Chemical, experimental, and morphological evidence for diagenetically altered melanin in exceptionally preserved fossils

TLDR

Melanin, a common pigment that imparts black to reddish‑brown hues, has been detected preserved in exceptionally fossilized specimens, enabling reconstruction of ancient color patterns, yet its chemical preservation and distribution remain poorly understood. Our study demonstrates that melanin survives in soft‑bodied fossils but is chemically altered by prolonged high‑pressure, high‑temperature burial, and its widespread occurrence supports color reconstruction while refuting microbial origin hypotheses.

Abstract

Significance Melanin is a widespread pigment that provides black to reddish brown hues to organisms. Recent evidence has shown that melanin is retained in exceptionally preserved fossils, including feathered dinosaurs, allowing the reconstruction of ancient color patterns. However, little is known about the chemical preservation of melanin or its distribution in the fossil record. Here, we show that melanin is preserved in a number of soft-bodied fossils, but its burial under high pressure and temperature for millions of years alters its original chemistry. The widespread occurrence of melanin substantiates the applicability of reconstructing aspects of original color patterns and allows us to dismiss the alternative suggestion that these structures are microbial in origin.