Late Wenlock biostratigraphy and the Pristiograptus virbalensis group (Graptolithina) in Lithuania and the Holy Cross Mountains

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Geo log i cal Quar terly, 2006, 50 (3): 333–344

Late Wen lock biostratigraphy and the Pristiograptus virbalensis group (Graptolithina) in Lith u a nia and the Holy Cross Moun tains

Sigitas RADZEVIÈIUS

Radzevièius S. (2006) — Late Wen lock biostratigraphy and the Pristiograptus virbalensis group (Graptolithina) in Lith u a nia and the Holy Cross Moun tains. Geol. Quart., 50 (3): 333–344. Warszawa.

Graptolites from Lith u a nia and the Holy Cross Moun tains com prise a suc ces sion of the lundgreni, parvus (ex cept for the Holy Cross Mts.), nassa, praedeubeli, deubeli and ludensis biozones of the up per Wen lock, the parvus, praedeubeli and deubeli biozones be ing rec - og nized for the first time in Lith u a nia, where a graptolite-free in ter val may also be dis tin guished. P. virbalensis Paškevièius, 1974 and the virbalensis group are not widely known, and are dis cussed here. Anal y sis of P. virbalensis shows this to be an in de pend ent taxon, closely re lated to P. auctus. There are three spe cies — P. virbalensis, P. jaegeri and P. auctus — in the virbalensis group.

Sigitas Radzevièius, De part ment of Ge ol ogy and Min er al ogy, Vilnius Uni ver sity, M. K. Èiurlionio 21/27, Vilnius, LT 03101, Lith u a nia;

In sti tute of Ge ol ogy, Uni ver sity of Tartu, Vanemuise 46, Tartu 51014, Es to nia; e-mail: sigitas.radzevicius@gf.vu.lt. (re ceived: March 17, 2005; ac cepted: Feb ru ary 10, 2006).

Key words: Lith u a nia, Holy Cross Mts., Si lu rian, up per Wen lock, biostratigraphy, Graptolithina.

INTRODUCTION

The graptolite ge nus Pristiograptus has been re corded from the Coronograptus cyphus to the Neocolonograptus parultimus–Neocolonograptus ultimus biozones in the Bal tic States. The high est di ver sity of pristiograptids oc curs in the late Wen lock Pristiograptus parvus–Pristiograptus ludensis biozones (Fig. 1) in Lith u a nia (Radzevièius and Paškevièius, 2000). Only pristiograptids and retiolitids have been re corded through out this in ter val, other char ac ter is tic Wen lock graptolite spe cies hav ing be come ex tinct by the end of the Cyrtograptus lundgreni Biozone. Con se quently, only pristiograptids and retiolitids can be ef fec tively used in the de tailed graptolite biostratigraphy of the parvus–ludensis in ter val. Ulst (Gailite et al., 1967; Ulst, 1974; Gailite et al., 1987) in ves ti gated the Pristiograptus spe cies of the Wen lock-Lud low bound ary in ter - val in the Bal tic Syneclise. Ulst re vealed the de tailed dis tri bu tion pat tern of graptolites from the up per part of the Monograptus tes tis (=lundgreni) Biozone up to the lower part of the Neodiversograptus nilssoni Biozone. Ulst (1974) de scribed a lo - cal parvus–Pristiograptus piltenensis (=Gothograptus nassa) biozone for the first time in Lat via. Paškevièius (1974, 1997) im - proved the graptolite biozonation and de scribed the dis tri bu tion of graptolites in the tes tis–nilssoni in ter val.

Tomczyk (1962), Jaworowski (1965), Teller (1972, 1997) and Szymañski and Teller (1998) in ves ti gated graptolites from the up per Wen lock of Po land. Koren’ and Urbanek (1994a) in - ves ti gated monograptid evo lu tion in the late Wen lock. The up - per Wen lock retiolitids, monograptids and biostratigraphy were in ves ti gated by Koz³owska-Dawidziuk (1990, 1997, 1999) Porêbska (1998) and Porêbska et al. (2004).

This pa per pro vides a re vised graptolite biozonation of the up per Wen lock of Lith u a nia and the Holy Cross Mts. (Po land).

The lundgreni, parvus (with a graptolite-free in ter val), nassa, Pristiograptus praedeubeli, Pristiograptus deubeli and ludensis biozones may be dis tin guished in Lith u a nia. In the Holy Cross Mts. the lundgreni, nassa, praedeubeli, deubeli, ludensis biozones may be dis tin guished. The lit tle known pristiograptids of the Pristiograptus virbalensis group are dis - cussed in the con text of re lated taxa.

MATERIAL

New palaeontological ma te rial of late Homerian (lundgreni–ludensis biozones) age (Fig. 1) has been re cov ered from Lith u a nia (west part of the East Eu ro pean Plat form or Baltica) and the Holy Cross Mts. (Ma³opolska Block, Kielce Unit). In Si lu rian time the Ma³opolska Block was near Baltica

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(Nawrocki, 2000); ad ja cent to the south-west mar gin of Baltica in the Mid Cam brian (Winchester, 2002; Trela, 2004), by the Late Si lu rian the Ma³opolska Block was lo cated at its pres ent po si tion at the south-west mar gin of Baltica (East Eu ro pean Plat form) (Nawrocki, 2000).

