Abstract
The Phylum Echinodermata, comprising approximately 7,000 living species, and 13,000 fossil species, is epitomized by the familiar sea star, a universal symbol of the marine realm. This distinctive group of animals may be briefly defined as possessing a skeleton of calcium carbonate in the form of calcite; a unique water-vascular system which mediates feeding, locomotion, and other functions; and a more or less conspicuous five-part radial symmetry. A closer look at some extant echinoderms will show that some taxa of sea cucumbers lack calcite in their body walls, some taxa of sea stars have “outgrown” five-part symmetry and may have 50 or more arms, and many echinoderms show a more or less conspicuous bilateral symmetry superimposed upon a radial pattern. Fossil echinoderms can be even more puzzling, for some are decidedly asymmetrical, and others may lack evidence of a water-vascular system. Perhaps the only truly reliable taxonomic character of the phylum is that its members today are restricted to the marine realm.
References
Ausich, W. (1998) Early phylogeny and subclass division of the Crinoidea (Phylum Echinodermata). Journal of Paleontology, 72(3), 499–510.
Ausich, W. (1999) Origin of crinoids. In: Candia Carnevali, M.D.C. & Bonasoro, F. (Eds.) Echinoderm research 1998. Balkema, Rotterdam, pp. 237–242.
Ausich, W. & Kammer, T.W. (2001) The study of crinoids during the 20th century and the challenges of the 21st century. Journal of Paleontology, 75(6), 1161–1173.
Ausich, W. & Webster, G.D. (in press) Echinoderm paleobiology. Indiana University Press, Bloomington.
Baker, A.N. (2003) Concentricycloidea (sea daisies). In: Hutchins, M., Thoney, D.A. & Schlager, D. (Eds.) Grzimek’s Animal Life Encyclopedia, 2nd edition. Volume 1. Gale Group, Farmington Hills, Michigan, pp. 381–386.
Baker, A.N., Rowe, F.W.E. & Clark, H.E.S. (1986) A new class of Echinodermata from New Zealand. Nature, 321, 862–864.
Barker, M. (2001) Echinoderms 2000. Balkema, Lisse, 590 pp.
Bather, F.A. (1900) Part III The Echinoderma. In: Lankester, E.R. (Ed.) A Treatise on Zoology. Adam & Charles Black, London, pp. 1–344.
Belyaev, G.M. (1990) Is it valid to isolate the genus Xyloplax as an independent class of echinoderms? Zoologicheskii Zhurnal, 69, 83–96.
Blake, D.B. (1987) A classification and phylogeny of post-Paleozoic sea stars (Asteroidea: Echinodermata). Journal of Natural History, 21, 481–528.
Blake, D.B. (1989) Asteroidea: functional morphology, classification and phylogeny. In: Jangoux, M. & Lawrence, J.M. (Eds.) Echinoderm Studies 3. Balkema, Rotterdam, pp. 179–233.
Blake, D.B. (2000) The Class Asteroidea (Echinodermata): fossils and the base crown group. American Zoologist 40, 316–325.
Blake, D.B. & Elliott, D.R. (2003) Ossicular homologies, systematics, and phylogenetic implications of certain North American Carboniferous asteroids (Echinodermata). Journal of Paleontology, 77(3), 476–489.
Blake, D.B. & Hagdorn, H. (2003) The Asteroidea (Echinodermata) of the Muschelkalk (Middle Triassic) of Germany. Paläontologische Zeitschrift, 77, 23–58.
Blake, D.B. & Hotchkiss, F.H.C. (2004) Recognition of the asteroid (Echinodermata) crown group: implications of the ventral skeleton. Journal of Paleontology, 78(2), 359–370.
Blake, D.B., Janies, D.A. & Mooi, R. (2000) Evolution of starfishes: morphology, molecules, development, and paleobiology. Introduction to the symposium. American Zoologist, 40, 311–315.
