title: Involvement of microbial mats in early fossilization by decay delay and formation of impressions and replicas of vertebrates and invertebrates.
abstract: Microbial mats have been hypothesized to improve the persistence and the preservation of organic remains during fossilization processes. We test this hypothesis with long-term experiments (up to 5.5 years) using invertebrate and vertebrate corpses. Once placed on mats, the microbial community coats the corpses and forms a three-dimensional sarcophagus composed of microbial cells and exopolymeric substances (EPS). This coverage provides a template for i) moulding superficial features, resulting in negative impressions, and ii) generating replicas. The impressions of fly setulae, fish scales and frog skin verrucae are shaped mainly by small cells in an EPS matrix. Microbes also replicate delicate structures such as the three successive layers that compose a fish eye. The sarcophagus protects the body integrity, allowing the persistence of inner organs such as the ovaries and digestive apparatus in flies, the swim bladder and muscles in fish, and the bone marrow in frog legs. This study brings strong experimental evidence to the idea that mats favour metazoan fossilization by moulding, replicating and delaying decay. Rapid burial has classically been invoked as a mechanism to explain exceptional preservation. However, mats may play a similar role during early fossilization as they can preserve complex features for a long time.
authors.affiliation: Department of Ecology, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Iniesto
authors.affiliation: Department of Biology, Universidad Autónoma de Madrid, 28049, Madrid Spain.
authors.forename: Ángela D
authors.initials: ÁD
authors.lastname: Buscalioni
authors.affiliation: Department of Ecology, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Carmen Guerrero
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie, Sorbonne Universités, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7590, Université Pierre et Marie Curie Paris 06, Muséum National d'Histoire Naturelle, Institut de Recherche pour le Développement Unité Mixte de Recherche 206, 75005 Paris, France.
authors.forename: Karim
authors.initials: K
authors.lastname: Benzerara
authors.affiliation: Unité d'Ecologie, Systématique et Evolution, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8079, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France.
authors.forename: David
authors.initials: D
authors.lastname: Moreira
authors.affiliation: Department of Ecology, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
authors.forename: Ana I
authors.initials: AI
authors.lastname: López-Archilla
mesh_terms: D000818:Animals; D001001:Anura / Q000382:microbiology; D001419:Bacteria / Q000145:classification / Q000254:growth & development* / Q000648:ultrastructure; D018441:Biofilms / Q000254:growth & development*; D004175:Diptera / Q000382:microbiology; D005399:Fishes / Q000382:microbiology; D005580:Fossils / Q000382:microbiology* / Q000648:ultrastructure; D007448:Invertebrates / Q000382:microbiology*; D008855:Microscopy, Electron, Scanning; D013997:Time Factors; D014714:Vertebrates / Q000382:microbiology*