The to tal thick ness of the up per Wen lock in ter val (parvus–

ludensis biozones) is about 40 m in Lith u a nia. It com prises (Fig. 1) grey argillite, clayey marl (West ern Lith u a nia), clayey marl, marl, clayey lime stone (Cen tral Lith u a nia), clayey lime - stone, dolomitic clayey lime stone and clayey do lo mite (East ern Lith u a nia) (Fig. 2B). The new Lith u a nian ma te rial is from the Vilkaviškis-131 bore hole (Fig. 2B) from the 1052–1100 m in - ter val (60 sam ples) and from the Šiupyliai-69 bore hole.

Graptolites were stud ied from the 966–1010 m in ter val (50 sam ples) in the KurtuvÅnai-161 bore hole and also from the 1274–1330 m in ter val (45 sam ples), while the Sutkai-87 bore - hole 760–805 m in ter val (25 sam ples) was also stud ied. All bore holes are from North ern and South ern Lith u a nia. In to tal about 180 sam ples were col lected and in ves ti gated.

Rhabdosomes were iso lated with HCl or HF from 80 sam - ples of bore hole core. About 500 iso lated frag ments of semi-flat tened and 3-dimensionally pre served rhabdosomes were col lected, in clud ing early astogenetic stages.

In the Holy Cross Mts. the up per Wen lock se quence is well ex posed in the Kielce Unit (Fig. 2C) about 2 km to the north from the vil lage of Bardo on the north ern side of the Bardo Syncline, es pe cially along the Pr¹gowiec ra vine (Fig. 2D). The to tal thick ness of the up per Wen lock and lower Lud low is about 600 m (Tomczyk, 1962). In this ra vine, the up per Wen - lock de pos its are rep re sented by dark yel low and brown clayey shale in the lundgreni Biozone (up per part of the Bardo Beds).

The nassa–Pristiograptus tumescens–Saetograptus leintwa - rdinensis biozones are rep re sented by dark grey silty shale, lo - cally with con cre tions of lime stone (Pr¹gowiec Beds) and Bohemograptus bohemicus Biozone (Fig. 2D) is rep re sented by greywacke (the Niewachlów Greywacke) (Tomczyk, 1962). 100 sam ples were taken from 9 ex po sures and 15 sam - ples were taken from screes (Fig. 2D). There are no iso lated rhabdosomes in col lec tions from the Holy Cross Mts., be cause

it was im pos si ble to iso late ei ther both with HCI or HF. Sam - ples from the nassa (up per part) and nilssoni (up per part) — bohemicus in ter vals were not taken, be cause the ra vine in this place is over grown with veg e ta tion.

Pho tos of the Lith u a nian ma te rial were made us ing the scan ning elec tronic mi cro scope (SEM) in the Lab o ra tory of Ma te ri als Re search at Tallinn Tech ni cal Uni ver sity (Es to nia) and in the In sti tute of Ge ol ogy, Lund University (Sweden).

The ma te rial from both Lith u a nia and in part from the Holy Cross Mts. is stored at the De part ment of Ge ol ogy and Min er al - ogy of Vilnius Uni ver sity. The ma te rial from the Holy Cross Mts. (lundgreni Biozone) is stored at the In sti tute of Geo log i cal Sci ences, Wroc³aw Uni ver sity (Po land).

BIOSTRATIGRAPHY

The re cent de tailed in for ma tion from the up per Homerian al lows dis tinc tion of the lundgreni, parvus, nassa, praedeubeli, deubeli and ludensis graptolite biozones in Lith u a nia and the lundgreni, nassa, praedeubeli, deubeli and ludensis biozones in the Holy Cross Mts. (Radzevièius, 2003a) (Fig. 1).

The lundgreni taxon-range Biozone was adapted by Paškevièius (1997) in Lith u a nia. This in ter val was for mally in - cluded in the tes tis Biozone (Paškevièius, 1979, 1991;

Brazauskas and Paškevièius, 1981). The up per bound ary of this biozone is placed where Cyrtograptus, Monograptus and Monoclimacis dis ap pear. In Lith u a nia this biozone in cludes:

Cyrtograptus lundgreni Tullberg, Monograptus t. tes tis (Barrande), M. t. inornatus Elles, M. f. flemingi (Salter), Monoclimacis flumendosae (Gorthani), Pristiograptus lodenicensis Pøibyl, P. pseudodubius (Bouèek) and Gothograptus cf. kozlowskii Koz³owska-Dawidziuk (Fig. 3).

