The latest evidence - 99-million-year-old insects caught in amber with incredible colours of purple, blue, and metallic green.

"The type of colour preserved in the amber fossils is called structural colour.

The team collected 35 amber specimens containing ancient insects that also possessed these intense structural colours.

Interestingly enough, the cuckoo wasps in amber (see, for example, the first green insect in the series of images above) were nearly the same colour as the cuckoo wasps that are around today.

After cutting through the exoskeleton of two of the vibrant wasps and one comparatively dull fossil, they found that in the dull sample, the cuticular structures which create the structural colours are damaged.