CHEMICAL CHARACTERIZATION OF COLOR PATTERNS PRESERVED IN THE OLIGOCENE ECHINOID HEMIPATAGUS CAROLINENSIS FROM THE RIVER BEND FORMATION OF NORTH TOPSAIL BEACH, NORTH CAROLINA

The modern world is bright and colorful, so it stands to reason that extinct organisms were similarly vibrant. While rare, the preservation of original color patterns in extinct animals is becoming increasingly more recognizable. Original pigments or related biomarkers have been described in a number of fossils, including melanins preserved in vertebrate integument and quinone pigments preserved in crinoids. However, we have only scratched the surface of color preservation in the fossil record, which helps us better understand the ecology and taphonomic history of the organisms in which original color patterns are preserved.

In 2015, offshore dredging near North Topsail Beach, North Carolina, stirred up numerous marine fossils from the Oligocene River Bend Formation that appear to preserve original color patterns. Among these fossils is the echinoid Hemipatagus carolinensis. Hundreds of specimens of this species collected between 2015 and 2019 exhibit violet-colored patterns in the ambulacral and interambulacral plates. While McCall previously described the appearance of these color patterns, their chemistry was unknown. Here, we use Raman spectroscopy and Fourier Transform Infrared Spectroscopy to chemically characterize the violet patterns preserved in H. carolinensis from North Topsail Beach. Chemical analyses reveal that the violet color is not due to diagenetic mineralization or mineral staining, but is instead indicative of the preservation of original pigments. To our knowledge, this is the first chemical analysis of original pigments preserved in extinct Echinoidea and in River Bend Formation fossils.