodina Müller. Euconodonts (assigned to Phylum Chordata, to Superclass Conodonta Pander, and to Class Conodonti Branson) include species of Cambrooistodus Miller, Coelocerodontus Ethington, Granatodontus Chen and Gong, Proconodontus Miller, and Teridontus Miller. Upper Middle Cambrian occurrences of Coelocerodontus and Granatodontus are some of the oldest occurrences of euconodonts. Seventeen species referable to eight genera are reported for the first time from the Middle to Upper Cambrian of Korea. These include the protoconodonts Gapparodus n. sp. A and Gumella cuneata Müller and Hinz and the paraconodonts Furnishina bicarinata Müller, F. curvata Müller and Hinz, F. gossmannae Müller and Hinz, F. ovata Müller and Hinz, F. pernica An, F. polonica Szaniawski, F. tortilis (Müller), F. vasmerae Müller and Hinz, Muellerodus? erectus (Xiang in An et al.), Prosagittodontus minimus Müller and Hinz, Westergaardodina nogamii Müller and Hinz, and W. quadrata An. Euconodonts recovered for the first time from the Machari Formation include Coelocerodontus bicostatus van Wamel, Granatodontus ani (Wang), and G. hwajeolensis (Lee and Lee). These taxa are illustrated and correlated herein with the equivalent local and global trilobite and conodont zonal schemes.

Resumen. Fauna de Conodontes de la Formación Macharí (Cámbrico Medio y Superior), área de Yeongweol, provincia de Gangeweon, Corea. La formación Machari en el área Yeongweol de la provincia de Gangweon, Corea, contiene una fauna diversa de protoconodontes, paraconodontes y euconodontes. Los protoconodontes (correspondientes al filo Chaetognatha Leuckart y al orden Protoconodontida Landing) incluyen Gapparodus Abaimova, Gumella Müller y Hinz, Hertzina Müller y Phakelodus Miller. Paraconodontes (correspondientes al filo Chordata Bateson, a la superclase Conodonta Pander, y a la clase Paraconodontida Müller) incluyen las especies Furnishina Müller, Muellerodus Miller, Proacodus Müller, Proacontiodus An, Prooneotodus Müller y Nogami, Prosagittodontus Müller y Nogami, y Westergaardodina Müller. Euconodontes (correspondientes al filo Chordata, la superclase Conodonta Pander, y a la clase Conodonti Branson) incluyen las especies Cambrooistodus Miller, Coelocerodontus Ethington, Granatodontus Chen y Gong, Proconodontus Miller, y Teridontus Miller. La presencia de Coelocerodontus y Granatodontus en el Cámbrico Medio corresponde a una de las mas antiguas occurrencias de euconodontes. Diecisiete especies pertenecientes a ocho géneros se reportan aquí por primera vez para el Cámbrico Medio y Cámbrico Superior de Corea. Estos incluyen los protoconodontes Gapparodus n. sp. A y Gumella cuneata Müller y Hinz, y los paraconodontes Furnishina bicarinata Müller, F. curvata Müller y Hinz, F. gossmannae Müller y Hinz, F. ovata Müller y Hinz, F. pernica An, F. polonica Szaniawski, F. tortilis (Müller), F. vasmerae Müller y Hinz, Muellerodus? erectus (Xiang en An et al.), Prosagittodontus minimus Müller y Hinz, Westergaardodina nogamii Müller y Hinz, y W. quadrata An. Euconodontes encontrados por vez primera en la Formación Machari incluyen Coelocerodontus bicostatus van Wamel, Granatodontus ani (Wang), and G. hwajeolensis (Lee and Lee). Se anexa su ilustración y su correlación con los esquemas zonales de trilobites y conodontes a escala local y global.

Key words. Conodonts; Taxonomy; Biostratigraphy; Middle Cambrian; Upper Cambrian; Machari Formation; Korea.

Palabras clave. Conodontes; Taxonomía; Bioestratigrafía; Cámbrico Medio; Cámbrico Superior; Formación Machari; Corea.

Introduction

The Machari Formation in Korea contains a diverse fauna of Middle to Upper Cambrian conodonts. The informal names of four fossil groups include the suffix "-conodonts," namely, euconodonts (Bengtson, 1976), paraconodonts (Müller, 1962), protoconodonts (Bengtson, 1976), and pseudoconodonts (Landing, 1995). Euconodont taxa were described first by Pander (1856), and the Machari Formation has yielded the euconodonts Cambrooistodus Miller, 1980, Coelocerodontus Ethington, 1959, Granatodontus Chen and Gong, 1986, Proconodontus Miller, 1969, and Teridontus Miller, 1980. Paraconodont taxa were described first by Müller (1959), and the Machari Formation has yielded the paraconodont genera Furnishina Müller, 1959, Muellerodus Miller, 1980, Proacodus Müller, 1959, Proacontiodus An, 1982, Prooneotodus Müller and Nogami, 1971, Prosagittodontus Müller and Nogami, 1971, and Westergaardodina Müller, 1959. Paraconodonts and euconodonts are considered to be primitive representatives of the Phylum Chordata Bateson, 1886, and they are probably vertebrates (Sweet and Donoghue, 2001). Protoconodonts are considered to be unrelated to paraconodonts and euconodonts, and Szaniawski (1982, 2002) and Sweet and Donoghue (2001) assign protoconodonts to the Phylum Chaetognatha Leuckart, 1854, commonly called arrow worms. The Machari Formation has yielded the protoconodont taxa Gapparodus Abaimova, 1978, Gumella Müller and Hinz, 1991, Hertzina Müller, 1959, and Phakelodus Miller, 1980.
Pseudoconodonts are latest Proterozoic to Early Cambrian phosphatic problematica that include Rhombocorniculum cancellatum Cobbold, 1921 and Protohertzina anabarica Missarzhevsky, 1977 (Landing, 1995); these taxa are unrelated to the other three groups of "-conodonts" and do not occur in the Machari Formation.
Bengtson's (1983) study of early conodonts and Landing's (1984) study of the histology and taxonomy of lapworthellids showed that these groups are not related to each other despite a grossly similar size and shape. Landing (1977, 1984) and Müller and Hinz (1991, 1998) revised the taxonomy and studied the internal structures of protoconodont and paraconodont elements. Their reports represent major advances in the taxonomy of Cambrian conodonts, but the details of the histological relationships among pseudoconodonts, protoconodonts, paraconodonts, and primitive euconodonts are incompletely known. Paraconodont and protoconodont faunas described prior to the report of Landing (1984) and Müller and Hinz (1991) may require reevaluation following the taxonomic revisions of those authors.
Conodonts are used extensively in Paleozoic and Triassic strata as biostratigraphic tools, and uppermost Cambrian to Triassic conodont zonal frameworks are based on euconodonts. The oldest conodont zones that have been recognized widely are based primarily on a succession of species of the primitive euconodont genus Proconodontus, namely Proconodontus tenuiserratus Miller, 1980, P. posterocostatus Miller, 1980, and P. muelleri Miller, 1969. Zones based on these species are recognizable in many parts of North America (Fåhraeus and Nowlan, 1978; Miller, 1980, 1988, 1992; Landing et al., 1980; Miller et al., 1982; Taylor et al., 1991; Runkel et al., 1999, 2007; Myrow et al., 2003) and in China (Chen et al., 1988; Dong et al., 2004). These species are also known in Kazakhstan (Dubinina, 1998, 2001) and Sweden (Szaniawski and Bengtson, 1998), and in
Australia (Shergold and Nicoll, 1992), where part of the Upper Cambrian conodont zonation is based on species of the primitive euconodont Hispidodontus Nicoll and Shergold, 1991, which has not been found in other areas.
Cambrian paraconodonts and protoconodonts may have less biostratigraphic utility than euconodonts. Some Middle Cambrian and lower Upper Cambrian conodont zones are based on paraconodont and protoconodont elements (An, 1982; Chen and Gong, 1986; Lee et al., 1991; Mei, 1993; Dong, 1999; Dong et al., 1999; Dong and Bergström, 2001; Dubinina, 2001; Dong et al., 2004; Qi et al., 2006; Bagnoli et al., 2008). These studies are mostly based on faunas from various parts of Asia. It cannot be determined if the regional zones proposed in those reports will have global utility until cosmopolitan faunas are found and until there is reevaluation of older reports of primitive conodonts. Some protoconodont and paraconodont taxa are known to have long stratigraphic ranges, and some may prove to be endemic; both situations pose potential limitations for their use in biostratigraphy. More occurrences of these taxa from other paleogeographic areas are needed. Eventually, evaluation of the stratigraphic and geographic distribution of protoconodont and paraconodont taxa may reveal consistencies that can be incorporated into a broadly applicable zonation for the part of the Cambrian that is below the interval containing the euconodont index genus Proconodontus.
In order to improve knowledge of the taxonomic diversity and the stratigraphic and paleogeographic distribution of Middle to Upper Cambrian conodont faunas, we document herein a diverse fauna of protoconodont, paraconodont, and euconodont taxa recovered from the Machari Formation in the Yeongweol area of Korea. Most taxa are paraconodonts, and Furnishina is the most common and diverse genus. Müller and Hinz (1991) named many of the taxa reported herein. The Machari Formation includes conodonts from two general stratigraphic intervals. The lower interval is characterized by many protoconodont and paraconodont elements as well as the primitive euconodont genera Coelocerodontus, Granatodontus, and Teridontus. The higher interval of strata contains many protoconodont and paraconodont elements as well as the primitive euconodont genera Cambrooistodus, Coelocerodontus, Proconodontus, and Teridontus.
We correlate these Korean conodont faunas with coeval trilobite and conodont biostratigraphic zones in other parts of the world. Conodont elements were recovered previously from the Upper Cambrian of Korea (Lee, 1975; Lee, 1988; Lee and Lee, 1988; Lee, 1989a, 1989b, 1990).