Bourlat, S.J., Juliusdottir, T., Lowe, C.J., Freeman, R., Aronowicz, J., Kirschner, M., Lander, E.S., Thorndyke, M., Nakano, H., Kohn, A.B., Heyland, A., Moroz, L.L., Copley, R,R,, Telford, M.J. (2006) Deuterostome phylogeny reveals monophyletic chordates and the new phylum Xenoturbellida. Nature, 444, 85–88.
Bruguière, J.G. (1791) Tableau encyclopédique et méthodique de trois règnes de la nature, vol. 7. Contenant l’helminthologie, ou les vers infusoires, les vers intestins, les vers mollusques &c. Panckoucke, Paris.
Cameron, C.B., Garey, J.R. & Swalla, B.J. (2000) Evolution of the chordate body plan: new insights from phylogenetic analyses of deuterostome phyla. Proceedings of the National Academy of Sciences USA 97, 4469–4474.
Candia Carnevali, M.D. & Bonasoro F. (2001) Echinoderm Research 1998: proceedings of the Fifth European Conference on Echinoderms, Milan, Italy, 7–12 September 1998. Balkema, Rotterdam, 550 pp.
Cisternas, P., Selvakumaraswamy, P. & Byrne, M. (2004) Evolution of development and the Ophiuroidea – revisited. In: Heinzeller, T. & Nebelsick, J.H. (Eds.) Echinoderms: München. Taylor & Francis, London, pp. 521–526.
Clark, A.M. & Downey, M.E. (1992) Starfishes of the Atlantic. Chapman & Hall, London, 794 pages.
Cohen, B.L., Améziane, N., Eleaume, M. & Richer de Forges, B. (2004) Crinoid phylogeny: a preliminary analysis (Echinodermata: Crinoidea). Marine Biology, 44(3), 605–617.
Cuénot, L. (1948) Anatomie, éthologie et systématiques des echinoderms. In: Grasse, P.P. (Ed.) Traité de Zoologie, vol. XI. Masson, Paris, pp. 3–275.
David, B., Lefebvre, B., Mooi, R. & Parsley, R. (1999) Homalozoans in the light of the extraxial-axial theory of skeletal homologies. In: Candia Carnevali, M.D.C. & Bonasoro, F. (Eds.) Echinoderm research 1998. Balkema, Rotterdam, p. 319 .
David, J., Roux, M., Messing, C.G. & Ameziane, N. (2006) Revision of the pentacrinid stalked crinoids of the genus Endoxocrinus (Echinodermata, Crinoidea), with a study of environmental control of characters and its consequences for taxonomy. Zootaxa, 1156, 1–50.
Dean, J. (1999) What makes an ophiuroid? A morphological study of the problematic Ordovician stelleroid Stenaster and the paleobiology of the earliest asteroids and ophiuroids. Zoological Journal of the Linnean Society, 126, 225–250.
Dominguez-Alonso, P. (1999) The early evolution of echinoderms: the class Ctenocystoidea and its closest relatives revisited. In: Candia Carnevali, M.D.C. & Bonasoro, F. (Eds.) Echinoderm research 1998. Balkema, Rotterdam, pp. 263– 268.
Fell, H.B. (1948) Echinoderm embryology and the origin of chordates. Biological Reviews of the Cambridge Philosophical Society, 23, 81–107.
Fell, H.B. (1962) Evidence for the validity of Matsumoto's classification of the Ophiuroidea. Publications of the Seto Marine Biological Laboratory, 10, 145–152.
Fell, H.B. (1963) The evolution of echinoderms. Annual Report of the Smithsonian institution for 1962, 457–490.
Fell, H.B. & Pawson, D.L. (1966a) Order Diadematoida. In: R.C. Moore (Ed.) Treatise on Invertebrate Paleontology. Part U, Echinodermata 3(2). University of Kansas Press, Lawrence, pp. 350–365.
Fell, H.B. & Pawson, D.L. (1966b) Echinacea. In: R.C. Moore (Ed.) Treatise on invertebrate Paleontology. Part U, Echinodermata 3(2). University of Kansas Press, Lawrence, pp. 367–440.
