DISSERTATIONES GEOLOGICAE UNIVERSITATIS TARTUENSIS 11 MORPHOGENESIS AND PHYLOGENETIC RELATIONSHIPS OF CLITAMBONITIDINES, ORDOVICIAN BRACHIOPODS OLEV VINN TARTU 2001 DISSERTATIONES GEOLOGICAE UNIVERSITATIS TARTUENSIS 11 MORPHOGENESIS AND PHYLOGENETIC RELATIONSHIPS OF CLITAMBONITIDINES, ORDOVICIAN BRACHIOPODS OLEV VINN TARTU UNIVERSITY PRESS Institute of Geology, Faculty of Biology and Geography, University of Tartu, Estonia. The Faculty Council of Biology and Geography, University of Tartu, has on January 19, 2001 accepted this dissertation to be defended for the degree of Doctor of Philosophy (in Geology). Opponent: Prof. Lars Holmer, University of Uppsala, Sweden. The thesis will be defended at the University of Tartu, Estonia, on March 19, 2000. Publication of this dissertation is granted by the Institute of Geology, University of Tartu. © Olev Vinn, 2001 Tartu Ülikooli Kirjastuse trükikoda Tiigi 78, Tartu 50410 Tellimus nr. 80 DISSERTATIONES GEOLOGICAE UNIVERSITATIS TARTUENSIS CONTENTS LIST OF ORIGINAL PUBLICATIONS........................................................ 6 ABSTRACT ..................................................................................................... 7 INTRODUCTION ............................................................................................. 8 CHAPTER 1. GENERA AND DISTRIBUTION.......................................... 10 CHAPTER 2. MORPHOLOGY ..................................................................... 14 CHAPTER 3. CLASSIFICATION ................................................................. 19 CHAPTER 4. PALAEOBIOGEOGRAPHY AND PALAEOECOLOGY ... 30 CHAPTER 5. CONCLUSIONS ...................................................................... 31 ACKNOWLEDGEMENTS.............................................................................. 32 REFERENCES .................................................................................................. 33 SUMMARY IN ESTONIAN: Ordoviitsiumi klitambonitiidsete käsijalgsete morfogenees ja fülogeneetilised seosed..................................................... 36 PUBLICATIONS............................................................................................... 37 1 LIST OF ORIGINAL PUBLICATIONS The present thesis is based on the following original papers which are referred to by their Roman numerals: I Vinn, O. and Rubel, M. 2000. The spondylium and related structures in the clitambonitidine brachiopods. Journal of Paleontology 74 (3), pp. 439^443. II Vinn, O. and Spjeldnaes, N. 2000. Clitambonitidine Brachiopods from the Middle and Upper Ordovician of the Oslo Region, Norway. Norsk Geo- logisk Tidsskrift, 80, pp. 275-288. III Popov, L., Vinn, O., Nikitina, O. (in press). Brachiopods of the redefined family Tritoechiidae from the Ordovician of Kazakhstan and South Urals. Geobios. IV Vinn, O. (in press). The occurrence of new subspecies of the clitambo­ nitidine brachiopod Estlandia catellatus (Öpik) in the Middle Ordovician of Osmussaar Island, Estonia. TA Toimetised, Geoloogia. ABSTRACT Clitambonitidine brachiopods have been studied since the 19th century. They constitute a peculiar group of brachiopods, often endemic to the Baltic, and limited to the Ordovician. According to the latest classification in the Treatise, clitambonitidines embrace 32 valid genera and one new Korinevskia gen.n. The study of juvenile shells of clitambonitidines resulted in the discovery of growth patterns of their ventral muscle attachment structure (spondylium). Spondylium evolved not by convergence of dental plates as previously believed, but is de­ rived from free spondylium, which lack the supporting median septum charac­ teristic for protorthids. Spondylium bearing (without dental plates) clitamboni­ tidines dorsal articulation structures resembles also those of Middle Cambrian arctohedrids (portorthid brachiopods). The Clitambonitidina is not mono- phyletic: Clitambonitoidea and Polytoechoidea are derived distantly related ancestors. 7 INTRODUCTION Clitambonitidines form a distinctive group of brachiopods limited to rocks of Ordovician age. Although widely distributed in the shallow seas of the time, clitambonitidines are particularly associated with the Baltic fauna of Estonia and western Russia (Ingria), which are key areas for the study of these brachiopods (Rubel and Wright 2000). The globally widespread clitambonitid brachiopods have been recognised for a long time, first described in the Baltic in the 19th century. Conceptions of the taxonomic content and evolutionary ideas of this group have changed through­ out more than a hundred years of research. Thus, Baltic clitambonitids were described as endemic brachiopods to this region. However, claims have been made that similar Ordovician brachiopods are