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Estonian Journal of Earth Sciences
ISSN 1736-7557 (Electronic)
ISSN 1736-4728 (Print)
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Anatomy of the Silurian thelodont Phlebolepis elegans Pander; pp. 261–276
PDF | doi: 10.3176/earth.2012.4.06

Mark V. H. Wilson, Tiiu Märss

The Silurian thelodont Phlebolepis elegans Pander from Saaremaa, Estonia, is one of the most-often illustrated early vertebrates, yet its external morphology has remained poorly known and experts seldom agree about its probable body form. We examined hundreds of articulated specimens from the type locality (Himmiste Quarry) to reconstruct its morphological features. We found that a reconstruction published more than four decades ago by A. Ritchie was the best available till now. We disagreed mostly in that the mouth is not terminal, but subterminal, and there is a slight development of a rostrum dorsal to the mouth. The pectoral fin originates close behind the orbits, but is otherwise similar to Ritchie’s reconstruction. We also found the caudal fin to be much larger, more flexible and more symmetrical (though not perfectly symmetrical) than earlier reconstructions, with a large dorsal lobe and an even larger ventral lobe, and a fin web supported by slender ‘ray-like’ scale-covered lobes. The shape, number and location of the branchial openings are notably still not certainly known. Our preferred morphological features are represented by an artist’s restoration. With this revised understanding, future representations of Phlebolepis elegans can be based on more reliable information and its morphology can be compared more accurately with that of other early vertebrates.


Berg, L. S. 1937. A classification of fish-like vertebrates. Bulletin de’l Académie des Sciences de l’URSS. Classe des sciences mathématiques et naturelles, 1937, 1277–1280 [in English and Russian].

Berg, L. S. 1940. Sistema ryboobraznykh i ryb, nyne zhivushchikh i iskopaemykh [Classification of Fish-like and Fishes, Recent and Fossil]. Trudy Zoologicheskogo Instituta Akademii Nauk SSSR, 5, 87–517.

Berg, L. S. 1955. Sistema ryboobraznykh i ryb, nyne zhivushchikh i iskopaemykh [Classification of Fish-like and Fishes, Recent and Fossil]. 2-oe izdanie. Trudy Zoologicheskogo Instituta AN SSSR, 20, 1–286.

Blieck, A. & Janvier, P. 1999. Silurian–Devonian vertebrate dominated communities, with particular references to agnathans. In Paleocommunities: A Case Study from the Silurian and Lower Devonian (Boucot, A. & Lawson, J. D., eds), pp. 79–105. Cambridge University Press.

Blom, H., Märss, T. & Miller, G. C. 2002 (for 2001). Silurian and earliest Devonian birkeniid anaspids from the Northern Hemisphere. Transactions of the Royal Society of Edinburgh: Earth Science, 92, 263–323.

Bystrow, A. P. 1949. Phlebolepis elegans Pander. Doklady Akademii Nauk SSSR, 64, 245–247.

Carroll, R. L. 1988. Vertebrate Paleontology and Evolution. W. H. Freeman & Company, New York, 698 pp.

Gross, W. 1967. Über Thelodontier-Schuppen. Palaeonto-graphica, A127, 1–67.

Gross, W. 1968. Porenschuppen und Sinneslinien des Thelodontiers Phlebolepis elegans Pander. Paläontologische Zeitschrift, 42, 131–146.

Hoppe, K.-H. 1931. Die Coelolepiden und Acanthodier des Obersilurs der Insel Ösel. Ihre Paläobiologie und Paläontologie. Palaeontographica, 76, 35–94.

Hoppe, K.-H. 1933. Phlebolepis elegans Pander aus dem Obersilur der Insel Ösel. Zentralblatt Mineralogie Geologie Paläontologie, 1933 (Abt. B2), 124–130.

Janvier, P. 1975. Remarques sur l’orifice naso-hypophysaire des céphalaspidomorphes. Annales de Paléontologie (Vertébrés), 61, 1–16.

Karatajūte-Talimaa, V. 1978. Telodonty silura i devona SSSR i Spitsbergena [Thelodonts of the Silurian and Devonian of the USSR and Spitsbergen]. Mokslas, Vilnius, 334 pp.

Kiaer, J. (ed. by Heintz, A.). 1932. New coelolepids from the Upper Silurian of Oesel (Esthonia). Publications of the Geological Institution of the University of Tartu, 27, 1–8.

Luha, A. 1940. Uusi ostrakoderme Saaremaa Eurypterus-lademest [New Ostracoderms from the Eurypterus-Beds of Saaremaa]. Eesti Loodus, 1, 17–24 [in Estonian].

Märss, T. 1979. Lateral line sensory system of the Ludlovian thelodont Phlebolepis elegans Pander. ENSV TA Toimetised, Geoloogia, 28, 108–111 [in Russian, with English summary].

Märss, T. 1986a. Squamation of the thelodont agnathan Phlebolepis. Journal of Vertebrate Paleontology, 6, 1–11.

Märss, T. 1986b. Silurian vertebrates of Estonia and West Latvia. Fossilia Baltica, 1, 1–104 [in Russian, with extended English summary].