Stratigraphy of the Machari Formation

The Joseon (formerly Choseon) Supergroup in the Yeongweol area (figure 1) comprises five lithostratigraphic units, namely the Sambangsan, Machari, Wagok (formerly Wagog), Mungok (formerly Mungog), and Yeongheung formations, in ascending order (figure 2). The lower three are Cambrian and the higher two are Ordovician. The Machari Formation conformably overlies the Sambangsan Formation and is conformably overlain by the Wagok Formation. The base of the Machari Formation is recognized by the lowest occurrence of thick-bedded bioclastic grainstones to packstones above light brown sandstones of the Sambangsan Formation. The top of the Machari Formation is defined by the base of the Wagok Formation and corresponds with the change to massive dolostone above the uppermost occurrence of thin-bedded dolostone with shale interlayers. The Machari Formation is approximately 300 m thick in the study area.


Figure 1. Map showing the location of measured sections of the Machari Formation in the Yeongweol area, Korea / mapa mostrando la localización de las secciones estudiadas en el área de Yeongweol, Corea.


Figure 2. Summary of Cambrian-Ordovician stratigraphy of the Yeongweol area, Korea (Kobayashi, 1961, 1962, 1966; Lee et al., 1991; Lee, et al., 1997; Lee and Lee, 1999). Traditional British Ordovician series names are used for general reference, but only Cambrian strata are discussed in this report / resumen de la estratigrafía del Cámbrico-Ordovícico del área de Yeongweol, Corea (Kobayashi, 1961, 1962, 1966; Lee et al., 1991; Lee, et al., 1997; Lee and Lee, 1999). Los nombres británicos tradicionales del Ordovícico son usados como referencia general pero sólo es discutida en este trabajo la estratigrafía del Cámbrico.

The Machari Formation (Yosimura, 1940) crops out as a broad belt across the south slope of Mt. Sambang (Sambangsan on figure 1) and extends farther south as north-south-trending narrow belts. This formation consists mainly of bioclastic grainstone to packstone, dark gray to black laminated shale, and dolomitic limestone and ribbon limestone; these strata display a distinctive banded structure (figure 3). Reedman and Um (1975) and Lee (1995) concluded that the Machari Formation was deposited in a deepwater environment ranging from deep shelf to pelagic basin, whereas Chung and Lee (1992) suggested that the formation was deposited on the slope of a carbonate platform, and sediments were introduced episodically by tubidity currents and debris flows.


Figure 3. Lithology, sample horizons, and some trilobite zones for measured sections. Solid bars to left of sample numbers indicate samples that produced conodonts; open bars indicate unproductive samples. Most strata shown are assigned to the Machari Formation; contact with underlying Sambangsan Formation is at base of Eodungol section, and contact with overlying Wagok Formation is at top of Deokwoo section. Only lower part of Eodungol section was sampled for conodonts, but the complete section is ~ 98 m thick. Middle Cambrian trilobites (Kootenia, Olenoides, Peronopsis, Tonkinella) occur in intervals 0-5 m and 62-65 m. Basal Upper Cambrian trilobite Glyptagnostus reticulatus occurs in interval 95-97 m. See figure 2 for succession of trilobite zones. Thrust faults occur at 49 m and 62 m /litología, horizontes muestreados y algunas zonas de trilobites de las secciones estudiadas. Barras sólidas a la izquierda de los números de muestra indican las muestras que proveyeron conodontes; barras abiertas indican las muestras no productivas. La mayoría de los estratos mostrados son asignados a la Formación Machari; el contacto con la subyacente Sambangsan Formation está en la base de la sección Eodungol y el contacto con la suprayacente Formación Wagok está al tope de la sección Deokwoo. Solamente la parte inferior de la sección Eodungol fue muestreada para conodontes, pero la sección completa posee aproximadamente 98 m de espesor. Trilobites del Cámbrico Medio (Kootenia, Olenoides, Peronopsis, Tonkinella) aparecen en los intervalos 0-5 m y 62-65 m. El trilobite del Cámbrico Superior basal Glyptagnostus reticulatus se encuentra en el intervalo 95-95 m. Ver figura 2 para la sucesión de zonas de trilobites. Un corrimiento ocurre a los 49 m y otro a los 62 m.

Some carbonate lithologies in the Machari Formation are slope deposits, such as limestone breccia, shell beds, and slump features. However, these lithofacies are very minor in volume, and the abundance of dark-colored lime mudstone and laminated black shale with thin, uniform stratification is interpreted to represent a hemipelagic sedimentation in a deep-water setting by suspension settling (Lee, 1995). Most of the Upper Cambrian trilobite specimens studied by Lee (1995), Choi and Lee (1995) and Choi et al. (2004, 2008) are disarticulated. Occasionally, some specimens preserved in the laminated black shale and shale-parted carbonate lithofacies are articulated. The presence of articulated exoskeletons, lack of obvious size sorting or fragmentation of disarticulated sclerites, and association with dark gray lime mudstone and black shale is interpreted to indicate that the trilobite faunas represent in situ basinal assemblages that lived at or near where their remains were buried. Lithologic features and the abundance of agnostoid trilobites suggest that the Machari Formation was deposited in a deep-water environment ranging from deep shelf to pelagic basin (Lee, 1995; Choi and Lee, 1995; Choi et al., 2004, 2008).
The boundary between the Middle and Upper Cambrian is now placed at the base of the Glyptagnostus reticulatus Trilobite Zone (Peng et al., 2004). The Machari Formation has been dated as late Middle to middle Late Cambrian, based primarily on trilobite assemblages reported by Kobayashi (1961, 1962, 1966), who established five zones: Olenoides, Tonkinella, Eochuangia, Komaspis-Koptura-Iwayaspis, and Olenus-Glypagnostus. This zonation was refined by Lee (1995) and Lee et al. (1997), who erected nine trilobite zones: Tonkinella, Glypagnostus stolidotus, Glypagnostus reticulatus, Proceratopyge tenue, Hancrania brevilimbata, Eugonocare longifrons, Eochuangia hana, Agnostodes orientalis, and Pseudoyuepingia asaphoides, in ascending order (figures 2, 4). Some of these trilobite zones are recognized in South China (Lu and Lin, 1989). Hong et al. (2000) also discussed trilobites from the Machari Formation.



