A group of scientists led by a member of UCD’s School of Geological Sciences, Dr Maria McNamara, have recently discovered the colour of ancient moths from analysis of their forty-seven million year old fossils.
The fossils were found in Germany, at the Messel oil-shale pit near Frankfurt, which is a UNESCO world heritage site. The shale-pit is a world-renowned fossil site, due to its importance in understanding ancient eco systems.
The fossils structures were analysed using scanning electron microscopy and transmission electron microscopy, which allowed Dr McNamara and her team to determine that the colour that moths bare today are not their original colours. Additionally, they were also able to show that the colour is not generated by pigments but is a structural colour and so, by using the preserved structural features, the team was able to reconstruct what the original colours would have been.
The reconstruction of the colour of the forewings as a matte, non-iridescent yellow-green allowed Dr McNamara and her team to determine that they had a double function, “these colours would have functioned as camouflage when the moths were resting in leafy backgrounds, but when the moths were feeding, these colours would have stood out against the background of any flowers they would have been feeding from. In that case, the flowers could have functioned as a warning signal … they’re extremely toxic so the colours could have presumably been advertising to predators, ‘hang on, I taste unpleasant’”.
Dr McNamara explains that there are two different aspects to the experiment, “working on fossils is one side of the story but the other is actually to try and replicate the fossilisation process in experiments; at the moment I’m working on a series of experiments on insects that have these kind of structural colours to try and simulate what happens to the colour when the animals are fossilised”.
Dr McNamara explained the significance of the findings, “on a small scale, finding evidence of coloured fossils is extremely rare, so just that fact in itself is a very significant find. Being able to actually reconstruct the original colours, to show that the colours we see today have been altered by the fossilisation process, that’s really important because the colours and colour patterns that the animal would have had are what tell you about how it communicated with others of the same species and other species”.
Similar techniques can be applied to many fossilised insects and potentially lots of other fossils too, as structural colours that leave physical traces in fossils can be found in birds, mammals, fish and plants.
The research for the project was not carried out in UCD but at Yale University, where Dr McNamara is currently on an IRCSET-Marie Curie International Mobility Fellowship.