Daniel F Goujet, Muséum National d'Histoire Naturelle, Paris, France
Published online: June 2001
DOI: 10.1038/npg.els.0001533
Placoderms are a group of fossil true jawed fishes restricted to the Middle Palaeozoic period (Silurian and Devonian). They were the dominant forms in the seas of this time with more than 300 species. They show adaptations to various modes of life including the first active vertebrate predators and numerous bottom-feeders.
Keywords: fossil fishes; gnathostomes; palaeozoic
|
Figure 1. Placoderm basic design. (a) General view of the skeleton of a placoderm: the arthrodire Coccosteus cuspidatus; modified from Miles and Westoll (1968). (b) Dermal armour of an arthrodire Mcnamaraspis caprios from the Gogo formation; modified from Long (1995).
|
|
Figure 2. Diversity of forms in placoderms. (a and b) A dolichothoracid arthrodire, Dicksonosteus arcticus. The dermal armour in dorsal view (a); cast of the endocranial cavities (b). From Goujet (1984). (c) An antiarch, Sherbonaspis hillsi; adapted from Young and Zhang (1992), (d) An acanthothoracid, Romundina stellina. (e) A ptyctodont, Ctenurella; adapted from Forey and Gardiner (1986) and Ørvig (1960).
|
|
Figure 3. Cladogram summarizing the interrelationships of placoderms; modified from Goujet and Young (1995).
|
| Further Reading | |
| Carr RK (1995) Placoderm diversity and evolution. Bulletin du Muséum National d'Histoire Naturelle, Paris 17(C, 1–4): 85–125. | |
| book Denison RH (1978) "Placodermi". In: Schultze HP (ed.) Handbook of Paleoichthyology, vol 2. Stuttgart: Gustav Fischer. | |
| Forey P and Gardiner B (1986) Observations on Ctenurella (Ptyctodontida) and the classification of placoderm fishes. Zoological Journal of the Linnean Society 86: 43–74. | |
| book Goujet D (1984) Les Poissons Placodermes du Spitsberg. Arthrodires Dolichothoraci de la Formation de Wood-Bay (Dévonien Inférieur). Paris: Editions du CNRS. | |
| proceedings Goujet D and Young GC (1995) Interrelationships of Placoderms Revisited. Premiers Vertébrés, Vertébrés Inférieurs, Paris, 4–9 September 1995, Geobios, Memoire Special 19: 89–95. | |
| book Janvier P (1996) Early Vertebrates. Oxford: Clarendon Press. | |
| book Long J (1991) "The long history of Australian fossil fishes". In: Vickers-Rich P (ed.) Paleontology of Australasia, pp. 337–428. Lilydale: Pioneer Design Studio Pty. | |
| Long JA (1995) A new plourdosteid arthrodire from the Upper Devonian Gogo formation of Western Australia. Palaeontology 38(1): 39–62. | |
| Miles RS and Westoll TS (1968) The placoderm fish Coccosteus cuspidatus Miller ex Agassiz from the Middle Old Red Sandstone of Scotland. Descriptive morphology: Part I. Transactions of the Royal Society of Edinburgh 67: 373–476. | |
| book Moy-Thomas JA and Miles RS (1971) Palaeozoic Fishes, 2nd edn. London: Chapman & Hall. | |
| Ørvig T (1960) New Finds of Acanthodians, Arthrodires, Crossopterygians, Ganoids and Dipnoans in the Upper Middle Devonian Calcareous Flags (Oberer Plattenkalk of the Bergisch Gladbach-Paffrath Trough (Part 1). Paläontologische Zeitschrift 34(3/4): 295–335. | |
| book Stensiö EA (1969) "Arthrodires". In: Piveteau J (ed.) Traité de Paléontologie, vol. 4, no. 2, pp. 71–692. Paris: Masson. | |
| other Young GC (1990) Devonian vertebrate distribution patterns, and cladistic analysis of biogeographic hypotheses. In: Palaeozoic Biogeography and Paleogeography. McKerrow WS and Scotese CR (eds) Geological Society Memoir 12: 243–255. | |
| Young GC and Zhang G (1992) Structure and function of the pectoral joint and operculum in Antiarchs, Devonian placoderm fishes. Palaeontology 35(2): 443–464. | |
Copyright © 2000-2013 by John Wiley & Sons, Inc., or related companies. All rights reserved.
