Pituriaspida
Philippe Janvier
- Pituriaspis
- Neeyambaspis
Introduction
The Pituriaspida are a small group of fossil, armored jawless vertebrates, only known by two genera, Pituriaspis and Neeyambaspis, from the late Early Devonian or early Middle Devonian (about 390 million years) of Queensland, Australia. The best documented form, however, is only Pituriaspis, which resembles the Osteostraci, although devoid of any median dorsal nasohypophysial opening. The nasal or nasohypophysial opening is supposed to lie ventrally, anteriorly to the mouth. The headshield of Pituriaspis shows a ventral oralobranchial chamber, as in the Osteostraci and Galeaspida, a long anterior rostral process, and two lateral cornual processes which bound anteriorly the area for the attachment of the paired fins. The headshield extends posteriorly to form a long abdominal division which probably reached the anal region.
Pituriaspids lived in a marine, deltaic environment, along with various placoderms.
Characteristics
The only unique characteristic of the Pituriaspida is a peculiar pit, of unknown function, ventrally to the orbits.References
Janvier, P. (1996). Early vertebrates. Oxford Monographs in Geology and Geophysics, 33, Oxford University Press, Oxford.
Young, G. C. (1991). The first armoured agnathan vertebrates from the Devonian of Australia. In Early vertebrates and related problems of evolutionary biology (ed. M. M.Chang, Y. H. Liu, and G. R. Zhang), pp. 67-85. Science Press, Beijing.
Title Illustrations
| Scientific Name | Pituriaspis |
|---|---|
| Location | Australia |
| Comments | Pituriaspids are mainly known by Pituriaspis, from the Devonian of Australia. As a whole, their headshield is quite similar to that of osteostracans, though devoid of a naso-hypophysial opening. The mouth, gill openings and presumably the nasal aperture were all situated on the ventral side of the head. Well-developed paired fins attached on either sides of the headshield. The only diagnostic feature of pituriaspids is an enigmatic pit adjacent to the eyes. |
| Reference | based on Young, G. C. (1991). The first armoured agnathan vertebrates from the Devonian of Australia. In Early vertebrates and related problems of evolutionary biology (ed. M. M. Chang, Y. H. Liu, and G. R. Zhang), pp. 67-85. Science Press, Beijing. |
| Specimen Condition | Fossil -- Period: Devonian |
| Image Use |
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| Copyright |
© 1997
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Muséum National d'Histoire Naturelle Paris, France
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Janvier, Philippe. 1997. Pituriaspida. Version 01 January 1997 (under construction). http://tolweb.org/Pituriaspida/14841/1997.01.01 in The Tree of Life Web Project, http://tolweb.org/
