Fig. 8: Proposed diatom-influenced taphonomic pathway.

Cartoon shows the entire proposed pathway: spider becomes entrained in planktonic diatom mat. Pieces of the diatom mat, both with and without spiders entrained within fall to the sediment floor against a background sedimentation of other diatoms and algae (gray dots). With time, these sediments become compressed and preserved into the rock record. a Chemical composition of chitin. Two chains of chitin are illustrated, organized in anti-parallel. Gray boxes indicate the carbonyl functionalities on the chitin. b Sulfonate-containing molecule, which are common in diatom EPS^26,27, can undergo microbial sulfate reduction (MSR), leading to the production of sulfide. c Chitin molecule after sulfurization. C–S bonds could potentially replace the carbonyl functionalities, and S–S bridges could form across the chitin chains^47,53,66. d Idealized molecule representing a chitin polymer after further diagenetic alteration, which could result in the formation of aromatized carbon⁵³.