Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 21 February 2003:
Vol. 299. no. 5610, pp. 1235 - 1236
DOI: 10.1126/science.1079623
Prev | Table of Contents | Next

Reports

Separate Evolutionary Origins of Teeth from Evidence in Fossil Jawed Vertebrates

Moya Meredith Smith,1* Zerina Johanson2

Placoderms are extinct jawed fishes of the class Placodermi and are basal among jawed vertebrates. It is generally thought that teeth are absent in placoderms and that the phylogenetic origin of teeth occurred after the evolution of jaws. However, we now report the presence of tooth rows in more derived placoderms, the arthrodires. New teeth are composed of gnathostome-type dentine and develop at specific locations. Hence, it appears that these placoderm teeth develop and are regulated as in other jawed vertebrates. Because tooth development occurs only in derived forms of placoderms, we suggest that teeth evolved at least twice, through a mechanism of convergent evolution.

1 Craniofacial Development, Dental Institute, King's College London, Guy's Campus, London Bridge, London SE1 9RT, UK.
2 Palaeontology, Australian Museum, 6 College Street, Sydney, NSW 2010, Australia.
*   To whom correspondence should be addressed. E-mail: moya.smith{at}kcl.ac.uk

Read the Full Text


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
A new genus and species of Ptyctodont (Placodermi) from the Late Devonian Gneudna Formation, Western Australia, and an analysis of Ptyctodont phylogeny.
K. TRINAJSTIC and J. A. LONG (2009)
Geological Magazine 146, 743-760
   Abstract »    Full Text »    PDF »
Reiterative pattern of sonic hedgehog expression in the catshark dentition reveals a phylogenetic template for jawed vertebrates.
M. M Smith, G. J Fraser, N. Chaplin, C. Hobbs, and A. Graham (2009)
Proc R Soc B 276, 1225-1233
   Abstract »    Full Text »    PDF »
Darwin's dilemma: the realities of the Cambrian 'explosion'.
S. Conway Morris (2006)
Phil Trans R Soc B 361, 1069-1083
   Abstract »    Full Text »    PDF »
Comment on "Separate Evolutionary Origins of Teeth from Evidence in Fossil Jawed Vertebrates".
C. J. Burrow (2003)
Science 300, 1661b
   Full Text »    PDF »
Response to Comment on "Separate Evolutionary Origins of Teeth from Evidence in Fossil Jawed Vertebrates".
M. M. Smith and Z. Johanson (2003)
Science 300, 1661c
   Full Text »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)