Table 1.
Setup parameters for five case histories.
Fig 1.
Laser mounted on a stereo microscope.
A 532 nm green laser mounted to the side of a stereo microscope. The blocking filter is mounted in front of the objective lens. No diffuser is used here for maximum effect with a smaller spot.
Fig 2.
A, Custom-built laser scanning device. B, Blue and green laser modules are mounted onto the scanning plate. A variable speed DC motor scans the plate back and forth laterally and is adjustable for degrees covered. C, Removable line lenses convert the laser spot to a more diffuse vertical line. Scale bar in Fig 2A equals 15 cm.
Fig 3.
Feather under reflected and matrix fluoresced illumination.
Green River Formation feather using identical images under different lighting conditions. A, Reflected light microscopy, only barbs are visible. B, Polarized light, some traces of barbules. C, Laser-stimulated fluorescence of matrix behind the carbon film backlights the feather and renders barbules visible across the entire field of view. Scale bar 0.5 mm.
Fig 4.
Feather structure comparison using white light, polarized and laser illumination.
A second Green River Formation feather specimen under: A, white light, B, polarized light, and C, laser illumination. Scale bar 0.2 mm.
Fig 5.
Micro-imaging—visible light vs.
laser fluorescence. Identical views of the same field. A, Reflected white light image of a purposely non-descript field. B, Same field illuminated with a 532 nm laser. Some features are at the specimen’s surface, but lack color contrast, others are visible within the matrix of the specimen. Black arrows indicate teeth found coincidentally in this image. Circles indicate reference landmarks. Scale bar 0.15 mm.
Fig 6.
Unidentified Liaoning fossil specimen.
An unidentifiable specimen from a Liaoning rock slab containing a Microraptor specimen (LVH 0026). No diagnostic bones are visible on the specimen surface, but laser penetration into the matrix induced fluorescence in multiple teeth and scales, making the identification of a fish possible. Scale bar 1 cm.
Fig 7.
Details enhanced with laser fluorescence.
A, White light photo. B, Fluoresced with a 457 nm blue laser. Fish scale on the surface is translucent and barely perceivable under white light. Growth rings on the scale are revealed under fluorescence and can be counted. Bone fragments are brought out in sharp detail. Arrows point to teeth in the matrix. Scale bar 0.5 mm.
Fig 8.
A, White light micrograph shows the bone fragment on the right entombed within matrix. B, Specimen under laser fluorescence. Photograph shows a high level of detail invisible under white light. Note that another much larger fragment also becomes visible (arrow). Scale bar 0.5 mm.
Fig 9.
blue laser. A direct comparison between a 15 watt fluorescent UV light illuminating all the fossils at a distance of 7cm, and a 447nm 500mw laser stimulating the specimens in the upper left corner. A, Specimens from the Lance Formation exhibit very low reactivity under fluorescent UVA bulbs. B, Specimens from the White River Formation typically fluoresce very well. This demonstrates that the intensity of laser stimulation can influence low reactivity specimens to fluorescence several orders of magnitude better than specimens known to fluoresce well under UV bulbs. Scale bar 1 cm.
Fig 10.
Proof-of-concept prototype automated micro-fossil picker. The feeder bowl guides a stream of matrix under the laser while a video camera detects ‘blobs’ of a certain size and brightness. Fluorescing fossils are guided down a tube into a tray by a puff of compressed air.
Fig 11.
A mid-Holocene-aged Gobero skeleton of a small girl preserved wearing an arm bracelet (G1B2; ~2835 B.C.E.) [25]. Due to the impossibility of removing the bracelet, analysis required portable, non-invasive techniques.
Fig 12.
Bracelet fluorescing under laser stimulation.
A, The bracelet (G1B2 [25]) under normal light, and B, The bracelet fluorescing under a hand-scanned laser. The cracking pattern in the upper left corner is only visible under fluorescence and aided in the identification of the bracelet material as hippopotamus tooth. Scale bar 2 cm.
Fig 13.
Is the skull of Microraptor IVPP V13320 a composite?
A, the skull of IVPP V13320 under white light conditions shows subtle color differences in the bone across a break in the slab—darker bone proximally and lighter bone distally. B, Under laser light stimulation, the bone fluoresces with the same color pattern observed under white light conditions (see A) indicating that the color differences relate to differences in fossil mineralogy. The latter indicates that the skull is a composite specimen, but it is also possible—but less likely—that the pattern observed reflects variable depositional and taphonomic conditions. Scale bar 1 cm. S2 Fig is a labelled version of this figure (see Supporting Information).