Féral, J.-P. & David, B. (2001) Echinoderm research 2001. Balkema, Rotterdam, 337 pp.
Forey P.L., Fortey, R.A., Kenrick, P. & Smith, A.B. (2004) Taxonomy and fossils: a critical appraisal. Philosophical Transactions of the Royal Society. Series B. Biological Sciences, 359, 639–653.
Gale, A.S. (1987) Phylogeny and classification of the Asteroidea (Echinodermata). Zoological Journal of the Linnaean Society 89, 107–132.
Gilliland, P. (1992) Holothurians in the Blue Lias of southern Britain. Palaeontology, 35(1), 159–210.
Gilliland, P. (1993) The skeletal morphology, systematics and evolutionary history of holothurians. Special Papers in Palaeontology, 47, 1–147.
Haude, R. (2004) Mode of life of ophiocistioids (Echinozoa) according to plated and “naked” forms in the Rhenish Devonian. In: Heinzeller, T. & Nebelsick, J.H. (Eds.) Echinoderms: München. Taylor & Francis, London, pp. 417–420.
Heinzeller, T. & Nebelsick, J.H. (2004) Echinoderms: München. Balkema, Leiden, 633 pp.
Herringshaw, L.G., Smith, M.P. & Thomas, A.T. (2007) Evolutionary and ecological significance of Lepidaster grayi, the earliest multiradiate starfish. Zoological Journal of the Linnean Society, 150(4), 743–754.
Hess, H., Ausich, W., Brett, C.E. & Simms, M.J. (2003) Fossil crinoids. Cambridge University Press, Cambridge, UK, 292 pp.
Hotchkiss, F.H.C. (1977) Ophiuroid Ophiocanops (Echinodermata) not a living fossil. Journal of Natural History 11, 377–380.
Hotchkiss, F.H.C. (1993) A new Devonian ophiuroid (Echinodermata: Ophiuroidea) from New York State and its bearing on the origin of ophiuroid upper arm plates. Proceedings of the Biological Society of Washington, 106(1), 63–84.
Hotchkiss, F.H.C. (1995) Loven’s law and adult ray homologies in echinoids, ophiuroid, edrioasteroids, and an ophiocistioid (Echinodermata: Eleutherozoa). Proceedings of the Biological Society of Washington, 108(3), 401–435.
Hotchkiss, F.H.C. (2000) On the number of rays in a starfish. American Zoologist, 40, 340–354.
Hrincevich, A.W., Axayácatl, R.-O. & Foltz, D.W. (2000) Phylogenetic analysis of molecular lineages in a species-rich subgenus of sea stars (Leptasterias subgenus Hexasterias). American Zoologist, 40, 365–374.
Hyman, L.H. (1955) The invertebrates: Echinodermata. McGraw-Hill, New York, 763 pp.
Jagt, J.W.M. (1999) Ophiuroid diversity in the type area of the Maastrichtian Stage. Geologie en Mijnbouw, 78(2), 197–206.
Jangoux, M. & Lawrence, J.M. (2001) Echinoderm Studies 6. Taylor & Francis, London, 285 pp.
Janies, D. (2001) Phylogenetic relationships of extant echinoderm classes. Canadian Journal of Zoology, 79, 1232–1250.
Janies, D. & Mooi, R. (1999) Xyloplax is an asteroid. In: Candia Carnevali C. & Bonasoro F. (Eds.), Echinoderm Research 1998. Balkema, Rotterdam, pp. 311– 316.
Jefferies, R.P.S., Brown, N.A. & Daley, P.E.J. (1996) The early phylogeny of chordates and echinoderms and the origins of chordate left-right asymmetry and bilateral symmetry. Acta Zoologica, 77, 101–122.
Kasyanov, V.L. (2001) Reproductive strategy of marine bivalves and echinoderms. Science Publishers, Enfield, New Hampshire, 240 pp.
Kerr, A.M. (2001) Phylogeny of the apodan holothurians (Echinodermata) inferred rom morphology. Zoological Journal of the Linnean Society, 133, 53–62.
