Biochemistry and adaptive colouration of an exceptionally preserved juvenile fossil sea turtle

Johan Lindgren – together with colleagues abroad as well as at his own department and at the infrared microspectroscopy beamline D7 at the old MAX IV Laboratory in Lund – studied the biomolecular inventory of the fossil turtle. The researchers identified residues of several different molecules, including beta-keratin, eumelanin, haemoglobin, and tropomyosin. Eumelanin is a pigment that provides dark skin colour also in humans. Researchers at Lund University in Sweden have discovered well-preserved pigments and other biomolecules in a 54 million-year-old baby sea turtle. The molecular analyses show that the turtle’s shell contained pigments to protect it from harmful UV rays of the sun.

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Image: Holotype of Tasbacka danica. (a) Photograph of the fossil. Fo, fontanelle (the light colour is a result of sediment infill); Hyo, hyoplastron; Hyp, hypoplastron; Ne, neural; Nu, nuchal; Pe, peripheral; Py, pygal. Arrowheads indicate neural nodes. (b) Detail of the carapace with the sampled area demarcated by a circle. Co, costal; Hu, humerus; Sc, scapula. (c) Higher magnification image showing marginal scutes (arrowheads), pigmentations on bones (arrows), and a brown-black film covering the fontanelles (stars).