Figure 4. Correlation chart of Upper Cambrian conodont and trilobite zones in Korea with those of Europe, western USA, and North and South China / cuadro de correlación de las zonas de conodontes y trilobites cámbricos de Corea con aquellas de Europa, Estados Unidos occidental y norte y sur de China.

Lee (1975) described some paraconodont elements from two exposures of the Machari Formationin the Yeongweol area, and he correlated these faunas with the Upper Cambrian of other areas. Later, Lee et al. (1991) studied the conodont fauna systematically and erected two zones, namely the lower Gapparodus bisulcatus-Westergaardodina matsushitai-W. moessebergensis Assemblage Zone and the upper Proconodontus muelleri-Cambrooistodus cambricus Assemblage Zone.

Measured sections and sample collection

Rock samples for conodont elements were collected from four sections of the Machari Formation in the northwestern Yeongweol area of Gangweon Province (figures 1, 3). The Eodungol section (~ 97 m thick) is about 1.5 km southeast of the summit of Mt. Sambang and exposes the top of the Sambangsan Formation. The base of the Machari Formation is noncalcareous laminated black shale overlain by thick dolomitic, bioclastic grainstone to packstone beds. Overlying strata are mainly dark gray laminated shale with intercalated thin-bedded limestone. Of sixteen samples, one yielded a variety of protoconodont, paraconodont, and euconodont elements. The Maji section (44 m thick) is at Maji village in the Pyeongchang area. The lower part of the section is covered, and exposure begins ~ 20 m above the base of the Machari Formation. Most strata are limestone with thin shale partings, but the lithology changes to massive limestone near the top. Only one of four samples yielded abundant protoconodont, paracon-odont, and euconodont elements.
The other two sections are located farther south (figure 1). The Deokwoo section (~ 180 m thick) is about 2 km south of Machari village and has two covered intervals (figure 3). The lower part of this section is mostly black shales with some thin limestones with thin shale partings; the upper part is massive shale-parted or banded limestone. Of ten samples, four yielded abundant conodont elements. The Bundeokchi section (43 m thick) is about 1 km south of the Deokwoo section and includes the highest strata of the four sections. Limestones with shale partings in the lower part of the section grade upward in-to thin-bedded limestone and dolostone. Of thirteen samples, two yielded abundant conodont elements.
Lithologies from which conodonts were extracted for this study are thin-bedded dolomitic limestone (with or without shale layers), shale-parted lime-stone, and light gray massive limestone. These lithologies were not deposited by turbidity currents and debris flows, thus negating the possibility of redeposition of conodonts from shallow depositional settings.

Processing methods and conodont faunas

Each of the 43 conodont samples from the Machari Formation had a mass of 1 to 3 kg and was dissaggregated in acetic acid. Eight of the 43 samples yielded a total of 1,305 conodont elements. The preservation is relatively good, but some specimens are corroded. The conodont elements are referred to 51 species referable to 16 genera (table 1). The two most productive samples are Bd8 (234 elements) and Bd9 (211 elements), and the dominant species are the paraconodonts Furnishina furnishi Müller, 1959 and Prooneotodus gallatini (Müller, 1959) and the protoconodonts Phakelodus tenuis (Müller, 1959) and P. elongatus (Zhang in An et al., 1983). These two samples yielded more than 34 percent of the total conodont elements.

Table 1. Numerical distribution of conodont taxa from the Machari Formation, Yeongweol area, Korea . One asterisk * indicates euconodonts, two asterisks ** indicate protoconodonts. Ohters are paraconodonts / distribución numérica de taxones de conodontes de la Formación Macharí, área de Yeongweol, Corea. Un asterisco * indica euconodontes, dos asteriscos ** indican protoconodontes. Otros son paraconodontes.

These numbers of productive samples and recovered elements are comparable to data from other reports of conodonts of similar age. Bagnoli et al. (2008) studied upper Middle Cambrian conodonts from the type section for the base of the Gushanian Stage in Hunan, South China. They collected 86 samples having a mass of 430 kg; 13 productive samples produced 236 conodont elements. Qi et al. (2006) studied upper Middle and lower Upper Cambrian conodonts from the type section for the base of the Furongian Series and the Paibian Stage in Hunan, South China. They collected 220 samples having a mass of 1000 kg; 26 productive samples produced 561 conodont elements.
Twenty-three species of ten genera were recovered for the first time from the Machari Formation, although some other species are known from other strata in Korea (Lee and Lee, 1999). These include the protoconodonts Gapparodus n. sp. A, Gumella cuneata Müller and Hinz, 1991, Hertzina americana Müller, 1959, and Hertzina triquetra Chen and Gong, 1986, and the paraconodonts Furnishina bicarinata Müller, 1959, F. curvata Müller and Hinz, 1991, F. gossmannae Müller and Hinz, 1991, F. longibasis Bednarczyk, 1979, F. ovata Müller and Hinz, 1991, F. pernica An, 1982, F. polonica Szaniawski, 1971, F. primitiva Müller, 1959, F. tortilis (Müller, 1959), F. vasmerae Müller and Hinz, 1991, Muellerodus pomeranensis (Szaniawski, 1971), Prooneotodus terashimai (Nogami, 1967), Prosagittodontus dahlmani (Müller, 1959), P. dunderbergiae (Müller, 1959), P. minimus Müller and Hinz, 1991, Westergaardodina nogamii Müller and Hinz, 1991, and W. quadrata An, 1982 (see figures 4, 5). Euconodonts recovered for the first time from the Machari Formation are Coelocerodontus bicostatus van Wamel, 1974, Granatodontus ani (Wang, 1985), and Granatodontus hwajeolensis (Lee and Lee, 1988).


Figure 5. Ranges and biozonal assignment of conodont taxa recovered from the Machari Formation, Yeongweol area, Korea / rangos y asignación bioestratigráfica de los taxones de conodontes recuperados de la Formación Macharí, área de Yeongweol, Corea.

Distribution and age of Machari conodont taxa

Intra- and interspecific variation in morphology, occurrence, and stratigraphic range of Middle Cambrian to lower Upper Cambrian paraconodonts are not fully understood at this time, although major paraconodont lineages are relatively well defined for the upper half of the Upper Cambrian (Dong, 1997). For these reasons, some stratigraphic intervals are correlated primarily on trilobite biostratigraphy (table 1, figures 3 and 4). Figure 3 shows in the Eodungol section the stratigraphic position of two trilobite collections that contain Kootenia Walcott, 1889, Olenoides Meek, 1877, Peronopsis Hawle and Corda, 1847, Tonkinella Mansuy, 1916, and other trilobites; these collections are assigned to the upper Middle Cambrian Tonkinella Zone. One higher collection contains the trilobite Glyptagnostus reticulatus Angelin, 1851 and is assigned to the basal Upper Cambrian G. reticulatus Zone. These collections demonstrate that the lower part of the Machari Formation is Middle Cambrian and the middle and upper parts are Upper Cambrian. Conodonts from samples Ed14 and Mj7 (figure 3) are from the Middle Cambrian part of the Machari Formation, and conodonts from other collections are from the Upper Cambrian part.