Kerr, A.M. & Kim, J. (1999) Bi-penta-bi-decaradial symmetry: a review of evolutionary and developmental trends in Holothuroidea (Echinodermata). Journal of Experimental Zoology, 285, 93–103.
Kerr, A.M. & Kim, J. (2001) Phylogeny of Holothuroidea (Echinodermata) inferred from morphology. Zoological Journal of the Linnean Society, 133, 63–81.
Kerr, A.M., Janies, D.A., Clouse, R.M., Samyn, Y., Kuszak, J., Kim, J. (2005) Molecular phylogeny of coral reef sea cucumbers (Holothuriidae: Aspidochirotida) based on 16S mitochondrial ribosomal DNA sequence. Marine Biotechnology, 7, 53–60.
Klein, J.T. (1734) Naturalis disposition echinodermatium. Accesseit Lucubratiuncula des aculeis echinorum marinorum, cun Spicilegio de belemnitis. Liutteris Schreiberianis, Gedani, 78 pp.
Knott, K.E. & Wray, G.A. (2000) Controversy and consensus in asteroid systematics: new insights to ordinal and familial relationships. American Zoologist 40, 382–392.
Kroh, A. (2004) First fossil record of the family Euryalidae (Echinodermata: Ophiuroidea) from the Middle Miocene of the central Mediterranean. In: Heinzeller, T. & Nebelsick, J.H. (Eds.) Echinoderms: München. Taylor & Francis, London, pp. 447–452.
Lacey, K.M.J., McCormack, G.P., Keegan, B.F. & Powell, R. (2005) Phylogenetic relationships within the class Holothuroidea, inferred from 18S rRNA gene data. Marine Biology, 147, 1149–1154.
Lafay, B., Smith A.B. & Christen, R. (1995) A combined morphological and molecular approach to the phylogeny of asteroids (Asteroidea: Echinodermata). Systematic Biology, 44(2), 190–208.
Lamarck, J.B.P. (1801) Système des animaux sans vertèbrès. Maillard, Paris, 432 pp.
Lawrence, J.M. (2001) Edible sea urchins: biology and ecology. Elsevier, Oxford, UK, 432 pp.
Lawrence, J.M. (2006) Edible sea urchins: biology and ecology, 37. Elsevier, Oxford, UK, 380 pp.
Lefebvre, B. (2007) Early Palaeozoic palaeobiogeography and palaeoecology of stylophoran echinoderms. Palaeogeography, Palaeoclimatology, Palaeoecology, 245, 156–199.
Le Gac, M., Féral, J.-P., Poulin, E., Veyret, M. & Chenuil, A. (2004) Identification of allopatric clades in the cosmopolitan ophiuroid species complex Amphipholis squamata (Echinodermata). The end of a paradox? Marine Ecology progress series, 278, 171–178.
Lee, Youn-Ho (2003) Molecular phylogenies and divergence times of sea urchin species of Strongylocentrotidae, Echinoida. Molecular Biology and Evolution, 20(8), 1211–1221.
Leuckart, R. (1854) Bericht über die Leistungen in der naturgeschichte der niederen Thiere während der Jahre 1848-1853. Archiv für Naturgeschichte 20(2), 289–473.
Linnaeus, C. (1758) Systema naturae. 10th edition. Lucae, Juntiniana, pp. 3–376.
Littlewood, D.T.J. (1995) Echinoderm class relationships revisited. In: Emson, R., Smith, A.B. & Campbell, A. (Eds.) Echinoderm Research 1995. Balkema, Rotterdam, pp. 19–28.
Littlewood, D.T.J. & Smith, A.B. (1995) A combined morphological and molecular phylogeny for sea urchins (Echinoidea: Echinodermata). Philosophical Transactions of the Royal Society of London. Series B. Biological Sciences, 347, 213–234.
Littlewood, D.T.J., Smith, A.B., Clough, K.A. & Emson, R.H. (1997) The interrelationships of the echinoderm classes: morphological and molecular evidence. Biological Journal of the Linnean Society, 67, 409–438.