These spe cies do not dis ap pear at the same time. P.

lodenicensis dis ap pears first, and then Monograptus tes tis tes - tis, M. t. inornatus and M. flumendosae. The last three spe cies dis ap pear be fore C. lundgreni in bore holes in Lith u a nia. But C.

lundgreni dis ap pears ear lier than M. t. tes tis (Porêbska et al.,

Fig. 1. Cor re la tion of the re vised Lith u a nian up per Wen lock graptolite biozonation with those of Cen tral Asia (Koren’ and Suyarkova, 1994); the Czech Re pub lic (the gerhardi-ludensis zonal bound ary is higher be cause C. gerhardi dis ap pears in the lower Lud low — Koz³owska-Dawidziuk et al., 1998); Arc tic Can ada (Lenz and Koz³owska-Dawidziuk, 2002); Po land (Szymañski and Teller, 1998; Lenz and Koz³owska-Dawidziuk, 2002);

Lith u a nia and Lat via (Radzevièius and Paškevièius, 2000; Radzevièius, 2004); and with re gional stages and for ma tions

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2004) in the Bartoszyce bore hole (Po land). C. lundgreni dis ap - pears to gether with M. f. flemingi, P. pseudodubius and Gothograptus sp., in the lower part of the Anèia Mem ber.

A graptolite-free in ter val and the parvus con cur rent-range Biozone are rec og nized for the first time in Lith u a nia (Fig. 3).

Pre vi ously the parvus Biozone in ter val was at trib uted to the lower part of the nassa Biozone. Ulst (1974) first sep a rated the P. parvus–P. piltenensis lo cal Biozone in Lat via, which in - cluded the en tire in ter val of the nassa Biozone. The lower bound ary of this biozone was placed where C. lundgreni, M. t.

Late Wenlock biostratigraphy and the Pristiograptus virbalensis group (Graptolithina) in Lithuania and the Holy Cross Mountains 335

Fig. 2. A — gen eral map of Lith u a nia and Po land with the Holy Cross Mts. (de lin eated area); B — the ex tent of GÅluva re gional stage (Lapinskas, 2000) and lo ca tion of the bore holes; C — lo ca tion of the Bardo ra vine in the Holy Cross Mts. (Masiak et al., 2003); D — stratigraphy of the Si lu - rian de pos its in the Bardo Syncline (Pr¹gowiec ra vine) af ter Tomczyk (1962, fig. 9) and pres ent sam pling sites

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tes tis, M. t. inornatus, M. f. flemingi, M. flumendosae, P. lodenicensis, P. pseudodubius and G. cf. kozlowski dis ap - pear. P. parvus Ulst and G. nassa (Holm) ap pear in the up per part of the Anèia Mem ber. Only two spe cies are found in this biozone. Graptolites are ab sent from the last oc cur rence of C.

lundgreni and P. pseudodubius to the first ap pear ance of P.

parvus and G. nassa (mid dle part of the Anèia Mem ber) (Fig. 3). The graptolite-free in ter val ranges from 0.7 m (Šiupyliai-69) to 2 m (Vilkaviškis-131) in thick ness. The up per bound ary of the biozone is rec og nized where P. parvus dis ap - pears. The ver ti cal ex tent of P. parvus ranges from 5 m in the KurtuvÅnai-161 bore hole to 2.4 m in the Vilkaviškis-131 bore - hole. There is a sim i lar graptolite-free in ter val in Gotland be - tween the lundgreni and parvus biozones (Calner and Jeppsson, 2003). This in ter val rep re sents the Bara Oolite and

the lower part of the Mulde Brick-clay Mem ber of the Halla For ma tion (Calner and Säll, 1999).

Paškevièius (1965) rec og nized the nassa Biozone in Lith - u a nia, which in cluded the in ter val with P. parvus. Later this biozone was di vided into two in ter vals: a lower part with P.

parvus and an up per part with P. d. ludlowensis (Bouèek) (Radzevièius, 2004). These two parts are shown as sep a rate biozones in this pa per. The lower bound ary of the nassa Biozone is marked where P. parvus dis ap pear and the up per bound ary where P. virbalensis Paškevièius and P.

praedeubeli (Jae ger) ap pear. The nassa Biozone, like the parvus Biozone, has few spe cies, though these are larger than those in the parvus Biozone: they com prise G. nassa (Fig. 4) and P. d. ludlowensis. The nassa Biozone is 6.5 m thick in the Vilkaviškis-131 bore hole.

The praedeubeli range Biozone is here rec og nized for the first time in Lith u a nia. Pre vi ously this in ter val was called the virbalensis–deubeli Biozone (Paškevièius, 1997; Radzevièius and Paškevièius, 2000); later, it was re ferred to as the lower part of the virbalensis Biozone with P. praedeubeli (Radzevièius and Paškevièius, 2005). The lower bound ary is marked where P. praedeubeli and P. virbalensis ap pear, while the up per bound ary is drawn when P. deubeli (Jae ger) ap pears. This biozone also in cludes G. nassa and P. d. ludlowensis. P.

idoneus? (Koren’) has been found in the lower part of the biozone for the first time, while P. jaegeri (Hol land, Rickards, War ren) oc curs in the up per part. The thick ness of the praedeubeli Biozone is 5.8 m in the Vilkaviškis-131 bore hole and 8 m in the Šiupyliai-69 bore hole.

