Decalcified vertebrate hard tissues (representing a total of 7 specimens). a Paleonisciform ganoid scale (Oxfordian (Jurassic), Xinjiang, China) showing articulated blood vessels (abv) of the dentine and organic matrix with peripheral aligned and ordered (otpn), or unordered (utnp), tubular nerve projections. The left scale bar equals 500μm, the right one 250μm. bBlood vessel (bv) fragments from a diplodocid sauropod (Jurassic, Wyoming, US). The basal lamina (bslm) shows original stratification even though the vascular wall is thickened compared to modern archosaur blood vessels. Osteocytes (oc) with dense filipodia (f) are embedded in the originally collagenous extracellular matrix (ecm). Osteocytes adjacent to the blood vessel preserve cellular detail, but elsewhere they have degraded leaving the osteocyte lacunae (ocl) in the organic matrix. The left scale bar equals 100μm, the right one 25μm. c Extracellular matrix from an Allosaurus fragilis vertebra (Late Jurassic, Wyoming, US). The originally collagenous matrix fibers are preserved, and osteocytes with filipodia are dark and infilled. The scale bar equals 25μm. d Extracellular matrix from an Apatosaurus sp. bone (Late Jurassic). Osteocyte lacunae are preserved. Decalcified avian and non-avian dinosaur eggshells. The scale bar equals 25μm. e (Left) Rhea (modern, in captivity, Montana, US), artificially matured spongy layer. The maturation gradient increases to the right of the image. The original spongy layer is green due to pigmentation, while the matured part is brown. The scale bar equals 500μm. (Center) Psammornis rothschildi (Holocene, Algeria), degraded spongy layer fragments. The scale bar equals 25μm. (Right) Oviraptorid Heyuannia huangi (Late Cretaceous, Jiangxi, China) spongy layer. The scale bar equals 25 μm






High-resolution Raman maps (3s exposure time, 3 accumulations) of remains of extracellular matrix extracted from Allosaurus fragilis bone in aqueous hydrochloric acid (pH=3). The dotted rectangles mark the area mapped, and the different shades of red represent the signal intensity of the protein fossilization product (PFP). The colored spheres framing the compound structures represent a N-heterocycle polymer context, and the red shading labels the functional unit that gives rise to each signal mapped out. The scale bar equals 300μm. a Dark residue of soft tissue. b Map of N-rich heterocycles (1550–1610cm−1), which cover most of the sample surface. c Pentosidine (980cm−1), the AGE marker, which corresponds to the spatial distribution of N-rich heterocycles. d Amide I generated by peptide bonds, which is a less precise match for the N-rich heterocycles (1690cm−1). e–gThe organic functional units representing the selected Raman shifts are shaded (red) below each map






Dinosaur blood vessel with adjacent bone matrix that still contains bone cells. These structures have a perfect morphological preservation over hundreds of millions of years, but are chemically transformed through oxidative crosslinking. The extract comes from a sauropod dinosaur in Howe Stephen’s Quarry, U.S. (Image credit: Jasmina Wiemann/Yale University)