Ludwig, H. (1889–1907) Echinodermen. In: Bronn, H.G. (Ed.) Klassen und Ordnungen des Tierreichs, 2 (3). Winter, Leipzig, 1602 pp.
Mah, C.L. (2000) Preliminary phylogeny of the forcipulatacean Asteroidea. American Zoologist, 40, 375–381.
Mah, C.L. (2006) A new species of Xyloplax (Echinodermata: Asteroidea: Concentricycloidea) from the northeast Pacific: comparative morphology and a reassessment of phylogeny. Invertebrate Biology, 125(2), 136–153.
Mah, C.L. (2007) Phylogeny of the Zoroasteridae (Zorocallina: Forcipulatida). Zoological Journal of the Linnean Society, 150, 177–210.
Matranga, V. (2005) Echinodermata. Springer-Verlag, Berlin, 277 pp.
Matsubara, M., Komatsu, M., Araki, T., Asakawa, S., Yokobori, S.-I., Watanabe, K. & Wada, H. (2005) The phylogenetic status of Paxillosida (Asteroidea) based on complete mitochondrial DNA sequences. Molecular Genetics and Evolution, 36, 598–605.
McEdward, L.R. & Miner, B.G. (2001) Larval and life-cycle patterns in echinoderms. Canadian Journal of Zoology 79, 1125–1170.
Messing, C.G. (1997) Living comatulids. In: Waters, J.A. & Maples, C.G. (Eds.) Geobiology of echinoderms. Paleontological Society papers 3. Paleontological Society, Pittsburgh, pp. 3–30.
Messing, C.G. (2007) The crinoid fauna (Echinodermata: Crinoidea) of Palau. Pacific Science, 61(1), 91–111.
Mooi, R. (2001) Not all written in stone: interdisciplinary syntheses in echinoderm paleontology. Canadian Journal of Zoology, 79, 1209–1231.
Mooi, R. & David, B. (2000) What a new model of skeletal homologies tells us about asteroid evolution. American Zoologist, 40, 326–339.
Mooi, R., Rowe, F.W.E., & David, B. (1998) Application of a theory of axial and extraxial skeletal homologies to concentricycloid morphology. In: Mooi, R. & Telford, M. (Eds.), Echinoderms: San Francisco. Balkema, Rotterdam, pp. 61–62.
Mooi, R. & Telford, M. (1998). Echinoderms: San Francisco. Balkema, Rotterdam, 923 pp.
Moore, R.C. (1966–1978) (Ed.) Treatise on Invertebrate Paleontology. Part S Echinodermata 1, Volumes 1,2 1967; Part T Echinodermata 2, Volumes 1,2,3 1978; Part U, Echinodermata 3 Volumes 1,2 1966. University of Kansas Press, Lawrence.
O’Loughlin, P.M. & Waters, J.M. (2004) A molecular and morphological revision of genera of Asterinidae (Echinodermata: Asteroidea). Memoirs of the Museum of Victoria, 61(1), 1–40.
Parsley, R. (1999) The Cincta (Homostelea) as blastozoans. In: Candia Carnevali, M.D.C. & Bonasoro, F. (Eds.) Echinoderm research 1998. Balkema, Rotterdam, pp. 369–375.
Pawson, D.L. (1966). Phylogeny and evolution of holothuroids. In: R.C. Moore (Ed.) Treatise on Invertebrate Paleontology. Part U, Echinodermata 3(2). University of Kansas Press, Lawrence, pp 641–646.
Pawson, D.L. (1980) Holothuroidea. In: Broadhead, T.W. & Waters, J.A. (Eds.) Echinoderms: Notes for a short course. University of Tennessee Studies in Geological Science 3. University of Tennessee, Knoxville, pp. 175–189.
Pawson, D.L & Fell, H.B. (1965) A revised classification of the dendrochirote holothurians. Breviora, 214, 1–7.
Pawson, D.L. & Kerr, A.M. (2001) Chitin in echinoderms? Tentacle sheaths in the deep-sea holothurian Ceraplectana trachyderma (Holothuroidea: Molpadiida). Gulf of Mexico Science, 19(2), 192.