Protoconodonts

Only four genera of protoconodonts (chaetognaths) occur in the Machari Formation. Gapparodus bisulcatus (Müller, 1959) (figures 6.1,11,15,22) was recovered only from sample Ed14, 22.55 m above the base of the formation. This sample is part of the Tonkinella Trilobite Zone (upper Middle Cambrian; figures 2, 3). Müller and Hinz (1991) recovered Gumella cuneata Müller and Hinz, 1991 from strata roughly equivalent to this horizon in Baltica. Phakelodus tenuis (Müller, 1959) (figures 6.12,14) and P. elongatus Zhang in An et al., 1983 (figures 6.9,10) are cosmopolitan Middle Cambrian to Early Ordovician protoconodonts that occur through the Machari Formation, the Sesong Slate (Lee, 1990), and the Hwajeol Formation (Lee and Lee, 1988). Gapparodus bisulcatus, Gumella cuneata, and Phakelodus tenuis occur in the upper Middle Cambrian and lowermost Upper Cambrian parts of the Huaqiao Formation in Hunan Province, South China (Qi et al., 2006; Bagnoli et al., 2008).


Figure 6. Scanning electron micrographs of conodonts from the Machari Formation, Yeongweol area, Korea. All images are lateral views except as noted below. See figure 3 for sample numbers / Microfotografías de barrido electrónico de conodontes de la Formación Macharí, área de Yeongweol, Corea. Todas las imágenes son vistas laterales excepto las indicadas debajo. Véase figura 3 para números de muestra. 1, 11, 15, 22, Gapparodus bisulcatus (SNUG 0005-0008), all from /todas de Ed14, 1 is a phosphatic internal mold /es un molde fosfático interno, X112, X58, X112, X58, respectively /respectivamente; 2, 4, 7, Furnishina primitiva, 2, (SNUG 0019), Bd8, X179, 4, 7 are posterolateral views / vistas posterolaterales (SNUG 0017, 0018), Mj7, Bd8, X83, X126, respectively / respectivamente; 3, Furnishina longibasis (SNUG 0020), Ed14, X146; 5, Furnishina bicarinata (SNUG 0021), posterior view / vista posterior, Bd9, X83; 6, Furnishina vasmerae (SNUG 0016), Bd9, X146; 8, Muellerodus? erectus (SNUG 0039), Dw7, X194; 9, 10, Phakelodus elongatus (SNUG 0003, 0004), both from / ambos de Ed14, X58, X73, respectively / respectivamente; 12, 14, Phakelodus tenuis, 12, (SNUG 0001), Mj7, X97, 14, (SNUG 0002), Ed14, X38; 13, 18, Gapparodus n. sp. A, both from / ambos de Ed14, 13, oblique posterolateral view/ vista posterior oblicua (SNUG 0009), X58, 18, (SNUG 0010), X58; 16, Furnishina gossmannae (SNUG 0022), posterior view / vista posterior, Bd8, X136; 17, Furnishina furnishi (SNUG 0023), posterior view /vista posterior, Bd9, X97; 19-21, Gumella cuneata (SNUG 0011-0013), all are "morphotype beta" of / todos son "morfotipos beta" de Müller and Hinz (1991), all from / todos de Ed14, X53, X53, X58, respectively / respectivamente; 23, Furnishina ovata (SNUG 0024), upper view /vista superior, Mj7, X146.

Hertzina americana (figure 7.20) is also known as a cosmopolitan Middle to Upper Cambrian protoconodont. It occurs in the Irvingella major Trilobite Zone in Nevada (Müller, 1959), the Gushan Formation in Shantung Province (An, 1982; An et al., 1983), the Chuangia or Changshania Trilobite Zone of the Changshan Formation in Shantung Province (An, 1982; An et al., 1983), and in the Eoconodontus notchpeakensis Conodont Zone in the Hwajeol Formation (Lee and Lee, 1988). Hertzina triquetra (figure 8.6) occurs in the upper Upper Cambrian Cordylodus proavus Conodont Zone in Jilin Province, North China (Chen and Gong, 1986).


Figure 7. Scanning electron micrographs of conodonts from the Machari Formation, Yeongweol area, Korea. All images are lateral views except as noted below. See figure 3 for sample numbers / microfotografías de barrido electrónico de conodontes de la Formación Macharí, área de Yeongweol, Corea. Todas las imágenes son vistas laterales excepto las indicadas debajo. Véase figura 3 para números de muestra. 1, Westergaardodina bicuspidata (SNUG 0070), posterior view / vista posterior, Ed14, X117; 2, Teridontus nakamurai (SNUG 0088), Bd8, X73; 3, Proconodontus sp. aff. posterocostatus (SNUG 0076), posterior view / vista posterior, Bd8, X194; 4, Muellerodus? erectus (SNUG 0043), posterolateral view / vista posterolateral, Mj7, X107; 5, Cambrooistodus cambricus (SNUG 0089), Bd9, X117; 6, Unassigned Coniform Element / elemento coniforme no asignado (SNUG 0075), form with a costa on one lateral face / forma con una costa en una cara lateral, Dw9, X97; 7, 9, Proconodontus posterocostatus, 7, (SNUG 0090), Dw7, X107; 9, (SNUG 0091), posterolateral view / vista posterolateral, Bd8, X112; 8, Proconodontus muelleri (SNUG 0080), Bd8, X74; 10, Muellerodus? oelandicus (SNUG 0044), Mj7, X194; 11, Furnishina curvata (SNUG 0036), posterior view / vista posterior, Bd9, X194; 12, 15, Prooneotodus gallatini, 12, (SNUG 0049), Dw7, X146; 15, (SNUG 0092), Bd9, X97; 13, 14, Coelocerodontus kosangolensis, 13, small, flattened tetracostate element / perqueño elemento tretacostulado aplastado (SNUG 0093), Dw7, X156; 14, small, flattened tricostate element / elemento pequeño, tricostulado aplastado (SNUG 0094), Dw7, X146; 16, Furnishina furnishi (SNUG 0038), Dd 9, X146; 17, Furnishina gossmannae (SNUG 0045), posterior view / vista posterior, Bd9, X194; 18, Coelocerodontus bicostatus (SNUG 0083), 'Morphotype alpha' of Müller and Hinz (1991), Mj7, X194; 19, Granatodontus ani (SNUG 0062), posterolateral view, Mj7, X146; 20, Hertzina americana (SNUG 0073), posterolateral view / vista posterolateral, Mj7, X117; 21, Prosagittodontus minimus (SNUG 0054), posterior view / vista posterior, Mj7, X194.


Figure 8. Scanning electron micrographs of conodonts from the Machari Formation, Yeongweol area, Korea. All images are lateral views except as noted below. See figure 3 for sample numbers / microfotografías de barrido electrónico de conodontes de la Formación Macharí, área de Yeongweol, Corea. Todas las imágenes son vistas laterales excepto las indicadas debajo. Véase figura 3 para números de muestra. 1, 13, Furnishina tortilis, 1, (SNUG 0029), posterior view / vista posterior, Bd9, X146; 13, (SNUG 0084), posterior view / vista posterior, Bd9, X87; 2, Granatodontus ani (SNUG 0061), Mj7, X146; 3, Muellerodus pomeranensis (SNUG 0042), Bd9, X146; 4, Furnishina pernica (SNUG 0030), posterior view, Dw13, X97; 5, Furnishina asymmetrica (SNUG 0031), oblique posterolateral view, Bd9, X194; 6, Hertzina triquetra (SNUG 0071), inner lateral view / vista interna lateral, Bd9, X194; 7, Prosagittodontus minimus (SNUG 0051), posterior view, Bd9, X146; 8, Prosagittodontus dunderbergiae (SNUG 0052), posterior view / vista posterior, Dw9, X194; 9, Furnishina gossmannae (SNUG 0032), Bd9, X194; 10, Furnishina furnishi (SNUG 0033), Dw13, X97; 11, Prosagittodontus eureka (SNUG 0053), oblique posterolateral view / vista oblicua posterolateral, Dw9, X194; 12, Furnishina polonica (SNUG 0034), Mj7, X97; 14, Furnishina ovata (SNUG 0035), posterior view / vista posterior, Bd9, X126; 15, Gumella cuneata (SNUG 0085), Ed14, X42; 16, Prooneotodus gallatini (SNUG 0086), Bd9, X97; 17, Westergaardodina moessebergensis (SNUG 0087), posterior view / vista posterior, Ed14, X78; 18, Westergaardodina nogamii (SNUG 0068), posterior view / vista posterior, Bd9, X97; 19, Westergaardodina quadrata (SNUG 0069), posterior view / vista posterior, Ed14, X117.