The deubeli range Biozone is here also re cog nized for the first time in Lith u a nia. Pre vi ously this in ter val was called the virbalensis–deubeli Biozone (Paškevièius, 1997; Radzevièius and Paškevièius, 2000). The lower bound ary is drawn at the first ap pear ance of P. deubeli. The up per bound ary is drawn where P. ludensis ap pears. The as sem blage com prises P.

jaegeri (in the lower part) P. deubeli, P. praedeubeli, P.

virbalensis and P. d. ludlowensis. We have been un able to de - ter mine the thick ness of this biozone in the Vilkaviškis-131 bore hole, be cause the up per part of the Wen lock has yielded no graptolites. The thick ness of the deubeli Biozone is 5 m in the Šiupyliai-69 bore hole.

The ludensis range Biozone was rec og nized by Paškevièius (1979). Pre vi ously this biozone en com passed the in ter val from the nassa to the nilssoni Biozones (Paškevièius, 1979), while Paškevièius (1997) rec og nized it in its pres ent mean ing. The lower bound ary of the biozone is drawn where P. ludensis (Murchi son) ap pears, and the up per bound ary where Neodiversograptus nilssoni (Barrande), Colono - graptus colonus (Barrande) and Bohemograptus b.

bohemicus (Barrande) ap pear. The graptolite as sem blage of this biozone in cludes P. ludensis, P. praedeubeli and P. d.

ludlowensis; in the up per part Colonograptus gerhardi (Kûhne) ap pears (Fig. 4), and this taxon is also found in the up per nilssoni Biozone.

Tomczyk (1962) rec og nized the lundgreni, tes tis, nassa, Pristiograptus vulgaris, P. dubius, Spinograptus spinosus–

Pristiograptus gotlandicus, nilssoni, Lobograptus scanicus, tumescens–leintwardinensis and bohemicus biozones in the Bardo syneclyse (Holy Cross Mts.) around the Wen lock-Lud -

Fig. 3. Dis tri bu tion of graptolites near the Wen lock-Lud low bound ary in the Vilkaviškis-131 bore hole

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Fig. 4. Graptolites from the up per Wen lock and lower Lud low of Lith u a nia

A — Monograptus cf. flemingi (Salter); ParovÅja-9 bore hole, depth 605.6 m, lundgreni Biozone; B — Pristiograptus dubius var. B, Paežeriai-222 bore - hole, depth 734.5 m, lundgreni Biozone, P.P222-216; C–F — Pristiograptus lodenicensis Pøibyl, ParovÅja-9 bore hole, lundgreni Biozone; C — depth 558.3 m, S.P9-211a; D — depth 561.9 m, P.P9-1; E — depth 558.3 m, P.P9-5; F — depth 561.9 m, P.P9-6; G–I — Gothograptus cf. kozlowskii Koz³owska-Dawidziusk, Šiupyliai-69 bore hole, depth 1010.0 m, lundgreni Biozone; G — gen eral view of rhabdosome; H — sec ond theca with hook; I — prox i mal end of rhabdosome; J, M — Colonograptus gerhardi (Kûhne), Šiupyliai-69 bore hole; J — depth 967.4 m, nilssoni Biozone, S.Š69-396; M — depth 976.7 m, ludensis Biozone, S.Š69-399; K, S, T — Pristiograptus praedeubeli (Jae ger); K — Šiupyliai-69 bore hole, depth 982.6 m, deubeli Biozone, S.Š69-397; S — Sutkai-87 bore hole, depth 776.0 m, praedeubeli Biozone, P.S87-134; T — Pilviškiai-143 bore hole, depth 779.5 m, praedeubeli Biozone, S.P143-84; L, R — Pristiograptus deubeli (Jae ger), deubeli Biozone; L — Šiupyliai-69 bore hole, depth 982.6 m, S.Š69-398; R — Pilviškiai-143 bore hole, depth 779.5 m, S.P143-148; N–P — Pristiograptus parvus Ulat, Kybartai-14 bore hole, parvus Biozone; N, O, — depth 1088.4 m; N — P.K14-109; O — P.K14-115; P — depth 1071.7 m, P.K17-108; Q — Gothograptus nassa (Holm), Šiupyliai-69 bore hole, depth 993.6 m, nassa Biozone; U — Colonograptus colonus (Barrande), Šiupyliai-69 bore hole, depth 958.4 m, pro gen i tor Biozone; V — Neodiversograptus nilssoni (Lapworth); Šiupyliai-69 bore hole, depth 967.5 m, nilssoni Biozone; W — Monograptus cf. micropoma Jae ger, Šiupyliai-69 bore hole, depth 971.5 m, pro gen i tor Biozone; X — Saetograptus schimaera (Barrande), Šiupyliai-69 bore hole, depth 937.35 m, pro gen i tor Biozone; Y, Z — Pristiograptus virbalensis Paškevièius, Sutkai-87 bore hole, praedeubeli Biozone; Y — depth 768.2 m, P.S87-121b; Z — depth 768.9 m, P.S87-71; AA — Dendroidea, Sutkai-87 bore hole, depth 787.8 m (in ter val be tween lundgreni–praedeubeli biozones)

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low bound ary (Fig. 5). Tomczyk (1962) also dis tin guished in - ter vals with trilobites in the lower part of the nassa Biozone.