Märss, T. 2006. Exoskeletal ultrasculpture of early agnathans and fishes. Journal of Vertebrate Paleontology, 26, 235–252.[235:EUOEV]2.0.CO;2

Märss, T. & Ritchie, A. 1998. Silurian thelodonts (Agnatha) of Scotland. Transactions of the Royal Society of Edinburgh, 88, 143–195.

Märss, T. & Wilson, M. V. H. 2008. Buccopharyngo-branchial denticles of Phlebolepis elegans Pander (Thelodonti, Agnatha). Journal of Vertebrate Paleontology, 28, 601–612.[601:BDOPEP]2.0.CO;2

Märss, T., Perens, H. & Klaos, T. 2003. Sedimentation of the Himmiste-Kuigu fish bed (Ludlow of Estonia), and taphonomy of the Phlebolepis elegans Pander (Thelodonti) shoal. Proceedings of the Estonian Academy of Sciences, Geology, 52, 239–264.

Märss, T., Wilson, M. V. H. & Thorsteinsson, R. 2006. Silurian and Lower Devonian thelodonts and putative chondri-chthyans from the Canadian Arctic Archipelago. Special Papers in Palaeontology, 75, 1–144.

Märss, T., Turner, S. & Karatajūte-Talimaa, V. 2007. “Agnatha” II (Thelodonti). Handbook of Paleoichthyology, vol. 1B (Schultze, H.-P., ed.). Pfeil, Munich, 143 pp.

Obruchev, D. V. 1964. Podklass Thelodonti (Coelolepides). In Osnovy Paleontologii. Beschelyustnye, Ryby [Fundamentals of Palaeontology. Agnathans, Fishes] (Obruchev, D. V., ed.), pp. 39–44. Nauka, Moscow [in Russian].

Pander, C. H. 1856. Monographie der fossilen Fische der silurischen Systems der Russisch-Baltischen Gouvernements. Obersilurische Fische. Buchdruckerei der Kaiserlichen Akademie des Wissenschaften, St. Petersburg, 91 pp.

Ritchie, A. 1968. Phlebolepis elegans, an Upper Silurian thelodont from Oesel, with remarks on the morphology of thelodonts. In Current Problems of Lower Vertebrate Phylogeny. 4th Nobel Symposium, Stockholm (Ørvig, T., ed.), pp. 81–88. Wiley Interscience, New York.

Robertson, G. M. 1938. The Tremataspidae. Parts I and II. American Journal of Science, 35, 172–296.

Soehn, K. L. & Wilson, M. V. H. 1990. A complete, articulated heterostracan from Wenlockian (Silurian) beds of the Delorme Group, Mackenzie Mountains, Northwest Territories, Canada. Journal of Vertebrate Paleontology, 19, 405–419.

Stensiö, E. A. 1964. Les Cyclostomes fossiles ou ostracodermes. In Traité de Paléontologie, vol. 4 (Piveteau, J., ed.), pp. 96–382, Masson, Paris.

Tinn, O., Meidla, T., Ainsaar, L. & Pani, T. 2009. Thallophytic algal flora from a new Silurian Lagerstätte. Estonian Journal of Earth Sciences, 58, 38–42.

Turner, S. 1991. Monophyly and interrelationships of the Thelodonti. In Early Vertebrates and Related Problems of Evolutionary Biology (Chang Mee-mann, Liu Yu-hai & Zhang Guo-rui, eds), pp. 87–119. Science Press, Beijing.

Westoll, T. S. 1945. A new cephalaspid fish from the Down­tonian of Scotland, with notes on the structure and classification of ostracoderms. Transactions of the Royal Society of Edinburgh, 61, 341–357.

Wilson, M. V. H. & Caldwell, M. W. 1993. New Silurian and Devonian fork-tailed ‘thelodonts’ are jawless vertebrates with stomachs and deep bodies. Nature, 361, 442–444.

Wilson, M. V. H. & Caldwell, M. W. 1998. The Furcacaudi­formes: a new order of jawless vertebrates with thelodont scales, based on articulated Silurian and Devonian fossils from northern Canada. Journal of Vertebrate Paleonto­logy, 18, 10–29.

Wilson, M. V. H. & Märss, T. 2004. Toward a phylogeny of the thelodonts. In Recent Advances in the Origin and Early Radiation of Vertebrates (Arratia, G., Wilson, M. V. H. & Cloutier, R., eds), pp. 95–108. Verlag Dr. Friedrich Pfeil, Munich.

Wilson, M. V. H. & Märss, T. 2005. Anatomy of the Silurian thelodont Phlebolepis elegans Pander. Journal of Vertebrate Paleontology, 27 (Supplement to No. 3), 130A–131A.

Wilson, M. V. H., Märss, T. & Hanke, G. F. 2007. Paired fins of jawless vertebrates and their homologies across the agnathan–gnathostome transition. In Major Transitions in Vertebrate Evolution (Sues, H.-D. & Anderson, J., eds), pp. 122–149. Indiana University Press, Bloomington, Indiana.

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