Nature 302, 243 - 244 (17 March 1983); doi:10.1038/302243a0

A reinterpretation of the amphisbaenian orbitosphenoid

A. d'A. Bellairs^* & Carl Gans^†

^*St Mary's Hospital Medical School, London W2 1PG, UK
^†Division of Biological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA

The Amphisbaenia is a successful group of some 140 species of strange, specialized burrowing reptiles with reduced eyes and limbs, found mainly in parts of Africa and America. Their systematic position has been much debated¹. They show many unique features, including a large orbitosphenoid bone which has previously been regarded as a cartilage ossification², like that of vertebrates in general³. However, appropriate embryonic material available for the first time shows that it is a membrane bone. This remarkable condition tends to emphasize the distinct status of the Amphisbaenia within the Squamata, as a sister-group equivalent to the lizards or the snakes^1,4,5

References

1.	Gans, C. zool. Soc. Lond. 34, 347−416 (1978).
2.	Bellairs, A. d'A. & Kamal, A. M. in Biology of the Reptilia Vol.11 (eds Gans, C. & Parsons, T. S.) 1−263 (Academic, London, 1981).
3.	De Beer, G. R. The Development of the Vertebrate Skull (Clarendon, Oxford, 1937).
4.	Peters, G. Summ. Lect. 1st Herp. Conf. Social. Countries, 35 (1981).
5.	Rage, J-C. C. r. hebd. Séanc. Acad. Sci., Paris 294, 563−566 (1982).
6.	El-Assy, Y. S. & Al-Nassar, N. A. J. Univ. Kuwait (Sci). 3, 113−141 (1976).
7.	May, E. Senckenbergiana biol. 59, 41−69 (1978).
8.	Patterson, C. Linnean Soc. Symp. 4, 77−121 (1977).
9.	Bellairs, A. d'A. in Studies in Vertebrate Evolution (eds Joysey, K. A. & Kemp, T. S.) 157−172 (Oliver & Boyd, Edinburgh, 1972).
10.	Dixon, J. R. Univ. Kansas Mus. nat. Hist. Misc. Publ. 57, 1−47 (1973).
11.	Böhme, E. in Handbuch der Reptilien und Amphibien Europas Vol. 1 (ed. Böhme, W.) 275−276 (Akademische Verlagsgesellschaft, Wiesbaden, 1981).