Bollettino della Società Paleontologica Italiana Modena, Novembre 1999
The suprageneric dassifìcation of some Ordovician prioniodontid conodonts
Svend STOUGE Gabriella BAGNOLI Geologica! Survey Dipartimento Scienze della Terra of Denmark and Greenland Università di Pisa
KEYWORDS- Conodonts, Suprageneric taxonomy, Ordovician.
ABSTRACT- Phylogenetic relationships among higher taxa within the conodonts that developed a complex apparatus and the resulting classifications are no t universally agreed upon due to the different patterns of the apparatus evolution within the c?ass. Using the most recent reconstructions ofthe prioniodontid apparatuses a picture ofiheir evolution is obtaineCl The proposed classification is base d on diffirent apparatus styles which persisted as unbroken linea_tes. The proposed suprageneric classiftcation for the prioniodontids includes the order Prioniodontida Dzik, 1976 with the supeifamilies Prioniodontoidea Bassler, 1925 and Balognathoidea Hass, 1959. The new order Polyplacognathida with the fomily Polyplacognathidae Bergstrom, 1981 and the new fomily Cahabagnathidae is introduced.
RJASS UNTO- [La classificazione sopragenerica di alcuni conodonti prioniodontidi ordoviciani]- Le relazioni filogenetiche e la conseguente classificazione a livello sopragenerico di conodonti con un apparato complesso, sono state oggetto di diffirenti interpretazioni a causa delle (iiverse mod'alità di evoluzione degli apparati nell'ambito della classe. Considerando i più recenti studi sullo stile ed architettura degli apparati dei prioniodontidi, viene qui proposto un diverso modello evolutivo. La classificazione proposta per i prioniodontidi prevede l'ordine .Prioniodontida Dzik, 1976 con le supeifamiglie Prioniodontoidea Bassler, 1925 e Balognath01dea Hass, 1959 ed il nuovo ordme Polyplacognathtda con la fomzglta Polyplacognathzdae Bergstrilm, 1981 e la nuova fomzglta Cahabagnathidae.
INTRODUCTION (1988) is used. However, one modifìcation is needed for those pectiniform elements with three main The origin, systematic position, and relationships processes and a secondary postero-lateral process. These between the different groups of the class Conodonta elements are described here as pseudostellate to Pander, 1856 were and still are, controversia!. The distinguish them from pastinate elements with just the recent classifìcations of euconodonts place the genera three primary processes (see Clark et al., 1981, p.W13, with complex apparatuses in the orders Prioniodontida, text-fig.10:1 and text-fig. 10:3). The letter Prioniodinida and Ozarkodinida. The complex abbreviations P, Sand M (Sweet, in Clark et al., 1981; apparatuses com p rise ramiform elements with processes Sweet, 1988) are used in reference to the position of together with coniform elements, blade-like and/or the elements in the apparatus in the same manner as platform-like elements. by Aldrigde et al. (1995). We have not speculated on In this paper, genera with prioniodontid apparatuses the precise orientation of the elements at their respective (Sweet, 1988) and referred to Prioniodontida, are position in the apparatus, because only a few natural reconsidered. The newly gained information dealing assemblages that are considered to be representative of with the biologica! affìnity of the conodonts (Aldridge the Prioniodontida are known (Aldridge et al., 1995; & Donoghue, 1998; Aldridge & Purnell, 1996), the Repetski et al., 1998). function of their skeletal apparatuses (e.g. Aldridge et Some of the representative genera are fìgured. We al., 1993; Aldridge et al., 1995; Dzik, 1991; Nicoll, follow the recommendation 29a of the ICZN (3rd 1987) and elemental growth (Donoghue, 1998) raised edition, 1985) and apply the suffìx -oidea for the a number of taxonomic questions an d new possibilities superfamilies in the systematic section. have arisen. In our treatment we provide diagnoses of the key taxa involved, insofar as they are known and provide HISTORY justifìcation for our taxonomic and evolutionary conclusions. Lindstrom (1970) presented the fìrst modern The descriptive terminology of the elements and suprageneric classifìcation and placed the conodonts the apparatuses given in the Treatise on Invertebrate in the orders Westergaardodinida Lindstrom, 1970 and Paleontology (Sweet, in Clark et al., 1981) and Sweet Conodontophorida Eichenberg, 1930. The two orders 146 S. STOUGE, G. BAGNOLI were further subdivided into eight superfamilies and with genera with the full suite of elements, to the 21 families. Dzik (1976) recognized three suborders Balognathidae Hass, 19 59 as specialized and 14 families. The Treatise (Clark et al., 1981) referred prioniodontides (Lindstrom, 1970; Bergstrom (in the conodonts to the phylum Conodonta Eichenberg, Clark et al., 1981), Sweet, 1988; Aldridge & Smith, 19 30 an d expanded the subdivision of the class 1993; Dzik, 1991). Conodonta Eichenberg, 19 30. In the Treatise New information obtained from work on the Lower classification, the phylum Conodonta and the class to Middle Ordovician conodonts from the Baltoscandic Conodonta were subdivided into two orders, 12 region (Bagnoli et al., 1988; Bagnoli & Stouge, 1997; superfamilies and 48 families. Fahrxus (1983, 1984) Lofgren, 1978, 1985, 1990, 1993a, b, 1994, 1997; criticized the Treatise classification and presented Rasmussen, 1991; Stouge & Bagnoli, 1990; Sturkell, alternative proposals for the phylogeny within the 1991; Zhang, 1997, 1998a, b, c; Zhang & Sturkell, phylum Conodonta Pander, 1856 (Fahrxus, 1983, 1998), Poland (Dzik, 1994; Bednarczyk, 1998), North 1984). America (Stouge & Bagnoli, 1988) and China (Zhang, Sweet (1988) presented a revised version of the 1998a, b) combined with the newly obtained suprageneric classification of the phylum Conodonta information on natura! prioniodontid apparatuses which was different in severa! ways from the older (Aldridge et al., 1995; Aldridge & Theron, 1993; classifications, especially that presented in the Treatise. Gabbott et al., 1995; Repetsk.i et al., 1998), change Sweet (1988) placed the conodonts in a distinct phylum the phylogenetic scenario somewhat and revisions to based on his interpretation of newly-discovered the suprageneric classifications of Sweet (1988), Dzik specimens of the conodont animai (see Aldridge et al., (1991) and Aldridge & Smith (1993) have been 1986; Briggs et al., 1983). In addition, Sweet (1988) proposed (Stouge & Bagnoli, 1998). excluded the protoconodonts and paraconodonts from the phylum Conodonta, and proposed the new classes Conodonti Branson, 1938 and Cavidonti Sweet, 1988. The prioniodontid apparatus Dzik (1991) improved his classification from the one he had presented earlier (Dzik, 1976) and referred The fundamental prioniodontid apparatus is the conodonts to the class Conodonta Pander, 1856 characterized by pectiniform P elements with three with five orders. Of these, the order Prioniodontida primary processes. The apparatus is bilaterally Dzik, 1976 comprised two superfamilies and six symmetrical and sexi- to multimembrate comprising families. two to four kinds of paired P elements, and 9 S Aldridge & Smith (1993) generally followed Sweet elements, one axial and four pairs, and a pair of M (1988) in their outline of the classification of the elements. Advanced prioniodontid apparatuses have Conodonta but also introduced important differences. three or four pairs of P elements. The most complex At that time the knowledge of the anatomy of the prioniodontid apparatus is that of Promissum with four conodont animai had improved (Aldridge et al., 1993) pairs of P elements with two and three primary and information on the zoologica! affinity of the processes (Aldridge et al., 1995). conodont animal pointed towards primitive vertebrates. The prioniodontid apparatus is first recognized in The conodonts were referred to the phylum Chordata Tremadoc strata and radiated in the Ordovician. The Bateson, 1886 and to the class Conodonta Eichenberg, prioniodontid apparatus persisted into the Silurian but 1930 sensu Clark et al., 1981 by Aldridge & Smith declined and disappeared at the end of the Devonian (1993). Aldridge & Donoghue (1998) and Aldridge (Sweet, 1988). & Purnell (1996) presented the most recent overview of the conodonts, and the evidence for the affinity of conodonts with primitive vertebrates related to the Evolution ofPrioniodontida hagfishes has been confirmed (Aldridge & Donoghue, 1998). The oldest representatives with the characteristic prioniodontid apparatus pian are "Acodus"· deltatus Lindstrom, 1955 and Diaphorodus Kennedy, 1980. THE ORDER PRlONIODONTIDA DZIK, 1976 Both taxa are known from the early Tremadoc (Bagnoli et al., 1988; Ethington & Clark, 1981; Kennedy, 1980; The order Prioniodontida Dzik, 197 6 in the recent Lofgren, 1993a; McTavish, 1973; Repetski, 1982; classifications of Sweet (1988), Dzik (1991) and Stouge & Bagnoli, 1988). The two taxa are the first Aldridge & Smith (1993) includes taxa with the representatives of the two major lineages of prioniodontid apparatus composed of elements in P, S Prioniodontida which respectively are reflected in the and M positions. In addition, conodonts forming two superfamilies Prioniodontoidea Bassler, 1925 and bimembrate apparatuses consisting only of pectiniform Balognathoidea Hass, 1959. The youngest Ordovician elements which presumbly occupied P positions were representative of the Prioniodontoidea is probably also included in the Prioniodontida and referred, along Phragmodus Branson & Mehl, 1933, which disappeared ORDOVICIAN PRIONIODONTID CON ODONTS 147
Prioniodontida Polyplacognathida ------'------, ,..------,
Prioniodontoidea Balognathoidea
Phragmodontidae Balognathidae Polyplacognathldae
;:l ..c"' ....l ....l c: i3 o I ""u V) rioniodontidae Cahabagnathidae ]:"' o Q.. ;:l"' "'Oo ;:l"' E -5 u E o :::> o ..c ..c"" "' o Q.. e- -5 o "'c: E o u ""u ti. "'OJ ;:l"' tj "'O c: >J. z z eo 0::: ..c o > .ft l z o
o ;:l"' "'Oo ..co t:> Oepikodontidae t:>
zw 0:::
u o o L: w --- ? "'1-
'------·------·---·- --·------·------__J Text-fìg. l - Evolution of genera in Prioniodontida Dzik, 1976 and Polyplacognatida new order.
in the late Ordovician. The Balognathoidea includes Tripodus Bradshaw, 1969 of the Oistodontidae taxa that persisted into the Silurian (Sweet, 1988; Lindstrom, 1970 (i.e. Sweet, 1988) was considered to Aldridge & Smith, 1993). be the ancestor of the Prioniodontidae (e. g. Dzik, 1976; The direct ancestors of "Acodus " deltatus and Sweet, 1988). Tripodus- which is no t synonymous with Diaphorodus are no t known an d can only be speculated Diaphorodus Kennedy, 1980 (Stouge & Bagnoli, 1988) upon. Previously, the early to middle Ordovician genus - and Oistodus Pander, 1856 together with the other 148 S. STOUGE, G. BAGNOLI genera that are placed in Oistodontidae display a style Lindstri::im, 1971) is the possible ancestor of Dzikodus. of apparatus that is fundamentally different from the Pygodus apparendy evolved from Dzikodus by reduction prioniodontid apparatus pian (Stouge, 1984; Stouge of the posterior process of the stelliscaphate elements & Bagnoli, 1988; Dzik, 1991). Hence, the genera of and loss of the M-element (e.g. Bergstri::im, 1983; the Oistodontidae are not considered to be closely Lindstri::im (in Ziegler, 1981); Zhang, 1998a, c). related to the Prioniodontida. Recendy, Dzik (1991) transferred the Oistodontidae to the Ozarkodinida Dzik, 1976 which is in better agreement with our THE ORDER POLYPLACOGNATHIDA N. ORDER interpretations. Another group of conodonts with a prioniodontid This new order is here introduced to include taxa apparatus includes the genera Eoneoprioniodus Mound, that are characterized by a bimembrate af>paratus, i. e. 1965 (=Pteracontiodus Harris & Harris, 1965) and only with pectiniform elements. O ne difference from Paraprioniodus Ethington & Clark, 1981; these have the recent classifications is that the genera with a apparatuses composed ofhyaline elements. Previously bimembrate apparatus are excluded from the order these taxa have been referred to the Multioistodontidae Prioniodontida. lnstead, these genera are recognized Harris, 1964 by Sweet (1988) and Aldridge & Smith as unique, distinct and independent taxa with their (1993), and to the Prioniodontidae Bassler (1925) by own evolutionary history. This possible evolutionary Dzik (1991). Later, Dzik (1994) allocated history was indicated previously by Lindstri::im (1964) Eoneoprioniodus to the Acodontidae Dzik, 1994 and and Bergstri::im (1983) and tentatively by Dzik (1991), Paraprioniodus to the Phragmodontidae Bergstri::im, but the former two authors did not follow this 1981. Here the genera are considered to represent an possibility at that time. independent stock that evolved from the Prioniodontidae Bassler, 1925 in Arenig times and are not considered to be related to the Multioistodontidae. The polyplacognathid apparatus Eoneoprioniodus and Triangulodus van Wamel, 197 4, both of which have an apparatus with hyaline The fundamental polyplacognathid apparatus elements, were placed in the Multioistodontidae comprises one kind of pectiniform element with three Bergstri::im, 1981 by Bergstri::im (in Clark et al., 1981) main processes (i.e. pastinate) and another kind of and in the Prioniodontida by Sweet (1988) mainly pectiniform element with three to four main processes because Triangulodus was considered to be an objective (i. e. stella te). junior synonym of Eoneoprioniodus (e.g. Sweet, 1988). However, the architecture of the Triangulodus apparatus is, in contrast with that of Eoneoprioniodus, not a Evolution ofthe Polyplacognathida prioniodontid apparatus (Stouge & Bagnoli, 1990; Bagnoli & Stouge, 1997) and Triangulodus probably Early platformal elements described as N. gen. n. evolved from an ancestor with affinities to the order sp. by Lindstri::im (1955, Pl. 6, figs. 43-44),Ambalodus Ozarkodinida Dzik, 1976. sp. by Lindstri::im (1955, Pl. 6, figs. 45-46) and platform The family Pygodontidae Bergstri::im, 1981 elementA by Bagnoli & Stouge (in Bagnoli et al., 1988, comprises Dzikodus Zhang, 1998a and Pygodus Lamont P l. 41, fig. 14) from the Tremadoc may be considered & Lindstri::im, 1957. The evolution of Dzikodus is not the ancestor of the Polyplacognathida (Text-fig. l). The clear. Olgun (1987) suggested that Dzikodus evolved record of taxa of this order from the Tremadoc to early from Amorphognathus variabilis Sergeeva, 1963a sensu Llanvirn is sparse bur Polonodus? loefgreni Stouge & Lindstri::im, 1971. Li::ifgren (1990) however proposed Bagnoli, 1988 from the Arenig is a possible candidate that Dzikodus derived from Baltoniodus Lindstri::im, representing an intermediate taxon in the evolurion 1971. The "Dzikodus-like" specimens described as from the Tremadocian unnamed platforms to . Polonodus? corbatoi (Serpagli, 1974) by Stouge & Eoplacognathus. Bagnoli (1988, Pl. 10, figs. 1-5), platform element B The genera Eoplacognathus Hamar, 1966, by Bagnoli et al. (1988, Pl. 41, fig. 12), or illustrated Cahabagnathus Bergstri::im, 1983, Polonodus Dzik, by Li::ifgren (1993, fig. 9: Y, Z) as Polonodus? sp. may 1976 (sensu Zhang, 1998a) and Polyplacognathus be related to Dzikodus (see, however, Li::ifgren, 1990 Stauffer, 1935 belong to this order. Zhang (1998a) fora discussion). Gen et sp. indet. A Zhang, 1998 erected the genera Yangtzeplacognathus Zhang, 1998 (Zhang, 1998a, Pl. 20, figs. 9-14) from China is and Baltoplacognathus Zhang, 1998 thar we also refer probably the youngest known representative of this to this order. The possible evolurion of Eoplacognathus, lineage and affinities of this taxon with Dzikodus and Polyplacognathus an d Cahabagnathus has been oudined therefore with the Balognathidae is likely. At this stage, by Bergstri::im (1983) and Dzik (1976), whereas Zhang however, we follow the interpretation promoted by (1998b) presented an evolutionary m o del that differed Olgun (1987) and propose that Lenodus (pars = from the previous interpretations. Amorphognathus variabilis Sergeeva, 1963a sensu Earlier the majority of the authors (e. g. Bergstri::im, ORDOVICIAN PRIONIODONTID CONODONTS 149
1971; Dzik, 1976) suggested that the oldest The lack of information available from the Tremadoc representative of the order, i. e. Eoplacognathus, evolved to late Arenig or early Llanvirn is considered to be due from the Lower to Middle Ordovician taxon that is to rarity of specimens rather than evidence that the known as Amorphognathus variabilis 5ergeeva, 1963a evolution of the polyplacognathid apparatus started sensu Lindstrom, 1971, by reduction of the number of during late Arenig/ early Llanvirn. The sporadic records elements in the apparatus. The multielemental from the Arenig of taxa that probably belong to the reconstruction of elements that have been referred to Polyplacognathida n. order support this interpretation. Amorphognathus variabilis sensu Lindstrom, 1971 is however no t yet fully accomplished (5touge & Bagnoli, 1990, Bagnoli & 5touge, 1997; Zhang, 1997, 1998a). SYSTEMATIC PALAEONTOLOGY The multielemental genus Lenodus 5ergeeva, 1963b (i. e. 5touge & Bagnoli, 1990; Bagnoli & 5touge, 1997) has Phylum CHORDATA Bateson, 1886 a septimembrate apparatus with pastiniscaphate and pseudostelliscaphate P elements, a complete set of 5 Class CONODONTA Pander, 1856 elements and paired, geniculate M elements (5touge [nom. transl. Dzik, 1991, p. 311, ex phylum Conodonra & Bagnoli, 1990; Bagnoli & 5touge, 1997; Zhang, Pander, 1856, nom. transl. Fahr
Family PRIONIODONTIDAE Bassler, 1925 Diagnosis - The apparatus is seximembrate; [nom. correct. Moore & Sylvesrer-Bradley, 1957, p. 28, pro elements in the P positions are of two kinds and both Prioniodidae Bassler, 1925, p. 218] are pastinate and paired; the S elements are paired dolabrate-bipennate, tertiopedate and quadriramate; Diagnosis - Apparatus is septimembrate. Ali P the element in the M position is geniculate, paired, elements are pastinate. The M elements may develop and adenticulated. denricles on the anrerior and posterior processes during evolution. Remarks- An alate element has no t been identified and the unpaired and symmetrical element in the Sa Genera included - Diaphorodus Kennedy, 1980, position of the apparatus of Oepikodontidae is Prioniodus Pander, 18 56, Tetraprioniodus Lindstrom, dolabrate, bipennate or quadriramate and hence cannot 19 55 an d Baltoniodus Lindstrom, 1971. easily be distinguished from other S elements in the apparatus. Occurrence- Lower (Tremadoc) to Upper (Caradoc During evolution the latera! processes of the or Ashgill) Ordovician. First Diaphorodus species (Pl. tertiopedate elements may be reduced in which case l, figs. 1-7) is recorded from the Tremadoc. Las t known tertiopedate and dolabrate elements are not easily species is Baltoniodus alobatus Bergstrom, 1971 from distinguished. the Caradoc. Genera included- Only Oepikodus Lindstrom, 195 5. Comments on the genera - Diaphorodus Kennedy, 1980 comprises severa! species that have been referred Occurrence- The oldest known species is Oepikodus
EXPLANATION OF PLATE l
Represenrarive genera of rhe Prioniodonrida Dzik, 1976.
Figs 1-7 - Diaphorodus sp. A; Cow Head Group, Manin Poinr Sourh, wesrern Newfoundland, Canada; Tremadoe. l) P elemenr, MGUH 25096, x35; 2) P elemenr, MGUH 25097, x52; 3) Sa elemenr, MHUH 25098, x62; 4) Sb elemenr, MGUH 25099, x62; 5) Se elemenr, MGUH 26000, x48; 6) Sd elemenr, MGUH 26001, x58; 7) M elemenr, MGUH 26002, x44. Figs 8-14 - Prioniodus gilberti Srouge & Bagnoli, 1988; Cow Head Group, Manin Poinr Sourh, wesrern Newfoundland, Canada; Tremadoe. 8) P elemenr, MGUH 26003, x52; 9) P elemenr, MGUH 26004, x46; 10) Sa elemenr, MGUH 26005, x76; 11) Sb elemenr, MGUH 26006, x46; 12) Se elemenr, MGUH 26007, x35; 13) Sd elemenr, MGUH 26008, x54; 14) M elemenr, MGUH 26009, X48. Figs 15-21 - Baltoniodus medius Dzik, 1976, (early rype), Holen Limesrone, Gillberga Quarry, Oland, Sweden; Middle Kundan (Llanvirn). 15) P elemenr, MGUH 26010, x42; 16) P elemenr, MGUH 26011, x49; 17) Sa elemenr, MGUH 26012, x54; 18) Sb elemenr, MGUH 26013, x48; 19) Se elemenr, MGUH 26014, x5 0; 20) Sd elemem, MGUH 26015, x68; 21) M elemenr, MGUH 26016, x 58. Figs 22-28 - Gothodus sp. A, Komsrad Limesrone, Fagelsang Quarry, Scania, Sweden; Kundan (Llanvirn). 22) P elemenr, MGUH 26017, x64; 23) P elemenr, MGUH 26018, x70; 24) Sa elemem, MGUH 26019, x62; 25) Sb elemem, MGUH 26020, x48; 26) Se elemem, MGUH 26021, x56; 27) Sd elemem, MGUH 26022, x57; 28) M elemem, MGUH 26023, x52. S. STOUGE, G. BAGNOLI, ORDOVICIAN PRIONIODONTID CONODONTS Pl. l 152 S. STOUGE, G. BAGNOLI sp. Stouge & Bagnoli, 1988 from the Tetragraptus Superfamily BALOGNATHOIDEA Hass, 1959 approximatus graptolite Zone (Lower Ordovician, Early [nom. trans., herein, ex Balognathidae Hass, 1959, Bergstriim, Areni g). The youngest known species is Oepikodus 1981 (in Clark et al. . ), p. W120] intermedius Serpagli, 1974 of late Arenig age. Diagnosis - The superfamily includes genera with septimembrate to multimembrate apparatuses. The Family PHRAGMODONTIDAE Bergstrom, 1981 elements in the P positions are pectiniform, paired and mostly not mirror images of each other. S elements are Diagnosis - The apparatus is septimembrate. The alate, paired dolabrate to bipennate, paired tertiopedate two kinds ofP elements are pastinate. The S elements and paired quadriramate. M element is paired and have short mainly adenticulated lateral processes and geniculate or tertiopedate. denticulated posterior process. M element is paired, geniculate and adenticulate. Families included- Balognathidae Hass, 1959 and Pygodontidae Bergstrom, 1981. Genera included- Gothodus Lindstrom, 1955 (Pl. l, figs. 22-28) andPhragmodus Branson & Mehl, 1933. Remarks- "Acodus" deltatus Lindstrom, 1955 (Text- Occurrence - The oldest recognized species is fig. 2) is the oldest representative of this superfamily Gothodus costulatus Lindstrom, 1955 from the (Text-fig. 1). Oepikodus evae Zone (Arenig) (Bagnoli & Stouge, 1997). The youngest species is Phragmodus undatus Occurrence- Tremadoc to Silurian. Branson & Mehl, 1933 (Upper Ordovician).
Remarks - Natural assemblages of Phragmodus suggest that the total number of elements in the apparatus is 15 (Repetski et al., 1998).
Text-fìg. 2 - "Acodus" deltatus 1955, Kopingsklint Text-fìg. 3- Trapezognathus diprion (Lin.dstriim, 1955), Bruddesta Formation, Furuhall, Oland, Sweden; Tremadoe. Formation, Horns Udde, Oland, Sweden; Billingen A) P element, MGUH 18167, x55; B) P element, Substage (Arenig). MHUH 18166, x51; C) Sb element, MGUH 18169, A) P element, MHUH 24114, x77; B) P element, x65; D) Se element, MGUH 18168, x65; E) Sd MGUH 24115, x77; C) Saelement, MGUH 24118, element, MGUH 18170, x65; F) M element, MGUH x77; D) Sb element, MGUH 24120, x45; E) Se 18172, x65. element,MGUH 24121,x77; F) Sdelement, MGUH 24119, x77; G) M element, MGUH 24117, x77. ORDOVICIAN PRIONIODONTID CONODONTS 153
Text-fig. 4- Lenodus variabilis (Sergeeva, 1963a) sensu latu, Holen Limestone, Halludden, Oland; Kundan Stage (Llanv!rn). A) P element (sinistra!), MHUH 25077, x63; B) P element (dextral), MGUH 25078, x42; C) P element (smistral), MGUH 25079, x54; D) P element (dexual), MGUH 25080, x43; E) Sa element, MGUH 25081, x43; F) Sb element, MGUH 25082, x59; G) Se element, MGUH 25083, x74; H) Sd element, MGUH 25084, x55; I) M element, MGUH 25085, x89.
Family BALOGNATHIDAE Hass, 1959 Branson & Mehl, 1933, Promissum Kovacs-Endrody, [nom. transl. Lindstrom, 1970, p. 435, ex Balognathinae Hass, 1987, Sagittodontina Kniipfer, 1967 an d probably 1959, p. 379] Rhodesognathus Bergstrom & Sweet, 1966.
Diagnosis- Apparatus is septi- to multimembrate. Remarks- Rhodesognathus Bergstrom & Sweet, 1966 The elements in P positions are paired, pectiniform is placed in the Balognathidae by Lindstrom (1970), elements with two, three and/or four processes. The Sweet (1988) and Dzik (1991, 1994). Fahrceus (1984) elements are mainly scaphate. In most taxa, the considered that the genus evolved from Baltoniodus pectiniform elements are not mirror images of each suggesting that Rhodesognathus could be placed in the other. S elements are alate, paired dolabrate to Prioniodontidae rather than in the Balognathidae. bipennate, paired tertiopedate and paired Promissum Kovacs-Endrody, 1987 belongs to the quadriramate. M element is paired and geniculate or Balognathidae according to Aldridge & Smith (1993) tertiopedate. and Aldridge et al. (1995). Promissum has a well documented apparatus (Aldridge et al., 1995) Genera included - "Acodus" deltatus Lindstrom, composed of 19 elements. Promissum is characterized 1955, Trapezognathus Lindstrom, 1955 (Text-fìg. 3), by having four morphologically distinct, paired P LenodusSergeeva, 1963b (Text-fìg. 4),Amorphognathus elements (i. e. Pa, Pb, Pc and P d elements) (Aldridge et 154 S. STOUGE, G. BAGNOLI al., 1995). The total number of elements in the Remarks - In this family the pseudostelliscaphate Promissum apparatus may be valid for other genera in elements have reduced posterior processes. The the family, even though the P elements do not display complete apparatuses of the two included genera have four morphological distinct units. In these genera i t is most recendy been discussed by Zhang (1998a, c). possible that morphologically similar P elements were placed in series and occupied the four P positions that have been observed in Promissum. Order POLYPLACOGNATHIDA n. order
Diagnosis - The apparatus is bimembrate with Family PYGODONTIDAE Bergstréim, 1981 pectiniform elements in P positions. The elements are paired, pastiniplanate and stelliplanate. Diagnosis-Apparatus is quinqui- to seximembrate. The elements in the P positions are paired, pastinate Families included- Polyplacognathidae Bergstrom, and/or pseudostellate, S elements are alate, paired 1981 and Cahabagnathidae n. fam. tertiopedate and paired quadriramate. M element, when present, is geniculate. Occurrence- Tremadoc to Upper Ordovician.
Genera included- Pygodus Lamont & Lindstréim, 1957 (Text-fìg. 5) and Dzikodus Zhang, 1998a (Fig. 6). Occurrence- Lower to Upper Ordovician.
Text-fìg. 5 -..Pygodus serra (Hadding, 1913), Kalla Limestone, Text-fìg. 6- Dzikodus sp. A, T ab le Point Formation, Litde Springs Oland, Sweden; Uhaku Stage (Llanvirn). Inlet, Western Newfoundland, Canada; Llanvirn. A) P element, MGUH 25086, x45; B) P element, A) P element, MGUH 25091, x 42; B) P element, MGUH 25087, x92; C) Sa element, MGUH 25088, MGUH 25092, x 49; C) Sa element, MHUH 25093, x90; D) Sb element, MGUH 25089, x60; E) Sd x 55; D) Sb element, MGUH 25094, x 48; E) Sd element; MGUH 25090, x80. element, MGUH 25095, x 50; F) M element, MGUH 25136, x50 . S. STOUGE, G. BAGNOLI, ORDOVICIAN PRIONIODONTID CONODONTS Pl. 2
EXPLANATION OF PLATE 2
Representative genera of the Polyplacognathida n. order.
Figs. 1-4 - Eoplacognathus elongatus (Bergstrom, 1962), Bl-150 Borehole, Lithuania; Idavere Stage (Caradoc). l) P element (sinistra!), MGUH 26024, x60; 2) P element (dextral), MGUH 26025, x37; 3) P element (sinistra!), MGUH 26026, x45; 4) P element (dextral), MGUH 26027, x45. Figs. 5-8 - Eoplacognathus lindstroemi (Hamar, 1964), Tartu-453 Borehole, Estonia; Uhaku Stage (Llanvirn). 5) P element (sinistral), MGUH 26028, x50; 6) P element (dextral), MGUH 26029, x55; 7) P element (sinistra!), MGUH 26030, x90; 8) P element (dextral), MGUH 26031, x70. Figs. 9-12 - Baltoplacognathus robustus (Bergstrom, 1971), Kalla Limestone, Kalla, Oland, Sweden; Uhaku Stage (Llanvirn). 9) P element (sinistal), MGUH 26032, x50; 10) P element (dextral), MGUH 26033, x45; 11) P element (sinistra!), MGUH 26034, x30; 12) P element (dextral); MGUH 26035, x47. 156 S. STOUGE, G. BAGNOLI
Family CAHABAGNATHIDAE n. fam. Philosophical Transactions of the Royal Society ofLondon, B, 340: 405-421. ALDRIDGE, R.J. & DoNOGHUE, P.C.J., 1998, Conodonts: a sister Diagnosis - Bimembrate apparatus consisting of group to Hagfishes? In J ergensen, J .M., Lomholdt, ].P. , W e ber, paired, pectiniform elements in P positions; the R.E. & Malte, H. (eds.), The Biology of Hagfishes: 15-31 , pectiniform elements are pastiniplanate and Chapman & Hall, London. stelliplanate both of which are mirror images of each ALDRIDGE, R.J. & PuRNELL, M.A., 1996, The co nodo n t controversies: Trends in Ecology and Evolurion, 11: 463-468. other. ALDRIDGE, R.J., PURNELL, M.A., GABBOTI, S.E. & THERON, J.N., 1995, The appararus architecrure and function of Promissum Genera included- Cahabagnathus Bergstrom, 1983 pulcrum Kovacs-Endri::idy (Conodonta, Upper Ordovician) and and Polonodus Dzik, 1976 (sensu Zhang, 1998). the prioniodontid pian: Philosophical Transactions of the Royal Society of London, B, 347: 275-291. ALDRIDGE, R.J. & SMITH, M .P., 1993, Conodonta.In Benton, M.J. Occurrence- The oldest known species is Polonodus (ed.), The Fossi! Record: 563-572. clivosus (Viira, 1974) (Llanvirn); the youngest species ALDRIDGE, R.J . & THERON, J .N., 1993, Conodonts with preserved is Cahabagnathus carnesi Bergstrom, 1983 ( Caradoc). soft tissue from a new Upper Ordovician Konservat- Lagerstatte: Journal of Micropalaeonrology, 12: 113-117. BAGNOLI, G. & STOUGE, S., 1997, Lower Ordovician (Billingenian - Kunda) conodont zonatiory. and provinces based o n sections Family POLYPLACOGNATHIDAE Bergstrom, 1981 from Horns Udde, north Oland, Sweden: Bollettino della Società Paleontologica Italiana, 35: 109-163, 8 pls. Diagnosis - Bimembrate apparatus consisting of BAGNOLI, G., STOUGE, S. & ToNGIORGI, M., 1988, Acritarchs and pastiniplanate and stelliplanate platformal elements in conodonts from the Cambro-Ordovician Furuhall (Ki::ipingsklint) section (Oland, Sweden): Rivista Italiana di P rwsitions; the P elements are morphologically Paleontologia e Stratigrafia, 94: 163-248, pls. 25-31. different and do not form mirror images. BASSLER, R.S., 1925, Classification and stratigraphic use of the conodonts: Geologica! Society of America Bulletin, 36: 218- Genera included- Baltoplacognathus Zhang, 1998a 220. BATESON, W., 1886, The ancestry of the chordata: Quarterly Journal 2, fìgs. 9-12), Hamar 1966 2, (P!. Eoplacognathus (P!. ofMicroscopical Science, 26: 535-571. fìgs. 1-8), Polyplacognathus Stauffer, 1935, Yangtze- BEDNARCZYK, W. S., 1998, Ordovician conodont biostratigraphy placognathus Zhang, 1998a and unnamed early of the Polish part of the Baltic Syneclise. In Szaniawski, H platforms. (ed.), Proceedings of the Sixth European Conodont Symposium (ECOS VI): Palaeontologia Polonica, 58: 107- 121, 2pls. Occurrence - Oldest species is represented by BERGSTROM, S.M., 1962, Conodonts from the Ludibundus unnamed platforms; youngest is Polyplacognathus Limestone (Middle Ordovician) of the Tvaren area (S. E. ramosus Stauffer, 1935 (Upper Ordovician). Sweden): Arkiv fi::ir Mineralogi og Geologie, 3: 1-61, 5 pls. BERGSTROM, S.M., 1971 , Conodont biostratigraphy of the Middle and Upper Ordovician ofEurope and eastern Norrh America. In Sweet, W.C. & Bergstri::im, S.M. (eds), Symposium on Conodont Biostratigraphy: Geologica! Society of America, ACKNOWLEDGEMENTS Memoir 127: 83-164, 2 pls. BERGSTROM, S.M., 1981, In Robison, R.A. (ed.), Treatise on We gratefully acknowledge grants supporting the work from Invertebrate Paleontology, part W, Miscellanea, suppl. 2, the Danish Research Council to S. Stouge and from the Consiglio Conodonta, Wl-W202, Geologica! Society of America and Nazionale delle Ricerche to G. Bagnoli. We thank J. Fuglsang University ofKansas, Boulder, Colorado & Lawrence, Kansas. (University of Copenhagen) for support an d help with the SEM. BERGSTROM, S.M., 1983, Biogeography, evolutionary relationships, ]. Lautrup (Geologica! Survey of Denmark and Greenland) and and biostratigraphic signifìcance of Ordovician platform M. Gini (University of Pisa) did the photographic work. E. conodonts: Fossils and Strata, 15: 35-58. Melskens (Geologica! Survey ofDenmark and Greenland) prepared BERGSTROM, S.M. & SWEET, W.C., 1966, Conodonts from the the text-figure. Lexington Limestone (Middle Ordovician) of Kentucky an d R.J. Aldridge and J. Dzik carefully reveiwed the manuscript its latera! equivalent in Ohio an d Indiana: Bulletin of american and provided many useful suggestions. Paleontology, 50: 271-441, pls.28-35. S. Stouge publishes with the permission of the Director of the BRADSHAW, L. E., 1969, Conodonts from the Fort Pena Formation Geologica! Survey of Denmark and Greenland. (Middle Ordovician), Marathon Basin, Texas: Journal of Paleontology, 43: 1137-1168, pls.l31-137. BRANSON, E. B., 1938, Stratigraphy and paleonrology of the Lower Mississippian of Missouri. Part l: University of Missouri Srudies, 13: 1-208. BRANSON, E.B. & MEHL, M.G., 1933, Conodont Srudies No.1: REFERENCES University of Missouri Studies, 8: 5-72. BRIGGS, D.E.G., CLARKSON, E.N.K. &ALDRIDGE, R.J., 1983, The ALDRIDGE, R.J., BRIGGS, D.E.G., CLARKSON, E.N.K. & SMITH, conodont animai: Lethaia, 16: 1-14. M.P. , 1986, The affinites of conodonts- new evidence from CLARK, D .L., SWEET, W. C., BERGSTROM, S.M., KlAPPER, G., AuSTrN, the Carboniferous ofEdinburgh, Scotland: Lethaia, 19: 1-14. R.L., RHooES, F. H. T., M OLLER, K.J., ZIEGLER, W. , LINDSTROM, ALDRIDGE, R.J., BRIGGS, D .E.G., SMITH, M.P., CLARKSON, E.N.K. M., MILLER, J.F.& HARRI S, A.G., 1981 , Conodonta. In & CLARK, N .D.L., 1993, The anatomy of conodonts: Robison, R.A. (ed.), Treatise o n Invertebrate Paleonrology, part ORDOVICIAN PRJONIODONTID CONODONTS 157
