Tyrannosaurus Rex, Triceratops, Saber-toothed Tiger…as kids, we probably imagined these creatures using a variety of crayon colors. But what if we could figure out what color these creatures actually were? A scientific technique developed by Roy Wogelius involving the Interdisciplinary Centre for Ancient Life at the University of Manchester may paint the ancient world in its truest form. Paleontologists use information contained in fossils to try and reconstruct an understanding of a life-form as it might have existed thousands or even millions of years ago. While the skeletal structure of an organism can be deduced from fossils, soft tissues like skin and feathers do not preserve well and are notoriously difficult to study.
One way to determine an organism’s coloration has been to examine the structure of fossilized melanosomes under the microscope. Melanosomes are small storage sacs within cells that store pigment. Two main flavors of pigments are found in animal tissues called eumelanin and pheomelanin. Eumelanin (the kind of melanin found in human skin) is more prevalent and produces a dark brown or black hue depending on its abundance. Pheomelanin forms lighter red-brown pigments and has been much trickier to identify. Classically, scientists have examined the microscopic structure to distinguish between eumelanosomes and pheomelanosomes. However, these structures are often difficult to distinguish microscopically and mineralized microbes can often be mistaken for these organelles.
The genius of Wogelius and his collaborators was to study the chemistry of eumelanin and pheomelanin from modern surviving organisms and then apply what they found to ancient samples. It turns out that each form of melanin has a distinctive associated element – copper for eumelanin and zinc for pheomelanin. X-ray beams can be bounced off the fossil melanosomes, and the way they are reflected depends on the different elements of these pigments. The exact distribution of eumelanin and pheomelanin can be mapped onto a fossil’s structure, providing something like a ‘paint for numbers’ for the fossils! This technique has already been used to paint a picture of an extinct red mouse that lived 3 million years ago. Now investigators hope to use the technique to go even further back in time to capture pictures of the earliest organisms to roam the planet.
Original scientific article: https://www.nature.com/articles/s41467-019-10087-2 – Sec8
Managing Correspondent: Radhika Agarwal
Image Credit: Phillip L. Manning, https://www.nature.com/articles/s41467-019-10087-2 – Sec8