Fig 1.
Geographical and geological location of the collecting sites.
(A) Location of the Nemegt Valley on a map of Mongolia (B) Map of the Nemegt Valley with the locations of the Altan Ula, Nemegt and Tsagan Khushu sites (from Kremer et al., 2012, modified) (C) Lithological profiles with the indicated position of the examined specimens from the Nemegt and Tsagan Khushu sites (after Gradziński et al, 1977, modified) (D) Fragment of a metatarsal; specimen ZPAL MgD I/181. E: Polished transversal sections of dinosaur bones from specimen ZPAL MgD I/alt. The position of mineralised fungal or saprolegnia mycelia is indicated by an arrow. Note the middle of the marrow canal filled with transparent calcite and canal walls encrusted with oxides.
Fig 2.
Transmitted light images of mycelia preserved inside dinosaur bone.
(A‒C) Bifurcating translucent hyphae embedded in calcite inside the marrow cavity of ZPAL MgD I/alt bone (D) A network of hyphae embedded in calcite filling a bone void; note the changing mode of hyphae mineralisation, from black manganese oxides to brown iron oxides (E‒G) Network of hyphae with putative asexual reproductive bodies (?spores) indicated with arrows (H) Fragment of iron-manganese-oxide-permineralised mycelium showing the distinctly siphonous organisation of the branching hyphae. Scale bars: (A‒C) 100μm (D) 50 μm (E-G) 20 μm (H 5) μm.
Fig 3.
SEM/BSE images of mycelia mineralised with Fe/Mn oxides and calcite with an occasional admixture of barite.
The mycelia (white) occur either as dense biofilms composed of subglobular hyphal aggregates covering the wall of the marrow cavity (A‒C) or as individual sunflower-like aggregates and networks of hyphae filling the resorption canals inside the compact bone tissue (D‒F). Specimen ZPAL MgD I/8 (B, C, F), specimen ZPAL MgD I/alt (A, D, E).
Fig 4.
SEM/EDS elemental maps of hyphae from a resorption canal inside the dinosaur bone.
Specimen ZPAL MgD I/alt from the Altan Ula site. Scale bar for all images corresponds to 100 μm.
Fig 5.
SEM images of a mineralised mycelium exposed with formic acid etching from polished thin section ZPAL MgD I/8 bone.
(A) Hyphae and putative asexual reproductive bodies (?spores) covered with Fe/Mn nanograins (B) A fragment of organically preserved hyphae (left) and a rosette-flower-like pattern of ferromanganese micronodules precipitated into the mycelium biomass (right).
Fig 6.
SEM images, SEM/EDS data and light micrographs of the mineralised mycelia.
(A) SEM image of a mineralised mycelium from polished and formic-acid-etched thin section of ZPAL MgD I/8 bone. Note the reticulate pattern of hyphae covered by ferromanganese nanograins (arrowhead) and the mycelium associated with ferromanganese micronodules (arrow) (B) EDS spectrum of ferromanganese nanograins coating on hyphae indicated by arrowhead in (A) showing a high Fe signal (C) EDS spectrum from a mycelium-associated ferromanganese micronodules indicated by arrow in (A) showing a high Mn signal (D) Transmitted light micrograph of magnified hyphae showing sparse septation and ferromanganese micronodules precipitated on the surface (E) Highly magnified micrograph of a cross section of a ferromanganese micronodule (micro concretion) showing its concentric structure. Specimen ZPAL MgD I/181.
Table 1.
Electron microprobe analyses of the Mn- and Fe-rich mineral phases of fossilised biofilm from the Gallimimus bones.
Fig 7.
Raman spectral data collected from mineralised mycelium.
(A) Microscopic image of the studied bone in reflected light; the frame marks the mapping areas from which Raman spectra were collected (B) Colour-coded Raman map of five clusters after hierarchical cluster analysis (HCA), based on spectral similarities for the bone section studied here, shown in (A). Colour codes are assigned to each of the five identified clusters (C) The representative cluster Raman spectra obtained from HCA. Colours represent individual cluster classes (D) A representative Raman spectrum collected from mineralised mycelium. Specimen ZPAL MgD I/alt.
Fig 8.
Successively precipitated mineral phases in marrow cavity.
(A) Cross section of a femur bone (specimen ZPAL MgD I/8) showing a marrow cavity (delimited by arrows) filled almost entirely with largely microbially-mediated mineral succession (B) Schematic illustration of the mineral succession imaged in (A); 1 –massive bone, 2 –micritic calcite filling the marrow cavity colonised by fungi, 3 –mineralised fungal biofilm, 4 –abiotically precipitated crystalline calcite, 5 –barite, 6 –intrusion of clastic sediment, 7 –open space of the marrow cavity; lowercase letters indicate the sequence of precipitation of mineral phases from (a) to (e) (C) SEM/EDS spectrum documenting the presence of barite, precipitated in the marrow cavity as indicated in the mineral succession diagram in (B) (D) Cathodoluminescence image of banded calcite representing the later stage of mycelia mineralisation after the earlier diagenetically precipitated ferromanganese. (E) SEM/EDS spectrum documenting the presence of calcite.