Scientists have made an important discovery in understanding the effect oxygen has on vertebrate evolution.

Studies were carried out into the development of bone structures in alligator eggs raised under varying oxygen concentrations and a link created to fossil records of the evolution of vertebrates and prehistoric atmospheric oxygen concentrations.

A paper presented at the Earth System Processes 2 meeting in Alberta, Canada, detailed the work carried out – an important step in understanding the complex interaction between vertebrate development and oxygen levels.

One of the scientists, John Vanden Brooks, said: “Alligator eggs are an ideal self-contained unit for studying the effects of oxygen on development - they have a limited food source in the yolk and they are incubated in their nesting material at a constant temperature of 89°F and 100 per cent relative humidity.”

And he said large-scale changes in atmospheric partial oxygen pressure would have had wide-ranging effects on vertebrate evolution and development throughout geologic time. Five different partial oxygen pressures were studied with the optimum found to be 27 per cent oxygen. Both low and high oxygen levels altered growth patterns and affected the timing and extent of bone development, its chemical composition and the mortality of the developing eggs.

The range of atmospheric oxygen levels was characterised by Robert Berner who found an upper value of around 31 per cent oxygen and the lowest around 12 per cent. There is currently around 21 per cent oxygen in the atmosphere.