Cur rent strati graphic schemes do not in clude the tes tis, vulgaris, dubius and spinosus-gotlandicus biozones of the up - per Wen lock.

Anal y sis of the Pr¹gowiec ra vine sam ples al lowed sep a ra - tion of the lundgreni, nassa, praedeubeli, deubeli, ludensis and nilssoni biozones. The ex act bound aries of these biozones could not be de ter mined be cause of a lack of ma te rial. The old - est graptolite biozone found, the lundgreni Biozone, oc curs in the up per part of the up per Bardo Beds. The graptolite as sem - blage from the A09 ex po sure in cludes M. t. tes tis, M. f.

flemingi, C. lundgreni and G. cf. kozlowskii.

The nassa, praedeubeli, deubeli, ludensis and nilssoni biozones were also rec og nized in the Pr¹gowiec ra vine.

Rocks of the scanicus-bohemicus in ter val were not found, be cause that in ter val is thickly grown over with bushes and trees. The parvus Biozone has also not been found in the Pr¹goviec ra vine, be cause P. parvus has not yet been dis cov - ered there. The ver ti cal dis tri bu tion of P. parvus is very nar - row in Lith u a nia. The ab sence of this spe cies may there fore re sult from the wide in ter val of sam pling, or parvus Biozone may equate to the in ter val with trilobites that oc curs above the lundgreni Biozone. The graptolite as sem blage of the nassa Biozone found in the A08 ex po sure com prises G. nassa, P. d.

ludlowensis.

The graptolite as sem blage of the praedeubeli Biozone in the Pr¹gowiec ra vine, found in the A07, A01 and A02 ex po - sures is very sim i lar to that of the praedeubeli Biozone of Lith - u a nia: G. nassa, P. d. ludlowensis, P. virbalensis, P.

praedeubeli and P. cf. ? idoneus (Figs. 6 and 7).

The graptolite as sem blage of the deubeli Biozone was found in the A01 (lower part), A02 and A04 ex po sures and it in cludes G. nassa ?, P. d. ludlowensis, P. praedeubeli and P.

virbalensis. There is rare P. praedeubeli in the deubeli Biozone in Lith u a nia, but this spe cies also oc curs in the deubeli and ludensis biozones of north ern Naratau and the Alai Ridge (Cen tral Asia) (Koren’ and Suyrkova, 1994b) and Arc tic Can - ada (Lenz and Koz³owska-Dawidziuk, 2002).

The graptolite as sem blage of the ludensis Biozone was found at ex po sures A03, A04 and A05 and in cludes P. d.

ludlowensis, P. praedeubeli, P. deubeli, P. virbalensis and C.

gerhardi (Fig. 7). P. virbalensis does not oc cur in the ludensis Biozone of Lith u a nia.

It is dif fi cult to cor re late the praedeubeli, deubeli and ludensis biozones with the biozones rec og nized by Tomczyk (1962) from Pr¹gowiec (Fig. 5), be cause P. gotlandicus and P.

vulgaris are not now rec og nized as valid taxa. It would be nec - es sary to re vise of Tomczyk’s col lec tion from the Pr¹gowiec ra vine for this cor re la tion to be made.

The graptolite as sem blage of the nilssoni Biozone, found in the A05 (lower part) and A06 ex po sures, com prises C.

gerhardi (Fig. 7), N. nilssoni and Saetograptus sp.

PRISTIOGRAPTUS VIRBALENSIS GROUP

Four pristiograptid mor pho log i cal groups are re cog nized in the up per Wen lock: dubius, lodenicensis, deubeli (ludensis or Ludensograptus) and virbalensis (Radzevièius and Paškevièius, 2000). The first three are wide spread and well-known (Pøibyl, 1943; Tsegelnjuk, 1988; Radzevièius, 2003b; Rickards and Wright, 2003). P. pseudodubius does not equate with P. parvus (Rickards and Wright, 2003). P. parvus is a clearly-marked taxon with a very nar row dis tri bu tion in time. These two spe cies are sim i lar be cause they are both of dubius type, but P. parvus is smaller. The max i mum width of the rhabdosome is 1 mm and that of P. pseudodubius is 1.5 mm.

The first P. parvus theca orig i nates are at the sicula ap er ture or very close to it, while the free part of the P. pseudodubius sicula wall is 0.25 mm long.

Our new data helps to con strain the up per limit of P.

lodenicensis; this spe cies dis ap pears be fore M. t. testis and C.

lundgreni.

