Upper Silurian thelodonts from Severnaya Zemlya Archipelago (Russia) Valentina KARATAJŪTĒ-TALIMAA Institute of Geology of Lithuania, S˘ evc˘ enkos 13, Vilnius LR 2600 (Lithuania) [email protected] Tiiu MÄRSS Institute of Geology, Tallinn Technical University, 7 Estonia Avenue, Tallinn 10143 (Estonia) [email protected] Karatajūtē-Talimaa V. & Märss T. 2002. — Upper Silurian thelodonts from Severnaya 406 Zemlya Archipelago (Russia). Geodiversitas 24 (2) : 405-443. ABSTRACT Thelodonts have been found in the Bol’shaya, Matusevich, Obryvistaya, Pod”emnaya, Spokojnaya, Ushakov rivers and Cape October sections of October Revolution Island, and Komsomolets and Pioneer islands sections, Severnaya Zemlya Archipelago, Russia. Two new families, one new genus and six new species belonging to the orders Katoporida and Thelodontida are described from the Upper Silurian. Seven taxa are re-described. Scattered scales of Loganellia cuneata (Gross, 1947), Paralogania ex gr. martinssoni (Gross, 1967), Paralogania menneri n. sp., Valiukia flabellata n. gen., n. sp., Phlebolepis elegans Pander, 1856, Thelodus visvaldi n. sp., Thelodus matukhini n. sp., Thelodus ex gr. schmidti (Pander, 1856), Thelodus sp. indet. and Lanarkia? sp. are characteristic for the Ludlow part of the sequence (Ust-Spokojnaya Formation of October Revolution Island and its analogue on Pioneer and Komsomolets islands). Thelodus parvidens(?), Loganellia cuneata, Paralogania wilsoni n. sp., P. kachanovi n. sp., Paralogania sp. cf. ū ē KEY WORDS P. borealis (Karataj t -Talimaa, 1978), Goniporus alatus (Gross, 1947) and Thelodonti, Nikolivia elongata Karatajūtē-Talimaa, 1978 are distributed in the sections Upper Silurian, of Krasnaya Bukhta Formation on October Revolution Island and coeval Severnaya Zemlya Archipelago, scale morphology, strata of Pioneer Island (Pridoli). Thelodus visvaldi n. sp. is also present in histology. Wenlock of Pioneer Island. GEODIVERSITAS • 2002 • 24 (2) © Publications Scientifiques du Muséum national d’Histoire naturelle, Paris. www.mnhn.fr/publication/ 405 Karatajūtē-Talimaa V. & Märss T. RÉSUMÉ Thélodontes du Silurien supérieur de l’Archipel de Severnaya Zemlya (Russie). Des Thélodontes ont été récoltés dans les vallées des rivières Bol’shaya, Matusevich, Obryvistaya, Pod”emnaya, Spokojnaya, Ushakov ainsi que dans les sections du Cap Octobre de l’Île de la Révolution d’Octobre et des îles Komsomolets et Pionnier. Deux nouvelles familles, un nouveau genre et six nouvelles espèces du Silurien supérieur appartenant aux ordres des Katoporida et des Thelodontida sont décrits. Sept taxons sont redécrits. Les écailles isolées de Loganellia cuneata (Gross, 1947), Paralogania ex gr. mar- tinssoni (Gross, 1967), Paralogania menneri n. sp., Valiukia flabellata n. gen., n. sp., Phlebolepis elegans Pander, 1856, Thelodus visvaldi n. sp., Thelodus matukhini n. sp., Thelodus ex gr. schmidti (Pander, 1856), Thelodus sp. indet. et Lanarkia ? sp. sont caractéristiques de la partie Ludlow de la séquence (Formation Ust-Spokojnaya de l’Île de la Révolution d’Octobre, et son homologue des îles Pionnier et Komsomolets). Thelodus parvidens (?), Loganellia cuneata, Paralogania wilsoni n. sp., P. kachanovi n. sp., Paralogania sp. cf. P. borealis (Karatajūtē-Talimaa, 1978), Goniporus ū ē MOTS CLÉS alatus (Gross, 1947) and Nikolivia elongata Karataj t -Talimaa, 1978 sont Thelodonti, distribuées dans les sections de la Formation de Krasnaya Bukhta de l’Île de Silurien supérieur, la Révolution d’Octobre et dans les strates équivalentes de l’Île Pionnier Archipel de Severnaya Zemlya, morphologie des écailles, (Pridoli). Thelodus visvaldi n. sp. est également présent dans le Wenlock de histologie. l’Île Pionnier. INTRODUCTION represented in the Krasnaya Bay and Spokojnaya River area of the eastern part of the October Isolated scales of thelodonts have been found at Revolution Island (see Märss & Karatajūtē- numerous levels in the Upper Silurian sequence Talimaa 2002: fig. 1). of the October Revolution, Pioneer and The Silurian of Pioneer Island was discovered Komsomolets islands of Severnaya Zemlya and studied by B. A. Klubov and E. I. Kachanov Archipelago. The research level of the deposits during a field trip in 1976 (Klubov et al. 1980: varies in the sections. The interval between sam- fig. 1, I-II, III and V areas). The 210 m thick ples was different and therefore there is an beds of dolomitic and oncolitic limestones were incomplete picture of the vertical distribution of dated as Ludlow (members 1-2 of the I-II and thelodont species and assemblages even from III areas), and a 90 m thick complex (member 3 the main Upper Silurian sections on October of the V area) was treated as Pridoli. Samples Revolution Island. The upper part of the Ust- with vertebrate microremains of these rocks Spokojnaya Formation (Ludlow) on the banks were given to V. Karatajūtē-Talimaa and identi- of the Matusevich River (outcrop 2) is the best fications made by