BY PETER D. MOORE
Department of Biology
King’s College
London, U.K.
" The shells of dinosaur eggs developed in a manner that more closely resembles some birds’ eggs than it does modern reptiles’ eggs. The texture changes abruptly in sequential layers as a result of organic material periodically interrupting calcite deposition. This structure is also found in the thick shells of modern rarities such as ostrich and rhea.
H. Silyn-Roberts, R.M. Sharp, “The similarity of preferred orientation development in eggshell calcite of the dinosaurs and birds,” Proceedings of the Royal Society of London B, 235 (1281), 347-363, 23 January 1989.
Theoretical studies in extinction rates suggest that low population size and high population variability result in a high risk of extinction. Field data on bird populations from islands around the British coast have confirmed these relationships but have also shown that at high-population density, large-bodied birds are more at risk ...