Paraconodonts

Paraconodonts comprise most of the taxa found in the Machari Formation. Furnishina is the most abundant and diverse genus, and most of the Furnishina elements were recovered from sample Mj7. Of fourteen species of Furnishina recovered, eight were found for the first time in Korea. In terms of global occurrence, Furnishina bicarinata (figure 6.5) ranges throughout the Upper Cambrian. Furnishina longibasis (figure 6.3), F. pernica (figure 8.4), and F. vasmerae (figure 6.6) are confined to the lower Upper Cambrian. Furnishina tortilis (figures 8.1,13) occurs at the top of the Middle Cambrian and ranges into the lower Upper Cambrian in South China (Qi et al., 2006); elsewhere it ranges throughout the Upper Cambrian. Furnishina longibasis was reported from the Upper Cambrian of Poland (Bednarczyk, 1979), the Olenus Trilobite Zone of Sweden (Müller and Hinz, 1991), the Gushan Formation of North China (An et al., 1983), and the lower part of the Upper Cambrian in Hunan Province, South China (Qi et al., 2006). Furnishina longibasis is recorded in samples Ed14, Mj7, Bd8, and Bd9.
Furnishina curvata Müller and Hinz, 1991 (figure 7.11), F. furnishi (figures 6.17, 7.16, 8.10), F. asymmetrica Müller, 1959 (figures 8.5, 9.4) and F. gossmannae (figures 6.16, 7.17, 8.9) are common and occur world-wide in the middle to upper Upper Cambrian, e.g., in the Olenus Trilobite Zone of Sweden (Müller and Hinz, 1991). Furnishina furnishi occurs throughout the Proconodontus Conodont Zone of the Hwajeol Formation of Korea (Lee and Lee, 1988), whereas the species occurs from the uppermost part of the Changxia Formation (Middle Cambrian) to the Fengshan Formation (upper Upper Cambrian) of North China (An et al., 1983). Furnishina ovata (figures 6.23, 8.14) was known previously only from the Protopeltura praecursor Trilobite Zone to the Peltura scarabaeoides Trilobite Zone of Sweden (Müller and Hinz, 1991). The stratigraphic occurrence of this species in Sweden is similar to that of Korea.


Figure 9. Scanning electron micrographs of conodonts from the Machari Formation, Yeongweol area, Korea. All images are lateral views except as noted below. See figure 3 for sample numbers / microfotografías de barrido electrónico de conodontes de la Formación Macharí, área de Yeongweol, Corea. Todas las imágenes son vistas laterales excepto las indicadas debajo. Véase figura 3 para números de muestra. 1, Prooneotodus rotundatus (SNUG 0046), Mj7, X92; 2, Prooneotodus gallatini (SNUG 0047), Bd8, X146; 3, Muellerodus cambricus (SNUG 0041), Mj7, X126; 4, Furnishina asymmetrica (SNUG 0025), posterior view / vista posterior,, Mj7, X136; 5, 9, Furnishina sp., posterolateral view / vista posterolateral, (SNUG 0026), Bd9, X185, 9, posterior view / vista posterior, (SNUG 0027), Bd8, X224; 6, Prosagittodontus dahlmani (SNUG 0050), posterior view, Bd9, X117; 7, Proacodus cf. pulcherus (SNUG 0055), posterior view / vista posterior, Mj7, X126; 8, 13, Proacontiodus palmeri, large, inflated distacodiform elements / elementos distacodiformes grandes, inflados, 8, (SNUG 0056), Bd9, X97; 13, (SNUG 0057), Ed14, X126; 10, Granatodontus hwajeolensis (SNUG 0060), posterolateral view / vista posterolateral, Mj7, X156; 11, Prooneotodus terashimai, (SNUG 0048), Mj7, X107; 12, Muellerodus? erectus (SNUG 0040), Bd9, X126; 14, Westergaardodina moessebergensis (SNUG 0062), posterior view / vista posterior, Ed14, X78; 15, Furnishina triangulata (SNUG 0028), posterior view / vista posterior, Bd9, X165; 16, Westergaardodina quadrata (SNUG 0064), posterior view / vista posterior, Ed14, X63; 17, Westergaardodina sp. (SNUG 0065), posterior view / vista posterior, Ed14, X73.