The virbalensis group was dis tin guished by Radzevièius and Paškevièius (2000) for the first time, and it ex tended through late Wen lock and early Lud low time. P. virbalenis Paškevièius, 1974 (Fig. 8G) is not widely known, and is dis - cussed here. In the new ma te rial from Lith u a nia and the Holy Cross Mts. there is no typ i cal P. auctus Rickard, that has a large bulb-like ter mi na tion to the virgella. A pristiograptid sim i lar to P. auctus was find only in the praedeubeli–ludensis biozones.

The new ma te rial from Lith u a nia and the Holy Cross Mts., en - ables re vi sion of this group.

The Pristiograptus of the virbalensis group pos sesses a mas sive virgella, and the thecae are in clined at 40–45° to the axis of the rhabdosome. The ap er tural an gle (b) (Fig. 9G) of the thecae is ob tuse in the prox i mal part of the rhabdosome and it is a right an gle (90°) in the me dial and dis tal parts. The virgella is ob tuse and mas sive (Figs. 6M, L and 8A, B, D, E, G). There are three spe cies in the virbalensis group: P. auctus Rickards (Fig. 8L), P. jaegeri (Fig. 8H–K) and P. virbalensis.

These spe cies are very sim i lar. The main char ac ter is tic of P.

auctus, is “...the pres ence of a short virgella (0.6 mm) which swells into a bulb-like shape, and has the ap pear ance of a drop let hang ing from the prox i mal end of the rhabdosome.

Fig. 5. Cor re la tion of the Holy Cross Mts. (Tomczyk, 1962) up per Wen lock graptolite biozonation with those of re vised

Holy Cross Mts. and Lith u a nian biozonations

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Fig. 6. Monograptids from the Holy Cross Mountains

A–C, J — Pristiograptus ludensis (Murchi son), ludensis Biozone; A — ŠV-A04-07, B — ŠV-A04-08, C — ŠV-A05-11, J — ŠV-A03-01; D — Pristiograptus praedeubeli (Jae ger), deubeli Biozone, ŠV-A05-05; E — Pristiograptus deubeli (Jae ger), deubeli Biozone, ŠV-A01-10; F, L — Pristiograptus virbalensis Paškevièius, deubeli Biozone, ŠV-A04-02, F — gen eral view, L — prox i mal end of rhabdosome, virgella with virgella nub; G

— Pristiograptus cf. idoneus Kpren’, praedeubeli Biozone, ŠV-A07-01; H, I, M — Pristiograptus virbalensis Paškevièius, praedeubeli Biozone, ŠV-A02-01, H — gen eral view, I — the sixth theca ap er tural lip, M — prox i mal end of rhabdosome virgella with virgella nub; K — Saetograptus sp., nilssoni Biozone, ŠV-A06-05; black bars rep re sent 1 mm

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It’s swell ing is 0.4–0.5 mm in di am e ter...” (Rickards, 1965, p.

260). The P. virbalensis rhabdosome looks most sim i lar to P.

auctus. It is straight with a hang ing “drop let” on the end of the virgella (Figs. 8D and 9G). In some cases the virgella does not have a drop let but is ob tuse (Pristiograptus of dubius type have a sharply-ended virgella). The drop let is 0.1 mm in di -

am e ter and is a lit tle thicker than the virgella it self. The virgella of P. virbalensis is twice as long as that of P. auctus.

P. cf. auctus with a very short virgella and with a small “bub - ble” at its end was found in the Sutkai-87 bore hole (Fig. 8C, F); this “bub ble” does not ex ceed 0.2 mm in di am e ter. The thick ness of the virgella is about 0.1 mm, so the thick en ing to

Fig. 7. Monograptids from the Holy Cross Mountains

A–D, I, J — Pristiograptus deubeli (Jae ger), deubeli Biozone; A — ŠV-A01-02, B — SV-A01-08, C — SV-A02-10, D — ŠV-A01-07, I — ŠV-A019; J — ŠV-A04-23; E, F, K — Colonograptus gerhardi (Kûhne), ludensis Biozone; E — ŠV-A06-10, F — ŠV-06-01, K — ŠV-A06-02; G — Pristiograptus ludensis (Murchi son), ludensis Biozone, ŠV-A05-13; H — Pristiograptus praedeubeli (Jae ger), deubeli Biozone, ŠV-A02-08; black bars rep re sent 1 mm

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0.4–0.5 mm is marked. Lo cally there are de gen er ate ex am ples of P. virbalensis (Fig. 8B, E). They have a thick ened virgella end, but the di am e ter of the drop let does not ex ceed 0.25 mm.

Rickards (1965), de scribed about 40 spec i mens of P. auctus, so it is in con ceiv able that all these are de gen er ate. There are Pristiograptus with sim i lar virgellae to P. virbalensis from the R. Ulst col lec tion (Lat via). Jepsson’s graptolite col lec tion from Gotland also in cludes P. auctus, but these do not have a 0.4–0.5 mm thick en ing at the end of the virgella and so are atyp i cal.

P. virbalensis is also found in the Holy Cross Moun tains (Radzevièius, 2003a) in the praedeubeli–ludensis biozones.

It oc cu pies a dif fer ent strati graphi cal po si tion to P. auctus and P. virbalensis. P. virbalensis is found in the virbalen - sis–deubeli (= praedeubeli–deubeli) biozones, while P.

auctus is re stricted to the nilssoni Biozone. Ac cord ing to Jae -

ger (1991), P. auctus ranges from the up per part of the praedeubeli Biozone to the mid dle of the vulgaris–gerhardi (= ludensis) in ter val. Jae ger’s P. auctus was found in a sim i lar in ter val to P. virbalensis. There fore it is un likely that P.

virbalensis is a sub spe cies of P. auctus, on which more de - tailed stud ies are needed.

P. jaegeri is at trib uted to the virbalensis group, as noted above. In P. jaegeri the ap er tural part of the two first thecae with the free part of the neigh bour ing thecae makes an ob tuse an gle (Lenz and Koz³owska-Dawidziuk, 2002). This an gle in P. virbalensis is also ob tuse (Radzevièius and Paškevièius, 2000), be com ing a right an gle in the me dial and dis tal parts.

The thecae of P. jaegeri are in clined at 40° (Hol land et al., 1969). Those of P. jaegeri from Arc tic Can ada are in clined at 20° in the prox i mal, and at 30° in the dis tal part (Lenz and Koz³owska-Dawidziuk, 2002). The thecae of P. virbalensis are

Fig 8. P. virbalensis group from Lith u a nia near the Wen lock-Lud low bound ary

A, D — Pristiograptus virbalensis Paškevièius; Sutkai-87 bore hole, depth 768.2 m, P.S87-121a, praedeubeli Biozone, A — gen eral view, D — prox i mal end of rhabdosome; B, E — P. virbalensis; Sutkai-87 bore hole, depth 877 m, P.S87-382, praedeubeli Biozone, B — gen eral view, E — mouth of sicula with ab nor mal virgella (vir); C, F — Pristiograptus cf. auctus? Rickards; Sutkai-87 bore hole, 768.2 m depth, P.S87-362, deubeli Biozone; C — gen eral view, F — prox i mal end of rhabdosome; G — P. virbalensis; Virbalis-5 bore hole, depth 1026.75 m, holotype, no. 920, praedeubeli Biozone; H, I, J, K — P. jaegeri Hol land, Rickards et War ren; Vilkaviškis-131 bore hole, depth 1073.2 m, 8004, deubeli Biozone; H — gen eral view, I — dis tal part, J — me dial part, K — prox i mal part; L — P. auctus Rickards (1965) holotype, HUR./7W/46, text-fig. 2h, nilssoni–scanicus Biozone; in the orig i nal pic ture (Rickards, 1965) nei ther the scale nor the mag ni fi ca tion is given

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in clined at 30° in the prox i mal and at 40° in the dis tal part of rhabdosome (Paškevièius, 1974). The rhabdosome of P.

jaegeri (found in Lith u a nia) sud denly wid ens over the fourth theca (Fig. 8H). The free part of the sixth theca is no tice ably smaller than that of the other thecae. P. jaegeri from Arc tic Can ada looks sim i lar to this (Lenz and Koz³owska- Dawidziuk,

2002, pl. 17, fig. 6). The sicula of P. jaegeri is sim i lar to the sicula of Pristiograptus virbalensis type and is close to the dubius type, but not to the deubeli (ludensis) type. This spe cies dif fers slightly from other pristiograptids of virbalensis type.

The virgella of the virbalensis type is ob tuse while that of P.

jaegeri is sharp, but mas sive. Lenz (Lenz and Koz³owska-

Fig. 9. Draw ings of monograptids from Lith u a nia and the Holy Cross Mts. near the Wen lock-Lud low bound ary A — Pristiograptus praedeubeli (Jae ger); Šiupyliai-69 bore hole, 994.1 m depth, praedeubeli Biozone, S.S69-34; B — P.

praedeubeli; Šiupyliai-69 bore hole, 992 m depth, praedeubeli Biozone, S.S69-80; C — P. deubeli (Jaegeri) with dis tinct dor - sal pro cess (dp); Vilkaviškis-131 bore hole, 1069.2 m depth, deubeli Biozone, S.V131-378; D — Colonograptus gerhardi Kühne; Holy Cross Mts., out crop A06, nilssoni Biozone, SV-06-2; E — P. cf. auctus Rickards with virgella nub (v);

Sutkai-87 bore hole, 769.2 m depth, praedeubeli Biozone, no P.S87-126; F — P. virbalensis with dis tinct dor sal pro cess (dp);

