Researchers report an approach to reconstruct the soft tissue anatomy of fossil vertebrates using fossil melanosomes, aggregations of melanin pigment. Melanin, aggregated into melanosomes in vertebrates, produces skin coloring. However, the discovery of melanin in nonskin tissues of both living and fossil vertebrates hints at other roles for the pigment. Valentina Rossi, Maria McNamara, and colleagues sampled melanosomes from 15 living vertebrate groups and from preserved soft tissue in fossils. All tissues from living species contained melanin, with more melanin present in the organs of amphibians and reptiles than in the organs of birds and mammals. Melanosome size and geometry differed between taxa and also between organs within a species. Skin melanosomes, for instance, were generally smaller than melanosomes from other tissues. The authors also found elemental variation among the melanosomes, particularly in concentrations of iron, calcium, and zinc between organs. Melanosomes sampled from fossils also differed significantly in size, geometry, and chemistry depending on body region. The pigment's affinity for metals suggests that melanosomes may play a role in metal metabolism. According to the authors, the variation in melanosomes helps identify organs and other internal anatomical features of fossilized soft tissue and can also help reconstruct the evolutionary history and functions of melanosomes in vertebrates.
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Article #18-20285: "Tissue-specific geometry and chemistry of modern and fossilized melanosomes reveal internal anatomy of extinct vertebrates," by Valentina Rossi, Maria E. McNamara, Sam Webb, Shosuke Ito, and Kazumasa Wakamatzu.
MEDIA CONTACT: Maria E. McNamara, University College Cork, IRELAND; tel: +353 21 490 4570; e-mail: maria.mcnamara@ucc.ie ; Valentina Rossi, University College Cork, IRELAND; e-mail: valentina.rossi@ucc.ie
Proceedings of the National Academy of Sciences