Furnishina polonica (Fig. 8.12) was recorded originally from the upper Middle Cambrian Agnostus pisiformis Trilobite Zone of Poland (Szaniawski, 1971). Later, this species was reported from strata of similar or slightly younger age in California (Miller and Paden, 1976), North China (An, 1982), South China (Qi et al., 2006), Sweden (Müller and Hinz, 1991), and Canada (Hein and Nowlan, 1998). Furnishina pernica and F. triangulata Xiang and Zhang in An et al., 1983 (figure 9.15) were recovered originally from the middle Upper Cambrian Blackwelderia paronai Trilobite Zone of China (An, 1982; An et al., 1983). Furnishina triangulata was recovered from somewhat younger beds (samples Dw13, Dw4, Bd8 and Bd9) in the Machari Formation. Furnishina primitiva (figures 6.2,4,7) has a long range through the Machari Formation (samples Mj7, Dw13, Dw9, Dw7, Bd8, Bd9), and it was known previously from Sweden (Müller, 1959; Müller and Hinz, 1991), Poland (Abaimova and Ergaliev, 1976), China (Wang, 1985; Chen and Gong, 1986; An, 1987), and Korea (Lee and Lee, 1988).
Muellerodus cambricus (Müller, 1959) (figure 9.3) occurs in the lower (sample Mj7) and upper (sample Bd8) parts of the Machari Formation. Muellerodus? oelandicus (Müller, 1959) (figure 7.10) occurs in the lower (sample Mj7) to upper beds (sample Dw4) (table 1, figure 5). Muellerodus pomeranensis (figure 8.3) was recovered in the upper part (sample Bd9) of the Machari Formation. These species were reported from the uppermost Middle Cambrian to the lower to middle Upper Cambrian of Sweden (Müller, 1959; Müller and Hinz, 1991), North and South China (Nogami, 1966; An, 1982; An et al., 1983; Dong, 1993, 1999; Qi et al., 2006), and north Poland (Szaniawski, 1971; Bednarczyk, 1979). In Korea, Muellerodus cambricus, M.? oelandicus, and M. pomeranensis were recovered previously from the lower to middle part of the Hwajeol Formation (Lee et al., 1991; Lee and Lee, 1988). Muellerodus? erectus (Xiang in An et al., 1983) (figures 6.8, 7.4, 9.12) is an endemic species of the middle Upper Cambrian Chengshan Formation of North China (An, 1982; An et al., 1983; Mei, 1993). In this study, M.? erectus was recovered from the lower (sample Mj7) to middle beds (sample Bd9) of the Machari Formation.
Proacontiodus palmeri (Müller, 1959) (Figs. 9.8,13) was recovered from the Elvinia Trilobite Zone in the USA (Müller, 1959), from the Quadraticephalus Trilobite Zone of the Changshan and Fengshan formations of North China (An, 1982; An et al., 1983), from the lower part of the upper member of the Machari Formation (Lee et al., 1991), and from the Proconodontus to Eoconodontus notchpeakensis conodont zones (Lee and Lee, 1988) of Korea.
Prooneotodus gallatini (figures 7.12,15, 8.16, 9.2) and P. rotundatus (Druce and Jones, 1971) (figure 9.1) are longranging species, but Prooneotodus terashimai (figure 9.11) is restricted to the lower half of the Upper Cambrian (Nogami, 1966; An, 1982; An et al., 1983; Lee and Lee, 1988). In this study, Prooneotodus terashimai is known in the lower to upper parts of the Machari Formation (figure 5).
Prosagittodontus dunderbergiae (figure 8.8) occurs in slightly lower beds than P. eureka (Müller, 1959) (figure 8.11) (Nogami, 1966; Müller, 1973; An et al., 1983; An, 1987; Lee and Lee, 1988; Lee et al., 1991; this
paper). Also, these two species occur in the Elvinia Trilobite Zone in the USA (Müller, 1959), in the Changshania Trilobite Zone of North China (An, 1982; An et al., 1983; Mei, 1993), and in the Proconodontus to Cambrooistodus minutus conodont zones of the Hwajeol Formation of Korea (Lee and Lee, 1988). The lowest occurrence of P. dunderbergiae herein is from sample Mj7.
Prosagittodontus dahlmani (figure 9.6) and P. minimus (figures 7.21, 8.7) are common in sample Mj7. The former is a long-ranging species in the Upper Cambrian, but the latter is restricted to the middle to upper Upper Cambrian (Müller and Hinz, 1991; An and Mei, 1994).
Five species of Westergaardodina were recovered from the Machari Formation. Westergaardodina bicuspidata Müller, 1959 (figure 7.1) was recovered from the lower to upper Upper Cambrian of Sweden (Müller and Hinz, 1991), north Poland (Bednarczyk, 1979), Estonia (Mens et al., 1993), western New-foundland (Fortey et al., 1982), New York (Landing, 1977), Argentina (Heredia, 1999), China (Chen and Gong, 1986; Jiang et al., 1986; Dong, 1999; Qi et al., 2006), and Korea (Lee and Lee, 1988; Lee et al., 1991). This species occurs in the lower to middle parts of the Machari Formation.
Westergaardodina moessebergensis Müller, 1959 (figures 8.17, 9.14), W. nogamii (figure 8.18), and W. quadrata (figures 8.19, 9.16) are good index fossils for the upper Middle Cambrian to lower Upper Cambrian. Westergaardodina moessebergensis is known from the Agnostus pisiformis Trilobite Zone and the Olenus Trilobite Zone of Sweden (Szaniawski, 1971; Müller and Hinz, 1991). Westergaardodina moessebergensis was reported also from correlative beds of the upper Middle to lower Upper Cambrian, namely the Chatsworth Limestone of Australia (Jones, 1971), Gushan Formation of North China (Nogami, 1966; An et al., 1983; Mei, 1993), the lower part of the Machari Formation in the Eodungol section (Lee et al., 1991) and the Sesong Slate (Lee, 1990) of Korea. Westergaardodina moessebergensis and W. nogamii oc-cur commonly in upper Middle Cambrian strata in China. However, W. moessebergensis ranges from the Agnostus pisiformis Trilobite Zone to the lowermost part of the Parabolina spinulosa Trilobite Zone in
Estonia (Mens et al., 1993). Westergaardodina nogamii occurs in sample Bd9 with Proconodontus posterocostatus and P. muelleri..
Westergaardodina quadrata was found first in the
Blackwelderia paronai Trilobite Zone of the Gushan Formation (upper Middle Cambrian) of North China (An, 1982; Dong, 1993). Later the species was recovered from the Agnostus pisiformis Trilobite Zone and the Olenus Trilobite Zone of Sweden (Müller and Hinz, 1991), from the Chefu Formation and the Huaqiao Formation (lower Upper Cambrian) of South China (Dong, 1999; Qi et al., 2006), and from the lower part of the Machari Formation in this study.

Euconodonts

Only five euconodont genera occur in the Machari Formation. Coelocerodontus bicostatus (figures 7.18) previously was reported from the upper Middle Cambrian to Ordovician (van Wamel, 1974; Apollonov et al., 1984; Landing, 1984; An, 1987; Dong, 1999; Lee and Lee, 1988; Dong et al., 2004; Qi et al., 2006), and it occurs in the upper Middle Cambrian part of the Machari Formation. Coelocerodontus kosangolensis Lee, Choi, and Lee, 1991 (figures 7.13,14) was recovered from the middle part of the Machari Formation (Lee et al., 1991), and the occurrence of this species herein is roughly equivalent to that of Lee et al. (1991). Both of these species were recovered from the lower Upper Cambrian part of the Machari Formation.
Granatodontus ani (Wang, 1985) (Figs. 7.19, 8.2) previously was known from China, Korea, southern Kazakhstan, and western Canada (see discussion in systematics). This species occurs in the Middle Cambrian part of the Machari Formation (samples Ed14 and Mj7; figure 3). Granatodontus hwajeolensis Lee and Lee, 1988 (figure 9.10) is an endemic species. Both species of Granatodontus occur in sample Mj7, and in general the genus ranges from the upper Middle Cambrian to the middle Upper Cambrian.
Species of Proconodontus and Cambrooistodus cambricus (Miller, 1969) are key elements of Upper Cambrian conodont zones in many parts of the world. Proconodontus posterocostatus (figures 7.7,9; also see figure 7.3) and P. muelleri (figure 7.8) cooccur in two of the youngest samples, namely Bd8 (57.5 m below the top of the formation) and Bd9 (2.5 m below Bd8), and Cambrooistodus cambricus (figure 7.5) occurs in sample Bd9 (figure 3). These two sample horizons belong to the Pseudoyuepingia asaphoides Trilobite Zone of Lee (1995) (figure 2). Teridontus nakamurai (Nogami, 1967) (figure 7.2) is known from China, Korea, Iran, southern Kazakhstan, Siberia, Australia, USA, and Canada (western Newfoundland). Teridontus nakamurai is a long-ranging species in the Upper Cambrian and lowermost Ordovician. In this study, T. nakamurai was recovered from the middle (sample Dw13) to upper beds (sample Bd8) of the Machari Formation.

