title: Melanosomes and ancient coloration re-examined: A response to Vinther 2015 (DOI 10.1002/bies.201500018).
abstract: Round to elongate microbodies associated with fossil vertebrate soft tissues were interpreted as microbial traces until 2008, when they were re-described as remnant melanosomes - intracellular, pigment-containing eukaryotic organelles. Since then, multiple claims for melanosome preservation and inferences of organismal color, behavior, and physiology have been advanced, based upon the shape and size of these microstructures. Here, we re-examine evidence for ancient melanosomes in light of information reviewed in Vinther (2015), and literature regarding the preservation potential of microorganisms and their exopolymeric secretions. We: (i) address statements in Vinther's recent (2015) review that are incorrect or which misrepresent published data; (ii) discuss the need for caution in interpreting "voids" and microbodies associated with degraded fossil soft tissues; (iii) present evidence that microorganisms are in many cases an equally parsimonious source for these "voids" as are remnant melanosomes; and (iv) suggest methods/criteria for differentiating melanosomes from microbial traces in the fossil record.
authors.affiliation: Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA.|North Carolina Museum of Natural Sciences, Raleigh, NC, USA.|Department of Geology, Lund University, Lund, Sweden.
authors.forename: Mary H
authors.initials: MH
authors.lastname: Schweitzer
authors.affiliation: Department of Geology, Lund University, Lund, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Lindgren
authors.affiliation: Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA.
authors.forename: Alison E
authors.initials: AE
authors.lastname: Moyer
mesh_terms: D000818:Animals; D006801:Humans; D008543:Melanins / Q000032:analysis*; D010858:Pigmentation
chemical_list: D008543:Melanins
keywords: ancient color; fossil feather; melanin; melanosome; microbe; molecular paleontology; parsimony