Sutkai-87 bore hole, 769.2 m depth, praedeubeli Biozone, P.S87-125; G — P. virbalensis with virgella nub (v), ap er tures an - gle (b) — the an gle be tween the thecal ap er tural lip and the suc ceed ing metathecal wall; Pašaltuonis-143 bore hole, 765.3 m depth, praedeubeli Biozone, S.P143-181; H — C. gerhardi; Šiupyliai-69 bore hole, 976.7 m depth, ludensis Biozone, S.S69-285; I — P. deubeli with bro ken sicula; Šiupyliai-69 bore hole, 982.6 m depth, deubeli Biozone, S.S69-348; J — C.

gerhardi, Šiupyliai-69 bore hole, 976.7 m depth, ludensis Biozone, S.S69-285a

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Dawidziuk, 2002) at trib utes P. jaegeri to the group type (dubius/jaegeri), emphasising that this spe cies is in ter me di ate be tween P. dubius and P. praedeubeli. P. jaegeri is found in the up per part of the lundgreni Biozone to the nilssoni Biozone in North Wales (Hol land et al., 1969). In Arc tic Can ada this spe cies is found in the nassa–dubius–ludensis in ter val (Lenz and Koz³owska- Dawidziuk, 2002). Ulst (1974) de scribed Pristiograptus sp. A in Lat via and con sid ered it to be P.

jaegeri. The ap pear ance of P. sp. A. co in cides with the ex tinc - tion of G. nassa. This spe cies (P. sp. A) dis ap peared be fore the ap pear ance of N. nilssoni and Monograptus uncinatus. While in ves ti gat ing Ulst’s col lec tion of graptolites autor con cluded that some P. sp. A. spec i mens are P. praedeubeli. In Lith u a nia P. jaegeri is found in the deubeli Biozone in the Vilkaviškis-131 bore hole.

The pristiograptids of the virbalensis group evolved from, those of dubius type at the be gin ning of the praedeubeli Biozone. The virgella of dubius type pristiograptids be came more mas sive and thicker at the end of the nassa Biozone. The praedeubeli Biozone in cludes P. virbalensis pos sess ing an ob - tuse virgella with a clear drop-shaped thick en ing at its end, sim i lar to that of P. auctus. It is pos si ble that P. auctus evolved from P. virbalensis at the be gin ning of Lud low time. In deubeli Biozone some P. virbalensis spec i mens have dis tinctly wider sicula ap er tures (Fig. 9F), re sem bling the fun nel shape of P.

deubeli, but they are smaller. The other mor pho log i cal fea tures are sim i lar to P. virbalensis.

CONCLUSION

The graptolite as sem blages around the Wen lock-Lud low bound ary in Lith u a nia (west part of Baltica) and the Holy Cross Moun tains (Ma³opolska Block, Kielce Unit) are very sim i lar.

The fol low ing graptolite biozones may be rec og nized in Lith u -

a nia and the Holy Cross Moun tains: lundgreni, parvus (ex cept for the Holy Cross Mts.), nassa, praedeubeli, deubeli, and ludensis. The up per bound ary of the lundgreni Biozone is marked by the ex tinc tion of C. lundgreni, P. pseudodubius and M. f. flemingi. M. t. tes tis and P. lodenicensis dis ap pear ear lier than C. lundgreni in Lith u a nia. There is a graptolite-free in ter - val (at trib uted to the parvus Biozone) about 2 m thick be tween the last C. lundgreni and the first P. parvus. We may cor re late this graptolite-free in ter val with the “in ter val with trilobites” in the Holy Cross Moun tains and with the Bara Oolite in Gotland.

The virbalensis group of pristiograptids is pres ent at the Wen lock-Lud low bound ary in Lith u a nia and the Holy Cross Mts. Three spe cies of the virbalensis group are found in the nassa–nilssoni biozones: P. jaegeri, P. virbalensis and P.

auctus. P. virbalensis may be in ter preted ei ther as an in de pend - ent taxon, or as a sub spe cies of P. auctus. Vari a tions of P.

virbalensis (sicula with dor sal pro cess, short virgella) are found at the end of the praedeubeli Biozone and the deubeli Biozone, rep re sent ing the evo lu tion of short-lived group.

Ac knowl edge ments. Prof. J. Paškevièius (Vilnius Uni ver - sity, Lith u a nia) is thanked for valu able com ments dur ing the prep a ra tion of the pa per. Dr. P. Raczyñski (Wroc³aw Uni ver - sity) helped with col lect ing graptolites in the Holy Cross Moun tains; prof. L. Jeppsson (Lund Uni ver sity) shared his col - lec tion of graptolites from Gotland; dr. A. Èeèys and T. Miyazu (Lund Uni ver sity) helped in pho to graph ing graptolites by SEM. J. StasevièiñtÅ–RadzevièienÅ and dr. J. Zalasiewicz (Uni ver sity of Leicester) are ac knowl edged for im prove ment of the Eng lish of the manu script. The re search was sup ported by the Es to nian Min is try of Ed u ca tion and Re search (No.

0182531s03), the Es to nian Sci ence Foun da tion (grant No.

6460) and the Swed ish In sti tute. The ef forts of the re view ers of this pa per, dr A. Koz³owska (Warszawa) and an anon y mous re - viewer, are highly ap pre ci ated.

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