W, Miscellanea, suppl. 2, Conodonra, Wl-W202, Geologica! LINDSTROM, M., 1955, Conodonrs from rh e lowermost Ordovician Society of America and University of Kansas, Boulder, strata of south-central Sweden: Geologiska Foreningens i Colorado & Lawrence, Kansas. Srockholm Forhandlingar, 76 (21): 517-603, 10 pls. DoNOGHUE, P.C.J ., 1998, Growth an d patterning in the conodonr LI NDSTROM, M., 1964, Conodonts, 196 pp., Elsevier Pubi. Co., skeleron: Philosophical Transactions of the Royal Society of Amsterdam. London, B, 353: 633-666. LINDSTROM, M., 1970, A suprageneric taxonomy of the conodonts: DziK, ]., 1976, Remarks on the evolution ofOrdovician conodonrs: Lethaia, 3: 427-445. Acta Palaeonrologica Polonica, 21 (4): 395-455. LI NDSTROM, M ., 1971, Lower Ordovician conodonrs of Europe. DzrK, ]., 1991, Evolution of oral apparatuses in the conodont In. Sweet, W.C. & Bergstrom, S.M. (eds), Symposium on chordates: Acta Palaeonrologica Polonica, 36 (3): 265-323. Conodonr Biostratigraphy: Geologica! Society of America, D z rK , J ., 1994, Conodonts of the Mòjcza Limestone: Memoir 127: 21-61, l p!. Palaeonrologia Polonica, 53: 43-128. LOFGREN, A. , 1978, Arenigian and Llanvirnian conodonts from EICHENBERG, W., 1930, Conodonren aus dem Culm des Harzes: Jamdand, northern Sweden: Fossils and Strata, 13: 1-129, 16 Palaonrologische Zeitschrift, 12: 177-182. pls. ETHI NG TO N, R.L. & C LARK , D.L., 1981, Lower and Middle LOFG REN, A. , 1985, Early Ordovician conodonr biozonation at Ordovician conodonrs from the Ibex Area Western Millard Finngrundet, south Bornian Bay, Sweden (Geology of the County, Utah: Brigham Young University of Geologica! southern Bornian Sea. Part III.): Bulletin of the Geologica! Srudies, 28 (2): 1-155, 14 pls. Institutions of the University ofUppsala, N.S., 10: 115-128, FAHRJEUS , L.E., 1983, Phylum Conodonra Pander, 1856 and 4 text-fìgs. nomenclatural priority: Systematic Zoology, 32: 455-459. LOFGREN, A., 1990, Non-platform elemenrs of the Ordovician FAHRJEUS, L.E., 1984, A criticallook at the Treatise family-group conodonr genus Polonodus : Palaonrologische Zeitschrift, 64: classifìcation of Conodonra: an exercise in eclecticism: Lethaia, 245-259, 3 text-fìgs. 17: 293-305. LOFGREN, A. , 1993a, Conodonrs from the lower Ordovician at GABBOTT, S.E., ALDRIDGE, R.J. & TH ERON , J.N., 1995, A gianr Hunneberg, south-central Sweden: Geologica! Magazine, 130 conodont with preserved muscle tissue from the Upper (2): 215-232, 2 fìgs. Ordovician of Sourh Africa: Nature, 374: 800-803. LOFGREN, A., 1993b, Arenig conodonr succession from centra! H AD DI NG , A. , 1913, Undre dicellograptusskiffern i Skane jamte Sweden: Geologiska Foreningens i Srockholm Forhandlingar, nagra darmed ekvivalenra bildningar: Lunds Universitets 115 (3): 193-207, l text-fìg. Arssktift Avd. 2, 9: 1-90, 8 pls. LOFGREN, A., 1994, Arenig (Lower Ordovician) conodonrs and HAMAR, G., 1964, The Middle Ordovician of the Oslo region, biozonation in the eastern Siljan district, centra! Sweden: Norway. 17. Conodonts from the lower Middle Ordovician Journal ofPaleonrology, 68: 1350-1368. ofRingerike: Norsk GeologiskTidsskrift, 44, 243-292, 6 pls. LOFGREN, A. , 1997, Conodonr faunas from the upper Tremadoc HAMAR, G., 1966, The Middle Ordovician of the Oslo region, at Brattefors, sourh-cenrral Sweden, and reconstruction of the Norway. 22. Preliminary report o n conodonts from the Oslo- Pa!todus apparatus: GFF, 119 (4): 257-266, 2 text-fìgs. Asker and Ringerrike districts: Norsk Geologisk Tidssktift, MAc FARLANE, J.M., 1923, The evolution and distriburion of fìshes, 46: 27-83, 7 pls. 451 pp, MacMillan Co., New York. H ARRI S, R. W., 1964, Subgenera of the co nodo n t genus McTAVI SH, R.A. , 1973, Prioniodonracean Conodonrs from the Multioistodus in Simpson-Burgen (Ordovician Arbuckle) Emanuel Formation (Lower Ordovician) ofWestern Australia: conodonrs from Oklahoma: Oklahoma geologica! Notes, 24: Geologica et Palaeonrologica, 7: 27-58, 3 pls. 108-118. M OORE, R.C. & SYLVESTER-BRADLEY, P.C., 1957, First HARRJ S, R.W & HARRIS, B., 1965, Some West Spring Creek supplemenral application: Application for ruling of the (OrdovicianArbuckle) conodonrs from Oklahoma: Oklahoma Inrernational Commission directing that the classifìcation and geologica! Notes, 25: 34-47, p!. l. nomenclature of discrete conodonrs be in terms of"parataxà': H ASS , W.H., 1959, Conodonrs from the C hapell limestone of Bulletin of Zoologica! Nomenclature, 15 , Sect. A, p t. l l 4, Texas: U.S. Geologica! Survey Professional Paper, 294-J: 365- Doc. 1/2: 14-34. 400, pls.46-50. MouND, M.C., 1965, Two new conodont genera from the Joins H UDDLE, J.W., 1934, Conodonts from the New Albany shale of Formation (lower Middle Ordovician) ofOklahoma: Biologica! Indiana: Bulletin of American Paleonrology, 21 (72): 1-136, Society ofWashington Proceedings, 78: 193-200. 12 pls. Nr COLL, R.S., 1987, Form and function of the Pa elemenr in the JNTERNAT IONAL COMMI SSION ON ZOO LO GICAL N OMENCLATURE, conodont animai. In Aldridge, R.J. (ed.), Palaeobiology of 1985, International Code of Zoologica! Nomenclature, third Conodonrs: 77-90, Ellis Horwood, Chichester. edition, 338 pp., International Trust for Zological 0 LGUN, 0., 1987, Komponenten-Analyse und Conodonten- Nomenclature, London. Stratigraphie der Orrhocerenkalksteine i m Gebiet, Falbygden, KENN EDY, D.]