her were also included. one. The samples from the Ludlow part of the New and previously known data on vertebrate deposits croping out on the Ushakov and microremains, mainly thelodonts, and cono- Spokojnaya rivers also yielded a great number donts allows a precise dating of the Silurian of well preserved scales. Thelodonts of Ludlow deposits. Based on conodonts (Männik 2002), a age were discovered in the rocks of October considerable part of the Lower Silurian (mem- Cape (sample MF 34-1, formation not defined). bers 1-4) corresponds to the middle? and upper The Krasnaya Bukhta Formation, Pridoli, is Llandovery. Member 7 (40 m thick), because of 406 GEODIVERSITAS • 2002 • 24 (2) Upper Silurian thelodonts from Severnaya Zemlya Archipelago -Talimma, 2002 -Talimma, ē t ū (Gross, 1967) (Gross, (Pander, 1856) (Pander, n. sp. Series Märss & Karataj Member (?) Agassiz, 1839 Samples Ozarkodina confluens (Gross, 1947) (Gross, martinssoni n. sp. schmidti Thickness (m) sp. ex gr. ex gr. sp. indet. sp. indet. n. sp. 1 sp. indet. (Viira, 1983) (Viira, sp. (n. sp.?) ex. gr. ex. gr. Samples with thelodonts D1 (Lochk) Valiukia Area Thelodonti indet. Loganelliidae indet. Loganellia Paralogania kachanovi Loganellia Paralogania Thelodus cf. Loganellia cuneata Paralogania Paralogania klubovi Thelodus visvaldi bucerus Thelodus Thelodus parvidens Apsidognathus 12 V 3 90 90 8-E 2 100 9-E 9-ж 8-д-1 5-M, 5M-1 100- 200-210 1 110 6-Б 6-A 8-г,8-г-1 740 8г-2 III I-II ? 5-д 5-и, 5-K 5-B 5-г-2 6 100 5-K,5ж-1 5-E,5E-2 5-A SILURIAN4-E SYSTEM 570 4-д,4д-1 ? 4-г 4504-B 330>460 4-A,Б 3 I 2-Xи 2-K-2 2 100 2- 2-ж 2-д 2-B 2-A Llandovery Wenlock Ludlow7-A Pridoli 10-B 1 70 10-A 7-Б I-II ? 1234 5678 FIG. 1. — Distribution of thelodonts in the Silurian section of Pioneer Island; 1, sandstone; 2, sandstone and silty sandstone; 3, argillite; 4, biomorphic limestone; 5, dolomite; 6, dolomitic limestone; 7, oolitic limestone; 8, stromatoporoidal limestone (after Klubov et al. 1980: fig. 2; modified). Cyrillic letters in fig. 2 of Klubov et al. 1980 are in present paper transliterated as follows: A = a; Б = b; B = v; г = g; д = d; E = e; 3 = zh; и = i; K = k; M = m; H = kh. the enclosed vertebrate species, can be treated as pared with that in Klubov et al. (1980). Most Ludlow and not as Wenlock. In this way, the likely, only members 5 and 6 (170 m thick in the volume of the latter is strongly reduced if com- III area) can be attributed to the Wenlock. GEODIVERSITAS • 2002 • 24 (2) 407 Karatajūtē-Talimaa V. & Märss T. In Fig. 1 the distribution of thelodonts in the Loganellia cuneata (Gross, 1947) Silurian of Pioneer Island is given. The litholog- (Fig. 2J-R) ical column, the number of samples and areas are as they were given in Klubov et al. (1980: MATERIAL EXAMINED. — About 50 scales from the Ust-Spokojnaya Formation, Ludlow, and over 100 fig. 2). Some samples did not yield phosphatic scales from the Pridoli part of the sequence. remains or they were not studied. In addition, the material of the expedition of E. N. Lenkin to Pioneer Island in 1974 was used to determine REMARKS the Ludlow thelodont assemblages. Scales of The synonymy of Loganellia cuneata s.l. is thelodonts were also found in a few rock sam- given by Turner (1976) and Märss (1986). ples from Komsomolets Island (samples col- Karatajūtē-Talimaa (1978) described Loganellia lected by A. F. Khapilin in 1974). They all come (= Logania) cuneata from the Pridoli of North from the Ludlow part of the Upper Silurian. Timan. The scales with postero-lateral spines of The formations distinguished within the the crown were not included in the morphologi- Silurian of October Revolution Island cannot cal set of this species (L. cuneata s.str.). Later with certainty be traced on the other islands of Karatajūtē-Talimaa (1997) revised the taxonomy the archipelago but series are determined and of loganelliid thelodonts and gave morphologi- correlated by thelodonts and other early verte- cal criteria for the genera Loganellia and brates. Paralogania. To the genus Loganellia were Distribution of thelodont taxa in the Ordovician ascribed only forms having a squamation of to Devonian sections of October Revolution and simple, ribbed scales as described by Gross Srednij islands is given in the paper by Märss & (1947, 1967). Karatajūtē-Talimaa (2002: fig. 1). Distribution of outcrops and stratigraphical subdivision of the DESCRIPTION AND COMMENTS Upper Silurian series on Severnaya Zemlya is Rare scales of Loganellia cuneata associated reported by Männik et al. (2002). with numerous scales of the genus Paralogania (P. ex gr. martinssoni and P. menneri n. sp.) in the samples 2-23, and 47-14 on October SYSTEMATICS Revolution Island, and in the sample 5d on Pioneer Island of Ludlow part of the sections. In this work the thelodonts taxonomy estab- L. cuneata scales are better represented in the lished by Gross (1967) and Karatajūtē-Talimaa Krasnaya Bukhta Formation of October (1978, 1997) has been used.