Nature 383, 810 - 812 (31 October 1996); doi:10.1038/383810a0

A possible Late Cambrian vertebrate from Australia

Gavin C. Young^*, Valya N. Karatajute-Talimaa^† & Moya M. Smith^‡

^* Australian Geological Survey Organisation, PO Box 378, Canberra ACT 2601, Australia
^† Lithuanian Institute of Geology, Sevcenkos 13, 2600, Vilnius, Lithuania
^‡ Craniofacial Development, Division of Dentistry, UMDS, Guy's Hospital, London Bridge, London SE1 9RT, UK

THE fossil record of early vertebrates starts with certainty with the dermal armour of agnathan fish from the Early−Middle Ordovician of Australia^1,2. Recent controversial acceptance that conodonts³ and the fragments called Anatolepis ^4,5 may be vertebrate remains⁶, extends their fossil record back to the Late Cambrian. Now a new type of phosphatic skeleton from Australia shows a three-layered structure that indicates vertebrate affinity, but with several unique features not known in other vertebrates. The new evidence challenges the most widely accepted current theory for the development of the vertebrate skeleton⁷⁻¹¹, which assumes the odontode (skin denticle) to be the primitive patterning component. The Australian material provides an alternative model for early vertebrate dermal armour with which to assess the vertebrate-like hard tissues in conodonts^12,13 and the dermal armour of Anatolepis ^4−6,14.

References

1.	Young, G. C. J. Vert. Paleontol. (in the press).
2.	Forey, P. L. & Janvier, P. Am. Scientist 82, 554−565 (1994).
3.	Janvier, P. Nature 374, 761−762 (1995). | Article | ChemPort |
4.	Bockelie, T. & Fortey, R. A. Nature 260, 36−38 (1976). | Article |
5.	Repetski, J. E. Science 200, 529−531 (1978).
6.	Smith, M. P., Sansom, I. J. & Repetski, J. E. Nature 380, 702−704 (1996). | Article | ISI | ChemPort |
7.	Ørvig, T. in Structural and Chemical Organization of Teeth (ed. Miles, A. E. W.) 45−110 (Academic, London, 1967).
8.	Ørvig, T. in Current Problems in Lower Vertebrate Phylogeny (ed. Ørvig, T.) 374−397 (Almquist & Wiksell, Stockholm, 1968).
9.	Ørvig, T. in Problems in Vertebrate Evolution (eds Andrews, S. M., Miles, R. S. & Walker, A. D.) 53−75 (Academic, London, 1977).
10.	Reif, W.-E. Evolut. Biol. 15, 287−368 (1982).
11.	Smith, M. M. & Hall, B. K. Biol. Rev. 65, 277−373 (1990). | PubMed | ChemPort |
12.	Sansom, I. J., Smith, M. P., Armstrong, H. A. & Smith, M. M. Science 256, 1308−1311 (1992). | PubMed | ChemPort |
13.	Sansom, I. J., Smith, M. P. & Smith, M. M. Nature 368, 591 (1994). | Article |
14.	Smith, M. P. & Sansom, I. J. Geobios. Mém. Spéc. 19, 61−64 (1995).
15.	Nicoll, R. S. AGSO J. Aust. Geol. & Geophys. 15, 367−379 (1994).
16.	Ritchie, A. & Gilbert-Tomlinson, J. Alcheringa 1, 351−368 (1977).
17.	Young, G. C. & Laurie, J. R. (eds) An Australian Phanerozoic Timescale (Oxford Univ. Press, Melbourne, 1996).
18.	Dalingwater, J. E., Hutchinson, S. J., Mutvei, H. & Siveter, D. J. Palaeontographica Abt. A 229, 37−49 (1993).
19.	Sansom, I. J., Smith, M. M. & Smith, M. P. Nature 379, 628−630 (1996). | Article | ChemPort |
20.	Walcott, C. D. Geol. Soc. Am. Bull. 3, 153−172 (1892).
21.	Smith, M. M. Science 251, 301−303 (1991).
22.	Smith, M. M., Sansom, I. J. & Smith, M. P. Modern Geol. (in the press).
23.	Maisey, J. G. Evol. Biol. 22, 1−36 (1988).
24.	Halstead, L. B. Vertebrate Hard Tissues (Wykeham, London and Winchester, 1974).
25.	Gans, C. Biol. Rev. 64, 221−268 (1989). | PubMed | ISI | ChemPort |
26.	Gross, W. Kungl. Svensk VetenskapsAkad. Handl. 4 Ser. 5, 1−140 (1956).
27.	Thomson, K. S. in Problems in Vertebrate Evolution (eds Andrews, S. M., Miles, R. S. & Walker, A. D.) 247−270 (Academic, London, 1977).
28.	Northcutt, R. G. & Gans, C. Quart. Rev. Biol. 58, 1−28 (1983). | Article | PubMed | ISI | ChemPort |
29.	Chen, J.-Y., Dzik, J., Edgecombe, G. D., Ramskold, L. & Zhou, G.-Q. Nature 377, 720−722 (1995). | Article | ISI | ChemPort |