A green and black colubrid snake lived about 10 million years ago in what is today Spain, according to a team of scientists led by University College Cork paleobiologist Dr. Maria McNamara.
An artistic representation of the Miocene snake as it would have appeared in life. Image credit: Jim Robbins.
This snake’s skin was fossilized in calcium phosphate, a mineral that preserves details on a subcellular level.
“The fossil skin – from a 10 million-year-old colubrid snake from the Late Miocene Libros Lagerstätte (Teruel, Spain) – preserves dermal pigment cells (chromatophores) in calcium phosphate,” Dr. McNamara and her colleagues from Ireland and Spain said.
The scientists discovered the mineralized skin cells when viewing the fossil under a scanning electron microscope and then matched the shapes up with pigment cells in modern snakes to determine what colors they might have produced.
They determined that the fossilized snakeskin had three types of pigment cells in various combinations:
(i) melanophores, which contain the pigment melanin;
(ii) xanthophores, which contain carotenoid and pterin pigments;
(iii) iridophores, which create iridescence.
According to the scientists, the snake was a mottled green and black, with a pale underside — colors that likely aided in daytime camouflage.
“Comparison with chromatophore abundance and position in extant reptiles indicates that the fossil snake was pale-colored in ventral regions; dorsal and lateral regions were green with brown-black and yellow-green transverse blotches,” they said.
“Such coloration most likely functioned in substrate matching and intraspecific signaling.”
This image shows a layout of the color-producing cells in skin samples from different regions of the fossil, and the resulting color as the snake would have appeared in life. Image credit: Maria E. McNamara et al / Current Biology, doi: 10.1016/j.cub.2016.02.038.
“Up until this discovery, the only prospect for skin color being preserved in fossils was organic remains related to melanin,” Dr. McNamara said.
“But now that we know color can be preserved even for tissues that are mineralized, it’s very exciting.”
The results were published online March 31, 2016 in the Current Biology.
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Maria E. McNamara et al. Reconstructing Carotenoid-Based and Structural Coloration in Fossil Skin. Current Biology, published online March 31, 2016; doi: 10.1016/j.cub.2016.02.038