Pearse, V.B. & Pearse, J.S. (1994) Echinoderm phylogeny and the place of concentricycloids. In: David, B., Guille, A., Féral, J.-P., Roux, M. (Eds.), Echinoderms Through Time. Balkema, Rotterdam, pp. 121–126.
Pearse, V.B., Pearse, J.S., Hendler, G. & Byrne, M. (1998) An accessible population of Ophiocanops off NE Sulawesi, Indonesia. In: Mooi, R. & Telford, M. (Eds.) Echinoderms: San Francisco. Balkema, Rotterdam, pp. 413–418.
Rasmussen, H.W. & Sieverts-Doreck, H. (1978) Articulata. In: Moore, R.C. & Teichert, C. (Eds.) Treatise on Invertebrate Paleontology Part T Echinodermata 2 (3). University of Kansas Press, Lawrence, pp. T814–T1027.
Reich, M. (2002) Holothurien (Echinodermata) aus der Oberkreide des Ostseeraumes: Teil 1. Myriotrochidae Théel, 1877. Neues Jahrbuch für Geologie und Paläotologie Abhandlungen, 224(3), 373–409.
Reich, M. (2004) Fossil Holothuroidea (Echinodermata): an overview. In: Heinzeller, T. & Nebelsick, J.H. (Eds.) Echinoderms: München. Taylor & Francis, London, p. 602.
Reich, M. & Haude, R. (2004). Ophiocistioidea (fossil Echinodermata): an overview. In: Heinzeller, T. & Nebelsick, J.H. (Eds.) Echinoderms: München. Taylor & Francis, London, pp. 489–494.
Rose, E.P.F. & Olver, J.P.S. (1988) Jurassic echinoids of the family Menopygidae: implications for the evolutionary interpretation and classification of early Irregularia. In: Burke, R.D., Mladenov, P.V., Lambert, P. & Parsley, R.L. (Eds.) Echinoderm biology. Balkema, Rotterdam, pp. 149–158.
Roux, M., Messing, C.G. & Améziane, N. (2002) Artificial keys to the genera of living stalked crinoids (Echinodermata). Bulletin of Marine Science, 70(3), 799–830.
Rowe, F.W.E., Baker, A.N. & Clark, H.E.S. (1988) The morphology, development, and taxonomic status of Xyloplax Baker, Rowe, and Clark, 1986 (Echinodermata: Concentricycloidea) with the description of a new species. Proceedings of the Royal Society of London. Series B. Biological Sciences, 233, 431–459.
Shackleton, J.D. (2005) Skeletal homologies, phylogeny and classification of the earliest asterozoan echinoderms. Journal of Systematic Palaeontology, 3(1), 29–114.
Shu, D.-G., Conway Morris, S., Han, J., Zhang, Z.-F. & Liu, J.-N. (2002) Ancestral echinoderms from the Chengjiang deposits of China. Nature, 430, 422–428.
Simms, M.J. (1988) The phylogeny of post-Paleozoic crinoids. In: Paul, C.R.C. & Smith, A.B. (Eds.) Echinoderm phylogeny and evolutionary biology. Clarendon Press, Oxford, pp. 269–284.
Simms, M.J., Gale, A.S., Gilliland, P., Rose, E.P.F. & Sevastopulo, G.D. (1993) Echinodermata. In: Benton, M.J. (Ed.) The fossil record 2. Chapman & Hall, London, pp. 492–528.
Smirnov, A.V. (1998) On the classification of the apodid holothurians. In: Mooi, R. & Telford, M. (Eds.) Echinoderms: San Francisco. Balkema, Rotterdam, pp.517–522.
Smirnov, A.V. (1999) The origin of the Order Apodida (Holothuroidea) and its families. In: Candia Carnevali, M.D.C. & Bonasoro, F. (Eds.) Echinoderm research 1998. Balkema, Rotterdam, pp. 393–395.
Smith, A.B. (1984) Echinoid palaeobiology. George Allen & Unwin, London, 190 pp.
