Title: Maturation experiments reveal bias in the chemistry of fossil melanosomes

Abstract

Fossil melanosomes are a major focus of paleobiological research because they can inform on the original coloration, phylogenetic affinities, and internal anatomy of ancient animals. Recent studies of vertebrate melanosomes revealed tissue-specific trends in melanosome-metal associations that can persist in fossils. In some fossil vertebrates, however, melanosomes from all body regions are enriched only in Cu, suggesting diagenetic overprinting of original chemistry. We tested this hypothesis using laboratory experiments on melanosomes from skin and liver of the African clawed frog Xenopus laevis. After maturation in Cu-rich media, the metal chemistry of melanosomes from these tissues converged toward a common composition, and original differences in Cu oxidation state were lost. Elevated Cu concentrations and a pervasive Cu(II) signal are likely indicators of diagenetically altered melanosomes. These results provide a robust experimental basis for interpretating the chemistry of fossil melanosomes.

Authors:

Rossi, Valentina ^[1]; Webb, Samuel M. ^[2]; McNamara, Maria ^[1]

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+ Show Author Affiliations

1. University College, Cork (Ireland)
2. SLAC National Accelerator Lab., Menlo Park, CA (United States)

Publication Date:

Mon Mar 22 00:00:00 EDT 2021

Research Org.:

SLAC National Accelerator Lab., Menlo Park, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1820152

Grant/Contract Number:  

AC02-76SF00515

Resource Type:

Accepted Manuscript

Journal Name:

Geology

Additional Journal Information:

Journal Volume: 49; Journal Issue: 7; Journal ID: ISSN 0091-7613

Publisher:

Geological Society of America

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES