Extended Data Fig. 6: High-resolution Raman point measurements of eggshell sediment samples.

n = 12 independent samples. Measurement parameters are identical to those used to process eggshell samples, to guarantee comparability (300–2,000 cm⁻¹ ± 2 cm⁻¹, 6 accumulatations, 20 s of exposure, base-lined and normalized). Each sediment measurement was repeated three times independently and yielded similar results. The coloured dots label potential pigment-band positions (biliverdin, blue; protoporphyrin IX red). For comparison, a pigment-positive spectrum of H. huangi eggshell (1) is provided at the bottom, followed by sediments associated with M. peeblesorum (YPM VP PU 023464) (2); M. peeblesorum (YPM PU 22523) (3); South American saltasaurid (4); French titanosaurid (5); H. huangi (6); Mongolian microtroodontid (7); North American troodontid (8); Chinese troodontid (9); Mongolian troodontid (10); D. antirrhopus (11); Mongolian enantiornithine (12); and North American ornithoid ratite (13) eggshells. None of the sediments contains substantial amounts of eggshell pigments.