Smith, A.B. (1988a) Fossil evidence for the relationships of extant echinoderm classes and their times of divergence. In: Paul, C.R.C. & Smith, AZ.B. (Eds.) Echinoderm phylogeny and evolutionary biology. Clarendon Press, Oxford, pp. 85–97.
Smith, A.B. (1988b) Phylogenetic relationship, divergence times, and rates of molecular evolution for camarodont sea urchins. Molecular Biology and Evolution 5(4), 345–365.
Smith, A.B. (1997) Echinoderm larvae and phylogeny. Annual Review of Ecology and Systematics, 28, 219–241.
Smith, A.B. (2004a) Deuterostome phylogeny and the interpretation of problematic fossil echinoderms. In: Heinzeller, T. & Nebelsick, J.H. (Eds.) Echinoderms: München. Taylor & Francis, London, pp. 543–546.
Smith, A.B. (2004b) Echinoderm roots. Nature, 430, 411–412.
Smith, A.B. (2007) Intrinsic versus extrinsic biases in the fossil record: contrasting the fossil record of echinoids in the Triassic and early Jurassic using sampling data, phylogenetic analysis, and molecular clocks. Paleobiology, 33(2), 310–323.
Smith, A.B., Lafay, B. & Christen, R. (1992) Comparative variation of morphological and molecular evolution through geologic time: 28s ribosomal RNA versus morphology in echinoids. Philosophical Transactions of the Royal Society of London. Series B. Biological Sciences, 338, 365–382.
Smith, A.B., Paterson, G.L.J. & Lafay, B. (1995) Ophiuroid phylogeny and higher taxonomy: morphological, molecular and palaeontological perspectives. Zoological Journal of the Linnean Society, 114, 213–243.
Smith, A.B., Pisani, D., Mackenzie-Dodds, J.A., Stockley, B, Webster, B.L. & Littlewood, T.J. (2006) Testing the molecular clock: molecular and paleontological estimates oif divergence times in the Echinoidea (Echinodermata). Molecular Biology and Evolution, 23(10), 1832–1851.
Solovjev, A.N. & Markov, A.V. (2004) The early evolution of irregular echinoids. In: Heinzeller, T. & Nebelsick, J.H. (Eds.) Echinoderms: München. Taylor & Francis, London, pp. 551–556.
Stockley, B., Smith, A.B., Littlewood, T., Lessios, H.A. & Mackenzie-Dodds, J.A. (2005) Phylogenetic relationships of spatangoid sea urchins (Echinoidea): taxon sampling density and congruence between morphological and molecular estimates. Zoological Scripta, 34(5), 447–468.
Sumrall, C.D. & Wray, G.A. (2007) Ontogeny in the fossil record: diversification of body plans and the evolution of “aberrant” symmetry in Paleozoic echinoderms. Paleobiology, 33(1), 149–163.
Vickery, M. & McClintock, J.B. (2000) Comparative morphology of tube feet among the Asteroidea: phylogenetic implications. American Zoologist, 40, 355–364.
Wada, H. & N. Satoh, 1994. Phylogenetic relationships among extasnt classes of echinoderms, as inferred from sequences of 18S rDNA, coincide with relationships deduced from the fossil record. Journal of Molecular Evolution, 38, 41–49.
Wagner, G.P., Lo, J., Laine, R. & Almeder, M. (1993) Chitin in the epidermal cuticle of a vertebrate (Paralipophrys trigloides, Blenniidae, Teleostei). Cellular and Molecular Life Sciences, 49(4), 317–319.
Wilson, N.G., Hunter, R.L., Lockhart, S.J. & Halanych, K.M. (2007) Multiple lineages and absence of panmixia in the “circumpolar” crinoid Promachocrinus kerguelensis from the Atlantic sector of Antarctica. Marine Biology, 152(4), 895–904.
Yokota, Y., Matranga, V. & Smolenicka, Z. (2002) The sea urchin: from basic biology to aquaculture. Balkema, Rotterdam, 293 pp.