Pigments don’t survive fossilization; even though we have fossil skin from dinos

ID: 1610319 • Letter: P

Question

Pigments don’t survive fossilization; even though we have fossil skin from dinosaurs, we don’t know what color

they were. But fossilization does preserve structure. Specimens from a rare cache of 50-million-year-old beetle

fossils still show the microscopic layers that produced structural color in the living creatures, and we can deduce

the colors from an understanding of thin-film interference. One fossil showed 80 nm layers of fossilized chitin

(modern samples have index n =1.56) separated by fossilized tissue (n =1.33). What is the longest wavelength

for which there is constructive interference for the chitin layers? Given this, what color was the beetle?

formula for constructive inference id

2t*n = (m-1/2)Lambda

Lambda = 2t*n / (m-1/2)

= 2*80*10^-9*1.56/(1 /2) m

= 4.992*10^-7 m

= 499.2 nm

which is in the visible region