related to Baltic clitambonitids. Several stocks have been included and excluded from the clitambonitids, so there has been no generally accepted concept of what constitutes a clitambo­ nitid. In his basic monograph “Über Klitamboniten,” Öpik (1934) established the systematics and basic concept of clitambonitid morphology. According to the Opik’s vision, the clitambonitidines in addition to the Baltic representatives, Estlandiidae, Kullervoidea, Clitambonitiidae sensu Öpik (1934) also include the following non-Baltic, somewhat different Polytoechiidae, Finkelnburgiidae and Skenidiidae. Interestingly, the presence of a raised spondylium triplex-like ventral muscle field in Polytoechia led Öpik to include this genus in the family Estlandiidae (see Öpik 1934, p. 76). The next wholesale revision of the clitambonitidines was by Williams (1965), in which three types of spondylium were introduced, and groups with some orthid features (finkelnburgiids and skenidioids) were excluded. Recently, Wright and Rubel (1996) revised the morphology of clitambo­ nitids to reflect the relationships between themselves as well as with other early •barchiopods. However, in a subsequent classification, Rubel and Wright (2000), proposed only two clades, Polytoechioidea and Clitambonitoidea, the latter with two families, Clitambonitidae and Gonambonitidae, leaving open the use of other structures as well as their phylogenetic analysis with recent tools. The task of this research was to describe clitambonitidine morphological diversity by encompassing all morphological features in all genera, and to study the critical yet poorly understood ontogeny of the shell using available and new collections, especially those of the earliest representatives, in order to clarify phylogenetic relationships between the clitambonitidines themselves and their possible ancestors. The revision of the morphological structures was based on rich and excep­ tionally well-preserved collections of Baltic clitambonitoids and related brachiopods which allowed re-evaluation of the understanding of some struc­ tures (spondylium, delthyrial covers, shell material, cardinalia, vascular marks) including their ontogeny on direct observations of neanic specimens, serial sectioning and SEM microscopy. The main collections on the Clitambonitoidea studied include those of the Baltic and Ingermanland Ordovician housed in the geological museum of The University of Tartu, Geological Institute of Tallinn Technical University, State University of Petersburg, The Natural Museum of London, and The Museum of Natural History in Stockholm. The following were described from new collections: Middle Ordovician clitambonitoids from Norway (Vinn and Spjeldnaes 2000 — PAPER П), Ordovician polytoechioids from Kazakhstan and the southern Urals (Popov et al. in press — PAPER Ш), as well as one Middle Ordovician species from Estonia (Vinn in press — PAPER IV). 3 9 CHAPTER 1. THE GENERA AND DISTRIBUTION Williams (1965) recorded 31 generic names that had been ascribed to clitambo­ nitidines, of which 23 were considered to be valid. According to the data set of Rex Doescher, recently modified by Thomas Dutro and Maurice Grolier, Smithsonian Institution, Washington D. C., 43 generic names are currently ascribed to the Clitambonitidina. Of these the genus Eosotrematorthis Wang (1955, p. 336, type species E. sinensis) was transferred to the suborder Orthidina soon after its description (see Williams, 1965). Similarly, the genus D jin d ella Menakova (1991, p. 26, type species D. p la n a ) with its bifurcated cardinal process and pseudopunctate shell substance is associated more appro­ priately with strophomenid brachiopods. The systematic position of the genus Anomalorthis Ulrich and Cooper (1936, p. 622, type species A. utahensis) may be the most controversial, and its relationship with other clitambonitidines, especially genera Progonambonites and Oslogonites (see Williams 1965, p. H355), has not been confirmed by analysis of overall similarity and phyloge­ netic relationships. According to its orthid cardinalia, exceptionally fine radial costellation and fibrous shell substance with atypical pseudopunctae, the affinities of this genus are more likely to lie with the orthidines rather than the clitambonitidines (see Cooper 1956, p. 391; Wright and Rubel 1996). There are four objective and four subjective synonyms among the remaining 40 generic names. The generic rank and content of species of the genus H em i- p ro n ite s Pander, 1830 have been changed from that of Schuchert and Cooper (1932) to the concepts of Öpik (1934) and Williams (1965). The well-preserved deltidial covers in some specimens of the genus Progonambonites Öpik 1934 suggests it is congeneric with the genus Gonambonites Pander 1830