Biostratigraphic summary

Lee et al. (1991, figure 4) divided the conodont faunal assemblages of the Machari Formation into two conodont zones, namely the lower Gapparodus bisulcatus-Westergaardodina matsushitai-Westergaardodina moessebergensis Zone and the upper Proconodontus muelleri-Cambrooistodus cambricus Zone. For brevity, we herein shorten the name of the former zone to the Gapparodus bisulcatus-Westergaardodina moessebergensis Zone. The present conodont assemblages fit well into this zonation, although the examined samples are not closely spaced enough to delineate the precise boundary between the two zones (see Lee et al., 1991 for detail). Accordingly, we recognize a Barren Interzone between strata assigned to the two conodont zones (figure 5). This generalized biozonation is appropriate for this report because the number of samples and the recovered faunas reported herein are relatively small.
Coelocerodontus bicostatus, Gapparodus bisulcatus, Gumella cuneata, Granatodontus ani, Granatodontus hwajeolensis, Teridontus nakamurai, Westergaardodina moessebergensis, and W. quadrata and is roughly equivalent to the lower zone of Lee et al. (1991). We assign three of the eight fossiliferous samples to this lower conodont zone, namely samples Ed14, Mj7, and Dw13 (figure 5). The Gapparodus bisulcatus-W. moessebergensis Zone correlates well with the Westergaardodina matsushitai-W. moessebergensis Zone of the Sesong Slate, Korea (Lee, 1990), the early Late Cambrian fauna of northern Europe and North America (Müller, 1959; Müller and Hinz; 1991), the fauna of the Gushan Formation (Nogami, 1966), and the W. matsushitai Zone or W. matsushitai-W. grandidens Zone of North and South China (An et al., 1983; Mei, 1993; Dong, 1999; Dong et al., 2004; see figure 4 herein). No conodont biozonation has been established for coeval strata in North America (figure 4).
Coelocerodontus bicostatus, C. kosangolensis, Granatodontus ani, and G. hwajeolensis in the Gapparodus bisulcatus-W. moessebergensis Zone are some of the oldest occurrences of euconodonts known anywhere in the world. Qi et al. (2006) reported one element of Coelocerodontus bicostatus from the upper Middle part of the Huaqiao Formation in Hunan Province, South China. Occurrences of this species in the Machari Formation are of approximately the same age. These Middle Cambrian occurrences in the Machari Formation are only slightly older than previously reported occurrences of euconodonts in Hunan Province, South China by Dong et al. (2004, Fig. 2). They reported C. bicostatus from as low as the lowest Upper Cambrian Westergaardodina lui-W. ani Zone, and they reported Granatodontus ani from as low as the overlying Westergaardodina cf. calix-Prooneotodus rotundatus Zone (figure 4). Both species have relatively long ranges and occur in younger zones in Hunan.
The Barren Interzone between samples Dw13 and Dw9 (figures 3-5) may correlate with the Wester
gaardodina lui-W. ani Zone, W. cf. calix-Prooneotodus rotundatus Zone, and the Proconodontus tenuiserratus Zone in Hunan, South China (Dong et al., 2004).
Proconodontus posterocostatus, P. muelleri, and Cambrooistodus cambricus and is roughly equivalent to the Proconodontus muelleri-Cambrooistodus cambricus Zone of Lee et al. (1991). Many taxa recovered from the Machari Formation occur in both of the zones recognized herein (figure 5). The Proconodontus muelleri-Cambrooistodus cambricus Zone is recognized through the upper part of the Machari Formation, and we assign five of the fossil-iferous samples to this upper conodont zone, namely samples Dw7, Dw9, Bd8, Bd9, and Dw4 (figures 3, 5). The above taxa are characteristic elements of the Proconodontus Conodont Zone of the Hwajeol Formation in the Duwibong area of Korea (Lee and Lee, 1988). Therefore, the zone is closely correlated with zones of the middle Upper Cambrian, including the P. muelleri Conodont Zone and lower part of the Eoconodontus Conodont Zone of western United States (Miller, 1988; Ross et al., 1997; Miller et al., 2003), the P. muelleri muelleri Subzone of the Proconodontus Conodont Zone of the Canadian Arctic Islands and western Canada (Nowlan, 1985, Hein and Nowlan, 1998), and the upper part of the Proconodontus Zone and the lower part of the Cambrooistodus Zone of North China (An et al., 1983; Chen and Gong, 1986; Chen et al., 1988).

Systematic paleontology

This report illustrates new faunas from the Middle to Upper Cambrian Machari Formation, Korea (figures 6-9). Taxa discussed include those described for the first time in Korea, taxa named since the report of Lee et al. (1991) (especially those named by Müller and Hinz, 1991), and some taxa in open nomenclature. All figured specimens are deposited in the collections of the School of Earth and Environmental Sciences, Seoul National University, Seoul, and have collection numbers SNUG 0001-0094.
Conodont taxonomists often have not dealt with suprageneric classification of conodont faunas, but that procedure is impossible for this report, which deals with taxa as different as protoconodonts (classified in one phylum) and paraconodonts and euconodonts (classified in another phylum). Herein we assign to Phylum Chaetognatha and Order Protoconodontida those conodonts with protoconodont histology. Sweet (1988) assigned euconodonts to Phylum Conodonta, which is based on the informal name Conodonten of Pander (1856). We follow the classification of Sweet and Donoghue (2001) and recognize their Superclass Conodonta, and we assign to it those genera with paraconodont or euconodont histology. Superclass Conodonta is assigned to Phylum Chordata Bateson, 1886. We transfer the Order Paraconodonta of Müller (1962) to the level of Class Paraconodonta Müller, 1962 and assign to it those genera with paraconodont histology. Sweet (1988) and Sweet and Donoghue (2001) assigned euconodonts to Subclass Conodonti Branson, 1938, although they raised it to the level of Class. We follow this classification and assign conodonts with euconodont histology to Class Conodonti Branson, 1938.
There has been uncertainty about whether some Cambrian conodont genera have paraconodont versus euconodont histology. Dong et al. (2005) studied the histology of some Cambrian conodont genera and clarified some of that uncertainty. Based on their research, we assign to the euconodonts the genera Coelocerodontus Ethington, 1959 and Granatodontus Chen and Gong, 1986, which we recovered from the Machari Formation. Some genera recovered from the Machari Formation have always been considered to be euconodonts, including Cambrooistodus Miller, 1969, Proconodontus Miller, 1969, and Teridontus Miller, 1980.
Several short, general taxonomic comments are presented here: 1) This study follows Müller and Hinz (1991, 1998), which was based on large collections, in taxonomic assignment based on internal structure and the outer morphologic features; 2) Furnishina lingulata Xiang in An et al., 1983 is regarded herein as a junior subjective synonym of F. longibasis Bednarczyk, 1979; 3) Proacontiodus palmeri (Müller,
1959) has symmetrical to subsymmetrical tri- and tetracostate elements with a broad basal cavity; 4) Coelocerodontus kosangolensis Lee, Choi, and Lee, 1991 has symmetrical to asymmetrical tri- and tetracostate elements with a small lateral expansion of the cusp; and 5) Coelocerodontus bicostatus van Wamel, 1974 has a different costae and cusp morphology compared with C. kosangolensis Lee, Choi, and Lee, 1991. Coelocerocontus bicostatus is relatively large, bilaterally expanded, and has a lateral costa(e), but C. kosan-golensis is relatively small, slightly expanded, and has two posterior or/and anterior costae.

Protoconodonts

Phylum Chaetognatha Leuckart, 1854
Order Protoconodontida Landing, 1995

Genus Gapparodus Abaimova, 1978

Type species. Hertzina? bisulcata Müller, 1959.

Gapparodus new species A Figures 6.13, 6.18

Occurrence. Sample Ed14; Gapparodus bisulcatus-W. moessebergensis Zone.
Diagnosis. Long, slightly expanded coniform protoconodont with a very deep internal cavity. Anterior side rounded, posterior side flat to obliquely concave, producing two posterolateral costae.
Description. Very long, slender, evenly recurved coniform elements with deep internal cavities extending to near the apical end. Anterior side broadly rounded, and posterior side flat or slightly concave, no lateral furrows.

Material examined. Illustrated specimens SNUG 0009, 0010, and one additional element.

Remarks. These specimens closely resemble other species of the genus, but this species lacks any lateral furrows.

Paraconodonts

Phylum Chordata Bateson, 1886
Superclass Conodonta Pander, 1856 [ nomen translatum (pro phylum Conodonta Sweet, 1988, p. 170); ex Conodonten Pander, 1856]
Class Paraconodontida Müller, 1962 [ nomen translatum (pro Order Paraconodontida Müller, 1962), emended Landing, 1995]

Genus Furnishina Müller, 1959

Type species. Furnishina furnishi Müller, 1959.

Furnishina polonica Szaniawski, 1971 Figure 8.12

See synonymy in Müller and Hinz (1991).

Occurrence. Sample Mj7; Gapparodus bisulcatus-W. moessebergensis Zone.

Material examined. Illustrated specimen SNUG 0034, plus one other element.

Remarks. Our elements are proclined and consist of a circular cusp set off from the flared base, a convex anterior face with two anterolateral keels, and an extremely large base without a distinct posterior costa. The present specimens coincide with the type material in overall morphologic characters, although the anterior face is broadly convex and not flat as are the figured types of Szaniawski (1971).

Furnishina sp. Figures 9.5, 9.9

Occurrence. Samples Mj7, Dw13, Dw9, Dw7, Dw4, Bd8, Bd9; Gapparodus bisulcatus-W. moessebergensis Zone and Proconodontus muelleri-Cambrooistodus cam-bricus Zone.