. , 1980, A restudy of conodonts described by Branson Vastergorland, Mittelschweden: Sveriges Geologiska & Mehl, 1933, from the Jefferson City Formation, Lower Undersokning, Ca 70: 1-79. Ordovician, Missouri: Geologica et Palaeonrologica, 14: 45- PANDER, C.H., 1856, Monographie der fossilen Fische des 76. silurischen Systems der russisch-baltischen Gouvernemenrs: KNO PF ER, J ., 1967, Zur Fauna un d Biostratigraphie d es Akademie der Wissenschaften St. Petersburg: 91/p., 7 pls. Ordoviciums (Grafenthaler Schichten) in Thiiringen: RAsMUSSEN, J.A., 1991, Conodonr stratigraphy o the Lower Freiberger Forschungshefte, C, 220: 1-199, 19 pls. Ordovician Huk Formation at Slemmestad, southern Norway: KovAcs-ENDRODY, E. , 1987, The earliest known vascular plant, Norsk Geologisk Tidsskrift, 7 1: 265-288. or a possible ancesror of vascular planrs in the flora of the REPETSKI , J .E., 1982, Conodonrs from El Paso Group (Lower Lower Silurian Cedarberg Formation, T ab le Mountain Group, Ordovician) of westernmost Texas and southern New Mexico: Sourh Africa: Anna! es of the Geologica! Survey ofSourh Africa, New Mexico Bureau ofMines & Minerai Resources, Memoir 20: 93-118. 40: 1-121. LAMONT, A. & LINDSTROM, M.,l957, Arenigian and Llandeilian REPETSKI , J.E., PURNELL, M.A. & BARRETT, S. F. , 1998, The cherts idenrifìed in the Sourhern Uplands ofScodand by means apparatus architecture of Phragrnodus. In Bagnoli, G. (ed.), of conodonts, etc.: Transactions of the Edinburgh Geologica! ECOS VII Absrracts, Bologna-Modena, 1998: 91-92, Society, 17: 60-70, 5 pls. Tipografia Compositori Bologna. 158 S. STOUGE, G. BAGNOLI
SERGEEVA, S.P., 1963a, Conodonts from rhe Lower Ordovician in ZHANG ]IAN-HUA, 1997, The lower Ordovician conodonr the Leningrad regio n: Akademie Nauk SSSR: Palaontologische Eoplacognathus crassus Chen & Zhang, 1993: GFF, 119: 61- Zeitschrift, 1963 (2): 93-108, pls. 7-8 (in Russian). 65, 2 fìgs. SERGEEVA, S.P., 1963b, A new Early Ordovician conodont genus ZHANG ]IAN-HUA, 1998a, Conodonts from the Guniutan of the family Prioniodinidae: Akademie Nauk SSSR: Formation (Llanvirnian) in Hubei and Hunan Provinces, Palaontologische Zeitschrift, 1963 (4): 138-140 (in Russian). south-central China: Acta Universitatis Stockholmensis, SERPAGLI, E., 1974, Lower Ordovician conodonrs from the Stockholm Contriburion in Geology, 46: 1-161, 20 pls .. Precordilleran Argentina (Province of San Juan): Bollettino ZHANG ]IAN-HUA, 1998b, Middle Ordovician conodonts from the della Società Paleontologica Italiana, 13: 17-98, pls.7-31. Adantic Fauna! Region and the evolurion of Key conodont STAUFFER, C.R., 1935, The conodont fauna ofthe Decorah shale genera: Meddelande fran Stockholms Universitets Insritut for (Ordovician): Journal ofPaleontology, 9: 596-620, pls.71-75. Geologi och Geokemi, 298: 1-27, 5 appendices. STOUGE, S.S., 1984, Conodonts from the Middle Ordovician Table ZHANG J IAN-HUA, 1998c, The Ordovician conodont genus Pygodus. Head Formation, western Newfoundland: Fossils and Strata, In Szaniawski, H, (ed.), Proceedings of the sixth European 16, 1-145, 18 pls .. Conodont Symposium (ECOS VI): Palaeontologia Polonica, STOUGE, S.S. & BAGNOLI G., 1988, Early Ordovician Conodonts 58, 87-l 05, 3 pls. from the Cow Head Peninsula, western Newfoundland: ZHANG ]IAN-HUA& STURKELL E.F.F., 1998, Aserian and Palaeontographia Italica, 75: 89-179, 16 pls. Lasnamagian (Middle Ordovician) conodont biosrratigraphy STOUGE, S.S. & BAGNOLI G., 1990, Lower Ordovician (Volkhovian- and lithology at Kullstaberg and Lunne in Jamdand, north Kundan) conodonrs from Hagudden, norrhern Oland, Sweden: GFF, 120 (1): 75-83, l pl. Sweden: Palaeonrographia Italica, 77: 1-54, 10 pls. ZIEGLER W.(ed.), 1981, Catalogue of Conodonts IV: 291-293, STOUGE, S.S. & BAGNOLI G., 1998, Comments on some Lower Stuttgart. Ordovician multielement conodont genera: implications for conodont suprageneric taxonomy. In Bagnoli, G. (ed.), ECOS VII Abstracts, Bologna-Modena, 1998: 108, Tipografia (manuscript received january Il, 1999 Compositori Bologna. accepted March, 23) STURKELL, E., 1991, Tremadocian Ceratopyge Limestone identifìed by means of conodonts, in Jamdand, Sweden: Geologiska Foreningens i Stockholm Forhandlingar, 113: 185-188. Svend STOUGE SWEET, W.C., 1988, The Conodonta, Morphology, Taxonomy, Paleoecology, and Evolutionary History of a Long-Extinct Geologica! Survey of Denmark an d Greenland,GEUS Animai Phylum: Oxford Monographs on Geology and Thoravej 8, 2400 Copenhagen NV, Denmark Geophysics, 10: 1-212, Clarendon Press, Oxford, New York. e-mail: [email protected] VAN W AMEL, W.A., 197 4, Conodont biostratigraphy of the .Upper Cambrian and Lower Ordovician of norrh-western Oland, south-eastern Sweden: Urrecht Micropaleonrological Bulletins, Gabriella BAGNOLI 10: 125 pp., 8 pls. VnRA, V, 1974, Ordovician conodonts of the east Ba! tic: Geologica! Dipartimento Scienze della Terra, Universita di Pisa Institure of the Academy of Sciences of the Estonian SSR: Via S. Maria 53, 56100 Pisa, Italy 142 pp., 13 pls., Valgus Publisher, Tallinn (in Russian). e-mail: [email protected]