Material examined. Illustrated specimens SNUG 0026, 0027, plus 67 other elements.

Remarks. These are preserved commonly as elements (figure 9.5) that were distorted due to post-sedimentation deformation, or they are elements with broken bases (figure 9.9). As a result, they do not allow a specific identification.

Genus Proacodus Müller, 1959

Type species. Proacodus obliquus Müller, 1959.

Proacodus cf. pulcherus (An, 1982) Figure 9.7

1982. Muellerodus pulcherus n. sp. An, p. 139, pl. 9, figs. 13, 15; pl. 10, figs. 12, 14.
1991. Muellerodus pulcherus An. Müller and Hinz, p. 34, 35, pl. 22.3-5, 7-11; fig. 13A, B.

Occurrence. Sample Mj7; Gapparodus bisulcatus-W. moessebergensis Zone.

Material examined. One element, illustrated specimen SNUG 0055.

Remarks. Our specimen differs from Proacodus pulcherus (An, 1982) in having a cusp that is undifferentiated from the base, but the remaining characteristics conform to those of the holotype of this species.

Genus Westergaardodina Müller, 1959

Type species. Westergaardodina bicuspidata Müller, 1959.

Westergaardodina sp. Figure 9.17

Occurrence. Sample Ed14; Gapparodus bisulcatus-W. moessebergensis Zone.

Material examined. Illustrated specimen SNUG 0065, plus 15 other elements.

Remarks. Two of our elements have a strong similarity to those of Westergaardodina matsushitai in their shape and size, but the basal part has a strong similarity to that of W. bicuspidata. Accordingly, we leave them in open nomenclature.

Euconodonts

Class Conodonti Branson, 1938 [ nomen translatum (pro Subclass Conodonti Branson, 1938)]

Genus Granatodontus Chen and Gong, 1986

Type species. Hirsutodontus? ani Wang, 1985.

Remarks. Chen and Gong (1986, p. 148, 149) assigned Hirsutodontus? ani Wang, 1985 to the genus Granatodontus Chen and Gong, 1986 because elements have no white matter, and they considered this species and Granatodontus to be paraconodonts. However, we assign this genus to the euconodonts because Chen and Gong's (1986) elements appear to have euconodont histology, as does the genus Hirsutodontus (Dong et al., 2005). The species name Granatodontus ani (Wang, 1985) is appropriate rather than Hirsutodontus primitivus An et al., 1985, because the latter species was designated without any relevant description as a new species, so it is a nomen nudum (see Chen and Gong, 1986, p. 149).
Granatodontus, with fine granulose ornament, is a distinctive genus that is closely related to the euconodont genera Rotundoconus An and Zhang in An et al., 1983, Hirsutodontus Miller, 1969, Dasytodus Chen and Gong, 1986, and Teridontus Miller, 1980. Rotundoconus and Granatodontus are euconodonts (Dong et al., 2005) with fine granulose ornament. Both are primitive in that they are not differentiated into a distinct base and a cusp, which the other genera possess. Granatodontus has a pointed tip, whereas the tip of Rotundoconus has a rounded to bulbous tip. Both genera had been considered as endemic to Korea and China, but Pyle and Barnes (2002) reported Granatodontus cf. ani in western Canada; their material is Tremadocian in age. Miller et al. (2003) reported Rotundoconus sp. from the Proconodontus posterocostatus Zone in the Ibex area, Utah; they reported a different species (Rotundoconus? sp.) from top of the Cambrooistodus minutus Subzone of the Eoconodontus Zone in the Ibex area, Utah and in central Texas, USA. The latter species was illustrated by Miller et al. (2006, Figs. 9G, 10G) as Rotundoconus sp.

Dubinina (2001) considered Granatodontus to be a junior synonym of Hirsutodontus. We disagree and consider both to be valid genera that are closely related. Granatodontus has fine granulose ornament and is primitive in not being differentiated into a distinct base and cusp. Hirsutodontus has nodose or spiny ornament and is advanced in having a distinct base and cusp, and the cusp often contains white matter.

Granatodontus hwajeolensis (Lee and Lee, 1988) Figure 9.10

1988. Hirsutodontus n. sp. A, Lee, p. 88, 89, pl. 5, figs. 7-12, text-figs. 5.G-12.
1988. Hirsutodontus hwajeolensis Lee and Lee, p. 366, 367, pl. 2, figs. 1, 2.

Occurrence. Sample Mj7; Gapparodus bisulcatus-W. moessebergensis Zone.

Material examined. One element, illustrated specimen SNUG 0060.

Description. Nearly erect, posteriorly expanded, undifferentiated coniform euconodont with deep basal cavity extending nearly to tip of cusp. Anterior side flat to broadly rounded, posterior side carinated, showing a triangular cross section in posterior view. Surface sculptured with numerous tiny spines and nodes, especially on the posterior face.
Remarks. Granatodontus hwajeolensis is easily distinguished from Granatodontus ani by its subtriangular cross section. Granatodontus ani has a rounded to oval cross section.

Genus Proconodontus Miller, 1969

Type species. Proconodontus muelleri Miller, 1969.

Proconodontus sp. aff. posterocostatus Miller, 1980 Figure 7.3

Occurrence.  Sample Bd8; Proconodontus muelleri-Cambrooistodus cambricus Zone.

Material examined. One element, illustrated specimen SNUG 0076.

Remarks. Very small, nearly erect coniform conodont with deep basal cavity. This single specimen resembles Proconodontus posterocostatus in having a costa on the entire length of the posterior edge, but it is greatly expanded in all directions, producing a circular cross section throughout the cone (compare figure 7.3 with figures 7.7,9).

Unassigned Coniform Element Figure 7.6

Occurrence. Samples Dw9, Bd8; Proconodontus muelleri-Cambrooistodus cambricus Zone.

Material examined. Illustrated specimen SNUG 0075, plus one other element.

Remarks. Two elements recovered herein have a postero-lateral costa and a furrow. All other sides are smooth, rounded, and lack any surface structures. The illustrated specimen is badly corroded. Similar elements that lack the costa and furrow are assigned to Teridontus nakamurai (figure 7.2), but the two elements considered here are left in open nomenclature.

Conclusions

The Machari Formation (upper Middle Cambrian to middle Upper Cambrian) is ~ 300 m thick in the Yeongweol area, Gangweon Province, Korea. Forty-three conodont samples were collected from four measured sections of the Machari Formation; eight samples produced 1,305 conodont elements. Elements are assigned to four genera and seven species of protoconodonts (Phylum Chaetognatha, Order Protoconodontida), seven genera and thirty-five species of paraconodonts (Phylum Chordata, Superclass Conodonta, Class Paraconodontida), and five genera and nine species of euconodonts (Phylum Chordata, Superclass Conodonta, Class Conodonti). Twenty-three species of ten genera were recovered for the first time from the Machari Formation, but other species are known from many parts of the world. Upper Middle Cambrian occurrences of Coelocerodontus and Granatodontus are among the oldest occurrences of euconodonts known anywhere. The lower three productive samples are assigned to the upper Middle Cambrian Gapparodus bisulcatus-Westergaardodina moessebergensis Zone. The upper five productive samples are assigned to the middle Upper Cambrian Proconodontus muelleri-Cambrooistodus cambricus Zone. Strata from the lower part of the Upper Cambrian are represented by a Barren Interzone. These faunas allow correlation with regional conodont biozonal frameworks in various parts of the world.

Acknowledgments

S. Dubinina, S. Heredia, E. Landing and P. Smith read various versions of this report and made suggestions that greatly improved the final manuscript. M. Gutierrez (Missouri State University) translated the abstract from English to Spanish.

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Recibido: 23 de julio de 2008.
Aceptado: 5 de mayo de 2009.